JP5891120B2 - Speed calculation device, speed calculation method, speed calculation program, and recording medium - Google Patents

Description

  The present invention relates to a speed calculation device, a speed calculation method, a speed calculation program, and a recording medium.

  Conventionally, a navigation device mounted on a moving body such as a vehicle has a vehicle speed output from the vehicle at a time interval proportional to GPS information from a GPS (Global Positioning System) satellite, an output shaft of a transmission, and a rotation speed of a tire. In addition to the signal, the speed is calculated using various signals output from various sensors.

  The vehicle speed signal may not be used depending on the situation in use and the model of the navigation device. For example, in a vehicle equipped with ABS (Anti Lock Brake System), when traveling at low speed, the vehicle speed sensor cannot determine whether the wheel is locked or rotating, and the vehicle speed sensor does not output a vehicle speed signal. There is. In view of this, a technique has been proposed in which the speed can be detected during low-speed traveling (for example, see Patent Document 1 below).

  In addition, portable portable products called PND (Portable Navigation Device) are widely used in navigation devices. For example, the PND calculates the speed of the vehicle when the user brings it into the vehicle and installs it at a predetermined position. Since the PND is brought into the vehicle by the user, various information from the vehicle cannot be acquired, and in particular, a vehicle speed signal cannot be acquired. Therefore, when calculating the speed, the speed is calculated using, for example, a built-in acceleration sensor.

JP 2003-322533 A

  However, the above-described prior art has a problem that it is not possible to always calculate a stable and accurate speed. Specifically, the technique of Patent Document 1 described above is premised on a configuration capable of acquiring a vehicle speed signal. If the vehicle speed signal cannot be used for some reason, such as a vehicle speed sensor failure, the speed is set. The problem that it cannot be calculated is an example.

  Also, for example, in a simple product such as PND, if the speed is calculated using only the acceleration sensor, the vehicle's acceleration is integrated to calculate the speed, so the inclination angle when traveling on the slope is accumulated. Various errors are accumulated at the time of calculation, such as an error at the time of correction and an error of a midpoint voltage that varies with a change in power supply voltage. As a result, there is a problem that the speed cannot be calculated with high accuracy.

  In order to solve the above-described problems and achieve the object, the speed calculation device according to the invention of claim 1 detects a roll angle indicating a left-right inclination of a moving body and a yaw angle indicating an angle at which the moving body turns. Based on the angle detection means, the first acceleration detection means for detecting acceleration in a direction perpendicular to the traveling direction of the moving body, the roll angle and the yaw angle, and the acceleration, First calculating means for calculating a moving speed of the moving body in the moving direction when the moving body turns without using the acceleration in the moving direction.

It is a block diagram which shows an example of a functional structure of the speed calculation apparatus concerning this Embodiment. It is explanatory drawing which shows the coordinate system centering on a vehicle. It is a flowchart which shows an example of the speed calculation process sequence of the speed calculation apparatus concerning this Embodiment. It is a block diagram which shows an example of the hardware constitutions of the navigation apparatus concerning a present Example. It is a flowchart which shows an example of the speed calculation process sequence of a navigation apparatus. It is explanatory drawing which shows an example of the driving | running | working locus | trajectory of the vehicle on the conditions which cannot receive GPS information. It is explanatory drawing which shows an example of the moving speed of the vehicle on the conditions which cannot receive GPS information. It is explanatory drawing which shows an example of the display screen displayed on a display.

  Exemplary embodiments of a speed calculation device, a speed calculation method, a speed calculation program, and a recording medium according to the present invention will be explained below in detail with reference to the accompanying drawings.

(Embodiment)
(Functional configuration of speed calculation device)
The functional configuration of the speed calculation apparatus according to the embodiment of the present invention will be described with reference to FIG. FIG. 1 is a block diagram illustrating an example of a functional configuration of the speed calculation device according to the present embodiment. The speed calculation device 100 is intended for a simple navigation device that cannot acquire a vehicle speed signal detected at a time interval proportional to the rotation speed of a tire. For example, a PND (Portable Navigation Device), a smartphone, a mobile phone Realized by electronic devices such as

  The speed calculation device 100 calculates the speed of the moving body. The moving object is mainly intended for three or more automobiles including auto three-wheelers, ordinary automobiles, and large automobiles, but is not limited thereto, and may be a vehicle that travels on rails such as a railway vehicle.

