WO2022225437A1

WO2022225437A1 - Method for controlling a gear-shifting operation of a vehicle

Info

Publication number: WO2022225437A1
Application number: PCT/SE2022/050377
Authority: WO
Inventors: Simon MAGNUSSON
Original assignee: Epiroc Rock Drills Aktiebolag
Priority date: 2021-04-20
Filing date: 2022-04-19
Publication date: 2022-10-27
Also published as: SE2150489A1; CA3215436A1; AU2022263175A1

Abstract

A method performed by a control unit (10) for controlling a gear-shifting operation of a vehicle, wherein the vehicle comprises the control unit (10), at least one propulsion device, and at least one transmission arrangement; and wherein the method comprises steps of estimating (101) a road resistance, estimating (104) a power transfer, and determining (105) the gear-shifting operation based on the estimated road resistance and the estimated power transfer.

Description

METHOD FOR CONTROLLING A GEAR-SHIFTING OPERATION OF A VEHICLE

TECHNICAL FIELD

The present disclosure relates to a method performed by a control unit for controlling a gear-shifting operation of a vehicle, a computer program product for carrying out the method and a computer-readable storage medium storing the computer program product.

BACKGROUND

A transmission of a vehicle ensures that the right amount of power generated by an engine is transmitted to the driving wheels under any circumstances. Power loss is inevitable during a torque transmission in a gear-shifting operation due to a number of factors including engine torque reduction, bearing friction and motion of lubricant within a transmission. Thus, it is a common problem that the transmission may experience gear hunting, which can result in increased fuel consumption, transmission damage, and operator discomfort.

Gear hunting is a circle of oscillating upshifts and downshifts when an automatic transmission is operated around a predefined shift point of the transmission. In the course of an upshift from a lower gear to a higher gear, the torque transmission in the higher gear may be too low to maintain the vehicle speed thereby instantly causing the automatic transmission to downshift to the lower gear. Once back in the lower gear, the torque transmission may increase sufficiently to accelerate the vehicle speed such that the automatic transmission shifts into the higher gear again.

Gear hunting may be induced by a variety of factors including vehicle conditions, a heavy load, the step size between gears in a gear-shifting operation, the road and the environment affecting the vehicle. The problem of gear hunting has huge impacts on the performance of heavy-duty vehicles such as agricultural, mining and construction machines.

The problem of gear hunting may be solved by manually selecting the lower gear to prevent a gear-shifting to a higher gear. However, there is a risk of holding the transmission in the lower gear for a longer time than necessary. The solution relies upon an operator’s "feel" and experience for determining when an upshift should be enabled, which presents a real burden to an operator.

The problem of gear hunting may also be solved by controlling a gear-shifting operation based on predetermined reference values of vehicle load and slope inclination. Real time values of vehicle load and slope inclination may be measured by means of a load cell and a tilt sensor respectively, which are compared with the reference values to determine the gear-shifting operation. However, the solution is not sufficiently adaptive which application is restricted to the situations definable by the reference values. An upshift of a transmission would be disabled unnecessarily in a more complicated situation that cannot be defined exclusively by the reference values even if the more complicated situation allows the upshift.

The problem of gear hunting may also be solved by controlling a gear-shifting operation based on a vehicle acceleration, wherein specific static shift points are predetermined for a lower vehicle acceleration. However, due to hysteresis the solution is often unable to respond to a decrease in torque transmission quickly enough for determining when an upshift shall be enabled.

US 6,663,534 B2 discloses a method for preventing oscillating gearshifts of an automatic transmission with an electronic control device. The control device monitors the current road resistance from a comparison of measured vehicle acceleration with a theoretical vehicle acceleration and determines therefrom the value of differential acceleration, which is used for determining whether a reduction of the engine torque is needed. The result is that the vehicle's speed remains constant due to the downregulation of engine speed, which inhibits a forced upshift of the transmission and thereby avoiding oscillating gearshifts. It is implicitly disclosed in US 6,663,534 B2 that the method would require a means for regulating the engine speed to reduce the engine torque if the conditions (a) to (e) are fulfilled.

Furthermore, current automatic methods of controlling a gear-shifting operation often require excessive computation time and unacceptably large memory capacity, which is detrimental to work efficiency and productivity.

