Drive control device, drive control method

Abstract

During the transition period after the end of the backlash section, a large amount of the high-frequency components included in the torque command value can be retained in the final torque value. [Solution] The drive control device generates a final torque value so that the drive torque of a controlled object with a dead zone (backlash) follows the torque command value. In the backlash section, which is the section through which the backlash passes, the final torque value is set to a value different from the torque command value. In the transition period after the end of the backlash section, when the final torque value is changed to the torque command value, the final torque value includes components of the torque command value with a predetermined frequency or higher and an amplitude or higher.

Description

Technical Field

[0001] The present invention relates to a drive control device and a drive control method.

Background Art

[0002] In a vehicle in which power is transmitted from an in-vehicle drive device to wheels and tires provided on the wheels via various gears, the following causes of abnormal noise and deterioration of riding comfort are known. That is, due to the backlash (dead zone) that inevitably exists in the gears, the mechanical connection between the motor and the tire is broken, and the motor side becomes lighter and accelerates suddenly, so that a shock of collision occurs when the gears are re-engaged (crossing the dead zone), resulting in abnormal noise and deterioration of riding comfort. Drive control techniques for suppressing the influence of noise and vibration caused by such a dead zone of gears are known. Patent Document 1 discloses a control device for a vehicle provided with a motor, in which torque output from the motor is transmitted from a drive shaft to drive wheels via a power transmission system, the control device controlling the motor, the control device including a rotation state detection unit that detects a rotation state of the drive shaft, and a dead zone determination unit that determines a dead zone of the power transmission system caused by backlash of a gear provided in the power transmission system based on the rotation state of the drive shaft.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] In the invention described in Patent Document 1, there is room for improvement in the method of determining the final torque value during the transition period after the end of the backlash section.

Means for Solving the Problems

[0005] A drive control device according to a first aspect of the present invention is a drive control device that generates a final torque value so that the drive torque of a controlled object having a dead zone called backlash follows a torque command value, wherein the final torque value is set to a value different from the torque command value in the backlash section, which is the section through which the backlash passes, and in the transition period after the end of the backlash section in which the final torque value is changed to the torque command value, the final torque value includes a component of the torque command value with a predetermined frequency or higher and an amplitude or higher. A second aspect of the present invention is a drive control method executed by a drive control device which is a computer, and includes a torque final value calculation process that generates a torque final value so that the drive torque of a controlled object having a dead zone called backlash follows a torque command value, wherein in the torque final value calculation process, the torque final value is set to a value different from the torque command value in the backlash section which is the section through which the backlash passes, and in the transition period after the end of the backlash section in which the torque final value is changed to the torque command value, the torque final value includes a component of the torque command value with a predetermined frequency or higher with a predetermined amplitude or higher. [Effects of the Invention]

[0006] According to the present invention, in the transition period after the end of the backlash section, a large amount of high-frequency components included in the torque command value can be retained in the final torque value. Other issues, configurations, and effects not mentioned above will be clarified by the following description of the embodiments. [Brief explanation of the drawing]

[0007] [Figure 1] Overall configuration diagram of a vehicle equipped with a drive control system. [Figure 2] Diagram showing the vehicle's drive unit. [Figure 3] Diagram explaining backlash [Figure 4] A diagram showing the effect of backlash on motor rotation. [Figure 5] Figure showing an example of the time progression in a known backlash compensation method. [Figure 6] Figure showing problems of the conventional method shown in FIG. 5 [Figure 7] Figure showing an example of a general solution to the problems shown in FIG. 6 [Figure 8] Figure showing problems of a general backlash exit countermeasure shown in FIG. 7 [Figure 9] Functional block diagram of the drive control device 1 in the first embodiment [Figure 10] Time series diagram of motor torque showing the control result by the drive control device [Figure 11] Time series diagram of motor torque showing the control result by the drive control device [Figure 12] Figure showing the simulation result of the control by the drive control device [Figure 13] Functional block diagram of the drive control device in the second embodiment [Figure 14] Functional block diagram of the drive control device in the third embodiment [Figure 15] Time series diagram of motor torque showing the control result by the drive control device [Figure 16] Functional block diagram of the drive control device in the fourth embodiment [Figure 17] Time series diagram of motor torque showing the control result by the drive control device [Figure 18] Functional block diagram of the drive control device in Modification 1 [Figure 19] Hardware configuration diagram of the drive control device

BEST MODE FOR CARRYING OUT THE INVENTION

[0008] —First Embodiment— Hereinafter, referring to FIGS. 1 to 12, the first embodiment of the drive control device and the drive control method will be described.

[0009] FIG. 1 is an overall configuration diagram of a vehicle 21 equipped with a drive control device 1. The vehicle 21 includes tires 20. In the present embodiment, the symbol FL means the left front wheel, the symbol FR means the right front wheel, the symbol RL means the left rear wheel, and the symbol RR means the right rear wheel. That is, the tires 20 are an aggregate of 20FL, 20FR, 20RL, and 20RR.

[0010] The vehicle 21 includes a motor 22 as a drive device that generates drive torque (driving force) for controlling the acceleration and deceleration of the vehicle 21 in the traveling direction. The drive control device 1 is supplied with electric power from a battery (not shown) mounted on the vehicle body, controls the current of the motor 22, and generates drive torque according to a torque command value described later. Note that this drive torque is the torque final value 8 described later. The drive torque generated by the motor 22 is transmitted to the left drive shaft 24L and the right drive shaft 24R via a differential gear 23. Further, the drive torque is transmitted from the left drive shaft 24L to the left front wheel 20FL and from the right drive shaft 24R to the right front wheel 20FR. By transmitting this drive torque, the drive control device 1 accelerates and decelerates the vehicle 21. Here, the vehicle is described as an electric vehicle equipped with the motor 22, but an engine may be used as the drive device (drive source) instead of the motor 22. Also, here the vehicle is described as a front-wheel drive vehicle, but rear-wheel drive or four-wheel drive may be used.

[0011] The vehicle 21 includes a steering control mechanism 30 for controlling the traveling direction, a brake control mechanism 33, and a traveling control device 25 that calculates command values for the drive control device 1. Hereinafter, the traveling control device 25 may be referred to as a "superior controller" in some cases. The vehicle 21 includes a steering control device 28 that controls the steering control mechanism 30 based on a command value from the traveling control device 25, and a braking control device 35 that controls the brake control mechanism 33 based on the command value and adjusts the brake force distribution of each wheel.

[0012] The drive control device 1, although not shown in detail in Figure 1, includes a power semiconductor (e.g., an IGBT) that controls the current of the motor 22 by switching, a CPU, ROM, RAM, and input / output devices for controlling the switching of the power semiconductor. The ROM stores the drive control flow, which will be explained using Figure 6, etc. As will be described in detail later, the drive control device 1 calculates the motor torque to be generated based on the torque command value 2 received from the travel control device 25 and the motor rotation angle 60 and motor rotation speed 61 obtained by the rotation angle sensor 51 attached to the motor 22 (see Figure 4), and controls the current flowing to the motor 22 by switching the power semiconductor to achieve the motor torque.