  In FIG. 1, an angle detection unit 101, a first acceleration detection unit 102, a first calculation unit 103, an output unit 104, an acquisition unit 105, a second acceleration detection unit 106, a second calculation unit 107, And a correction unit 108. The angle detection unit 101 has a function of detecting a roll angle indicating a left-right inclination of the vehicle and a yaw angle indicating an angle at which the vehicle turns.

  Here, a coordinate system centered on the vehicle will be described with reference to FIG. FIG. 2 is an explanatory diagram showing a coordinate system centered on the vehicle. In FIG. 2, with the vehicle 200 as the center, the horizontal direction of travel of the vehicle is the x axis, the right and left directions are perpendicular to the direction of travel and the left and right directions are the y axis and the vertical direction is the z axis.

  The rotation angle around the x axis is called a roll angle, the up and down swing angle around the y axis is called a pitch angle, and the left and right swing angle around the z axis is called a yaw angle. Specifically, the roll angle indicates the left / right inclination of the vehicle 200, for example, the inclination of the vehicle during turning. The yaw angle indicates an angle when the vehicle 200 turns, for example, an angle obtained by turning a handle. The pitch angle indicates the forward / backward inclination of the vehicle 200. The front and rear of the vehicle 200 are the front and rear of the vehicle. The pitch angle indicates the degree of inclination of the vehicle forward or backward, and specifically corresponds to the inclination angle of the slope with respect to the horizontal direction.

  Returning to FIG. 1, the angle detection unit 101 detects a roll angle by a roll angle gyro sensor (for example, a three-axis gyro sensor), but is not limited thereto, and uses information output from a y-axis acceleration sensor. It is also possible. Further, the angle detection unit 101 detects the yaw angle by a yaw angle gyro sensor (for example, a three-axis gyro sensor), but is not limited thereto, and detects the yaw angle by using GPS information received by a GPS receiver. It is also possible to do.

  The first acceleration detection unit 102 has a function of detecting acceleration in a direction perpendicular to and horizontal to the traveling direction of the vehicle. Assuming that the horizontal direction of travel of the vehicle is the x-axis, the right-and-left direction is the y-axis, and the vertical direction is the z-axis, the first acceleration detection unit 102 performs acceleration in the y-axis direction (y-axis acceleration). Is detected. The first acceleration detection unit 102 detects by an acceleration sensor for the y-axis direction.

  The first calculation unit 103 calculates a moving speed when the vehicle is turning based on the roll angle and yaw angle detected by the angle detection unit 101 and the y-axis acceleration detected by the first acceleration detection unit 102. . Specifically, turning is a state in which the steering wheel is turned, typically turning right or left or driving a curve, but also includes lane changes. The output unit 104 outputs the movement speed calculated by the first calculation unit 103. The output unit 104 outputs, for example, the moving speed as a display or a voice.

Here, the calculation method of the moving speed at the time of the turn calculated by the first calculation unit 103 will be specifically described. First, as a relational expression between the y-axis and the z-axis, when the lateral acceleration of the vehicle is Y, the gravitational acceleration is g, the y-axis acceleration is ya, and the roll angle is θ,
ya = Y × cos θ + g × sin θ (1) The lateral acceleration Y of the vehicle is an acceleration applied in a direction horizontal to the road surface and perpendicular to the traveling direction.

Further, assuming that the vehicle is turning at a constant velocity and circular motion, δ is the yaw angle, and S is the moving speed when turning,
Y = δ × S (2) From equation (1) and equation (2), by calculating Y by eliminating Y,
ya = (δ × S) × cos θ + g × sin θ
(Δ × S) × cos θ = ya−g × sin θ
S = (ya−g × sin θ) / (δ × cos θ) (3).
As described above, in the present embodiment, the moving speed at the time of turning of the vehicle can be calculated from the y-axis acceleration ya, the gravitational acceleration g, the roll angle θ, and the yaw angle δ.

  The acquisition unit 105 acquires vehicle position information. Specifically, the acquisition unit 105 acquires latitude / longitude information from the GPS receiver at a predetermined timing. The first calculation unit 103 calculates the moving speed of the vehicle using the position information under conditions where the acquisition unit 105 can acquire the position information. For calculating the movement speed using the position information, a known technique may be used, and the description thereof is omitted here.