Thus, there is a need for an improved method of controlling a gear-shifting operation for solving the problem of gear hunting taking into account of the above-mentioned drawbacks of the state of the art. SUMMARY

In view of the above, one object of the present disclosure is therefore to solve the problem of gear hunting in a gear-shifting operation. Another object of the disclosure is to increase work efficiency and productivity of a vehicle.

Yet another object of the disclosure is to reduce manual workload for controlling a gear-shifting operation of a vehicle.

Yet another object of the disclosure is to provide a novel and advantageous method for controlling a gear-shifting operation of a vehicle.

Yet another object of the disclosure is to provide an alternative method for controlling a gear-shifting operation of a vehicle.

Yet another object of the disclosure is to provide an adaptive method for controlling a gear-shifting operation of a vehicle. Yet another object of the disclosure is to provide a robust and reliable method for controlling a gear-shifting operation of a vehicle.

Yet another object of the disclosure is to provide a simple method for controlling a gear-shifting operation of a vehicle.

Yet another object of the disclosure is to provide an at least partially automatic method for controlling a gear-shifting operation of a vehicle.

The above mentioned objects are achieved according to a first aspect of the disclosure by a method performed by a control unit for controlling a gear-shifting operation of a vehicle, wherein the vehicle comprises the control unit, at least one propulsion device, and at least one transmission arrangement, and wherein the method comprises steps of estimating a road resistance, and determining the gear-shifting operation based on the estimated road resistance.

The use of an estimated road resistance for determining a gear-shifting operation leads to a dynamic method that adapts to changing conditions in any unforeseen occasions that could induce gear hunting. The method has the advantages of providing a simple, robust and reliable solution to the problem of gear hunting by controlling a gear-shifting operation based on the road resistance estimation. In some embodiments, the method may be performed by a computer connected to the control unit, which enables remote control of the gear-shifting operation.

In some embodiments, the method as was described above further comprises steps of estimating a torque margin or a force margin based on the estimated road resistance, and determining the gear-shifting operation based on the estimated torque margin or the estimated force margin. In other words, the estimated torque margin or the estimated force margin derived from the estimated road resistance is used for determining the gear-shifting operation.

In some embodiments, the method as was described above further comprises steps of calculating an acceleration margin based on the estimated torque margin or the estimated force margin, and determining the gear-shifting operation based on the calculated acceleration margin. In other words, the calculated acceleration margin reflecting the estimated road resistance is used for determining the gear-shifting operation.

In some embodiments, the method as was described above further comprises steps of estimating a power transfer, and determining the gear-shifting operation based on the estimated road resistance and the estimated power transfer. The method comprising the step of power transfer estimation not only eliminates any risk of gear hunting in a gear-shifting operation, but also ensures that the gear-shifting operation is beneficial for good vehicle performance.

In some embodiments, the step of estimating a power transfer may be based on the estimated road resistance.

In some embodiments, at least one of the steps in the method as was described above is performed real-time. The method is responsive to dynamic variables and adaptive to changing conditions in any unforeseen occasions that could induce gear hunting.

In some embodiments, the step of estimating a road resistance is performed on the basis of a model of computation, and wherein input parameters of the model of computation include torque and speed. The model of computation enables at least partial automation of the method as was described above.

In some embodiments, input parameters of the model of computation further include data received from at least one sensor of the vehicle. In some embodiments, the at least one sensor is a torque sensor, a speed sensor, an inclinometer, a load cell, an accelerometer or a force sensor.

The above mentioned objects are also achieved according to a second aspect of the disclosure by a control unit configured to perform the method as was described above, wherein the control unit is configured to estimate a road resistance, and determine the gear-shifting operation based on the estimated road resistance.

The control unit according to the present disclosure has all the advantages that have been described above in conjunction with the method as was described above for controlling a gear-shifting operation of a vehicle.

In some embodiments, the control unit as was described above is further configured to estimate a torque margin or a force margin based on the estimated road resistance, and determine the gear-shifting operation based on the estimated torque margin or the estimated force margin. In other words, the estimated torque margin or the estimated force margin derived from the estimated road resistance is used for determining the gear-shifting operation.

