FR2861359A1 - Electrical power steering controlling apparatus for vehicle, has torque detector to output rear-end torque estimation value using low pass filter whose time constant is determined using speeds of vehicle and power steering motor - Google Patents

Abstract

The apparatus has speed detectors (11, 13) for detecting speed of a vehicle and rotational speed of an electrical power steering motor (4), respectively. A road surfacing rear-end torque detector (15) outputs an estimation value of a road surfacing rear-end torque by filtering a rear-end torque signal of a steering shaft using a low pass filter whose time constant is determined using the speeds of the vehicle and motor.

Description

ELECTRIC POWER STEERING CONTROL APPARATUS Background of

the invention

  Field of the Invention The present invention relates to an electric power steering control apparatus for controlling an electric motor device which generates an assist torque for assisting a steering torque of an automobile driver.

Description of the Related Art

  Among the conventional electrical power steering control apparatuses, one is described in JP-A-2001-239951 in which one or more stages of first-order low-pass filters are formed to estimate the reaction torque at the same time. pavement and time constants of the low-pass filters are established according to the steering speed. JP-A-2001-122146 discloses an electric power steering control apparatus in which the time constant of a low-pass filter is set according to the speed of the vehicle.

  However, the conventional technique of establishing time constants of the low-pass filters only in accordance with the steering speed presents a problem in that the accuracy of the road surface reaction torque estimation is diminished as and when the speed of the vehicle auymente.

  The technique of establishing the time constant of the low-pass filter solely according to the speed of the vehicle presents a problem in that the precision of estimation of the reaction torque to the road surface is reduced as the speed SR 23981 JP / DB of direction increases. No technique has been proposed which determines the time constant of a low-pass filter according to both the vehicle speed and the steering speed or rotational speed of the electric motor device which generates the assist torque.

  SUMMARY OF THE INVENTION The present invention has been carried out to solve the foregoing problems, and it is therefore an object of the present invention to provide an electric power steering control apparatus capable of increasing the accuracy of the power estimation. reaction torque to the road surface by determining the time constant of a low-pass filter using both the vehicle speed and the rotational speed of an electric motor device that generates an assist torque.

  The present invention provides an electric power steering control apparatus having an electric motor device which applies an assist torque to assist the steering torque of a driver to a steering shaft which is coupled to an axle of a steering wheel. vehicle. The electric power steering control apparatus comprises vehicle speed sensing means, engine speed sensing means, steering shaft reaction torque signal output means, and torque sensing means. reaction to the road surface. The vehicle speed sensing means detects a vehicle speed. The motor speed detecting means detects a rotational speed of the electric motor device. The steering shaft reaction torque output signal output means outputs a steering shaft reaction torque signal which corresponds to a steering shaft reaction torque acting on the steering shaft reaction torque. direction. The road surface reaction torque detection means generates an estimate value of the road surface reaction torque to be used for a control on the assist torque by filtering the steering shaft reaction torque signal by a signal. low pass filter operation. And a time constant of the low pass filter operation is determined according to the speed of the vehicle detected by the vehicle speed detecting means and the speed of rotation of the engine detected by the engine speed detecting means.

  In the electric power steering control apparatus according to the invention, the road surface reaction torque can be estimated even if the rotational speed of the electric motor device which produces the assist torque varies or the speed of the vehicle varies and an electric power steering control that responds to such variation can be achieved.

Brief description of the drawings

  Fig. 1 shows the configuration of an electric power steering control apparatus according to a first embodiment of the present invention; FIG. 2 shows the calculation principle for estimating a road surface reaction torque in the electric power steering control apparatus according to the first embodiment of the present invention; Fig. 3 is a characteristic diagram showing the road surface reaction torque and the friction torque in the electric power steering control apparatus according to the first embodiment of the invention; Figure 4 is a block diagram of the electric power steering control apparatus according to the first embodiment of the invention; Fig. 5 is a functional block diagram of a road surface reaction torque sensor of the power steering control apparatus according to the first embodiment of the invention; Fig. 6 is a flowchart of a method that is performed by the road surface reaction torque sensor of the power steering control apparatus according to the first embodiment of the invention; Fig. 7 is a characteristic diagram showing a relationship between the vehicle speed and the ratio (alignment torque) / (steering angle) in the power steering control apparatus according to the first embodiment of the invention. ; Fig. 8 is a block diagram showing the configuration of a motor speed calculation section of the power steering control apparatus according to the first embodiment of the invention; Fig. 9 is a block diagram of the electric power steering control apparatus according to a second embodiment of the invention; Fig. 10 is a block diagram of a road surface reaction torque sensor SR 23981 JP / DB of the electric power steering control apparatus according to the second embodiment of the invention; Fig. 11 is a flowchart of a method that is performed by the road surface reaction torque sensor of the power steering control apparatus according to the second embodiment of the invention; Fig. 12 is a characteristic diagram showing a relationship between the road surface reaction torque and the steering angle in an electric power steering control apparatus according to a third embodiment of the invention; Fig. 13 is a block diagram of a road surface reaction torque sensor of the power steering control apparatus according to the third embodiment of the invention; Fig. 14 is a flowchart of a method that is performed by the road surface reaction torque sensor of the power steering control apparatus according to the third embodiment of the invention; Fig. 15 is a block diagram of another road surface reaction torque sensor of the power steering control apparatus according to the third embodiment of the invention; Fig. 16 is a block diagram of a road surface reaction torque sensor of an electric power steering control apparatus according to a fourth embodiment of the invention; Fig. 17 is a flowchart of a method that is performed by the road surface reaction torque sensor of the power steering control apparatus according to the fourth embodiment of the invention; Fig. 18 is a block diagram of a road surface reaction torque sensor of an electric power steering control apparatus according to a fifth embodiment of the invention; Fig. 19A is a block diagram of a road surface reaction torque sensor of an electric power steering control apparatus according to a sixth embodiment of the invention; Fig. 19B is a characteristic diagram showing a relationship between steering speed and vehicle speed in the power steering control apparatus according to the sixth embodiment of the invention; Fig. 20 shows the configuration of an electric power steering control apparatus according to a seventh embodiment of the present invention; and Fig. 21 shows the configuration of an electric power steering control apparatus according to an eighth embodiment of the present invention.

  Description of the preferred embodiments

  Embodiment 1 Fig. 1 is a simplified diagram showing an electric power steering control apparatus SR 23981 JP / DB according to a first embodiment of the present invention.

  In Figure 1, reference numeral 1 represents a steering wheel of an automobile which is handled by a driver. The steering wheel 1 is coupled to a steering shaft 1A. Numeral 2 represents the tires which are attached to both ends of an axle 2A of the automobile. The steering shaft 1 is coupled to the axle 2A so as to direct it. Numeral 3 represents a torque sensor which is disposed in a steering torque transmission mechanism of the steering wheel 1 to the tires 2, for example attached to the steering shaft 1A. The torque sensor 3 detects a steering torque that is generated by a steering manipulation of the driver. Numeral 4 represents an EPS motor (electric power steering) which is disposed in the steering torque transmission mechanism of the steering wheel 1 to the tires 2, for example attached to the steering shaft 1A so as to apply a torque thereto. assistance. The EPS 4 engine generates assist torque to assist the driver's steering torque. Numeral 5 represents an electronic control unit EPS (hereinafter abbreviated EPS-UCE) for controlling the EPS motor 4. The reference numeral 6 represents a steering angle sensor which is provided to detect an angle d The steering angle sensor 6 detects a steering angle with respect to a neutral position of the steering wheel 1. The numeral 7 represents reduction gears disposed between the EPS motor 4 and the steering shaft 1A. The EPS motor 4 drives by reduction SR 23981 JP / DB the steering shaft 1A via the reduction gears 7.