  Further, the first calculation unit 103 uses the above equation (3) based on the roll angle, the yaw angle, and the y-axis acceleration under conditions where the acquisition unit 105 cannot acquire the position information. Calculate the moving speed. Specifically, the conditions under which position information cannot be acquired are situations where GPS information is difficult to receive, such as in tunnels, multistory parking lots, underpasses, and underpasses.

  The second acceleration detection unit 106 detects the acceleration in the traveling direction of the vehicle. The acceleration in the traveling direction of the vehicle is acceleration in the x-axis direction (x-axis acceleration). The second acceleration detection unit 106 detects an x-axis acceleration using an acceleration sensor.

  The second calculation unit 107 calculates a moving speed in the traveling direction of the vehicle (hereinafter referred to as “second calculation speed”) based on the x-axis acceleration detected by the second acceleration detection unit 106. The second calculator 107 detects the velocity in the x-axis direction by integrating the x-axis acceleration that is the detection result of the acceleration sensor. The second calculation unit 107 can calculate the second calculation speed when the vehicle is turning and traveling straight.

  Since the second calculation unit 107 calculates the speed by accumulating the x-axis acceleration, a difference occurs due to an error when accumulating the inclination angle when the vehicle travels on the slope or a change in the power supply voltage. Various errors may accumulate during calculation, such as point voltage errors. Therefore, the correction unit 108 corrects the second calculation speed.

  Specifically, the correction unit 108 corrects the second calculated speed based on the amount of deviation between the second calculated speed and the first calculated speed. Specifically, the correction unit 108 performs correction to bring the second calculation speed closer to the first calculation speed. For example, when the second calculation speed is 10 m / s and the first calculation speed is 12 m / s, the correction unit 108 sets 2 m / s corresponding to the difference between the second calculation speed and the first calculation speed to the second value. A correction is made to add to the calculation speed.

  The output unit 104 outputs a first calculated speed as the moving speed of the vehicle when the vehicle is turning. The output unit 104 outputs the second calculated speed corrected by the correction unit 108 when the vehicle is traveling straight ahead.

(Speed calculation processing procedure of the speed calculation device)
Next, the speed calculation processing procedure of the speed calculation apparatus 100 will be described with reference to FIG. FIG. 3 is a flowchart illustrating an example of a speed calculation processing procedure of the speed calculation apparatus 100 according to the present embodiment.

  In the flowchart of FIG. 3, the speed calculation device 100 determines whether or not it has been activated (step S301). The speed calculation device 100 waits until it starts (step S301: No), and when it starts (step S301: Yes), detects the roll angle using, for example, a roll angle gyro sensor (step S302). The speed calculation device 100 detects the yaw angle using, for example, a yaw angle gyro sensor (step S303). Further, the speed calculation device 100 detects the y-axis acceleration using an acceleration sensor for the y-axis direction (step S304).

  Then, the speed calculation device 100 calculates the moving speed of the vehicle by using the above-described equation (3) (step S305). Next, the speed calculating device 100 outputs the calculated moving speed (step S306), and ends a series of processes according to this flowchart.

  As described above, the speed calculation device 100 according to the present embodiment calculates and outputs the moving speed of the vehicle during turning using the roll angle, the yaw angle, and the y-axis acceleration. Therefore, it is possible to calculate a moving speed close to the actual moving speed during a turn without using a vehicle speed signal, and to present an accurate speed to the user.

  Furthermore, in the present embodiment, under the condition where the position information of the vehicle can be acquired by the GPS receiver, the moving speed of the vehicle is calculated using the position information, and under the condition where the position information cannot be acquired, If the moving speed of the vehicle is calculated based on the roll angle, the yaw angle, and the y-axis acceleration, it is possible to present an accurate moving speed according to the reception status of the position information.

  In the present embodiment, the amount of deviation between the second calculated speed calculated using the x-axis acceleration and the first calculated speed calculated using the roll angle, the yaw angle, the y-axis acceleration, and the gravitational acceleration. The second calculated speed may be corrected based on the above, and the corrected second calculated speed may be output when the vehicle is traveling straight. Thereby, when various errors are accumulated during the calculation of the movement speed by the second calculation unit 107, the second calculation speed can be brought close to the actual movement speed, and the movement speed during straight traveling can be made accurate. it can.