[0013] The operation of the brakes on vehicle 21 is described below. When the driver is operating vehicle 21, the force applied by the driver to the brake pedal 32 is amplified by a brake booster (not shown) if necessary, and a master cylinder (not shown) generates hydraulic pressure corresponding to that force. The generated hydraulic pressure is supplied via the brake control mechanism 33 to wheel cylinders 36FL, 36FR, 36RL, and 36RR, which are provided on each wheel. The wheel cylinders 36FL to 36RR consist of a cylinder, piston, pad, disc rotor, etc. (not shown). The piston is propelled by the hydraulic fluid supplied from the master cylinder, and the pad connected to the piston is pressed against the disc rotor. The disc rotor rotates with the wheel. Therefore, the brake torque acting on the disc rotor becomes the braking force acting between the wheel and the road surface. In this way, braking force can be generated on each wheel in response to the driver's brake pedal operation. It should be noted that the brake booster and master cylinder are not essential components of the vehicle 21. Alternatively, the brake pedal 32 and the brake control mechanism 33 may be directly connected, and the brake control mechanism 33 may operate directly when the driver presses the brake pedal 32.

[0014] The braking control device 35, although not shown in detail in Figure 1, includes, for example, a CPU, ROM, RAM, and input / output devices. The braking control device 35 receives inputs such as a combine sensor 34 capable of detecting longitudinal acceleration, lateral acceleration, and yaw rate, wheel speed sensors 31FL, 31FR, 31RL, and 31RR installed on each wheel, sensor signals from a steering angle detection device 39 via a steering control device 28 (described later), and brake force command values ​​from the aforementioned driving control device 25. The output of the braking control device 35 is connected to a brake control mechanism 33 having a pump and control valve (not shown), and can generate any braking force on each wheel independently of the driver's brake pedal operation. The driving control device 25 communicates brake force command values ​​to the braking control device 35, thereby generating any braking force on the vehicle 21, and plays a role in automatically applying brakes in autonomous driving where no driver input is required. However, the braking control device 35 is not an essential component of the vehicle 21, and other actuators such as brake-by-wire may be used.

[0015] The steering operation of vehicle 21 will now be explained. When the driver is operating vehicle 21, the steering torque and steering angle input by the driver via the steering wheel 26 are detected by the steering torque detection device 27 and the steering angle detection device 39, respectively. The steering control device 28 uses the detected steering torque and steering angle to control the steering motor 29 and generate assist torque. Although not shown in detail in Figure 1, the steering control device 28, like the braking control device 35, includes, for example, a CPU, ROM, RAM, and input / output devices. The resultant force of the driver's steering torque and the assist torque from the steering motor 29 moves the steering control mechanism 30, operating the front wheels (FL wheels, FR wheels). Meanwhile, according to the steering angle of the front wheels, the reaction force from the road surface is transmitted to the steering control mechanism 30 and transmitted to the driver as a road reaction force. Note that the steering torque detection device 27 is not an essential component of vehicle 21. The steering control device 28 does not operate when the driver operates the steering wheel 26, and no assist torque is generated; this is a so-called manual steering mechanism.

[0016] The steering control device 28 can generate torque using the steering motor 29 and control the steering control mechanism 30 independently of the driver's steering input. Therefore, the driving control device 25 can control the front wheels to any desired steering angle by communicating steering force command values ​​to the steering control device 28, and plays a role in automatically steering in autonomous driving where there is no driver input. However, the steering control device 28 is not an essential component of the vehicle 21, and other actuators such as steer-by-wire may be used.

[0017] The operation of the accelerator of vehicle 21 will now be explained. The amount the driver depresses the accelerator pedal 37 is detected by the stroke sensor 38, converted into a torque command value 2 by the driving control device 25, and input to the drive control device 1. Although not shown in detail in Figure 1, the driving control device 25 and the drive control device 1 also have components such as a CPU, ROM, RAM, and input / output devices, similar to the braking control device 35. The driving control device 25 controls the motor torque of the motor 22 according to the amount the accelerator pedal 37 is depressed, for example. As a result, the vehicle 21 can be accelerated in response to the driver's accelerator pedal operation.

[0018] Furthermore, the driving control device 25 can command the motor torque of the motor 22 independently of the driver's accelerator operation. Therefore, by communicating the torque command value to the drive control device 1, the driving control device 25 can control the motor torque of the motor 22 to generate any desired acceleration in the vehicle 21, and in autonomous driving where there is no driver input, it plays the role of automatically accelerating. In addition, on slippery road surfaces, it plays the role of slip control (traction control) by changing the torque command value 2 to prevent tire slippage, regardless of the driver's accelerator or brake commands. Note that the vehicle 21 does not necessarily have to be an electric vehicle with an electric motor as its main drive device; it may also have an engine as its main drive device. In this case, the driving control device 25 calculates the throttle opening degree according to the amount the accelerator pedal 37 is pressed, and the drive control device 1 controls the engine operating state to achieve the throttle opening degree.

[0019] As described above, the driving control device 25 calculates command values ​​(brake force command value, steering force command value, torque command value (acceleration command value)) based on signals obtained from various sensors installed on the vehicle 21, and transmits the calculated command values ​​(brake force command value, steering force command value, torque command value (acceleration command value)) to each control device (braking control device 35, steering control device 28, drive control device 1), thereby controlling the braking force, front wheel steering angle, acceleration, etc. of the vehicle 21, and allowing arbitrary control of the driving state of the vehicle 21. In the explanation so far, it has been stated that the vehicle 21 is equipped with a steering wheel 26, accelerator pedal 37, and brake pedal 32, but the vehicle 21 does not have to be equipped with these input devices. In this case, the vehicle 21 becomes a fully autonomous vehicle that does not require driver operation, or a remotely driven vehicle that receives driving commands remotely and drives, and the driving control device 25 plays the role of its brain. In addition, the driving control device 25 may not exist, and the drive control device 1 may calculate (generate) the aforementioned command values.

[0020] To simplify the explanation below, the drive shaft connected to the drive wheel, which is connected to the motor 22 and rotated, will be referred to as the drive shaft 24, the tire mounted on the drive wheel will be referred to as the tire 20, and the wheel speed sensor installed on the drive wheel will be referred to as the wheel speed sensor 31.

[0021] Referring to Figures 2(a) and (b), the drive unit of a vehicle 21, which includes a motor 22, a differential gear 23, a drive shaft 24, etc., will be described. Figure 2(a) is a component diagram of the drive unit. The drive torque generated in the motor 22 is transmitted to the differential gear 23 via the reduction gear 52, and the drive torque is distributed to the left and right wheels by the differential gear 23, and then transmitted to the tires 20 via the drive shaft 24. Figure 2(b) is a physical model of the drive unit. As shown in Figure 2(b), the drive unit includes two inertial components, namely the motor 22 and the tires 20. The motor 22 and the tires 20 are connected by the drive shaft 24, which is a spring element. In other words, the drive unit is represented by a physical model of a two-inertial system. Although not shown in this figure, the tires 20 are in contact with the road surface, and a nonlinear frictional force is generated between the tires 20 and the road surface. Furthermore, the motor 22 is mounted on the vehicle body via a motor mount 53. Since the motor mount 53 typically has an elastic material for shock absorption, a spring element is assumed between the motor 22 and the vehicle body, as shown in Figure 2(b). Hereafter, the motor 22 will be referred to as the motor side, and the tire 20 side (including the inertia of the vehicle 21) will be referred to as the load side.

[0022] Figure 3 illustrates backlash. Gears such as the differential gear 23 and the reduction gear 52 generally have a dead zone called backlash, as shown in Figure 3. Figure 3 is a schematic diagram drawn assuming two spur gears are meshed together, and the backlash, as circled in the figure, indicates the gap intentionally provided in the direction of motion. It is an essential element for smooth and effortless gear rotation, but when the meshing direction of the gears reverses, the mechanical connection between the gears is broken, and when the gears are re-engaged, collisions can occur, which can generate abnormal noise and vibration.