  The symbol Ohdl represents a steering angle of the steering wheel 1; Osens, a direction angle detection signal that is output by the steering angle sensor 6; Tsens, a steering torque sensing signal that is outputted by the torque sensor 3; Imtr sense, a drive current detection signal EPS 4; Vt direction, an EPS 4 motor drive voltage detection signal; Vsupply, an EPS 4 power supply voltage; Tassist, a couple of assistance that the EPS motor 4 applies to the steering shaft 1A; Thdl, a steering couple that the driver applies to the steering wheel 1; Ttran, a steering shaft reaction torque that is exerted on the steering shaft 1A from the tires 2; Tfrp, a friction torque in a steering path from the steering shaft 1A to the axle 2A; and Talign, a reaction torque to the road surface that is received from the tires 2.

  Fig. 2 is a diagram showing the calculation principle for estimating the road surface reaction torque in the electric power steering control apparatus according to the first embodiment of the invention. The diagram comprises a low-pass filter element 151. A microprocessor in the EPS-ECCE 5 serves as a low-pass filter element 151 for signal processing to generate a signal that would be obtained by inputting a signal of input to an effective low-pass filter; it is not necessary to use a hardware low-pass filter.

  In FIG. 2, the symbol Ttire is an estimation value of the reaction torque to the road surface, t i is a time constant of SR 23981 JP / DB the low pass filter element 151, and s is a variable of Laplace transform. The low-pass filter element 151 receives the steering shaft reaction torque signal T in direction and outputs the estimate value of the reaction torque to the road surface Ttire is by multiplying the tree reaction torque signal. Trans-direction direction by 1 / (Test X s + 1) FIG. 3 is a characteristic diagram showing temporal variations of torque in the electric power steering control apparatus according to the first embodiment of the invention.

  In Figure 3, the vertical axis represents the torque (NEM) and the horizontal axis represents the time (s).

  The characteristic A shows a variation of the reaction torque of the steering shaft Ttran, the characteristic B shows a variation of the reaction torque estimation value Ttire road surface is, and the characteristic C shows a variation of the torque of friction Tfrp. Characteristic A is the sum of characteristic B and characteristic C. FIG. 4 is a block diagram showing the configuration of the electric power steering control apparatus according to the first embodiment of the invention. In FIG. 4, the reference numeral 10 represents a calculation block intended to calculate a target value of the drive current Imtr of the motor 4.

  In Fig. 4, reference numeral 11 represents a vehicle speed detector (i.e. vehicle speed detection means) for detecting a vehicle speed Sveh of the automobile and generates a vehicle speed signal Sveh sense . Numeral 12 shows a steering torque sensor (i.e., steering torque detecting means) for detecting, as a torque sensing signal Tsens, a steering torque Thd1 which is applied to the steering wheel 1. The numeral 13 represents a motor speed sensor (i.e. motor speed detection means) for detecting, as a rotational speed detection signal Smtr sense, a rotation speed. Smtr of the EPS motor 4.

  Reference numeral 14 represents an engine acceleration sensor (i.e. engine acceleration sensing means) for detecting, as the Amtr_sens rotation acceleration signal, an Amtr rotation acceleration (or deceleration). 4. The reference numeral 15 represents a road surface reaction torque sensor (i.e., a road surface reaction torque detection means). The road surface reaction torque sensor 15 receives a steering shaft reaction torque Ttran and outputs a reaction torque estimate value to the road surface Ttire is using the vehicle speed signal Sveh sense and the signal Smtr sensing motor speed detection senses that are output by the vehicle speed detector 11 and the motor speed detector 13, respectively. Numeral 16 represents an assist torque determining block which determines the assist torque Tassist to assist the steering torque Thd1 on the basis of the vehicle speed signal Sveh direction from the vehicle speed detector 11, the Tsens direction torque detection signal from the steering torque detector 12, the speed detection signal of the motor Smtr direction coming from the motor speed detector 13, the acceleration detection signal the rotation of the motor Amtr direction from the acceleration sensor of the motor 14, and the value of the torque estimate of the road surface reaction Ttire is from the reaction sensor torque to the road surface 15. The reference numeral 17 represents a motor current determining unit for determining a target value of the drive current Imtr of the EPS motor 4 based on the Tassist assistance torque value as output of the assist torque determination block 16. The reference numeral 18 represents a pilot unit of the motor for driving the EPS motor 4. The reference numeral 20 represents a motor current sensor for detect an attack current Imtr of the motor EPS 4 and outputs a current detection signal of the motor Imtr sense. The pilot unit of the motor 18 drives the motor EPS 4 so that the current detection signal of the motor Imtr direction which is detected by the current detector of the motor 20 becomes equal to the target value of the drive current Imtr which is provided by the motor current determining unit 17.

  The EPS 4 engine generates the Tassist assistance torque.

  Fig. 5 is a functional block diagram showing a specific configuration of the road surface reaction torque sensor 15 of the power steering control apparatus according to the first embodiment of the invention. The block enclosed in dot dotted lines is the road surface reaction torque sensor 15.

  In Fig. 5, reference numeral 21 represents a detection block of the steering shaft reaction torque Ttran for generating a steering shaft reaction torque signal Ttran_sens on the basis of the torque of Ttran steering shaft reaction. Numeral 22 represents a calculation block of the Kalign report for calculating a Kalign ratio of the road surface reaction torque (ie the alignment torque) Talign at the steering angle Ohdl on the basis of a signal of Sveh vehicle speed meaning that is provided by the vehicle speed detector 11. The reference numeral 23 represents a time constant calculation block for calculating a time constant of the low pass filter element 151 on the basis of of the Kalign report and a Smtr direction motor rotation speed signal that are provided by the calculation block 22 and the motor speed detector 13, respectively. Numeral 24 represents a low-pass filter calculation block for calculating and outputting a roadside reaction torque estimate value .Thir is based on the directional shaft reaction torque signal Ttran direction provided by the detection block 21 and the output of the time constant calculation block 23.

  Fig. 6 is a flow diagram of a method that is performed by the road surface reaction torque sensor 15 of the power steering control apparatus according to the first embodiment of the invention. This flowchart comprises seven steps, namely steps S101 to S107 (described later), between the beginning and the end.

  FIG. 7 is a characteristic diagram of the characteristic D which is a relationship between the speed of the automobile vehicle Sveh and the Kalign ratio, namely (reaction torque to the road surface (alignment torque) Talign) / (steering angle Ohdl), in the electric power steering control apparatus according to the first embodiment of the invention.

  In FIG. 7, the horizontal axis represents the vehicle speed and the vertical axis represents the Kalign ratio of the reaction torque to the road surface (alignment torque) Talign at the steering angle Ohdl. Characteristic D shows that the Kalign ratio of the reaction torque to the road surface (alignment torque) Talign at the steering angle Ohdl is small when the vehicle speed Sveh is low and increases as the speed of the vehicle changes. Sveh vehicle becomes high.

  Subsequently, the operation of the first embodiment will be described.