  Examples of the present invention will be described below. In the present embodiment, an example in which the speed calculation device 100 configured by a navigation device is implemented will be described. The navigation device used in the present embodiment is a simple type (PND) that cannot acquire a vehicle speed signal detected at a time interval proportional to the rotational speed of the tire.

(Hardware configuration of navigation device)
The hardware configuration of the navigation apparatus 400 according to the present embodiment will be described with reference to FIG. FIG. 4 is a block diagram illustrating an example of a hardware configuration of the navigation device 400 according to the present embodiment.

  In FIG. 4, a navigation device 400 includes a CPU 401, a ROM 402, a RAM 403, a magnetic disk drive 404, a magnetic disk 405, an optical disk drive 406, an optical disk 407, an audio I / F (interface) 408, and a speaker 409. An input device 410, a video I / F 411, a display 412, a communication I / F 413, a GPS unit 414, and various sensors 415. Each component 401 to 415 is connected by a bus 420.

  The CPU 401 governs overall control of the navigation device 400. A rewritable nonvolatile memory such as the ROM 402 or the flash ROM records various programs such as a boot program, a current location calculation program, a route search program, a route guidance program, and a speed calculation program. The RAM 403 is used as a work area for the CPU 401.

  The current location calculation program is a program for calculating the current location of the vehicle (the current location of the navigation device 400) based on output information from various sensors 415 such as the GPS unit 414 and the acceleration sensor 421, for example.

  The route search program is a program for searching for an optimum route from the departure point to the destination point using map data, route calculation data, and the like recorded on the magnetic disk 405. The optimum route is the shortest (or fastest) route to the destination point or the route that best meets the conditions specified by the user. Further, not only the destination point but also a route to a stop point or a rest point may be searched. The searched guidance route is output to the audio I / F 408 and the video I / F 411 via the CPU 401.

  The route guidance program includes guidance route information searched by executing the route search program, information on the current location of the vehicle calculated by executing the current location calculation program, and a map read from the magnetic disk 405. This is a program for generating real-time route guidance information based on data and the like. The generated route guidance information is output to the audio I / F 408 and the video I / F 411 via the CPU 401.

  The speed calculation program calculates the moving speed of the vehicle based on the roll angle, the yaw angle, and the y-axis acceleration detected by the various sensors 415, or the vehicle based on the GPS information indicating the current location received by the GPS unit 414. It is a program that calculates the moving speed of

  The magnetic disk drive 404 controls the reading / writing of the data with respect to the magnetic disk 405 according to control of CPU401. The magnetic disk 405 records data written under the control of the magnetic disk drive 404. As the magnetic disk 405, for example, HD (hard disk) or FD (flexible disk) can be used. Map data, route calculation data, and the like are recorded on the magnetic disk 405.

  The optical disk drive 406 controls the reading / writing of the data with respect to the optical disk 407 according to control of CPU401. The optical disc 407 is a detachable recording medium from which data is read according to the control of the optical disc drive 406. As the optical disc 407, a writable recording medium can be used. In addition to the optical disk 407, the removable recording medium may be an MO, a memory card, or the like.

  The audio I / F 408 is connected to the speaker 409. Audio information is output from the speaker 409. Examples of the input device 410 include a remote controller including a plurality of keys for inputting characters, numerical values, various instructions, a keyboard, a mouse, a touch panel, and the like. The input device 410 may be realized by any one of a remote controller, a keyboard, a mouse, and a touch panel, or may be realized by a plurality of forms.

  The video I / F 411 is connected to the display 412. Specifically, the video I / F 411 includes, for example, a graphic controller that controls the entire display 412, a buffer memory such as a VRAM (Video RAM) that temporarily records image information that can be displayed immediately, and a graphic controller. Based on the output image data, the display 412 is configured by a control IC or the like.

  The display 412 displays icons, cursors, menus, windows, or various data such as characters and images. As the display 412, for example, a CRT, a TFT liquid crystal display, a plasma display, or the like can be adopted.