[0023] Figure 4 shows the effect of backlash on the rotation of motor 22. In the two-inertia frame configuration shown in Figure 2, the gear dead zone as shown in Figure 3 is mainly the dead zone element between motor 22 and differential gear 23. In this configuration, if the torque of motor 22 changes in the opposite direction, vibrations at the motor rotation speed 61 as shown in Figure 4 occur. A change in the torque of motor 22 in the opposite direction refers to, for example, a change from a positive value to a negative value, or a change from a negative value to a positive value. Hereafter, the change from a positive value to a negative value or from a negative value to a positive value will be referred to as "zero crossing".

[0024] Figure 4 shows the results of measurements taken in an electric-powered vehicle. The horizontal axis represents time, and the vertical axis, from top to bottom, represents motor rotation speed 61 and motor torque (final torque value 8). The upper figure shows the entire 2-second period, while the lower figure shows a magnified view of the 0.5-1 second period, centered around the time of passing through the dead zone. In the example shown in Figure 4, the driver releases the accelerator at 0 seconds while the vehicle is creeping, and the final torque value 8 is negative, causing the vehicle to decelerate slowly. Subsequently, by gradually pressing the accelerator from 0.5 seconds, the final torque value 8 crosses zero around 0.6 seconds, changing from a negative value to a positive value. Immediately afterward, the gears disengage, the vehicle enters the dead zone, and with only the motor 22's light inertia remaining, the motor rotation speed 61 accelerates rapidly at 0.6-0.7 seconds.

[0025] Subsequently, at 0.7 seconds, the motor reaches the exit of the dead zone, i.e., the meshing position on the opposite side of the gear. During this time, the motor rotation speed increases rapidly, but the tire rotation speed (not shown) does not change much, and a collision occurs due to the relative speed difference between the two, causing the motor rotation speed 61 to vibrate from 0.7 seconds onwards. This vibration is a resonance phenomenon caused by the drive shaft 24 acting as a spring. Alternatively, it may be a resonance phenomenon caused by the spring element of the motor mount 53. Thus, vibrations caused by the mechanical disengagement of the gear occur when passing through the dead zone, and a configuration to reduce this vibration will be explained below.

[0026] Figure 5 shows an example of the time progression in a known backlash compensation method. By applying a known backlash compensation method, the vibration of the motor rotation speed 61 caused by the gear dead zone shown in Figure 4 can be suppressed to some extent. However, this figure is only an example, and other known methods may be used. Figure 5 shows the time progression of (a) motor torque, (b) motor rotation speed, and (c) backlash position 65 from top to bottom, and the three time series graphs are synchronized. Specifically, the dashed line running through Figures 5(a) to (c) represents the same time, from time t1 to t4.

[0027] In Figure 5(a), the dashed line represents the torque command value 2 received from the travel control device 25, and the solid line represents the final torque value 8 after applying a known backlash compensation method (hereinafter also referred to as the "conventional method"). In Figure 5(b), the dashed line represents the motor rotation speed 61' that occurs when no compensation is applied, and the solid line represents the motor rotation speed 61 when the conventional method is applied. In Figure 5(c), the backlash position 65 represents the relative angle of the motor-side gear to the tire-side gear. In Figure 5(c), the negative minimum value is defined when the gear is meshed in the direction of deceleration of the motor 22, the positive maximum value is defined when it is meshed in the direction of acceleration, and the point exactly in between (the center of the dead zone) is defined as 0°. The difference between this negative minimum value and positive maximum value is the backlash width 66. The dashed line represents the backlash position 65' when no compensation is applied, and the solid line represents the backlash position 65 when the backlash compensation method is applied.

[0028] First, in the motor torque shown in Figure 5(a), similar to the behavior in the actual vehicle shown in Figure 4, as the vehicle creeps forward, the driver gradually presses the accelerator, causing the torque command value 2, shown by the dashed line, to gradually increase from a negative value and change from a negative value to a positive value at time t1. From time t1 onward, the time progression of the motor rotation speed 61 shown in Figure 5(b) is recorded, and the reference rotation speed 62, shown by the dashed line, is calculated. Here, at some point after time t1 when the torque command value 2 crosses zero, the gear enters the dead zone region.

[0029] As shown in Figure 5(b) from time t1 onwards, the motor rotation speed 61 increases rapidly, and the speed deviation 63 of the motor rotation speed 61 relative to the reference rotation speed 62 increases. In this figure, the calculation of the reference rotation speed 62 is shown in its simplest form, where the value of the motor rotation speed 61 at time t1 is kept constant. Subsequently, a known compensation method retrieves the speed deviation 63 stored from time t3 to time t2. Then, the speed deviation 63 at the current time t (time t2) is obtained.

[0030] As shown in Figure 5(c), the speed deviation 63 is integrated for each hourly sample from time t3 to time t2 to obtain the time progression of the backlash position 65. Furthermore, based on the speed deviation 63, which is the difference between the motor rotation speed 61 and the reference rotation speed 62 at time t2, and the backlash position 65, a future point in time is set as time t4, and a constant correction torque is calculated. Then, as shown by the solid line from time t2 to time t4 in Figure 5(a), the torque command value 2 is replaced with the aforementioned correction torque from time t2 until it is determined that time t4 or the exit of the dead zone has been reached, to obtain the final torque value 8.

[0031] In the conventional method, the motor torque shown in Figure 5(a) is equivalent to the case where the torque command value 2 is not compensated for at all. From time t2 to time t4, it is replaced by a corrected torque and generated as a final torque value of 8. Focusing on Figure 5(b), in the case without compensation, the motor rotation speed 61' increases rapidly after time t1 as it enters the dead zone. It continues to increase after time t2, immediately reaching a peak, then the rotation speed decreases rapidly, a rebound occurs in the negative direction, and returns to the original speed around time t4. This means that around the time the speed reaches its peak, it reaches the exit of the dead zone and gear meshing (collision) occurs, causing a rapid decrease in speed and vibration due to the spring component of the drive shaft 24 and motor mount 53. In contrast, in the conventional technology, the increase in motor rotation speed after time t2 turns into a gradual (almost linear) deceleration, and returns to the original speed at time t4. There are no sudden speed changes caused by gear meshing (collision) at the exit of the dead zone, nor are there any subsequent vibrations, thus reducing vibrations and abnormal noises that can lead to discomfort for the driver or a decrease in ride comfort.

[0032] The effects described above can also be seen from the time variation of the backlash position in Figure 5(c). Without compensation, the backlash position 65' begins to increase from time t3, and without slowing down, reaches a displacement corresponding to the backlash width 66 after time t2, i.e., near the peak of the motor rotation speed 61', and then changes discontinuously to a constant value. This discontinuous change represents a collision. In contrast, in the conventional method, the rate of increase of the backlash position 65 slows down after time t2, and at time t4 it reaches a displacement corresponding to the backlash width 66, and at the same time the slope becomes almost horizontal and converges continuously. This indicates that no collision is occurring.

[0033] For the purposes of the following explanation, we define the "backlash section" and the "transition period." The backlash section is the section in which the mechanical connection between the gears is broken, and can also be called the "section passing through backlash" or the "period in which the gears are not meshed." In Figure 4, the time period from the dead zone entrance to the dead zone exit, and the state of the gears during that time period, constitute the backlash section. The transition period is the period from immediately after the end of the backlash section until the final torque value 8 approximately matches the torque command value 2. Approximately matches means that the difference between the final torque value 8 and the torque command value 2 may be less than or equal to a predetermined value, or the difference may be less than or equal to a predetermined percentage of the torque command value 2, for example, 5%. For example, in the example shown in Figure 8, the period of the transition period is time t8c.