  The electric power steering control apparatus has a main function of measuring the steering torque Thdl of a manipulation of the driver on the steering wheel 1 with the torque sensor 3 as a torque detection signal Tsens and generates a Tassist assistance torque to assist the Thdl steering torque in accordance with the Tsens steering torque detection signal. To achieve better feel and superior steering stability, sensors are provided that measure a steering angle θd1 of the flywheel 1 and a rotational speed or rotational angular velocity (or angular acceleration obtained by differentiating it) from the EPS motor. A detection signal Imtr direction of the driving current Imtr of the motor EPS 4 and a detection signal Vt_sens of the driving voltage SR 23981 JP / DB Vt applied between the terminals of the motor 4 are also sensed by the EPS- UCE 5.

  In terms of dynamics, the sum of the steering torque Thd1 and the assisting torque Tassist rotates the steering shaft 1A against the steering shaft reaction torque Tran. During the rotation of the wheel 1, a term of inertia (J represents the inertia gain of the engine 4) of the engine 4 also contributes. Accordingly, an Equation (1) relation is satisfied: Ttran = Thd1 + Tassist - JEdw / dt (1) The Tassist assist torque of motor 4 is given by Equation (2): Tassist = Ggear X Kt X Imtr (2) where Ggear is the reduction gear ratio of the reduction gears 7 of the electric power steering control apparatus.

  On the other hand, the Ttran steering shaft reaction torque is the sum of the Talign road surface reaction torque and the Tfric all friction torque in the steering mechanism and is given by Equation (3). Tran = Talign + Tfric. .. (3) The EPS-UCE 5 which is a control unit of the electric power steering control apparatus calculates a target value of the drive current Imtr of the EPS motor 4 based on the previously mentioned sensor signals. and performs current JP / DB control so that the effective drive current Iact of the EPS motor 4 coincides with the calculated target value. The EPS motor 4 generates a prescribed torque that is a drive current value multiplied by a torque constant and a gear ratio motor-to-steering shaft, and the resulting torque assists the steering torque Thdl of the driver.

  Subsequently, a method of estimating the reaction torque to the road surface will be described.

  Built for lane change handling during a medium or low speed trip, conventional road surface reaction torque sensors of power steering control apparatus may only correctly estimate the reaction torque to the road surface in the case of a low frequency steering while driving at medium or low speed. It is an object of the present invention to provide a correct estimate of the road surface reaction torque over a wide range of operating conditions and to thereby make it possible to use a road surface reaction torque estimate value as the target value of the road surface reaction torque. a steering torque generating device of a yarn-driven apparatus in which a steering wheel and tires are not mechanically connected to each other.

  The road surface reaction torque sensor 15 makes an estimate according to the calculation principle of the road surface reaction torque shown in FIG. 2. In the electric power steering control apparatus, it is difficult to directly remove the road surface reaction torque. influence of the friction term because the rotational speed of the steering shaft can not be detected with a high accuracy. This is the reason why a filter is used for estimation.

  As shown in Fig. 2, a road surface reaction torque estimate value τ is estimated by inputting a steering shaft reaction torque signal Tran_sens to the low pass filter element 151.

  Although the steering is performed in various types of situations such as a displacement along a curved road and a lane change, within a prescribed period, their steering patterns are seen as ramp-like models having a speed constant. With this assumption, the reaction torque to the road surface varies as the characteristic B in Figure 3 and the friction torque varies as the characteristic C in Figure 3. The reaction torque of the steering shaft Ttran which is the sum the reaction torque to the road surface and the friction torque varies as the characteristic A in Figure 3. Namely, the reaction torque to the road surface Talign and the reaction torque of the steering shaft Ttran are given by the equations (4) and (5), respectively (s Laplace transform variable): Talign = Tgrad / s2 (4) Ttran = Tgrad / s2 + (Ggear x Tfric + Tfrp) / s .. (5) where Tgrad is the speed of temporal variation of the reaction torque to the road surface Talign, Ggear is the reduction gear ratio of the reduction gears 7 of the electric power steering control apparatus, Tfric is the friction torque to SR 23981 JP / DB stationary state of the EPS motor 4 and Tfrp is the friction torque in the steering mechanism.

  The value of the reaction torque of the road surface reaction Ttire is that obtained by filtering the steering shaft reaction torque Ttran with the low-pass filter element 151 is given by Equation (6): Ttire is = {Tgrad / s2 + (Ggear X Tfric + Tfrp) / s} 10 X 1 / ('test X s + 1) (6) The estimation error E (s) of the torque estimation value The response to the road surface Ttire is from the reaction torque to the Talign road surface as a state variable to be estimated is given by Equation (7). E (s) = Tgrad / s2 - {Tgrad / s 2 + (Ggear X Tfric + Tfrp) / s} X 1 / ('test X s + 1) = {Tgrad X' test - (Ggear x 20 Tfric + Tfrp )} / {s X ('test X s + 1)} (7) Consequently, the estimation error E (s) becomes 0 when the time constant' test of the low-pass filter element 151 is given by the equation in (8) (see Figure 3). test = (Ggear x Tfric + Tfrp) / Tgrad (8) The temporal variation speed Tgrad of the Talign road surface reaction torque 30 is given by Equation (9) as a product of the cos direction speed and the Kalign ratio. the reaction torque to the Talign road surface at the steering angle: SR 23981 JP / DB Tgrad = dTalign / dt = dTalign / dOs x dOs / dt = Kalign x cos (9) Among these factors, the Kalign ratio of the torque of Response to Talign road surface at the steering angle is only determined for each vehicle speed as shown in Figure 7, if a vehicle type is specified. The direction speed cos can be detected. As a result, an optimal value of the time constant tiest of the low pass filter element 151 is given by Equation (10): tiest = (Ggear x Tfric + Tfrp) / Tgrad = (Ggear x Tfric + Tfrp) / (Kalign x cos). ... (10) Accordingly, by making the tiest time constant of the low pass filter element 151 variable using the blocks 22 to 24 as shown in the block diagram of FIG. 5, the reaction torque The road surface can be estimated even if the steering speed varies due to a variation of the Smtr speed of the EPS motor 4 or the speed of the vehicle Sveh varies.

  Figures 4 and 5 show the configuration of the first embodiment.

  In the first embodiment, the controlled variable electric power steering is determined by the vehicle speed signal Sveh direction of the vehicle speed sensor 11, the direction torque detection signal Tsens of the steering torque sensor 12 , the road surface reaction estimation value SR 23981 JP / DB Ttire is the road surface reaction sensor 15, the motor rotation speed signal Smtr direction of the motor speed detector 13, and the signal of Motor acceleration sensor acceleration Amtr_sens 14. Since the novel feature of the invention relies on the detection of the road surface reaction torque, the road surface reaction detector 15 will be described below in detail.

  In the first embodiment, in the road surface reaction detector 15, as shown in FIG. 5, a steering shaft reaction torque Ttran is supplied to the block 21 to detect the tree reaction torque signal. direction Ttran sense. A Sveh direction vehicle speed signal is provided at block 22 to calculate a Kalign ratio of the road surface reaction torque at a steering angle. A motor rotation speed signal Smtr sense is input to block 23 to calculate a time constant tiest of the low pass filter element 151.

  A directional shaft reaction torque signal T direction can be obtained by attaching a sensor such as a load cell (i.e., steering shaft reaction torque detecting means) to the shaft column. direction and measuring its state variable, and is detected as torque (i.e. steering shaft reaction torque) occurring on the steering shaft column.

  A speed signal of the motor Smtr direction is obtained by using an output of the speed sensor of the motor 13. Alternatively, a rotational speed of the motor can be obtained according to the following equation (11) in FIG. using an output of the motor current.