  The communication I / F 413 is connected to a communication network such as the Internet via wireless and functions as an interface between the communication network and the CPU 401. The GPS unit 414 receives radio waves from GPS satellites and outputs GPS information indicating the current location of the vehicle. The GPS information is information for specifying one point on the map data such as latitude / longitude and altitude. The output information of the GPS unit 414 is used when the CPU 401 calculates the current position of the vehicle and the moving speed.

  The various sensors 415 include an acceleration sensor 421, a gyro sensor 422, and the like, and output information that can determine the position and behavior of the vehicle. The acceleration sensor 421 can measure accelerations in the x-axis direction indicating the traveling direction of the vehicle, the y-axis direction indicating a direction perpendicular to the traveling direction and horizontal, and the z-axis direction indicating the vertical direction 3 It is an axial acceleration sensor. The navigation device 400 can calculate the velocity in each direction by integrating the acceleration in each direction. The acceleration sensor 421 may be any sensor that can detect at least x-axis acceleration in the x-axis direction and y-axis acceleration in the y-axis direction.

  The gyro sensor 422 outputs an azimuth change amount, and in particular, a sensor that can detect a roll angle and a yaw angle is used. In this embodiment, the gyro sensor 422 is a three-axis gyro sensor that can detect the angular velocity of the roll angle, the yaw angle, and the pitch angle. The output values of the various sensors 415 are used by the CPU 401 to calculate the current location of the vehicle and the speed. Note that since the navigation device 400 is a simple PND, the various sensors 415 do not include a vehicle speed sensor that detects the moving speed of the vehicle.

  An angle detection unit 101, a first acceleration detection unit 102, a first calculation unit 103, an output unit 104, an acquisition unit 105, and a second unit included in the speed calculation device 100 according to the present embodiment illustrated in FIG. The acceleration detection unit 106, the second calculation unit 107, and the correction unit 108 use the programs and data recorded in the ROM 402, the magnetic disk 405, and the like in the navigation device 400 illustrated in FIG. The function is realized by executing.

(Speed calculation processing procedure of the navigation device 400)
Next, the speed calculation processing procedure of the navigation device 400 will be described with reference to FIG. FIG. 5 is a flowchart illustrating an example of the speed calculation processing procedure of the navigation device 400. In the flowchart of FIG. 5, the navigation apparatus 400 determines whether or not it has been activated (step S501). The navigation device 400 waits until it starts (step S501: No), and when it starts (step S501: Yes), it determines whether GPS information is received (step S502).

  When the GPS information is not received (step S502: No), that is, for example, when the vehicle is traveling in a tunnel, a multilevel parking garage, an underpass, an underpass or the like, the navigation device 400 uses a three-axis gyro sensor. Using this, the roll angle is detected (step S503).

  Then, the navigation apparatus 400 detects the yaw angle using the three-axis gyro sensor (step S504). Next, the navigation apparatus 400 detects a y-axis acceleration using a triaxial acceleration sensor (step S505). Then, the navigation apparatus 400 determines whether or not the y-axis acceleration is “0” (step S506).

  Note that the determination in step S506 is specifically a determination of whether or not the vehicle is turning, and is not limited to the determination of whether or not the y-axis acceleration is “0”, and the roll angle is “0”. It may be determined whether or not there is a yaw angle = “0”. In addition, in order to determine with high accuracy whether or not the vehicle is turning, whether or not the roll angle = “0”, the yaw angle = “0”, and the y-axis acceleration = “0” is determined in step S506. It may be determined whether or not at least two of the roll angle, the yaw angle, and the y-axis acceleration are “0”.

  When the y-axis acceleration is not “0” (step S506: No), that is, when the vehicle is turning, the navigation device 400 calculates the moving speed during the turn using the roll angle, the yaw angle, and the y-axis acceleration. (Step S507). For calculating the moving speed at the time of turning, the above-described equation (3) is used (see the embodiment).

  The navigation apparatus 400 stores a correction value indicating an error between the movement speed calculated by integrating the x-axis acceleration detected by the acceleration sensor 421 and the movement speed calculated in step S507 in the RAM 403 (step S508). ). Note that the process of calculating the moving speed by integrating the x-axis acceleration is not shown, but may be performed between step S507 and step S508, for example. Then, the navigation apparatus 400 outputs the calculated moving speed (step S509), and ends a series of processes according to this flowchart.