[0034] Figure 6 shows the problems with the conventional method shown in Figure 5. Similar to Figure 4, Figure 6 shows the results measured on an electric-powered vehicle, with the horizontal axis representing time and the vertical axis representing motor torque (torque command value 2, final torque value 8) and motor rotation speed 61 from top to bottom. Figure 6(a) shows driving without compensation, and Figure 6(b) shows driving with the conventional method shown in Figure 5 applied. In both cases, a 1-second period was extracted from the driving data, with the point of passing through the dead zone being 0.3 seconds from the left. Compared to Figure 4, Figure 6 was measured under conditions where the time rate of change when the positive and negative signs of the torque command value 2 from the higher level were reversed was large. Specifically, in Figure 4, the torque changed by approximately 20 Nm from 0.5 seconds to 1 second, i.e., a time rate of change of 40 Nm / second. In contrast, in Figure 6(a), the change was 45 Nm in 0.1 seconds from around 28.2 seconds, i.e., 450 Nm / second, which is about 10 times faster than the time rate of change in Figure 4.

[0035] In the absence of compensation shown in Figure 6(a), the torque command value 2a and the final torque value 8a are almost identical throughout the entire time. As a result, the motor rotation speed 61a oscillates from around 28.2 seconds, when the sign of the torque command value 2a reverses. On the other hand, in the conventional method shown in Figure 6(b), after passing around 40.45 seconds, when the sign of the torque reverses, the final torque value 8b changes relative to the torque command value 2b around 40.48-40.56 seconds, and the backlash compensation logic is activated. However, from around 40.58 seconds, after the operation of the backlash compensation method has finished, the motor rotation speed 61b oscillates, exhibiting an oscillation with almost the same amplitude as in Figure 6(a). In other words, the vibration reduction effect of the backlash compensation method is limited. The reason for the limited effect is that at the end of the backlash compensation method (40.56 seconds), the final torque value 8b changed in a step-like manner to follow the torque command value 2b. As will be described later, the compensation in this embodiment includes measures taken at the end of the backlash compensation (backlash exit).

[0036] Figure 7 shows an example of a common solution to the problem shown in Figure 6. Figure 7 shows the results of a driving simulation using an electric-powered vehicle model under the same conditions as in Figure 6. Specifically, in Figure 7, the horizontal axis represents time, and the vertical axis, from top to bottom, represents motor torque (torque command value 2, final torque value 8) and motor rotation speed 61. Figure 7(a) shows the conventional method without any special backlash exit countermeasures, i.e., under the same conditions as Figure 6(b), while Figure 7(b) shows the results with a common backlash exit countermeasure. In both cases, the torque command value 2 changes from negative to positive at 0.5 seconds, and the torque changes at a fast rate of change of about 450 Nm / second, similar to Figure 6. Here, a common backlash exit countermeasure is a method of applying a rate limiter, which limits the rate of change of the final torque value 8b to follow the torque command value 2b at the backlash exit to below a predetermined limit threshold. This limit threshold is a fixed value that is set in advance. Hereafter, the limit threshold will also be referred to as the "limit value," "first limit value," "second limit value," etc.

[0037] First, looking at Figure 7(a), a torque change due to the backlash compensation method occurs immediately from 0.5 seconds, and the final torque value 8a changes relative to the torque command value 2a. Subsequently, at 0.6 seconds, backlash compensation ends, and similar to Figure 6(b), the final torque value 8a changes in a step-like manner toward the torque command value 2a, and vibration occurs in the motor rotation speed 61a after 0.6 seconds. On the other hand, in Figure 7(b), after backlash compensation ends at 0.6 seconds, the final torque value 8a changes slowly toward the torque command value 2a at a time rate of change of 40 Nm / second. As a result, the vibration of the motor rotation speed 61b after 0.6 seconds is reduced compared to Figure 6(a). Thus, a rate limiter at the backlash exit is effective as an example of the backlash exit countermeasures described above.

[0038] Figure 8 is a time-series diagram of motor torque illustrating the challenges of the typical backlash exit countermeasures shown in Figure 7. Figure 8 schematically shows the characteristics of torque waveform changes due to typical backlash exit countermeasures. It represents an example of torque change over time, with the horizontal axis representing time and the vertical axis representing torque. The dashed line represents the torque command value 2, and the solid line represents the final torque value 8. Here, at time t8a, the torque command value 2 changes from negative to positive, and after a while, the final torque value 8 changes relative to the torque command value 2 due to the backlash compensation method. Then, at time t8b, it reaches the backlash exit, and thereafter, due to the rate limiter, it changes toward the torque command value 2 at a constant rate of change over time, finally matching the torque command value 2 at time t8c.

[0039] In the example shown in this figure, the torque command value 2 always contains fine vibrations, which suggests that the higher-level controller has added fine vibrations to the torque command value 2 for a specific purpose. This "specific purpose" could be, for example, torque fluctuations (vibration damping control) to reduce the resonance phenomenon mentioned in Figure 3, or torque fluctuations to reduce sprung mass vibrations of the vehicle 21 by utilizing the suspension geometry. In this case, with the backlash exit countermeasure using the rate limiter shown in Figure 8, it can be seen that the fine vibrations (high-frequency components) included in the torque command value 2 after time t8b are not included in the final torque value 8. This is a specification of the rate limiter, and from the perspective of the higher-level controller, from time t8b to time 68c, the fine vibrations (high-frequency components) added to the torque command value 2 for a specific purpose are not included in the final torque value 8, and the control effect cannot be achieved. Furthermore, if the torque fluctuations added by the higher-level controller have a feedback loop, this rate limiter may temporarily destabilize the feedback control.

[0040] Figure 9 is a functional block diagram of the drive control device 1. Control by this drive control device 1 can solve the problems shown in Figure 8, as will be described later. The drive control device 1 includes a torque command acquisition unit 3, a rotational speed calculation unit 4, a backlash compensation unit 5, a high-frequency extraction unit 6, and a torque change rate limiting unit 7.

[0041] The torque command acquisition unit 3 receives a torque command value 2 from the driving control device 25, which is a higher-level controller. The torque command value 2 is a command value for generating motor torque in the motor 22 in order to generate a predetermined acceleration in the vehicle 21. For example, when the driver is pressing the accelerator pedal 37, the torque command value 2 is received as a positive value to accelerate the vehicle 21. When the driver is not pressing the accelerator pedal 37, or when the brake pedal 32 is pressed, the torque command value 2 is received as a negative value corresponding to regenerative braking or engine braking. Generally, digital communication such as CAN (Controller Area Network) is used to receive the torque command value 2 from the driving control device 25. As mentioned above, it is also possible that the driving control device 25 does not exist, and the drive control device 1 calculates or generates the aforementioned command value.

[0042] The rotation speed calculation unit 4 calculates the motor rotation speed 61 by differentiating the motor rotation angle 60 obtained by the rotation angle sensor 51 attached to the motor 22 with respect to time (calculating the amount of change per unit time). The rotation angle sensor 51 is generally an encoder, resolver, or other sensor capable of obtaining the absolute angle of the motor 22.

[0043] The backlash compensation unit 5 uses the torque command value 2 obtained by the torque command acquisition unit 3 and the motor rotation speed 61 obtained by the rotation speed calculation unit 4 to perform backlash compensation when the torque is reversed. Here, the method described above in Figure 5 may be used, or the prior art described in Patent Document 1 may be applied using a known method based on conditions such as the availability of the tire rotation speed. If backlash compensation is not performed, the torque command value 2 is output as is.

[0044] The high-frequency extraction unit 6 extracts high-frequency components 70 from the torque command value 2 from time t8b to time t8c in Figure 8, after the backlash compensation unit 5 has performed backlash compensation, until the final torque value 8 matches the torque command value 2. During other time periods, it outputs 0. In extracting high frequencies, in order to reliably remove the low-frequency offset component, the final torque value 8 at time t8b is subtracted from the torque command value 2, and then high-frequency components are extracted using a filter or the like. As a method for extracting high-frequency components, for example, a commonly used first-order high-pass filter F(s), as shown in Equation 1 below, can be applied.