In some embodiments, the control unit as was described above is further configured to calculate an acceleration margin based on the estimated torque margin or the estimated force margin, and determine the gear-shifting operation based on the calculated acceleration margin. In other words, the calculated acceleration margin reflecting the estimated road resistance is used for determining the gear-shifting operation.

In some embodiments, the control unit as was described above is further configured to estimate a power transfer, and determine the gear-shifting operation based on the estimated road resistance and the estimated power transfer. The method comprising the step of power transfer estimation which is performed by the control unit not only eliminates any risk of gear hunting in a gear-shifting operation, but also ensures that the gear-shifting operation is beneficial for good vehicle performance.

The above mentioned objects are also achieved according to a third aspect of the disclosure by a vehicle comprising the control unit as was described above, at least one propulsion device, and at least one transmission arrangement. The vehicle has all the advantages that have been described above in conjunction with the method performed by the control unit or a computer connected to the control unit as was described above for controlling a gear-shifting operation of a vehicle.

In some embodiments, the vehicle as was described above is a heavy-duty vehicle, a mining or construction machine.

In some embodiments, the vehicle as was described above is a truck, a loader, an articulated hauler, a drilling or bolting rig.

In some embodiments, the vehicle as was described above is a mine truck for underground mining and tunneling applications such as haul, dump and excavation.

In some embodiments, the vehicle as was described above further comprises at least one sensor selected from the group consisting of a torque sensor, a speed sensor, an inclinometer, a load cell, an accelerometer and a force sensor.

The above mentioned objects are also achieved according to a fourth aspect of the disclosure by a computer program product comprising instructions which, when executed on at least one processor, cause the at least one processor to carry out the method as was described above for controlling a gear-shifting operation of a vehicle.

According to some embodiments herein there is provided a computer program which comprises program code for causing a control unit or a computer connected to the control unit to carry out the method as was described above for controlling a gear- shifting operation of a vehicle.

The computer program product provides all the advantages that have been described above in conjunction with the method as was described above for controlling a gear- shifting operation of a vehicle.

The above mentioned objects are also achieved according to a fifth aspect of the disclosure by a computer-readable storage medium storing a computer program product comprising instructions which, when executed on at least one processor, cause the at least one processor to carry out the method as was described above for controlling a gear-shifting operation of a vehicle.

According to some embodiments herein there is provided a computer-readable storage medium storing a computer program, wherein said computer program comprises program code for causing a control unit or a computer connected to the control unit to carry out the method as was described above for controlling a gear-shifting operation of a vehicle.

The computer-readable storage medium has all the advantages that have been described above in conjunction with the method as was described above for controlling a gear-shifting operation of a vehicle.

BRIEF DESCRIPTION OF THE DRAWINGS

With reference to the appended drawings, below follows a more detailed description of embodiments of the disclosure cited as examples.

In the drawings:

Figure 1 is a block diagram depicting a method for controlling a gear-shifting operation;

Figure 2 depicts a torque curve in the first and the second gear respectively to illustrate a disabled upward gear-shifting operation when the estimated road resistance is 200kN;

Figure 3 depicts a torque curve in the first and the second gear respectively to illustrate an enabled upward gear-shifting operation when the estimated road resistance is 150kN;

Figure 4 is a flowchart of an algorithm for controlling an upward gear-shifting operation;

Figure 5 is a flowchart of an algorithm for controlling a downward gear-shifting operation;

Figure 6 is a block diagram illustrating a control unit and connections with the control unit;

Figure 7 depicts a force curve in the first and the second gear respectively to illustrate a disabled upward gear-shifting operation at P1 due to a negative force margin after the upward gear-shifting operation, and an enabled upward gear-shifting operation at P2 due to a positive force margin after the upward gear-shifting operation. DETAILED DESCRIPTION

The present disclosure aims to solve the problem of gear hunting in a gear-shifting operation. The present disclosure further aims to reduce manual workload without compromising work efficiency or productivity. The present disclosure improves the gear-shifting operation by providing a novel, simple, robust and reliable solution which is advantageous over the state of the art.

According to a first aspect of the disclosure, there is provided a method performed by a control unit 10 for controlling a gear-shifting operation of a vehicle, wherein the vehicle comprises the control unit 10, at least one propulsion device, and at least one transmission arrangement.