  If the y-axis acceleration is “0” in step S506 (step S506: Yes), that is, if the vehicle is traveling straight, the navigation device 400 integrates the x-axis acceleration detected by the acceleration sensor 421. To calculate the moving speed (step S510). Then, it is determined whether or not the correction value is stored in the RAM 403 (step S511). When the correction value is not stored (step S511: No), the navigation device 400 proceeds to the process of step S509.

  When the correction value is stored (step S511: Yes), the navigation apparatus 400 corrects the moving speed using the correction value (step S512), and shifts to the processing of step S509. In step S502, when GPS information is received (step S502: Yes), the navigation apparatus 400 calculates the moving speed of the vehicle using the GPS information (step S513), and shifts to the processing of step S509.

  By the above-described processing, the moving speed close to the actual moving speed can be calculated by turning even under conditions where GPS information cannot be received such as in a tunnel. In the case of the navigation device 400 capable of acquiring a vehicle speed signal from the vehicle speed sensor, the speed can be calculated with high accuracy even under conditions where the vehicle speed signal cannot be used, such as when the vehicle speed sensor fails. Can do. Thereby, while being able to show an exact speed to a user, the exact arrival time to the destination can be shown.

  It should be noted that it is determined whether or not there is an emergency in which the vehicle speed sensor cannot be used, using the navigation device 400 capable of acquiring a vehicle speed signal from the vehicle speed sensor. The moving speed may be calculated based on the y-axis acceleration. According to such a configuration, it is possible to present an accurate movement speed by the vehicle speed sensor in a normal time, and it is possible to present an accurate movement speed based on the roll angle, the yaw angle, and the y-axis acceleration in an emergency. .

  Furthermore, in the above-described processing, the vehicle moving speed is calculated using the GPS information under a condition where the GPS information of the vehicle can be acquired. On the other hand, when the GPS information cannot be acquired, the roll angle, yaw The moving speed of the vehicle is calculated based on the angle and the y-axis acceleration. Therefore, an accurate moving speed can be calculated according to the reception status of GPS information.

  In the present embodiment, the correction value is used to correct the movement speed calculated using the x-axis acceleration, and the corrected movement speed is output when the vehicle is traveling straight. . As a result, when various errors are accumulated during the calculation of the movement speed using the x-axis acceleration, the movement speed calculated using the x-axis acceleration can be brought close to the actual movement speed, and the movement speed during straight traveling can be reduced. Accuracy can be improved. Therefore, an accurate speed can be presented even when traveling straight.

  In the above-described processing, the correction value is sequentially updated when the movement speed based on the roll angle, the yaw angle, and the y-axis acceleration is calculated. As a result, the correction value can be made more accurate, and an accurate speed can be presented during straight travel.

(An example of a vehicle trajectory under conditions where GPS information cannot be received)
Next, with reference to FIG. 6, an example of a traveling locus of the vehicle under a condition where GPS information cannot be received will be described. FIG. 6 is an explanatory diagram illustrating an example of a traveling locus of a vehicle under a condition in which GPS information cannot be received.

  In FIG. 6, it is assumed that a vehicle 600 travels in a tunnel or the like that cannot receive GPS information and travels at a constant speed. It is assumed that the vehicle 600 turns from point A to point B over 1 second. δ corresponds to a yaw angle that is an azimuth change amount. In the present embodiment, the moving speed can be calculated when the direction change amount is generated, and a specific example will be described with reference to FIG.

(Example of vehicle moving speed under conditions where GPS information cannot be received)
Next, an example of the moving speed of the vehicle under conditions where GPS information cannot be received will be described with reference to FIG. FIG. 7 is an explanatory diagram showing an example of the moving speed of the vehicle under conditions where GPS information cannot be received. In the graph 700 of FIG. 7, the vertical axis represents speed and azimuth change (yaw angle), and the horizontal axis represents time. The points A and B shown in FIG. 7 correspond to the points A and B shown in FIG.

  Here, a case where the detection results of various sensors 415 are acquired and the speed is calculated every second will be described as an example. Up to point A before turning, a straight path is assumed, and the direction change amount (yaw angle) is 0 °. Up to point A, the moving speed is calculated using the x-axis acceleration. Also, up to point A, for example, the calculated moving speed of 13 m / s is output. The actual speed described in a supplementary manner is 11.7 m / s, and there is a deviation of 1.3 m / s from the output moving speed.