[0045] F(s) = s / (s + ωc) ... (Equation 1)

[0046] However, in Equation 1, s is the Laplace operator and ωc is the cutoff frequency.

[0047] The torque change rate limiting unit 7 limits the torque change rate as follows, from the time t8b to the time t8c in Figure 8, after the backlash compensation unit 5 has performed backlash compensation, until the final torque value 8 matches the torque command value 2. Specifically, the torque change rate limiting unit 7 calculates a torque such that the time change rate from the final torque value 8 at time t8b toward the torque command value 2 is within a predetermined limit threshold, using the aforementioned rate limiter or low-pass filter as a low-frequency component 71. During other time periods, the output of the backlash compensation unit 5 is output as is without time change rate limitation.

[0048] The drive control device 1 obtains a final torque value 8 by adding the high-frequency components 70 extracted by the high-frequency extraction unit 6 and the low-frequency components 71 calculated by the torque change rate limiting unit 7. Then, it performs current control on the motor 22, which is the target of control, to generate a drive torque according to the final torque value 8. Since the final torque value 8 includes the high-frequency components 70, which are in the high-frequency range of the torque command value 2, i.e., components above a predetermined frequency, it can also be said that the final torque value includes components above a predetermined frequency of the torque command value 2 with an amplitude or greater.

[0049] Figures 10 and 11 are time-series diagrams of motor torque showing the control results by the drive control device 1. Figure 10 is a time waveform showing the control results of the drive control device 1 in a case similar to Figure 8. The same parts as in Figure 8 will not be explained. The difference from Figure 8 is the final torque value 8 from time t8b to time t8c. In Figure 8, the time waveform was a straight line without vibration due to the effect of the rate limiter, but in Figure 10, from time t8b to time t8c, the fine vibrations included in the torque command value 2 are also included in the final torque value 8. In Figure 10, these "fine vibrations" are illustrated as the shape of two peaks. That is, a predetermined time rate of change due to the rate limiter is applied to the final torque value 8, and components of the torque command value with a predetermined frequency or higher are included with a certain amplitude. In this way, the drive control device 1 can solve the problem of the conventional technology shown in Figure 8, where "fine vibrations (high-frequency components) added to the torque command value 2 for a certain purpose are not carried over to the final torque value 8".

[0050] Figure 11 is an explanatory diagram showing the time waveforms of the high-frequency component 70 and the low-frequency component 71, separated from the behavior in Figure 10. Sections similar to those in Figure 10 are omitted from explanation. The upper part of Figure 11 represents the low-frequency component 71, with the dotted line representing the torque command value 2 and the solid line representing the low-frequency component 71. The relationship between these two is the same as the relationship between the torque command value 2 and the final torque value 8 shown in Figure 8 when there is no backlash exit countermeasure. That is, at time t8b, the rate of change (convergence) of the low-frequency component 71 is limited by the rate limiter relative to the torque command value 2, and it only follows the torque command value 2 at time t8c. In other words, the convergence of the low-frequency component is low.

[0051] On the other hand, the lower part of Figure 11 shows the waveform of the high-frequency component 70. As mentioned above, the high-frequency component is extracted from the torque command value 2 only between time t8b and time t8c, and the high-frequency component 70 is zero at all other times. The dotted line shows an image of the added torque 72 added to the torque command value 2 in the higher-level controller. This waveform would normally be impossible to obtain separately because it is added together as the torque command value 2 inside the drive control device 1, but the high-frequency extraction unit 6 of the drive control device 1 can extract almost the same waveform as the high-frequency component 70. In other words, the high-frequency component of the torque command value 2 follows the added torque 72 in the higher-level controller, which is the command value, with higher convergence than the low-frequency component mentioned above.

[0052] Figure 12 shows the simulation results of control by the drive control device 1. Figure 12 shows the results of a driving simulation using an electric drive vehicle model, under the same conditions as Figure 7(b), but with the road surface friction coefficient changed to an icy road setting of 0.1. The horizontal axis represents time, and the vertical axis, from top to bottom, represents motor torque (torque command value 2, final torque value 8), motor rotation speed 61, and tire rotation speed 73. Figure 12(a) shows the control results of a general backlash exit countermeasure similar to Figure 7(b), and Figure 12(b) shows the control results by the drive control device 1. Here, a high-pass filter with a cutoff frequency ωc = 1 Hz is applied in the high-frequency extraction unit 6. This cutoff frequency is a parameter that indicates what high-frequency components above which are mainly extracted, and is set as a guideline, for example, the maximum frequency that can be generated by the driver's accelerator work. Other parts that are the same as in Figure 7 are omitted from explanation.

[0053] Unlike Figure 7, in this figure, the road surface friction coefficient is very small, so when the motor torque exceeds approximately 20 Nm, tire slip occurs and the motor rotation speed 61 and tire rotation speed 73 increase. As a result, the torque command value 2 from the higher-level controller detects the increase in tire rotation speed 73 and begins to decrease at around 1.25 seconds, decreasing linearly at a constant rate of change until it reaches 0.

[0054] In Figure 12(a), although the torque command value 2 begins to decrease around 1.25 seconds, the final torque value 8a continues to increase until time t8c. This is due to the rate limit specification as described above in Figure 8, and from the perspective of the higher-level controller, the following problem occurs from 1.25 seconds to time t8c: Although the torque command value 2 is changed in the negative direction to prevent tire slippage, the final torque value 8 does not change, and the tire slip prevention effect cannot be achieved.

[0055] In contrast, Figure 12(b) shows that when the torque command value 2 begins to decrease at 1.25 seconds, this change is extracted as a high-frequency component and added to the final torque value 8b. It is shown that the final torque value 8b begins to decelerate before time t8c, from 1.25 seconds, and continues to decrease ahead of the torque command value 2 even after time t8c. As an effect, focusing on the motor rotation speed 61 around 1.5 seconds, the control by the drive control device 1 (60b) suppresses the increase in rotation speed due to slip compared to the general method (60a). The same is true for the tire rotation speed 73. In other words, by extracting the high-frequency component, the drive control device 1 can appropriately include the torque fluctuation added intentionally by the higher-level controller in the final torque value 8, and this effect can be obtained even between times t8b and t68c.

[0056] In this embodiment, the case where the zero crossing occurs from negative to positive has been described, but the same applies to the case where it occurs from positive to negative. In this case, the rate limiter of the torque change rate limiting unit 7 is applied in the negative direction, not the positive direction.

[0057] According to the first embodiment described above, the following effects and advantages can be obtained. (1) The drive control device 1 generates a final torque value 8 so that the drive torque of the controlled object, which has a dead zone called backlash, follows the torque command value 2. In the backlash section, which is the section through which the backlash passes, the drive control device 1 sets the final torque value 8 to a value different from the torque command value 2. Furthermore, in the transition period after the end of the backlash section when the drive control device 1 changes the final torque value 8 to the torque command value 2, the final torque value 8 contains components of the torque command value with a predetermined frequency or higher and an amplitude or higher. Therefore, in the transition period after the end of the backlash section, a large amount of the high-frequency components included in the torque command value can be retained in the final torque value. This is expected to prevent interference with the higher-level controller.

[0058] (2) In the transition period, the final torque value shows that the high-frequency components converge more readily than the low-frequency components. Therefore, adverse effects on the higher-level controller are suppressed.

