JP2008141875A - Running system and drive control device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To suppress degradation in the running stability of a vehicle and obtain the intended turning performance of the vehicle even when there is a disturbance to the vehicle. <P>SOLUTION: The running system 100 is mounted in a vehicle 1 and causes the vehicle 1 to run. The running system 100 includes four driving wheels and the driving force of each driving wheel can be independently varied. Power applied to each driving wheel is adjusted by a drive control device 30 so that the rotational speed of each driving wheel becomes equal to a target rotational speed determined based on the turning radius of the vehicle 1. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a traveling device capable of independently changing the driving force of at least two driving wheels.

  Improving the turning performance of a vehicle such as a passenger car, a truck, or a bus is important for improving the running performance of the vehicle. In recent years, a technique for improving the turning performance of a vehicle by controlling the driving force of driving wheels while the vehicle is turning has been put into practical use. For example, in Patent Document 1, when a slip of a wheel is detected, the torque of a wheel that has slipped or a wheel that is paired with a slipped wheel is reduced, so that a yaw rate sensor, a slip angle sensor, etc. A technique for performing vehicle turning control without using a vehicle is disclosed.

JP, 2006-166572, A Paragraph number 0005, FIG. 1, FIG.

  However, in the technique disclosed in Patent Document 1, when the torque of a wheel is reduced due to the occurrence of slip, another wheel, for example, a wheel paired with a reduced torque wheel passes. Depending on the frictional state of the road surface, understeer or oversteer may occur. As a result, the drivability may be affected or the steering stability of the vehicle may be affected, and the planned turning performance may not be exhibited.

  Thus, the technique disclosed in Patent Document 1 may reduce the stability of the vehicle when a disturbance to the vehicle such as a change in the frictional state of the road surface occurs. Therefore, the present invention has been made in view of the above, and a traveling device and a drive control device that can ensure turning performance of a vehicle while suppressing a decrease in traveling stability of the vehicle even when there is a disturbance to the vehicle. The purpose is to provide.

  In order to solve the above-described problems and achieve the object, the present inventors have conducted extensive research, and as a result, focused on the fact that the attitude of the vehicle is determined by the rotational speed of the drive wheels, and completed the present invention. . That is, the traveling device according to the present invention includes a plurality of drive wheels and is mounted on a vehicle to cause the vehicle to travel, and the driving force is independently applied to at least two of the drive wheels. Power is applied to the drive wheels such that the rotation speed of the drive wheels that can be changed and the drive force can be changed is a target rotation speed when the vehicle is traveling.

  This travel device applies power to each drive wheel so that the actual rotation speed of the drive wheel becomes a target rotation speed that the drive wheel targets when the vehicle travels. As a result, the driving wheels can be controlled without depending on the road surface conditions through which the driving wheels of the vehicle pass. Therefore, even when there is a disturbance to the vehicle, the turning of the vehicle is suppressed while suppressing a decrease in the running stability of the vehicle. It becomes possible to ensure performance.

  In the traveling device as in the traveling device according to the present invention, it is preferable that the target rotational speed is set based on a traveling radius of the vehicle.

  As in the travel device according to the present invention, in the travel device, the travel radius of the vehicle is preferably set based on a steering angle of a steered wheel included in the vehicle and a travel speed of the vehicle.

  In the traveling device as in the traveling device according to the present invention, the target rotational speed may be set for each of the driving wheels. In this way, the accuracy of control is further improved.

  In the traveling device as in the traveling device according to the present invention, the target rotational speed may be a rotational speed difference between the pair of driving wheels. In this way, since the parameters used for control can be reduced, the control load can be reduced.

  As in the traveling device according to the next aspect of the present invention, in the traveling device, the plurality of drive wheels arranged on the same side surface of the vehicle may have the same target rotational speed. In this way, since the target rotational speed is common, the calculation load in the control can be reduced. In addition, since the turning posture of the vehicle is controlled so as to achieve a so-called neutral steer, it is possible to suppress a sense of incongruity that does not bend or an excessive sense of discomfort that is given to the driver of the vehicle.

  As in the traveling device according to the next aspect of the present invention, in the traveling device, the target rotational speed is preferably set to the smallest value among the plurality of driving wheels disposed on the same side of the vehicle. In this way, since the turning posture of the vehicle is controlled so as to achieve so-called neutral steer, it is possible to suppress a sense of incongruity that does not bend and an excessive sense of discomfort that is given to the driver of the vehicle.