  In the first embodiment and the following embodiments, the motor speed sensor 13 can detect a rotational speed of the motor, either by measurement or by calculation.

  For example, Figure 8 shows a case of detection of a rotational speed of the engine by calculation.

  FIG. 8 is a block diagram showing the configuration of a calculation section of the case of obtaining a rotational speed of the motor by calculation in the speed sensor of the motor 13 of the electrical steering control apparatus assisted according to the first embodiment of the invention.

  In FIG. 8, the reference numeral 161 represents an operating block corresponding to the EPS motor 4 in which the denominator is a sum of a coil resistor R of the motor EPS 4, and a product LS of a coil inductance. L of the EPS 4 engine and the Laplace transform variable s. The block 161 receives the difference Vt-Ve between a drive voltage Vt of the motor EPS 4 and a counterelectromotive force Ve of the motor EPS 4. The reference numeral 162 represents an operating block which receives the effective driving current Iact of the motor EPS 4 of the operating block 161 and generates a torque output by multiplying the effective driving current Iact by a torque constant Kt. The reference numeral 163 represents a gain operating block which receives the difference between the torque output of the operating block 162 and the disturbance torque Tdist. Reference symbols 164A and 164B represent integrators. The integrator 164A SR 23981 JP / DB integrates a gain operation block output 163 and provides the integration result to an operation block 165 of a counter electromotive force constant Kb. The operating block 165 generates the counter-electromotive force Ve. The calculation section of FIG. 8 can calculate the rotation speed co of the motor EPS 4 according to Equation (11) by using the driving voltage Vt of the motor EPS 4, the counter electromotive force Ve of the motor EPS 4 which is generated by the operation block 165 and the coil resistor R and the coil inductance L of the motor EPS 4.

  Figure 8 shows the configuration for estimating a rotational speed of the engine by calculation. With this configuration, the rotational speed of the motor co can be calculated according to Equation (11) using the drive voltage Vt of the motor EPS 4, its counterelectromotive force Ve and the coil resistance R and the coil inductance L which are constants specified by the EPS motor 4. In Equation (11), Kt is the torque constant, J is the constant gain of inertia of the EPS motor 4, Kb is the counter-electromotive force constant and s is the Laplace transform variable. The symbol Imtr represents the driving current of the motor EPS 4 and Imtr signifies its imaginary part.

  First, the following two relations are satisfied: R X Imrt + L X Imtr = Vt + Ve Ve = Vt - (R X Imtr + L X Imtr).

  Since L X Imtr is substantially 0 at the direction frequencies, the following equation is obtained: ## EQU1 ##

  As a result, a relation U = Ve / Kb = (Vt - R X Imtr) / Kb (11) is obtained.

  Subsequently, the operation of the road surface reaction torque sensor 15 will be described with reference to the flowchart of FIG. 6. In this method, a time constant t.sub.i is determined according to Equation (10) in FIG. step S105 in FIG.

  In step S101, a directional shaft reaction torque signal T direction is read from a memory. In step S102, a sense vehicle speed signal Sveh is read into the memory. In step S103, a speed signal of the motor Smtr direction is read in the memory. In step S104, a Kalign ratio of the reaction torque to the road surface at the steering angle is calculated according to Fig. 7 based on the speed of the vehicle Sveh direction. In step S105, a tiest time constant of the low pass filter element 151 is calculated based on the speed of rotation of the Smtr direction motor and the Kalign ratio. In step S106, the steering shaft reaction torque signal Ttran_sens is input to the low pass filter element 151 and filtered by its low pass filter operation. In step S107, an estimate value of the road surface reaction torque is obtained.

  In the first embodiment, the test time constant of the low-pass filter element 151 is determined according to the speed of the vehicle Sveh and the steering speed which is obtained from the rotational speed. Smtr of the EPS 4 engine, which makes it possible to estimate the reaction torque to the pavement even if the steering speed or the vehicle speed Sveh varies.

  Further, in the first embodiment, the test time constant of the low-pass filter element 151 is determined according to the equation tiest = (Ggear x Tfric + Tfrp) / (Kalign X c's) where Ggear is the gear ratio of the reduction gears 7 to transmit the assist torque Tassist of the motor EPS 4 to the steering shaft 1A, Tfric is the friction torque in the steady state of the motor EPS 4, Tfrp is the torque of friction in the steering mechanism, Kalign is the ratio of the reaction torque to the road surface that depends on the speed of the vehicle Sveh to the steering angle, and cos is the steering speed that is obtained from the rotational speed of the Smtr engine. Since the tiest time constant of the low pass filter element 151 changes according to the previous equation, the low pass filter element 151 can minimize the estimation error regardless of the displacement pattern; the estimation accuracy of the reaction torque to the road surface can be increased.

  Embodiment 2 Fig. 9 is a block diagram showing the configuration of an electric power steering control apparatus according to a second embodiment of the invention. A block 10A closed by dot dash lines in FIG. 9 is a block for calculating a target value of the drive current Imtr of the motor 4. In the second embodiment, a torque sensor of FIG. The road surface reaction 15A is used instead of the road surface reaction torque sensor 15 shown in FIGS. 4 and 5. FIG. 10 is a block diagram showing the configuration of the road surface reaction torque sensor 15A of FIG. electric power steering control apparatus according to the second embodiment of the invention. A block enclosed by dot dashed lines corresponds to the road surface reaction torque sensor 15A.

  In FIG. 9, while the road surface reaction torque sensor 15A is used, the sections 11 to 20 are identical to those in FIG. 4. As shown in FIG. 10, the road surface reaction torque sensor 15A comprises blocks 21A, 22, 23 and 24. Blocks 22 to 24 are identical to those of FIG. 5. Block 21A is a steering shaft reaction torque calculating block for calculating the reaction signal. Ttran steering shaft direction based on the direction torque detection signal Tsens, the motor current detection signal Imtr direction and the motor rotation acceleration signal Amtr direction entered at block 21A from the detector the steering torque 12, the motor current detector 20 and the engine acceleration sensor 14, respectively. In the second embodiment, no steering shaft reaction torque Ttran is inputted to block 21A as opposed to FIG. 4. Block 21A calculates the steering shaft reaction torque signal SR 23981 JP / DB Ttran senses on the basis of the directional torque detection signal Tsens, the motor current detection signal Imtr sense and the motor rotation acceleration signal Amtr sense, according to Equations (1) to (3). ).

  Fig. 11 is a flowchart of a method that is performed by the road surface reaction torque sensor 15A of the power steering control apparatus according to the second embodiment of the invention.

  The directional shaft reaction torque signal Ttran direction is filtered by the low pass filter element 151 to obtain a reaction torque signal to the road surface East. While in the first embodiment, the steering shaft reaction torque signal Ttran_sens is measured, in the second embodiment, the steering shaft reaction torque signal Ttran_sens which is calculated according to the equations ( 1) to (3) is used. Except for this difference, the method of FIG. 11 is identical to that of FIG.

  Subsequently, the operation of the road surface reaction torque sensor 15A will be described with reference to the flowchart of FIG. 11.

  In this method, a test time constant is determined according to Equation (10) in step S208.