[0059] (3) As shown in Figure 9, the drive control device 1 has a high-frequency extraction unit 6 that extracts a high-frequency component 70 from the torque command value 2 in the transition section, and a torque change rate limiting unit 7 adds the aforementioned high-frequency component 70 to the low-frequency component 71, which is a value obtained by limiting the rate of change of the torque command value 2 over time, to obtain the final torque value 8.

[0060] (Modification 1 of the first embodiment) In the first embodiment described above, the high-frequency components 70 extracted by the high-frequency extraction unit 6 were not restricted in any way and were added together with the output of the torque change rate limiting unit 7. However, the final torque value 8 may also be obtained by adding together the value obtained by restricting the time rate of change of the high-frequency components 70 extracted by the high-frequency extraction unit 6 and the output of the torque change rate limiting unit 7. However, even in this case, the restriction on the high-frequency components 70 is set to be looser than the restriction on the low-frequency components 71.

[0061] The threshold value used by the torque change rate limiting unit 7 to limit the time rate of change of the low-frequency component 71 is called the "first limit value," and the threshold value used to limit the time rate of change of the high-frequency component 70 is called the "second limit value." In this case, the second limit value is greater than the first limit value. The first embodiment can also be described as a case where the second limit value is set to infinity.

[0062] The following effects can be obtained with this modified version. (4) The drive control device 1 extracts high-frequency components 70 from the torque command value 2 in the transition section, and sets the final torque value 8 as the value obtained by adding a time rate of change restriction to the torque command value 2 and the value obtained by adding a time rate of change restriction to the aforementioned high-frequency components 70. Therefore, although not to the same extent as the low-frequency components, by adding a time rate of change restriction to the high-frequency components 70, the fluctuation of the final torque value 8 can be reduced.

[0063] (Modification 2 of the first embodiment) In the modified example 1 described above, the input to the torque change rate limiting unit 7 was the torque command value 2. However, a low-frequency extraction unit may be newly provided before the torque change rate limiting unit 7, and only the low-frequency region of the torque command value 2 may be explicitly extracted and used as the input to the torque change rate limiting unit 7. Hereafter, the extracted low-frequency region of the torque command value 2 will also be referred to as the "first torque component." In this modified example, the threshold value at which the torque change rate limiting unit 7 limits the time rate of change of the first torque component will be referred to as the "first limit value." The definition of the second limit value is the same as in the modified example 1 described above, and the relationship between the first limit value and the second limit value is also the same as in the modified example 1.

[0064] The drive control device 1 determines the final torque value 8 as the sum of a first torque-modified component obtained by changing the first torque component while limiting its rate of change over time to a first limit value, and a second torque-modified component obtained by changing the second torque component while limiting its rate of change over time to a second limit value.

[0065] The following effects can be obtained with this modified version. (5) The drive control device 1 divides the torque command value 2 in the transition section into a first torque component, which is a low-frequency component, and a high-frequency component 70. The final torque value in the transition section is the sum of the first torque modified component, which is obtained by applying the first rate of change over time to the first torque component, and the second torque modified component, which is obtained by applying the second rate of change over time to the high-frequency component 70. The first rate of change over time is slower than the second rate of change over time.

[0066] —Second Embodiment— Referring to Figure 13, a second embodiment of the drive control device and drive control method will be described. In the following description, the same reference numerals are used for components that are the same as in the first embodiment, and the differences will be mainly explained. Points that are not specifically explained are the same as in the first embodiment. This embodiment differs from the first embodiment mainly in that the high-frequency components of the torque command value 2 are also input to the drive control device 1A. That is, in the first embodiment, the drive control device 1 is given only the torque command value 2 from the higher-level controller, and the drive control device 1A separates the torque command value 2 into low-frequency and high-frequency components. In this embodiment, both can be acquired separately, and the same effect can be obtained without the drive control device 1 performing frequency-based extraction.

[0067] Figure 13 is a functional block diagram of the drive control device 1A in the second embodiment. The difference from the drive control device 1 in the first embodiment is that the high-frequency extraction unit 6 has been changed to an output switching unit 6A. The torque command acquisition unit 3 receives a torque command value 2 from the driving control device 25, which is a higher-level controller. This torque command value 2 is a command value for generating motor torque in the motor 22 in order to generate a predetermined acceleration in the vehicle 21.

[0068] In this process, the main torque command value 2s, which primarily determines the acceleration and deceleration of the vehicle and is caused by the driver's accelerator and brake operation, and the high-frequency torque command value 2t, which is a component in which the higher-level controller has intentionally varied the torque command value 2, are acquired separately. That is, the torque command value 2 in the first embodiment is the sum of the main torque command value 2s and the high-frequency torque command value 2t in this embodiment. Hereafter, the main torque command value 2s may be referred to as the "first torque component," and the high-frequency torque command value 2t as the "second torque component." However, the first torque component defined here differs from the definition in Modification 2 of the first embodiment.

[0069] The backlash compensation unit 5 uses the sum of the main torque command value 2s and the high-frequency torque command value 2t acquired by the torque command acquisition unit 3, and the motor rotation speed 61 to perform backlash compensation when the torque is reversed. Other behaviors of the backlash compensation unit 5 are the same as in the first embodiment.

[0070] The output switching unit 6A outputs the high-frequency torque command value 2t as a high-frequency component 70 from time t8b to time t8c in Figure 8, after the backlash compensation unit 5 has performed backlash compensation, until the final torque value 8 matches the torque command value 2. When the final torque value 8 matches the torque command value 2, the output switching unit 6A sets its output to zero. In other words, the output switching unit 6A does not include any filters or other devices to extract frequency components and functions simply as a switch.

[0071] The torque change rate limiting unit 7 performs the following processing from time t8b to time t8c in Figure 8, after the backlash compensation unit 5 has performed backlash compensation, until the final torque value 8 matches the sum of the torque command value 2 and the high-frequency torque command value 2t. Specifically, the torque change rate limiting unit 7 calculates a torque as a low-frequency component 71 from the final torque value 8 at time t8b, targeting the sum of the torque command value 2 and the high-frequency torque command value 2t, such that the time rate of change is within a predetermined limit threshold, by applying the aforementioned rate limiter, low-pass filter, etc. During other time periods, the output of the backlash compensation unit 5 is output as is without limiting the time rate of change. The output of the output switching unit 6A and the output of the torque change rate limiting unit 7 are then added together to obtain the final torque value 8.

[0072] According to the second embodiment described above, the following effects and advantages can be obtained. (6) The torque command acquisition unit 3 of the drive control device 1A separately acquires the main torque command value 2s and the high-frequency torque command value 2t, which are parts of the torque command value 2 determined by multiple means. The final torque value 8 is obtained by adding the low-frequency component 71 and the high-frequency component 70, which are values ​​obtained by setting the same time rate of change limit value for each of the main torque command value 2s and the high-frequency torque command value 2t in the transition section. Therefore, the individually obtained high-frequency torque command value 2t is included in the final torque value 8 without any restrictions, so interference with the higher-level controller can be prevented more reliably with respect to the high-frequency torque command value 2t.

[0073] (Modified version of the second embodiment) In the second embodiment described above, the high-frequency torque command value 2t was added to the low-frequency component 71 without any restrictions. However, a limit on the rate of change over time may also be applied to the high-frequency torque command value 2t. In this case as well, however, the limit on the high-frequency component is set more loosely than the limit on the low-frequency component, allowing for larger changes in the high-frequency component. In other words, the limit on the rate of change over time of the low-frequency component is smaller than the limit on the rate of change over time of the high-frequency component, and the limit on the rate of change over time of the high-frequency component is larger than the limit on the rate of change over time of the low-frequency component.