  As in the traveling device according to the present invention, in the traveling device, when the output required for the power generation means for driving the drive wheels exceeds the output that can be generated by the power generation means, the power The rotational speed of the driving wheel driven by the generating means may be reduced, and the rotational speed of the other driving wheel may be reduced at the same reduction rate as the driving wheel having the rotational speed reduced. As a result, the rotational speeds of the drive wheels are reduced at the same rate, and the rotational speed ratio between the drive wheels can be maintained. Therefore, it is possible to suppress the deterioration of the turning performance due to the disordered turning posture of the vehicle.

  As in the traveling apparatus according to the next aspect of the present invention, in the traveling apparatus, the traveling apparatus changes the steering angle of the steering wheel of the vehicle in response to a decrease in the rotational speed of the drive wheel. May be provided. As a result, a change in the turning radius of the vehicle due to a reduction in the rotational speed of the drive wheels can be suppressed, so that a change in turning performance can be suppressed.

  As in the traveling device according to the present invention, in the traveling device, the driving wheel power generation means is provided for each of the driving wheels, and is an electric motor that individually drives each of the driving wheels. It is preferable. If it does in this way, the traveling device which can change drive power for every drive wheel can be constituted simply.

  A drive control device according to the present invention includes a plurality of drive wheels, and at least two drive wheels can independently change the drive force, and the drive device is mounted on a vehicle and controls the travel device for running the vehicle. And a target rotational speed calculation unit for calculating a target rotational speed targeted by the driving wheel when the vehicle is driven, and the rotational speed of the driving wheel is the target rotational speed. And an output determining unit that determines the power to be applied to the driving wheel, and an output control unit that drives the driving wheel with the power determined by the output determining unit.

  This drive control device determines the power to be applied to each drive wheel so that the actual rotation speed of the drive wheel becomes a target rotation speed targeted by the drive wheel when the vehicle travels, Drive the drive wheels. As a result, the driving wheels can be controlled without depending on the road surface conditions through which the driving wheels of the vehicle pass. Therefore, even when there is a disturbance to the vehicle, the turning of the vehicle is suppressed while suppressing a decrease in the running stability of the vehicle. It becomes possible to ensure performance.

  As in the drive control apparatus according to the next aspect of the present invention, in the drive control apparatus, it is preferable that the target rotation speed calculation unit calculates the target rotation speed based on a travel radius of the vehicle.

  As in the drive control device according to the next aspect of the present invention, in the drive control device, the target rotational speed calculation unit is configured to travel the vehicle based on a steering angle of a steering wheel provided in the vehicle and a travel speed of the vehicle. It is preferable to calculate the radius.

  As in the drive control device according to the present invention, in the drive control device, the target rotation speed calculation unit may calculate the target rotation speed for each of the drive wheels. In this way, the accuracy of control is further improved.

  As in the drive control apparatus according to the next aspect of the present invention, in the drive control apparatus, the target rotational speed calculation unit may use a rotational speed difference between a pair of drive wheels as the target rotational speed. In this way, since the parameters used for control can be reduced, the control load can be reduced.

  As in the drive control apparatus according to the next aspect of the present invention, in the drive control apparatus, the target rotation speed calculation unit sets the target rotation speed for the plurality of drive wheels arranged on the same side of the vehicle. The same may be used. In this way, since the target rotational speed is common, the calculation load in the control can be reduced. In addition, since the turning posture of the vehicle is controlled so as to achieve a so-called neutral steer, it is possible to suppress a sense of incongruity that does not bend or an excessive sense of discomfort that is given to the driver of the vehicle.

  As in the drive control device according to the next aspect of the present invention, in the drive control device, the target rotation speed calculation unit sets the target rotation speed to the plurality of drive wheels arranged on the same side surface of the vehicle. It is preferable to adjust to the smallest value. In this way, since the turning posture of the vehicle is controlled so as to achieve so-called neutral steer, it is possible to suppress a sense of incongruity that does not bend and an excessive sense of discomfort that is given to the driver of the vehicle.

  As in the drive control device according to the next invention, in the drive control device, when the output required for the power generation means for driving the drive wheels exceeds the output that can be generated by the power generation means, The target rotation speed calculation unit reduces the rotation speed of the driving wheel driven by the power generation unit and reduces the rotation speed of the other driving wheel at the same reduction ratio as the driving wheel reduced in rotation speed. You may do it. As a result, the rotational speeds of the drive wheels are reduced at the same rate, and the rotational speed ratio between the drive wheels can be maintained. Therefore, it is possible to suppress the deterioration of the turning performance due to the disordered turning posture of the vehicle.

  As in the drive control device according to the next aspect of the present invention, in the drive control device, the amount of change of the steering angle of the steering wheel of the vehicle is calculated and calculated in accordance with the decrease in the rotational speed of the drive wheel. A steering angle control unit that steers the steered wheels of the vehicle so that the steering angle becomes the same may be provided. As a result, a change in the turning radius of the vehicle due to a reduction in the rotational speed of the drive wheels can be suppressed, so that a change in turning performance can be suppressed.