  In step S201, a direction torque detection signal Tsens of the steering torque detector 12 is read into a memory. In step S202, a current detection signal of the motor Imtr direction of the current sensor of the motor 20 is read from the memory. In step S203, a vehicle speed signal Sveh of the vehicle speed sensor 11 is read from the memory. In step S204, a speed signal of the motor Smtr direction of the motor speed detector 13 is read into the memory. In step S205, an acceleration signal of the motor Amtr direction of the acceleration sensor of the motor 14 is read into the memory. In step S206 (signal output torque of the steering shaft reaction torque), the feedback torque signal of the steering shaft T direction is calculated based on the steering torque detection signal. Tsens, motor current detection signal Imtr direction and motor rotation acceleration signal Amtr sense. In step S207, a Kalign ratio of the road surface reaction torque (alignment torque) at a steering angle is calculated based on the vehicle speed Sveh signal. In step S208, a test time constant of the low-pass filter element 151 is calculated based on the rotation speed signal of the Smtr direction motor and the Kalign ratio. In step S209, the feedback torque signal of the direction shaft Ttran direction is filtered by the low-pass filter element 151. At step 5210, a torque response value of the coating response Highway East is obtained.

  By calculating the forward direction shaft reaction torque signal T direction, the second embodiment provides the same advantages as the first embodiment even in the case where a Ttran steering shaft reaction torque can not be measured.

  Embodiment 3 Fig. 12 is a characteristic diagram showing a relationship between the road surface reaction torque and the steering angle in an electric power steering control apparatus according to a third embodiment of the invention. 'invention. In Figure 12, the vertical axis represents the torque (NEM) and the horizontal axis represents the time (s). Characteristic E is the Talign road surface reaction torque (divided by 50), the characteristic F is a steering angle Ahdl and the characteristic G is the speed of the steering shaft. The steering shaft speed is proportional to the rotational speed of the engine.

  Fig. 13 is a block diagram showing the configuration of a road surface reaction torque sensor 15B of the electric power steering control apparatus according to the third embodiment of the invention. A block enclosed by dotted dotted lines corresponds to the road surface reaction torque detector 15B.

  In FIG. 13, the blocks 21A, 22, 23 and 24 are identical to those shown in FIG. 10. The reference characters J and K represent the operators. The operator J multiplies a signal of acceleration of rotation of the motor Amtr direction by an inertia gain of the motor EPS 4, and the operator K multiplies a signal of acceleration of rotation of the motor Amtr sense by an acceleration gain EPS motor 4.

  Fig. 14 is a flowchart of a method that is performed by the road surface reaction torque sensor 15B of the power steering control apparatus according to the third embodiment of the invention.

  Fig. 15 is a block diagram showing the configuration of another road surface reaction torque sensor 15C used in the electric power steering control apparatus according to the third embodiment of the invention. . A block closed by dashed dotted lines corresponds to the 15C road surface reaction torque sensor.

  In Fig. 15, while the sections 21A, 22, 23, 24 are identical to those shown in Fig. 10, the forward direction steering torque reaction torque signal is calculated based on a transmission signal. Tsens direction torque detection and a motor current detection signal Imtr sense.

  In the second embodiment, a fast direction can cause an event in which the Talign road surface reaction torque (characteristic E in Fig. 12) leads to the in-phase Ohdl direction angle (characteristic F). In this case, at the time of a shutdown of the steering wheel 1, the reaction torque to the Talign road surface begins to decrease sooner than the signal of the steering speed is reversed. Equation (5) is not satisfied for the steering shaft reaction torque Ttran and assumes that such a waveform is delayed from the reaction torque at the Talign road surface.

  To avoid this phenomenon, it is effective to compensate for a delay in the speed of the steering shaft. To compensate for a delay in the speed of the steering shaft in Equation (1) in the first and second embodiments, a term which is a product of the acceleration of engine rotation (or acceleration of the shaft direction) and a proportional gain K is added as in the following Equation (12): SR 23981 JP / DB Ttran = Thdl + Tassist - JEdw / dt + KEDW / dt (12) The operators J and K in Figure 13 perform operations corresponding to the third and fourth terms, respectively, on the right-hand side of Equation (12).

  Since the entire configuration of the electric power steering control apparatus is identical to that of the second embodiment, only the road surface reaction torque sensor 15B is shown in FIG. 13.

  To obtain a reaction torque estimate value for the East road surface, a steering shaft reaction torque Ttran is filtered by the low-pass filter element 151. In the third embodiment, to compensate for delay of the speed of the steering shaft, the term which is the product of the motor rotation acceleration and the proportional gain K is added as in the previous equation (12) in the calculation of the reaction torque of Ttran steering shaft. The third embodiment is identical to the second embodiment, except for this feature.

  This operation will be described with reference to the flowchart of Fig. 14. In this method, a test time constant is determined according to Equation (10) in step S309.

  In step S301, a direction torque detection signal Tsens of the steering torque detector 12 is read into a memory. In step S302, a current detection signal of the Imtr direction motor is read in the memory. In step S303 a vehicle speed signal Sveh sense is read from the memory. In step S304, a rotational speed signal of the motor is read into the memory. In step S305, a rotation acceleration signal of the Amtr direction motor is read from the memory. In step S306, a phase pre-compensation steering shaft reaction torque signal is calculated based on the direction torque detection signal Tsens, the current detection signal of the motor Imtr sense and the Amtr motor rotation acceleration signal sens. In step 5307, the T-direction compensated steering shaft reaction torque signal is calculated by adding the product of the engine rotation acceleration of / dt and a proportional gain K to the reaction torque. steering shaft with pre-compensation in phase. In step S308, a Kalign ratio of the road surface reaction torque (alignment torque) Talign at an 8-direction angle is calculated on the basis of the vehicle speed signal Sveh_sens. In step S309, a test time constant of the low-pass filter element 151 is calculated based on the rotational speed signal of the Smtr direction motor and the Kalign ratio. In step S310, the forward-phase compensated direction shaft reaction torque signal is filtered by the low-pass filter element 151. In step S311, a torque estimate value of The road surface reaction is achieved.

  In the third embodiment, the forward phase compensated steering shaft reaction torque signal which is filtered by the low pass filter element 151 includes the term which is the product of a rotational acceleration of the engine / dt (ie, steering shaft rotation acceleration) and proportional gain K. This makes it possible to avoid the phenomenon in which the road surface reaction torque leads to the SR angle 23981 JP / DB direction in phase, and thus increase the estimation accuracy of the reaction torque to the road surface even for fast steering models.

  When the motor inertia gain is approximately equal to the acceleration gain, the road surface reaction torque sensor 15C of FIG. 15 can be used in which the acceleration term (s) is eliminated at the same time. equations (1) and (12). Even in this case, the same advantages as in the second embodiment can be provided. The road surface reaction torque sensor 15C of FIG. 15 is different from the road surface reaction torque sensor 15B of FIG. 13 in that no acceleration signal of the motor Amtr direction has entered block 21A and the Jet K operators are omitted.

  Embodiment 4 A fourth embodiment uses a road surface reaction torque sensor 15D. The fourth embodiment is identical to the first embodiment except for the configuration of the road surface reaction torque sensor 15D. As a result, the road configuration of the fourth embodiment will not be described.

  Fig. 16 is a block diagram showing the configuration of the road surface reaction torque sensor 15D of an electric power steering control apparatus according to the fourth embodiment of the invention. A block enclosed by dot dashed lines corresponds to the 15D road surface reaction torque sensor.