It is assumed that the yaw angle (azimuth change amount) δ = 0.2 ° and the roll angle θ = −2 ° are detected by the gyro sensor 422 at the point B. Further, it is assumed that the y-axis acceleration ya = 2 m / s ² is detected at the point B.

Using the following formula (3) shown in the embodiment,
S = (ya−g × sin θ) / (δ × cos θ) (3) The moving speed S (m / s) at the time of turning is:
S [m / s] ≈11.7
Is calculated as

  At point B, 11.7 m / s is output as the moving speed. At point B, there is 1.3 m / s between the moving speed 13 m / s calculated using the x-axis acceleration and the moving speed moving speed 11.7 m / s based on the roll angle, yaw angle and y-axis acceleration. It is determined that there is a deviation of s.

  For this reason, the calculation of the moving speed based on the roll angle, the yaw angle and the y-axis acceleration is not possible after the point C where the yaw angle becomes 0 °, but based on the x-axis acceleration using a deviated value of 1.3 m / s. The calculated moving speed can be corrected. As a correction method, for example, a difference may be added to the moving speed calculated using the x-axis acceleration, and specifically, 1.3 m / s may be reduced. Not limited to this, other methods may be used.

  In the present embodiment, the actual moving speed at the time of turning can be calculated even when the direction change amount is small, such as a lane change, without a sudden curve or a left or right turn. That is, the actual moving speed during traveling can be calculated based on the roll angle, the yaw angle, and the y-axis acceleration when turning with a slight azimuth change amount. In addition, when the vehicle goes straight after turning, the moving speed can be calculated using the correction value. The correction value can be updated every time the vehicle turns, and an accurate movement speed can be output even when the vehicle is traveling straight.

  Further, the correction value is stored for each road mode such as every slope positive or negative, such as an uphill slope or a downhill slope, or every slope angle of the slope. A correction value may be used. Thereby, a moving speed can be corrected according to a road mode, and a more accurate moving speed can be output when going straight.

  In the present embodiment, the speed is calculated using the GPS information under the condition that the GPS information can be received. That is, when GPS information is used, there is almost no deviation from the actual speed, and the speed is calculated with high accuracy. As described above, in this embodiment, when calculating the speed, the GPS information is used under the condition where the GPS information can be received, and is detected during the turn under the condition where the GPS information cannot be received. Roll angle, yaw angle, and y-axis acceleration are used. Therefore, an accurate speed can be output regardless of the reception state of the GPS information.

  Even under conditions where GPS information can be received, the vehicle moving speed is calculated using the roll angle, yaw angle, and y-axis acceleration during a turn, and calculated using the x-axis acceleration. By comparing with the moving speed, the amount of deviation may be updated as a correction value each time. This makes it possible to obtain a correction value without turning under conditions where it is impossible to receive GPS information, for example, it is possible to correct the moving speed when going straight after entering the tunnel, Accurate speed can be output. Specifically, the movement speed calculated using the x-axis acceleration can be corrected before the point B is reached, and an accurate speed can be output.

  In addition, the calculation of the moving speed using GPS information is suitable for high-speed driving at a predetermined speed or higher, but considering that errors are likely to occur at low speeds lower than the predetermined speed, it is possible to receive GPS information. However, when traveling at low speed, the moving speed may be calculated based on the roll angle, the yaw angle, and the y-axis acceleration. With such a configuration, it is possible to improve the accuracy of the moving speed during low-speed traveling.

  FIG. 6 shows only the case where the amount of azimuth change (yaw angle) in the right direction is positive and the amount of azimuth change is positive, but the amount of azimuth change is negative when turning leftward. When turning in the left direction, the azimuth change amount is set to be negative, and the same processing as the calculation of the moving speed at the time of turning in the right direction may be performed.

(Example of display screen displayed on display 412)
Next, an example of a display screen displayed on the display 412 will be described with reference to FIG. FIG. 8 is an explanatory diagram illustrating an example of a display screen displayed on the display 412. In FIG. 8, display screens 801 and 802 indicate a state where the vehicle is traveling in a tunnel where GPS information cannot be received. A display screen 801 shows a screen when traveling on a straight road, and a display screen 802 shows a screen during turning.