[0074] According to this modified version, the following effects can be obtained. (7) The drive control device 1A separately acquires a first torque command value and a second torque command value, which are parts of the torque command value 2 determined by multiple means. In the transition interval, different time rate of change limits are set for each of the first torque command value and the second torque command value, and they are changed and added together to obtain the final torque value 8.

[0075] —Third Embodiment— A third embodiment of the drive control device and drive control method will be described with reference to Figures 14 and 15. In the following description, the same reference numerals are used for components that are the same as in the first embodiment, and the differences will be mainly explained. Points that are not specifically explained are the same as in the first embodiment. This embodiment differs from the first embodiment mainly in that it does not have a high-frequency extraction unit 6. In the first embodiment, a method of extracting high-frequency components using a high-pass filter and adding them was shown, but depending on the control application of the higher-level controller, there is a concern that applying a high-pass filter in the middle of the control loop may reduce control performance or affect control stability. Therefore, instead of using a high-pass filter, the limit threshold, which is the rate limit applied to the torque change rate limiting unit 7, is changed according to the characteristics of the torque command value 2.

[0076] Figure 14 is a functional block diagram of the drive control device 1B in the third embodiment. The differences from the drive control device 1 in the first embodiment are that it does not have a high-frequency extraction unit 6, and the torque change rate limiting unit 7 has been changed to a torque change rate limiting unit 7a.

[0077] The torque change rate limiting unit 7a calculates a torque such that the rate of change over time is within a predetermined range, using the rate limiter and low-pass filter described above, after the backlash compensation unit 5 has performed backlash compensation, until the final torque value 8 matches the torque command value 2. At this time, the torque change rate limiting unit 7a extracts the amplitude of frequency components above a predetermined level in the torque command value 2, and the larger the amplitude, the smaller the limit threshold for the rate of change over time. In other words, while the limit threshold in the first embodiment was a fixed value, in this embodiment the limit threshold is a variable value. The torque change rate limiting unit 7a then controls the torque so that it follows the torque more quickly than when the amplitude of high-frequency components is small, if the amplitude of high-frequency components is large in the torque command value 2.

[0078] Figure 15 is a time-series diagram of motor torque showing the control results by the drive control device 1B. Figure 15 shows two cases with different high-frequency components in the torque command value 2. The torque command value 2p shown in Figure 15(a) has few high-frequency components, while the torque command value 2q shown in Figure 15(b) has many high-frequency components.

[0079] In Figure 15(a), the torque command value 2p is shown linearly because it has few high-frequency components. The torque change rate limiting unit 7a significantly limits the time rate of change of the final torque value 8a, so that the final torque value 8a changes relatively slowly from time t8b to time t8c, following the torque command value 2p. On the other hand, the torque command value 2q in Figure 14(b) has more high-frequency components than the torque command value 2p mentioned above. The torque change rate limiting unit 7 allows for a faster change by loosening the time rate of change of the final torque value 8b compared to Figure 15(a), so that the final torque value 8b follows the torque command value 2q at time t8cp, which is earlier than time t8c. This shortens the time it takes for the high-frequency components superimposed on the torque command value 2q to be removed, allowing the control objectives of the higher-level controller to be achieved earlier.

[0080] According to the third embodiment described above, the following effects and advantages can be obtained. (8) In the transition section, the drive control device 1B changes the time rate of change limit of the final torque value 8 based on the amount of high-frequency components contained in the torque command value 2. Specifically, as shown in Figure 15, if there are many high-frequency components in the torque command value 2, the time rate of change limit of the final torque value 8 is set to be larger, i.e., the limit is looser. Therefore, by changing only the time rate of change of the rate limit without using a high-pass filter, interference with the higher-level controller can be prevented while reducing the impact on control stability.

[0081] —Fourth Embodiment— A fourth embodiment of the drive control device and drive control method will be described with reference to Figures 16 and 17. In the following description, the same reference numerals are used for components that are the same as in the first embodiment, and the differences will be mainly explained. Points that are not specifically explained are the same as in the first embodiment. This embodiment differs from the first embodiment mainly in that it achieves both time rate of change limiting and high-frequency component addition without using rate limits or filters.

[0082] Figure 16 is a functional block diagram of the drive control device 1C in the fourth embodiment. The differences from the drive control device 1 in the first embodiment are that it does not have a high-frequency extraction unit 6, and the torque change rate limiting unit 7 has been changed to a torque change rate limiting unit 7b.

[0083] The torque change rate limiting unit 7b stores the final torque value at the end of backlash compensation after the backlash compensation unit 5 has performed backlash compensation, until the final torque value 8 matches the torque command value 2. The final torque value 8 is calculated by weighting the stored final torque value and the current torque command value 2. By continuously changing the weights over time, the rate of change of torque over time is limited, and as the weights approach the torque command value 2, the high-frequency components of the torque command value 2 are reflected in the final torque value 8. The final torque value at the end of backlash compensation is T mblcomp , the current torque command value is 2 T mref If we set it so that the final torque value T m For example, it is set as shown in Equation 2 below.

[0084] T m = λ T mref + (1-λ)T mblcomp ...(Formula 2)

[0085] In equation 2, λ represents the weight. λ is a real number between 0 and 1 (inclusive). If λ is 0, the final torque value matches the final torque value at the end of backlash compensation; if λ is 1, the final torque value matches the torque command value of 2. λ will also be referred to as weight 74 below.

[0086] Figure 17 is a time-series diagram of motor torque showing the control result by the drive control device 1C. This figure shows an example of torque waveform change in a case similar to Figure 10. The upper panel shows the time progression of the torque command value 2 and the final torque value 8, and the lower panel shows the time progression of the weight 74(λ). Similar to Figure 10, the torque command value 2b always contains fine vibrations and high-frequency components. The torque change rate limiting unit 7b sets the final torque value 8 at time t8b, when backlash compensation is completed, to T mblcomp This is stored in memory, and the final torque value 8 is calculated using Equation 2 from time t8b to time t8c.

[0087] The time progression of weight 74 is increased at a constant rate of change, starting from 0 at time t8b and becoming 1 at time t8c, as shown in the lower part of Figure 15, for example. As a result, the final torque value 8 gradually follows the torque command value 2 from time t8b to time t8c, and coincides with the torque command value 2 at time t8c. On the other hand, when comparing with Figure 10, the high-frequency components are not very visible in the final torque value 8 of the two peaks shown as an example of fine oscillations of the torque command value 2 from time t8b to time t8c. The first peak (closer to time t8b) is not very visible in the final torque value 8, while the second peak (closer to time t8c) is visible. Thus, as time approaches t8c, the final torque value 8 contains more high-frequency components of the torque command value 2.

[0088] According to the fourth embodiment described above, the following effects and advantages can be obtained. (9) As shown in Equation 2, the drive control device 1C calculates the final torque value Tm in the transition section as a weighted sum of the torque command value and the final torque value at the end of the backlash section. As shown in the lower part of Figure 17, the drive control device 1C increases the weight 74 of the torque command value over time. Therefore, it is possible to achieve both backlash exit countermeasures and interference prevention with the higher-level controller without using a rate limiter.

[0089] (Variation 1) Figure 18 is a functional block diagram showing the case where the drive control device 1 includes a vibration damping control function. The drive control device 1 shown in this figure includes a vibration damping control unit 9 that has a vibration damping control function. For example, the vibration damping control unit 9 takes a torque command value 2 and a motor rotation speed 61 as inputs and suppresses vibrations by adding a torque with the opposite phase to the vibration component due to resonance phenomena. The backlash compensation unit 5 then receives the torque with the aforementioned torque with the opposite phase added as a torque command value 2x and executes a backlash compensation method. The high-frequency extraction unit 6 also receives a torque command value 2x instead of a torque command value 2. With this configuration, the operation of the backlash compensation method is not affected by torque fluctuations by the vibration damping control unit 9, and the vibration suppression effect of the vibration damping control unit 9 can be obtained again when backlash compensation is completed. Note that although an example of adding a vibration damping control function to the configuration of the first embodiment has been described here, it can be similarly applied to the second to fourth implementations.