  In FIG. 16, the blocks 21 to 24 are identical to those in FIG. 5. A block 29 is an upper / lower limit time constant cutting section which receives an output of the calculation section. of low pass filter element time constant 23 and produces upper and lower limit values of the test time constant of the low pass filter element 151. The output of the section is entered in the calculation section Low-pass filter 24, whereby the test time constant of the low-pass filter element 151 is cut to lie within the range defined by the upper and lower limit values.

  Fig. 17 is a flowchart of a method that is performed by the road surface reaction torque sensor 15D of the power steering control apparatus according to the fourth embodiment of the invention.

  In the first to third embodiments, the road surface reaction torque Ttire_est is obtained by filtering the steering shaft reaction torque signal Ttrans direction by the first-order low-pass filter element 151. In the fourth embodiment, the upper and lower limits are set for the test time constant of the low pass filter element 151. The fourth embodiment is identical to the first embodiment except for this feature.

  Subsequently, the operation of the road surface reaction torque sensor 15D according to the fourth embodiment will be described with reference to the flowchart of FIG. 17. In this method, a test time constant is determined according to the equation. (10) at step S410 shown in FIG. 17.

  At step 5401, the directional shaft reaction torque signal T forward is read from a memory. In step S402, a vehicle speed Sveh sense is read from the memory. In step S403, a speed of rotation of the motor Smtr direction is read in the memory. In step S404, a Kalign ratio of the road surface reaction torque (ie the alignment torque) Talign at a direction angle of 9sens is calculated according to Fig. 7 based on the vehicle speed Sveh sense. In step S405, a test time constant of the low pass filter element 151 is calculated based on the speed of rotation of the Smtr direction motor and the Kalign ratio. In step S406, it is judged whether the test time constant of the low-pass filter element 151 is greater than an upper limit value.

  If the time constant t i is judged to be greater than the upper limit value, the test time constant is cut to the upper limit value at step S407 and the method goes to step S410. If it is judged in step S406 that the time constant tij of the low-pass filter element 151 is not greater than the upper limit value, it is judged at step S408 if the time constant we are smaller than a lower limit value. If the time constant tiest of the low-pass filter element 151 is judged to be smaller than the lower limit value, the test time constant is cut to the lower limit value at step S409 and the method goes to step S410. This method also goes to step S410 if it is judged in step S408 that the time constant t i is not smaller than the lower limit value.

  In step S410, the time constant τt of the low-pass filter element 151 is set. In step S411, the SR 23981 JP / DB steering shaft reaction torque signal Ttrans direction is filtered by the low-pass filter element 151. In step S412, a torque estimation value reaction to the road surface Ttire_est is obtained.

  When a tiest time constant of the low-pass filter element 151 is calculated according to equation (10) using the speed of rotation of the motor Smtr and a speed of the vehicle Sveh, a time constant t is too important obtained if the Sveh vehicle speed or steering speed is low. In this case, the filtering operation becomes close to the integration and therefore tends to be influenced by a component shifted by a true value of the steering shaft reaction torque signal Ttran_sens.

  On the other hand, a test time constant that is too small is obtained if the vehicle speed Sveh or the steering speed is high. In this case, the filtering characteristic becomes close to a gain characteristic and the low-pass filter element 151 can not reject the noise components. Establishing upper and lower limit values resolves these problems.

  As described above in the fourth embodiment, the tiest time constant of the low pass filter element 151 is in the range defined by the upper and lower limit values. This prevents an event in which the road surface reaction torque estimate value has an error too large compared to a true value, and thus prevents a divergence of the time constant Lest of the low pass filter element. 151.

  Embodiment 5 Fig. 18 is a block diagram showing the configuration of a road surface reaction torque sensor 15E of an electric power steering control apparatus according to a fifth embodiment of the invention. 'invention. A block enclosed by dot dotted lines corresponds to the road surface reaction torque detector 15E.

  In FIG. 18, the blocks 21 to 24 are identical to those in FIG. 5. A block 30 is a top / bottom limit section of directional speed that receives a signal of rotation speed of the Smtr direction and cutter motor. a steering speed at an upper or lower limit value.

  An analysis of the direction of conduct leads to the conclusion that the steering speed of a pipe has certain limitations. The road surface reaction torque sensor 15E is configured as shown in Fig. 18 by setting the upper and lower limits of the steering speed at 10 deg./s and 450 deg./s, for example, given consideration to effective steering speeds of conductors. In the road surface reaction torque detector 15E, a motor rotation speed signal Smtr_sens of the motor speed detector 13 is input to the additional block 30 and an output of the block 30 is supplied to the block 23. In the block 23, a time constant t i is calculated on the basis of a ratio Kalign and a directional speed divided into an upper / lower limit value which is provided by the block 30. This makes it possible to set a time constant t i which is appropriate for a steering speed of the driver.

  In accordance with the fifth embodiment, a time constant t.sub.i which is appropriate for a steering speed of the conductor is set and the same advantages as in the four embodiments can be provided. The fifth embodiment also provides an advantage that the divergence of equation (10) can be prevented.

  Embodiment 6 Fig. 19A is a block diagram showing the configuration of a road surface reaction torque sensor 15F of an electric power steering control apparatus according to a sixth embodiment of the invention. A block enclosed by dot dashed lines corresponds to the 15F road surface reaction torque sensor.

  In Fig. 19A, blocks 21 to 24 are the same as those in Fig. 5. Block 31 is an upper / lower direction speed limit cutting section which receives a directional speed signal Smtr of the motor and a Sveh vehicle speed signal senses and cuts a Shdl steering speed to an upper or lower limit value that is appropriate for Sveh vehicle speed. Fig. 19B shows a relationship between the steering speed Shdl and the vehicle speed Sveh in block 31. In Fig. 19B, the vertical axis represents the steering speed Shd1 and the horizontal axis represents the vehicle speed Sveh. The characteristic Lu is the upper limit value and the characteristic Ld is the lower limit value.

  An analysis of the direction of drivers leads to a conclusion that the steering speed Sveh of a general line tends to be high in a range of low speed of the vehicle and tends to be low in a high speed range. of the vehicle. The road surface reaction torque sensor 15F is configured as shown in Fig. 19A so that the upper and lower limit values Lu and Ld of the steering speed Shd1 vary with the speed of the vehicle Sveh. This makes it possible to determine the tiest time constant according to the vehicle speed Sveh and the steering speed Shdl of the driver.

  According to the sixth embodiment, a test time constant which is suitable for a vehicle speed Sveh and a steering speed Shdl of the driver is set and the same advantages as in the fourth embodiments can be provided. The sixth embodiment also provides an advantage that the divergence of equation (10) can be prevented.

  Embodiment 7 Fig. 20 is a simplified diagram showing an electric power steering control apparatus according to a seventh embodiment of the invention.

  In Fig. 20, the elements and unit represented by numerals 1 to 3 and 5 to 7 are identical to those shown in Fig. 1. Numeral 8 shows planetary gears attached to the steering shaft 1A. Numerals 9A and 9B show a variable gear motor (i.e., a first motor) and a pinion motor (i.e., a second motor), respectively. The variable gear motor 9A is coupled to the steering shaft 1A via the SR 23981 JP / DB reduction gears 7, and the pinion shaft motor 9B is coupled to the steering shaft 1A via the planet gears 8 The combination of the variable gear motor 9A and the pinion shaft motor 9B constitutes an electric motor device, instead of the electric motor 4 of Figure 1.