  The display screen 801 displays a traveling map screen, a current speed (movement speed) calculated using the x-axis acceleration, and a destination arrival time calculated using the current speed. A display screen 801 shows a screen when traveling on a straight road. Specifically, the display screen 801 displays, for example, a current speed before reaching the point B shown in FIG. 7 and a destination arrival time calculated using the current speed. Although the actual speed of the vehicle is 41 km / h, it is displayed as 47 km / h on the display screen 801.

  The display screen 802 includes a traveling map screen, a current speed (movement speed) calculated based on the roll angle, the yaw angle, and the y-axis acceleration, and a destination arrival time calculated using the current speed. Is displayed. Specifically, the display screen 802 displays a current speed after reaching the point B shown in FIG. 7 and a destination arrival time calculated using the current speed. Note that the actual speed of the vehicle is 41 km / h, which is also displayed as 41 km / h on the display screen 802.

  Thus, according to the present embodiment, the moving speed of the vehicle can be calculated with high accuracy and presented to the user. In addition, when the moving speed is calculated based on the roll angle, yaw angle and y-axis acceleration and the current speed is changed from 47 km / h to 41 km / h, a notification such as “corrected the current speed” is given. It may be. Thereby, the user can know that the present speed to be presented has been changed. In addition, if the user knows that GPS information cannot be received in the tunnel, the user can know that the current speed has been corrected by some process without using the GPS information. Can be improved.

  As described above, according to the speed calculation device, the speed calculation method, the speed calculation program, and the recording medium of the present invention, a movement speed close to the actual movement speed can be calculated without using a vehicle speed signal. Thereby, an accurate speed can be presented to the user, and the reliability of the speed to be presented can be improved.

  The speed calculation method described in this embodiment can be realized by executing a program prepared in advance on a computer such as a personal computer or a workstation. This program is recorded on a computer-readable recording medium such as a hard disk, a flexible disk, a CD-ROM, an MO, a DVD, or a memory card, and is executed by being read from the recording medium by the computer. The program may be a transmission medium that can be distributed via a network such as the Internet.

DESCRIPTION OF SYMBOLS 100 Speed calculation apparatus 101 Angle detection part 102 1st acceleration detection part 103 1st calculation part 104 Output part 105 Acquisition part 106 2nd acceleration detection part 107 2nd calculation part 108 Correction | amendment part 400 Navigation apparatus 412 Display 414 GPS unit 415 Various sensors 421 Acceleration sensor 422 Gyro sensor

Claims (3)

Angle detection means for detecting a roll angle indicating a left-right inclination of the moving body and a yaw angle indicating an angle at which the moving body turns;
First acceleration detection means for detecting acceleration in a direction perpendicular to and horizontal to the traveling direction of the moving body;
Before Symbol roll angle and the yaw angle, before SL on the basis of the acceleration, without using the acceleration in the traveling direction of the moving body, a first calculation for calculating a moving speed of the traveling direction of the moving body during a turn of the moving object Means,
A speed calculation device comprising: Further comprising an acquisition means for acquiring position information of the mobile body;
The first calculation unit calculates a moving speed of the moving body using the position information under a condition in which the acquisition unit can acquire the position information.
The moving speed of the moving body is calculated based on the roll angle, the yaw angle, and the acceleration under a condition in which the position information cannot be acquired by the acquiring unit. The speed calculation device described. Second acceleration detecting means for detecting acceleration in the traveling direction of the moving body;
Second calculation means for calculating a moving speed (hereinafter referred to as “second calculation speed”) of the moving body based on the acceleration detected by the second acceleration detecting means;
Correction means for correcting the second calculated speed based on an amount of deviation between the second calculated speed and the moving speed calculated by the first calculating means (hereinafter referred to as “first calculated speed”);
Recording means for recording the deviated amount;
Output means for outputting the moving speed calculated by either the first calculation means or the second calculation means;
Further comprising
And the output means, the moving speed relative to the road surface of the movable body, when the moving body is turning outputs the first calculated speed, when the moving body is straight, the movable body 3. The speed calculation device according to claim 1, wherein the second calculation speed corrected by the correction unit is output based on the deviated amount recorded when the vehicle is turning . 4.

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