In some embodiments, the method may be performed by a computer connected to the control unit 10, which enables remote control of the gear-shifting operation.

The method has the advantages of providing a simple, robust and reliable solution to the problem of gear hunting by controlling a gear-shifting operation based on a road resistance estimation. Example embodiments of the method will be described in a general way by referring to Fig. 1 in which the optional method steps are marked with dashed lines. The method comprises the following steps, which steps may be taken in any suitable order.

Step 101: estimating a road resistance The step 101 of estimating a road resistance leads to a dynamic method that adapts to changing conditions in any unforeseen occasions that could induce gear hunting. The estimated road resistance is used in the step 105 of determining the gear-shifting operation (Fig. 1).

With “estimating” is herein meant a prediction or judgment that precedes or takes the place of actual measuring or counting or testing out.

The road resistance that a vehicle can be subjected to comprises rolling resistance, air resistance, and resistance from road gradient. Road resistance may represent an absolutely major contribution to the total sum of resistance force or resistance torque that opposes the driving force or driving torque provided by an engine. Inherent vehicle properties including bearing friction and motion of lubricant within a transmission always contribute to the total sum of resistance force or resistance torque. In a steady state condition of speed, the driving torque equals the resistance torque. When the driving torque is larger than the resistance torque, an acceleration takes place. When the driving torque is less than the resistance torque, a deceleration takes place.

A road resistance may be estimated by a linear quadratic estimation (LQE), a.k.a. Kalman filter, or any other estimation method suitable for the intended use herein.

In some embodiments, a road resistance may be estimated by means of calculation from an engine load. In some embodiments, the engine load may be measured by a mass air flow sensor (MAF).

Step 102: estimating a torque margin or a force margin

The optional step 102 of estimating a torque margin or a force margin is based on the estimated road resistance.

With a “torque margin” is herein meant a value from a comparison of an estimated torque in a gear at an operating point with the theoretical maximum driving torque that can be provided in the gear. Estimation of the torque margin is dependent on the estimated road resistance that determines the estimated torque in a gear at an operating point. The estimated torque margin reflects the capacity of acceleration in the gear.

With a “force margin” is herein meant a value from a comparison of an estimated force in a gear at an operating point with the theoretical maximum driving force that can be provided in the gear. Estimation of the force margin is dependent on the estimated road resistance that determines the estimated force in a gear at an operating point. The estimated force margin reflects the capacity of acceleration in the gear.

The estimated torque margin or the estimated force margin derived from the estimated road resistance can be used in the step 105 of determining the gear-shifting operation (Fig. 1).

Fig. 2 illustrates a scenario with a torque curve in the first and the second gear respectively. An upward gear-shifting operation from the first gear to the second gear is scheduled to take place at the operating point D. The current road resistance is estimated to be 200kN, which contributes to an estimated speed loss and results in an estimated negative torque margin at the estimated operating point D^' after the upward gear-shifting operation. The negative torque margin will induce gear hunting, which eventually leads to the decision to disable the upward gear-shifting operation and remain in the first gear. Fig. 3 illustrates another scenario with a torque curve in the first and the second gear respectively. An upward gear-shifting operation from the first gear to the second gear is scheduled to take place at the operating point D. The current road resistance is estimated to be 150kN, which contributes to an estimated speed loss and results in an estimated positive torque margin at the estimated operating point D^' after the upward gear-shifting operation. The positive torque margin will not induce gear hunting, which eventually leads to the decision to enable the upward gear-shifting operation and upshift to the second gear.

Fig. 7 illustrates yet another scenario with a force curve in the first and the second gear respectively. An upward gear-shifting operation from the first gear to the second gear is scheduled to take place at an operating point P1. It is estimated that the current road resistance contributes to an estimated speed loss during the gear shifting from the operating point P1 to the estimated operating point PT and results in an estimated negative force margin at the estimated operating point PT after the upward gear- shifting operation. The negative force margin will induce gear hunting, which eventually leads to the decision to disable the upward gear-shifting operation and remain in the first gear.