  In FIG. 20, the symbol Ahd1 represents a steering angle of the steering wheel 1; esens, a steering angle detection signal of the steering wheel 1; Tsens, a steering torque detection signal; Imtr_sensl, a drive current detection signal of the variable gear motor 9a; Imtr_sens2, a drive current detection signal of the pinion shaft motor 9b; Vt_sensl, a drive voltage detection signal of the variable gear fitter 9a; Vt_sens2, an input voltage detection signal of the pinion shaft motor 9b; Vsupplyl, a supply voltage of the variable gear motor 9a; Vsupply2, a supply voltage of the pinion shaft motor 9b; Tgear, the gear output torque of the variable gear motor 9a; Tassist, the assist torque of the pinion shaft motor 9b; Thdl, the management couple; Ttran, the steering shaft reaction torque; Tfrp, the friction torque; and Talign, the reaction torque to the road surface.

  The steering angle superimposition-type electric steering control apparatus incorporating the variable gear motor 9a for controlling the gear output torque Tgear and the pinion shaft motor 9b for controlling the effective steering angle has the following main function. The steering torque Thd1 of a manipulation of the driver on the steering wheel 1 is measured by the torque sensor 3 as a detection signal of the steering torque Tsens. The gears of the variable gear mechanism are changed by the variable gear motor 9a according to the torque sensing signal Tsens, and the gear output torque Tgear is generated which is stronger than the steering torque Thd1 of a factor of a variable gear ratio. And the assist torque Tassist for assisting the actual steering torque is generated by the pinion shaft motor 9b based on the Tgear gear output torque.

  To achieve better feel and superior steering stability, sensors are provided which measure a steering angle Ghd1 of the flywheel 1 and a rotational speed or rotational angular velocity (or angular acceleration obtained by differentiating it) from the engine 9b. The detection signals of the drive current Imtr sens1 and Imtr sens2, the drive voltage detection signals Vtsens1 and Vtsens2, the supply voltage detection signals Vsupplyl and Vsupply2 of the motors 9a and 9b are also picked up by the sensor. EPS-UCE 5.

  In terms of dynamics, the steering torque Thdl is multiplied by the gear mechanism variable by the gear ratio Gvagear and the sum of the gear output torque Tgear and the assist torque Tassist rotates the gear shaft. 1A direction against steering shaft reaction torque Ttran. During rotation of the flywheel 1, a term of inertia of the pinion shaft motor 9b also contributes. As a consequence, a relation equation (13) is satisfied: Ttran = Tgear + Tassist - JÉdw / dt. The tassist assist torque of the pinion shaft motor 9b is given by equation (14). Tassist = Ggear x Kt x Imtr2 ... (14) where Imtr2 is the driving current of the motor 9b.

  Furthermore, the steering shaft reaction torque Ttran is the sum of the reaction torque to the Talign road surface and the friction torque Tfric all whose steering mechanism is given by equation (15): Ttran = Talign = Tfric all. ... (15) The control unit (EPS-UCE) 5 of the electric power steering control apparatus calculates a target value of the drive current Imtr2 of the motor 9b on the basis of the previously mentioned sensor signals and performs a current control so that the effective drive current of the motor 9b coincides with the calculated target value. The pinion shaft motor 9b generates a prescribed torque that is a drive current value multiplied by a torque constant and a shaft-steered motor gear ratio, and the resulting torque assists the steering torque. Thdl of the driver.

  The foregoing configuration is generally referred to as "steering angle overlay" and is characterized in that the hinge mechanism for articulating the steering wheel to the wheels comprises the variable gear mechanism for generating a gear output torque which is a driver-generated torque multiplied by a variable gear ratio and that the generated gear output torque is assisted by the torque generated by the pinion shaft motor 9b.

  The seventh embodiment is characterized in that it is capable of calculating the road surface reaction torque in the direction angle superposition configuration. The gear output torque can be measured by attaching the torque sensor 3 to a gear output torque generating portion of the steering shaft 1A. The steering shaft reaction torque Ttran can also be calculated according to equation (13).

  The technique described in the first to sixth embodiments can be applied, as it is, to a technique for calculating a reaction torque to the road surface after which the steering shaft reaction torque Ttran is obtained.

  Although, in the seventh embodiment, the gear output torque is detected using the sensor, an equivalent value can be obtained by multiplying the steering torque by a variable gear ratio in a range such as friction. in the variable gear mechanism is small even if no sensor is provided for this purpose.

  The seventh embodiment may provide the same advantages as the first to sixth embodiments even in the steering angle superimpose steering power steering apparatus.

  As described above, even in the direction angle superposition configuration, the seventh embodiment makes it possible to estimate the reaction torque to the road surface by detecting the SR 23981 JP / DB shaft reaction torque. steering even if the steering speed or vehicle speed varies.

  Embodiment 8 Fig. 21 is a simplified diagram showing an electric power steering control apparatus according to an eighth embodiment of the invention.

  In Fig. 21, the elements and the unit represented by numerals 1 to 3 and 5 are identical to those shown in Fig. 1. Reference symbols 7a and 7b show reduction gears. Reference symbols 10a and 10b represent a steering reaction torque control motor and an effective steering angle control motor, respectively. The combination of the steering reaction torque control motor 10a and the effective steering angle control motor 10b constitutes the electric motor device, instead of the electric motor 4 of FIG.

  The symbol 6hdl represents a steering angle of the steering wheel 1; esens, a steering angle detection signal of the steering wheel 1; Tsens, a steering torque detection signal; Imtr sensl and Imtr sens2, drive current detection signals 10a and 10b; Vt sens1 and Vt sens2, drive voltage detection signals of motors 10a and 10b; Vsupplyl and Vsupply2, supply voltages of the motors 10a and 10b; Tassistl, a motor assist torque 10a; Tassist2, a 10b engine assist torque; Thdl, a steering torque, Ttran, a steering shaft reaction torque; Tfrp, a couple of SR 23981 JP / DB friction; and Talign, a reaction couple to the road surface.

  The wire direction type power steering control apparatus incorporating the steering reaction torque control motor 10a for controlling the steering reaction torque and the effective steering angle control motor 10b for controlling the effective steering angle and wherein the steering wheel 1 to be handled by a driver and the wheels 2 are not mechanically connected to one another to the following main function. The steering torque Thdl of a handling of the driver of the steering wheel 1 is measured by the torque sensor 3 as a torque detection signal Tsens direction. The Tassistl steering reaction assisting torque for appropriately controlling the driver's steering torque Thdl which corresponds to a vehicle behavior is generated by the steering reaction torque control motor 10a on the basis of the steering reaction signal. Tsens torque detection. The effective steering angle control assist torque Tassist2 for controlling the effective steering angle of the tires 2 is generated by the effective steering angle control motor 10b.

  To achieve better feeling and superior steering stability, sensors are provided which measure a 0hdl steering angle of the flywheel 1 and rotational speeds or angular rotational speeds (or angular accelerations obtained by differentiating them) from the motors 10a and 10b. .

  The drive current detection signals Imtr sens1 and Imtr sens2 and the driving voltage detection signals Vt sens1 and Vt_sens2 of the motors 10a SR 23981 JP / DB and 10b and the supply voltage detection signals Vsupplyl and Vsupply2 applied between the motor terminals are also picked up by the EPS-UCE 5.

  In terms of dynamics, since the steering wheel 1 and the tires 2 are not mechanically connected to each other, completely independent relations are satisfied for them. The steering torque Thd1 and the steering reaction torque Tassistl are balanced with each other and the assisting torque Tassist2 which is generated by the effective steering angle control motor 10b rotates the wheels 2 against the steering shaft reaction torque Ttran. In the rotation of the tires 2, an inertia term of the effective steering angle control motor 10b also contributes to it. As a result, a relation of equation (16) is satisfied: Ttran = Tassist2 - JEdw2 / dt ... (16) where w2 is the angular velocity of the motor 10b.