  The traveling device and the drive control device according to the present invention can ensure the turning performance of the vehicle while suppressing a decrease in the traveling stability of the vehicle even when there is a disturbance to the vehicle.

  Hereinafter, the present invention will be described in detail with reference to the drawings. The present invention is not limited to the best mode for carrying out the invention (hereinafter referred to as an embodiment). In addition, constituent elements in the following embodiments include those that can be easily assumed by those skilled in the art, those that are substantially the same, and those in a so-called equivalent range. In the following, the case where the present invention is applied to a so-called electric vehicle using an electric motor as power generation means will be described, but the application target of the present invention is not limited to this, and includes a plurality of drive wheels, and at least It is sufficient if the driving force can be changed between the two driving wheels. Further, the power generation means is not limited to the electric motor, and for example, a heat engine such as an internal combustion engine may be used.

  The at least two driving wheels that can change the driving force may be a pair of left and right driving wheels of the vehicle. In this case, of the pair of left and right driving wheels of the front wheel or the pair of left and right driving wheels of the rear wheel At least one of them is sufficient if the driving force can be changed. Further, in a vehicle including three or more pairs of left and right drive wheels, it is only necessary that the driving force can be changed between at least one set of the drive wheels. Further, the driving force may be changed between one of the left and right front wheels and one of the left and right rear wheels. In addition, since this invention ensures turning performance, it is preferable that the at least two driving wheels capable of changing the driving force are at least a pair of left and right driving wheels of the vehicle.

(Embodiment 1)
In the first embodiment, at least two drive wheels included in a traveling device mounted on a vehicle can independently change the driving force, and the actual rotational speed of the drive wheels is caused to travel the vehicle. The driving wheel is characterized in that power is applied to the driving wheel so that the driving wheel has a target rotational speed. Here, the target rotation speed is determined on the basis of the vehicle traveling conditions such as the turning radius of the vehicle, the speed of the vehicle, or the steering angle of the steering wheel.

  FIG. 1-1 is a schematic diagram illustrating a configuration of a vehicle including the traveling device according to the first embodiment. Here, the left-right distinction is based on the direction in which the vehicle 1 moves forward (the direction of the arrow X in FIG. 1). That is, “left” refers to the left side in the direction in which the vehicle 1 moves forward, and “right” refers to the right side in the direction in which the vehicle 1 moves forward. Further, the direction in which the vehicle 1 moves forward is defined as the front, and the direction in which the vehicle 1 moves backward, that is, the direction opposite to the direction in which the vehicle 1 moves forward is defined as the rear.

  A vehicle 1 shown in FIG. 1-1 includes a traveling device 100 that uses an electric motor as power generation means. The traveling device 100 uses the left front wheel 21, the right front wheel 2r, the left rear wheel 31, and the right rear wheel 3r as drive wheels. Accordingly, the left front wheel 21, the right front wheel 2 r, the left rear wheel 3 l, and the right rear wheel 3 r are drive wheels of the vehicle 1. In this embodiment, the power generating means includes a left front motor 10l that drives the left front wheel 21, a right front motor 10r that drives the right front wheel 2r, a left rear motor 11l that drives the left rear wheel 3l, and a right rear motor. And a right rear motor 11r for driving the wheel 3r. The ECU (Electronic Control Unit) 50 and the drive control device 30 incorporated in the ECU 50 control the outputs of the left front motor 10l, the right front motor 10r, the left rear motor 11l, and the right rear motor 11r. The driving force of each driving wheel is controlled. In this embodiment, based on the opening degree of the accelerator 5 detected by the accelerator opening degree sensor 42, the ECU 50 and the drive control device 30 make the total driving force F of the traveling device 100, the left front wheel 21, the right front wheel 2r, the left side. The driving force of each of the rear wheel 3l and the right rear wheel 3r is controlled.

  In this traveling device 100, the left front wheel 21, the right front wheel 2r, the left rear wheel 31 and the right rear wheel 3r are driven by different electric motors. As described above, in the vehicle 1, all four wheels included in the traveling device 100 are drive wheels. In the present embodiment, the left front motor 10l, the right front motor 10r, the left rear motor 11l, and the right rear motor 11r are disposed in the wheels of the left front wheel 2l, the right front wheel 2r, the left rear wheel 3l, and the right rear wheel 3r. It is a so-called in-wheel configuration. The left front motor 101, the right front motor 10r, the left rear motor 11l, and the right rear motor 11r directly drive the left front wheel 21, the right front wheel 2r, the left rear wheel 31, and the right rear wheel 3r.