On the basis of a model of computation, an upward gear-shifting operation from the first gear to the second gear is to be enabled at an adaptive operating point P2 which is dependent on the current road resistance (Fig. 7). The current road resistance contributes to an estimated speed loss, which results in a positive force margin at the estimated operating point P2’ after the upward gear-shifting operation. The positive force margin will not induce gear hunting, which eventually leads to the decision to enable the upward gear-shifting operation and upshift to the second gear.

Step 103: calculating an acceleration margin

The optional step 103 of calculating an acceleration margin is based on the estimated torque margin or the estimated force margin. The calculated acceleration margin reflects the estimated road resistance and can be used in the step 105 of determining the gear-shifting operation (Fig. 1).

In some embodiments as illustrated in Figs. 4 and 5, the method for controlling a gear- shifting operation of a vehicle comprises steps of estimating 101 a road resistance, estimating 102 a torque margin based on the estimated road resistance, calculating 103 an acceleration margin based on the estimated torque margin, and determining 105 the gear-shifting operation based on the calculated acceleration margin.

The method is applicable for controlling an upward gear-shifting operation (Fig. 4) as well as a downward gear-shifting operation (Fig. 5). The method is applicable for controlling a fully automatic gear-shifting operation as well as a semiautomatic gear- shifting operation.

Fig. 4 is a flowchart of an algorithm for controlling an upward gear-shifting operation according to the method as was described above. If the calculated acceleration margin is positive or larger than a threshold value, the upshift is enabled. Otherwise, the upshift is disabled. The threshold value may be may be empirically determined for a vehicle. In some embodiments, the threshold value may be static and theoretical.

Fig. 5 is a flowchart of an algorithm for controlling a downward gear-shifting operation according to the method as was described above. If the calculated acceleration margin is positive or larger than a threshold value, the downshift is disabled. Otherwise, the downshift is enabled. The threshold value may be may be empirically determined for a vehicle. In some embodiments, the threshold value may be static and theoretical.

Step 104: estimating power transfer

In some embodiments, the method as was described above further comprises an optional step 104 of estimating a power transfer.

With a “power transfer” is herein meant a means for evaluating the benefit of a gear- shifting operation, wherein the power transfer refers preferably to an input or output power, a transmission efficiency or a fuel efficiency.

Power is the rate at which work is performed. An equation for power is: P = W/t, wherein “P” stands for power, “W’ stands for the amount of work done or energy expended, and “t” stands for the amount of time. Force applied over a distance creates work. An equation for work is: W = F · d, wherein “W’ stands for the amount of work done or energy expended, “F” stands for force, and “d” stands for displacement or distance.

Thus, power can also be expressed in another equation: P = F · d/t, wherein “P” stands for power, “F” stands for force, and “d/t” stands for displacement over time which is velocity or speed. Power increases with increased force or increased velocity, or in other words, power decreases with decreased force or decreased velocity. An engine usually produces its maximum power at an engine speed different from the engine speed at which a maximum torque or force is reached.

Engine power produced on two neighboring gears (e.g. the second and the third gears), may be the same for an operating point at which an upward gear-shifting operation from the lower gear (e.g. the second gear) to the upper gear (e.g. the third gear) results in a positive torque or force margin after the upward gear-shifting operation. The upward gear-shifting operation will not induce gear hunting due to the positive torque or force margin. However, the upward gear-shifting operation will result in an inefficient power transfer, which eventually leads to the decision to disable the upward gear-shifting operation at the operating point and remain in the lower gear.

The estimated power transfer together with the estimated road resistance can be used for determining 105 the gear-shifting operation The method comprising the step 104 of estimating a power transfer not only eliminates any risk of gear hunting in a gear- shifting operation, but also ensures that the gear-shifting operation is beneficial for good vehicle performance. In other words, a gear-shifting operation may be disabled due to a low power transfer even if there is no risk of gear hunting.

In some embodiments, the step 104 of estimating a power transfer may be based on the estimated road resistance.

Step 105: determining the gear-shifting operation

The step 105 of determining the gear-shifting operation may be based on an estimated road resistance.

In some embodiments, the step 105 of determining the gear-shifting operation may be based on an estimated torque margin or an estimated force margin reflecting an estimated road resistance.