[0090] (Modification 2) Figure 19 is a hardware configuration diagram of the drive control device 1. In the embodiments described above, the hardware configuration of the drive control device 1 was not shown in the drawings. The drive control device 1 may be implemented with the following hardware configuration. The drive control device 1 includes a CPU 41 which is a central processing unit, a ROM 42 which is a read-only storage device, a RAM 43 which is a read-write storage device, an input / output device 44 which is a user interface, and a communication device 45. The CPU 41 performs the various calculations described above by loading the program stored in the ROM 42 into the RAM 43 and executing it.

[0091] The drive control device 1 may be implemented using a rewritable logic circuit such as an FPGA (Field Programmable Gate Array) or an application-specific integrated circuit such as an ASIC (Application Specific Integrated Circuit) instead of the combination of CPU 41, ROM 42, and RAM 43. Alternatively, the drive control device 1 may be implemented using a different configuration, such as a combination of CPU 41, ROM 42, RAM 43 and FPGA, instead of the combination of CPU 41, ROM 42, and RAM 43.

[0092] The input / output device 44 is, for example, a liquid crystal display, a keyboard, or a push button. The user may use the input / output device 44 to set various fixed values, such as the frequency that defines high-frequency components or a value that limits the rate of change over time. However, the input / output device 44 is not a mandatory component, and the drive control device 1 does not need to have an input / output device 44. The communication device 45 is a communication module that enables communication between the drive control device 1 and other devices mounted on the vehicle 21. Although Figure 19 shows the drive control device 1 as being composed of a single hardware device for convenience, the drive control device 1 may be composed of multiple hardware devices. In this case, the hardware devices may be installed adjacent to each other, or they may be connected via a local area network or the internet.

[0093] (Variation 3) In the embodiments described so far, the vehicle 21 equipped with the drive control device 1 was an electric vehicle powered by an electric drive motor, but it is not limited to this. The drive control device 1 can be applied to any vehicle in which power is transmitted to the tires via a thin shaft such as a drive shaft, regardless of the power source. For example, it can be applied to engine cars, hybrid vehicles, construction machinery (such as mining dump trucks), and small mobility vehicles such as single-seater minicars. Furthermore, instead of distributing power to the left and right wheels via a differential gear, electric motors may be mounted independently on the left and right sides, and each may transmit power to the left and right wheels via a shaft.

[0094] It should be noted that the present invention is not limited to the embodiments and modifications described above, but includes various modifications. For example, the embodiments described above are described in detail to make the present invention easier to understand, and are not necessarily limited to those having all the configurations described. Furthermore, it is possible to replace parts of the configuration of one embodiment with the configuration of another embodiment, and it is also possible to add configurations from other embodiments to the configuration of one embodiment. In addition, it is possible to add, delete, or replace parts of the configuration of each embodiment with other configurations.

[0095] Furthermore, each of the above configurations, functions, processing units, and processing means may be implemented in hardware, either partially or entirely, for example, by designing them as integrated circuits. Alternatively, each of the above configurations and functions may be implemented in software by having the processor interpret and execute programs that realize each function. Information such as programs, tables, and files that realize each function can be stored in memory, storage devices such as hard disks and SSDs (Solid State Drives), or recording media such as IC cards, SD cards, and DVDs. Also, control lines and information lines are shown only if deemed necessary for explanation, and not all control lines and information lines are necessarily shown in the actual product. In practice, it can be assumed that almost all configurations are interconnected.

[0096] In the embodiments and modifications described above, the configuration of the functional blocks is merely an example. Several functional configurations shown as separate functional blocks may be integrated, or a configuration represented in one functional block diagram may be divided into two or more functions. Furthermore, some of the functions of one functional block may be provided by other functional blocks.

[0097] In the embodiments and modifications described above, the program is stored in ROM 42, but the program may be stored in a non-volatile storage device (not shown). Furthermore, the drive control device may have an input / output interface (not shown), and the program may be read from another device via a medium available to the input / output interface and the drive control device when needed. Here, the medium refers to, for example, a storage medium detachable from the input / output interface, or a communication medium, i.e., a wired, wireless, optical network, or a carrier wave or digital signal propagating through such a network. Also, some or all of the functions realized by the program may be realized by hardware circuits or an FPGA. [Explanation of symbols]

[0098] 1: Drive control device 2: Torque command value 5: Backlash Compensation Section 6: High frequency extraction section 6A: Output switching section 7: Torque change rate limiting unit 8: Final Torque Value 70: High-frequency components 71: Low-frequency components 74: Weight

Claims

1. In a drive control device that generates a final torque value so that the drive torque of a controlled object, which has a dead zone of backlash, follows the torque command value, A drive control device that sets the final torque value to a value different from the torque command value in a backlash section, which is a section through which the backlash passes, and in a transition period after the end of the backlash section in which the final torque value is changed to the torque command value, the final torque value includes components of the torque command value with a predetermined frequency or higher and an amplitude or higher.

2. In the drive control device according to claim 1, The final torque value during the transition period is determined by a drive control device in which the high-frequency component converges more readily than the low-frequency component.

3. In the drive control device according to claim 1, A drive control device that extracts a high-frequency component from the torque command value in the transition interval, and takes the value obtained by adding the high-frequency component to the torque command value, which is changed while limiting the rate of change over time, as the final torque value.

4. In the drive control device according to claim 1, A drive control device that separately acquires a first torque command value and a second torque command value, which are parts of the torque command value determined by multiple means, and obtains the final torque value by adding the second torque command value to the value obtained by changing each of the first torque command value and the second torque command value by setting the same time rate of change limit value for each in the transition interval.

5. In the drive control device according to claim 1, The torque command value in the transition interval is divided into a first torque component, which is a low-frequency component, and a second torque component, which is a high-frequency component. The final torque value in the transition interval is the sum of a first torque-modified component obtained by changing the first torque component while limiting its rate of change over time to a first limit value, and a second torque-modified component obtained by changing the second torque component while limiting its rate of change over time to a second limit value. A drive control device in which the first limit value is smaller and has a stricter limit than the second limit value.

6. In the drive control device according to claim 1, A drive control device that separately acquires a first torque command value and a second torque command value, which are parts of the torque command value determined by multiple means, and sets different time-varying limit values ​​for each of the first torque command value and the second torque command value in the transition interval, changes them, and adds them together to obtain the final torque value.

7. In the drive control device according to claim 1, A drive control device that, in the transition interval, changes the limit value of the time rate of change of the final torque value based on the amount of high-frequency components included in the torque command value.

8. In the drive control device according to claim 1, A drive control device wherein the final torque value in the transition interval is a weighted sum of the torque command value and the final torque value at the end of the backlash interval, and the weight of the torque command value is increased over time.

9. A drive control method performed by a drive control device which is a computer, The process includes a final torque value calculation process that generates a final torque value so that the drive torque of the controlled object, which has a dead zone (backlash), follows the torque command value. A drive control method comprising the following steps: in the torque final value calculation process, the torque final value is set to a value different from the torque command value in the backlash section, which is the section through which the backlash passes; and in the transition period after the end of the backlash section, the torque final value includes a component of the torque command value with a predetermined frequency or higher and an amplitude or higher.

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