  The assist torque Tassist2 of the effective steering angle control motor 10b is given by the equation (17) Tassist2 = Ggear2 x Kt x Imtr2 ... (17) where Ggear2 is the gear ratio of the gears. reduction 7b and Imtr2 is the driving current of the motor 10b.

  On the other hand, the Ttran steering shaft reaction torque is the sum of the Talign road surface reaction torque and the Tfric all friction torque in the steering mechanism and is given by Equation (18): SR 23981 JP / DB Ttran = Talign + Tfric garlic. ... (18) The control unit (EPS-UCE) 5 of the electric power steering control apparatus calculates a target value of the drive current Imtr2 of the motor 10b on the basis of the previously mentioned sensor signals and performs a current control so that the actual driving current of the motor 10b coincides with the calculated target value. The engine 10b generates a prescribed torque which is a driving current value multiplied by a constant torque and a gear ratio of the steering shaft motor, and the resulting torque assists the steering torque Thd1 of the driver.

  The previous configuration is generally referred to as "wire direction" and is characterized in that there is no mechanical articulation between the flywheel 1 and the tires 2 and that the steering reaction torque control motor 10a for controlling the torque steering reaction unit 1 which is transmitted to the steering wheel 1 and the effective steering angle control motor 10b for controlling the effective steering angle of the tires 2 on the basis of the steering angle of the driver and a variable of Vehicle condition are provided. Because there is no mechanical articulation between the wheel 1 and the tires 2, this mechanism increases the degree of freedom of the vehicle configuration and can stabilize the vehicle regardless of the direction of the driver. Although the equation for calculating the steering shaft reaction torque Ttran is different from the corresponding equation in the first embodiments, the mechanical configurations are different, the reaction torque of the control shaft is different. Direction can be obtained either by detection with a sensor or by calculation according to equation (16), as described in the first to sixth embodiments.

  The technique described in the first to sixth embodiments can be used, as such, as a technique for calculating the reaction torque to the road surface after which the steering shaft reaction torque Ttran is obtained.

  The eighth embodiment may provide the same advantages as those of the first to sixth embodiments even in the wire direction type power steering control apparatus. A road surface reaction torque estimate value may be used as the target value of the steering torque generating device of the wire steering apparatus in which the steering wheel 1 and the tires 2 are not mechanically connected to each other. one to another.

  As described above, even in the wire direction type configuration, the eighth embodiment makes it possible to estimate the reaction torque to the road surface by detecting a steering shaft reaction torque even if direction or the speed of the vehicle varies.

SR 23981 JP / DB

Claims (12)

  Electric power steering control apparatus comprising an electric motor device (4) which applies an assist torque to assist the steering torque of a driver to a steering shaft (1A) which is coupled to an axle ( 2A) of a vehicle, comprising: vehicle speed detecting means (11) for detecting a vehicle speed; motor speed detecting means (13) for detecting a rotational speed of the electric motor device (4); steering shaft reaction torque signal output means for outputting a steering shaft reaction torque signal (Ttran direction) which corresponds to a steering shaft reaction torque acting on the shaft steering (1A); and road surface reaction torque detecting means (15) for outputting a road surface reaction torque estimation value (East) to be used for a control on the assist torque by filtering the traffic signal. steering shaft reaction torque (Ttran direction) by a low-pass filter operation, wherein a time constant of the low-pass filter operation is determined according to the speed of the vehicle detected by the detection means of the vehicle speed (11) and according to the rotational speed of the engine detected by the engine speed detection means (13).   SR 23981 JP / DB An electric power steering control apparatus according to claim 1, wherein the steering shaft reaction torque output signal output means is a detection means for outputting the steering shaft reaction torque signal. (Ttran direction) as a function of the steering shaft reaction torque (Ttran).   An electric power steering control apparatus according to claim 1, wherein the steering shaft reaction torque output signal output means is a calculating means for calculating the steering shaft reaction torque signal. (Ttran direction) based on a direction torque detection signal (Tsens) as a function of the steering torque (Thdl), a motor current detection signal (Imtr sense) as a function of a motor current of the electric motor device (4) and a motor rotation acceleration signal (Amtr_sens) as a function of a rotation acceleration (Amtr) of the electric motor device (4).   An electric power steering control apparatus according to claim 1, wherein the test time constant of the low pass filtering operation is determined according to an equation r is = (Ggear x Tfric + Tfrp) / (Kalign xws) where Ggear is a ratio gear reduction gear (7) for transmitting the assist torque of the electric motor (4) to the drive shaft (1A), Tfric is a friction torque in the state stationary of the electric motor (4), and Tfrp SR 23981 JP / DB is a friction torque in a steering mechanism, Kalign is a ratio of the reaction torque to the road surface which depends on the speed of the vehicle at a steering angle, and ws is a steering speed which is obtained from the speed of rotation of the Smtr engine.   An electric power steering control apparatus according to claim 1, wherein the steering shaft reaction torque signal (Ttranssens) is filtered by the filter operation. _   Low-pass includes a term that is a product of an acceleration of rotation of the steering shaft (Amtr) and a proportional gain (K).   An electric power steering control apparatus according to claim 1, wherein the time constant (Test) of the low pass filter operation has an upper limit and a lower limit.   An electric power steering control apparatus according to claim 1, wherein the time constant (Test) of the low pass filter operation has an upper limit and a lower limit which depend on the vehicle speed (Sveh).   An electric power steering control apparatus according to claim 1, wherein a steering wheel (1) for driving the vehicle and the axle (2A) are connected to each other via the steering shaft (1A). , and the electric motor (4) is coupled to the steering shaft (1) via reduction gears (7).   SR 23981 JP / DB An electric power steering control apparatus according to claim 1, wherein the electric power steering control apparatus has a direction angle superposition configuration in which the electric motor device (4) comprises a first motor. electric motor (9a) and a second electric motor (9b), the first electric motor (9a) controls the gear output torque which is the driver's steering torque multiplied by a variable gear ratio, and the second electric motor. (9b) applies an assist torque for controlling an effective steering angle to the steering shaft (IA) in accordance with the gear output torque (Tgear).   Electric power steering control apparatus according to claim 9, wherein a steering wheel (1) for driving the vehicle and the axle (2A) is connected to each other via the steering shaft (1A ), the first electric motor (9a) is coupled to the steering shaft (1A) via reduction gears (7), and the second electric motor (9b) is coupled to the steering shaft (1A) via planetary gears (8).   11. Electrical control device. power steering system according to claim 1, wherein the electric power steering control apparatus has a wire-like configuration in which the electric motor device (4) comprises a first electric motor (9a) and a second electric motor. (9b), there is no mechanical articulation between a steering wheel (1) for driving the vehicle and the axle (2A), the first electric motor (9a) controls the reaction torque of direction which is transmitted to the steering wheel (1), and the second electric motor (9b) applies an assist torque for controlling an effective steering angle of the axle (2A) to the steering shaft (1A).   An electric power steering control apparatus according to claim 11, wherein the road surface reaction torque estimation value (Ttire_est) obtained by the road surface reaction torque detection means (15) is used to the steering reaction torque control and the effective steering angle control. SR 23981 JP / DB