In some embodiments, the step 105 of determining the gear-shifting operation may be based on a calculated acceleration margin reflecting an estimated road resistance.

In some embodiments, the step 105 of determining the gear-shifting operation may be based on an estimated road resistance and an estimated power transfer, which not only eliminates any risk of gear hunting in a gear-shifting operation, but also ensures that the gear-shifting operation is beneficial for good vehicle performance. In some embodiments, the step of estimating a road resistance is performed on the basis of a model of computation, and wherein input parameters of the model of computation include torque and speed.

The model of computation may be a linear quadratic estimation (LQE), a.k.a. Kalman filter, or any other estimation method suitable for the intended use herein.

The torque may be an engine torque, a wheel torque, an input torque acting on a transmission input shaft, or an output torque exerted by a transmission output shaft.

The speed may be an engine speed, a wheel speed or a vehicle speed.

The input parameters of the model of computation may be vehicle dependent and further include a vehicle weight, a load weight, an engine load, and/or any other inherent properties of the vehicle that may comprise propulsion devices, transmissions, brakes, retarders, wheels, tires, and et cetera.

The input parameters of the model of computation may also be vehicle independent and further include road conditions, weather conditions in the surroundings of the vehicle.

The input parameters of the model of computation may be obtainable from sensors connected to a Controller Area Network (CAN), or a memory 12 of a control unit 10.

In some embodiments, input parameters of the model of computation further include data received from at least one sensor of the vehicle, wherein the at least one sensor may be a torque sensor, a speed sensor, an inclinometer, a load cell, an accelerometer or a force sensor.

The output of the model of computation is an estimated road resistance in the current state of a vehicle. The road resistance estimation according to the present disclosure is responsive to dynamic changes in both the hardware and the surroundings of the vehicle. Thus, the method of controlling a gear-shifting operation based on the road resistance estimation is adaptive, reliable and simple.

According to a second aspect of the disclosure, there is provided a control unit 10 configured to perform the method as was described above, wherein the control unit 10 is configured to estimate a road resistance, and determine the gear-shifting operation based on the estimated road resistance.

As illustrated in Fig. 6, the control unit 10 may be connected with at least one sensor selected from the group consisting of a torque sensor, a speed sensor, an inclinometer, a load cell, an accelerometer and a force sensor via the communication links 10a, 10b, 10c, 10d, 10e and 10f respectively. The control unit 10 comprises at least one processor 11, at least one memory 12 and at least one data port 13. The at least one processor 11 is usually an electronic processing circuitry that processes input data and provides appropriate output. The control unit may apply a Kalman filter for producing estimates of the current state variables in a dynamic system such as a vehicle and its surroundings.

In some embodiments, the control unit as was described above is further configured to estimate a power transfer, and determine the gear-shifting operation based on the estimated road resistance and the estimated power transfer. The method comprising the step of power transfer estimation not only eliminates any risk of gear hunting in a gear-shifting operation, but also ensures that the gear-shifting operation is beneficial for good vehicle performance. In other words, a gear-shifting operation may be disabled due to a low power transfer even if there is no risk of gear hunting.

In some embodiments, the step of estimating a power transfer may be based on the estimated road resistance. According to a third aspect of the disclosure, there is provided a vehicle comprising the control unit 10 as was described above, at least one propulsion device, and at least one transmission arrangement. The vehicle may be provided with wheels and/or tracks.

The vehicle has all the advantages that have been described above in conjunction with the method performed by the control unit 10 or a computer connected to the control unit 10 as was described above for controlling a gear-shifting operation of a vehicle.

The at least one propulsion device may be an internal combustion engine, a hydraulic machine or an electrical machine. The propulsion device may be a hybrid propulsion device comprising a number of internal combustion engines, hydraulic machines and/or electrical machines. The electrical machine may work as an electrical motor for propelling the vehicle. The electrical machine may be a generator serving as a braking device. The propulsion device may be arranged within a chassis of the vehicle. Alternatively, the electrical machine may be arranged within the driving wheels. The vehicle may be further provided with at least one energy storage unit in order to provide the propulsion device with energy.

The at least one sensor selected from the group consisting of a torque sensor, a speed sensor, an inclinometer, a load cell, an accelerometer and a force sensor may be connected with the control unit 10 via the communication links 10a, 10b, 10c, 10d, 10e and 10f respectively (Fig. 6).

According to a fourth aspect of the disclosure, there is provided a computer program product comprising instructions which, when executed on at least one processor 11 , cause the at least one processor 11 to carry out the method as was described above for controlling a gear-shifting operation of a vehicle. According to some embodiments herein there is provided a computer program which comprises program code for causing a control unit 10 or a computer connected to the control unit 10 to carry out the method as was described above for controlling a gear- shifting operation of a vehicle.

According to a fifth aspect of the disclosure, there is provided a computer-readable storage medium storing a computer program product comprising instructions which, when executed on at least one processor 11 , cause the at least one processor 11 to carry out the method as was described above for controlling a gear-shifting operation of a vehicle. The computer-readable storage medium may comprise non-volatile memory (NVM) for storing the computer program product.

Although the invention has been described in terms of example embodiments as set forth above, it should be understood that the examples are given solely for the purpose of illustration and are not to be construed as limitations of the claims, as many variations thereof are possible without departing from the scope of the invention. Each feature disclosed or illustrated in the present disclosure may be incorporated in the claims, whether alone or in any appropriate combination with any other feature disclosed or illustrated herein.

Claims

1. A method performed by a control unit (10) for controlling a gear-shifting operation of a vehicle, wherein the vehicle comprises the control unit (10), at least one propulsion device, and at least one transmission arrangement; and wherein the method comprises steps of estimating (101) a road resistance, estimating (104) a power transfer, and determining (105) the gear-shifting operation based on the estimated road resistance and the estimated power transfer.

2. The method according to claim 1, wherein the method further comprises steps of estimating (102) a torque margin or a force margin based on the estimated road resistance, and determining (105) the gear-shifting operation based on the estimated torque margin or the estimated force margin.

3. The method according to claim 2, wherein the method further comprises steps of calculating (103) an acceleration margin based on the estimated torque margin or the estimated force margin, and determining (105) the gear-shifting operation based on the calculated acceleration margin.

4. The method according to any one of the preceding claims, wherein at least one of the steps is performed real-time.

5. The method according to any one of the preceding claims, wherein the step of estimating a road resistance is performed on the basis of a model of computation, and wherein input parameters of the model of computation include torque and speed.

6. The method according to claim 5, wherein the vehicle further comprises at least one sensor, and wherein input parameters of the model of computation further include data received from the at least one sensor of the vehicle.

7. The method according to claim 6, wherein the at least one sensor is a torque sensor, a speed sensor, an inclinometer, a load cell, an accelerometer or a force sensor.

8. A control unit (10) configured to perform the method according to any one of the preceding claims, wherein the control unit (10) is configured to estimate a road resistance, estimate a power transfer, and determine the gear-shifting operation based on the estimated road resistance and the estimated power transfer.

9. The control unit (10) according to claim 8, wherein the control unit (10) is further configured to estimate a torque margin or a force margin based on the estimated road resistance, and determine the gear-shifting operation based on the estimated torque margin or the estimated force margin.

10. The control unit (10) according to claim 9, wherein the control unit (10) is further configured to calculate an acceleration margin based on the estimated torque margin or the estimated force margin, and determine the gear-shifting operation based on the calculated acceleration margin.

11. A vehicle comprising the control unit (10) according to any one of the claims 8 to 10, at least one propulsion device, and at least one transmission arrangement.

12. The vehicle according to claim 11 , wherein the vehicle is a heavy-duty vehicle, a mining or construction machine.

13. The vehicle according to any one of the claims 11 or 12, wherein the vehicle further comprises at least one sensor selected from the group consisting of a torque sensor, a speed sensor, an inclinometer, a load cell, an accelerometer and a force sensor.

14. A computer program product comprising instructions which, when executed on at least one processor (11), cause the at least one processor (11) to carry out the method according to any one of the claims 1 to 7 for controlling a gear-shifting operation of a vehicle.

15. A computer-readable storage medium storing a computer program product comprising instructions which, when executed on at least one processor (11), cause the at least one processor (11) to carry out the method according to any one of the claims 1 to 7 for controlling a gear-shifting operation of a vehicle.