  A speed reduction mechanism is provided between the motor and the wheel to reduce the rotational speed of the left front motor 10l, the right front motor 10r, the left rear motor 11l, and the right rear motor 11r, and the left front wheel 2l and the right front wheel 2r. The left rear wheel 3l and the right rear wheel 3r may be transmitted. In general, when the electric motor is downsized, the torque decreases, but the torque of the electric motor can be increased by providing a speed reduction mechanism. Therefore, if the speed reduction mechanism is used, the left front motor 101, the right front motor 10r, the left rear motor 11l, and the right rear motor 11r can be reduced in size.

  The left front motor 10l, the right front motor 10r, the left rear motor 11l, and the right rear motor 11r are rotated by a left front resolver 40l, a right front resolver 40r, a left rear resolver 41l, and a right rear resolver 41r. Is detected. The outputs of the left front resolver 40l, the right front resolver 40r, the left rear resolver 41l, and the right rear resolver 41r are taken into the ECU 50 and the drive control device 30, and the left front motor 101, the right front motor 10r, and the left rear motor 11l and right rear motor 11r are used for control.

  The rotational speeds of the left front wheel 21, the right front wheel 2r, the left rear wheel 3l, and the right rear wheel 3r are respectively the left front wheel rotational speed sensor 44l, the right front wheel rotational speed sensor 44r, the left rear wheel rotational speed sensor 45l, and the right rear wheel. It is detected by the wheel rotation speed sensor 45r. The outputs of the left front wheel rotational speed sensor 44l, the right front wheel rotational speed sensor 44r, the left rear wheel rotational speed sensor 45l, and the right rear wheel rotational speed sensor 45r are taken into the ECU 50 and used for drive control of the traveling device 100.

  The left front motor 101, the right front motor 10r, the left rear motor 11l, and the right rear motor 11r are connected to the inverter 6. For example, an in-vehicle power source 7 such as a nickel-hydrogen battery or a lead storage battery is connected to the inverter 6, and electric power from the in-vehicle power source 7 is supplied to the left front motor 10 l and the right front motor 10 r via the inverter 6 as necessary. , And supplied to the left rear motor 11l and the right rear motor 11r.

  The outputs of the left front motor 101, the right front motor 10r, the left rear motor 11l, and the right rear motor 11r are controlled by controlling the inverter 6 according to commands from the ECU 50 and the drive control device 30. In this embodiment, in order to control the driving force of each driving wheel independently, one motor is controlled by one inverter. Thus, in order to control the left front motor 10l, the right front motor 10r, the left rear motor 11l, and the right rear motor 11r, the inverter 6 includes four inverters corresponding to the respective motors.

  When the left front motor 10l, the right front motor 10r, the left rear motor 11l, and the right rear motor 11r are used as power generation means of the traveling device 100, the electric power of the in-vehicle power supply 7 is supplied via the inverter 6. For example, when the vehicle 1 is decelerated, the left front motor 10l, the right front motor 10r, the left rear motor 11l, and the right rear motor 11r function as a generator to perform regenerative power generation, and the energy collected thereby is used as an on-vehicle power source. Save to 7. This is realized by the ECU 50 controlling the inverter 6 based on a signal such as a brake signal or an accelerator off.

  The left front wheel 2 l and the right front wheel 2 r of the traveling device 100 are steered by the handle 4 and function as steering wheels of the vehicle 1. The left front wheel 21 and the right front wheel 2r are detected by the steering angle sensor 43. Input from the steering wheel 4 is transmitted to the left front wheel 21 and the right front wheel 2r via the steering speed reduction device 8, and these are steered. The traveling direction of the vehicle 1 is changed by steering the left front wheel 21 and the right front wheel 2r. The steering speed reduction device 8 included in the traveling device 100 according to the present embodiment can change the speed reduction ratio by the actuator 8A controlled by the controller 8C. Thus, the steering angle of the left front wheel 21 and the right front wheel 2r, which are the steering wheels of the traveling device 100, can be changed while the operation amount of the handle 4 is constant. The steering reduction gear 8 is configured to change the reduction ratio of a planetary gear type reduction gear provided between the handle 4 and the left front wheel 21 and the right front wheel 2r, for example. Next, another example of the traveling device according to the present embodiment will be described.

  FIGS. 1-2 and 1-3 are schematic diagrams illustrating other examples of the traveling device according to the first embodiment. The traveling device 100a mounted on the vehicle 1a shown in FIG. 1-2 uses the left front wheel 21 and the right front wheel 2r driven by the left front motor 10l and the right front motor 10r as driving wheels, respectively, and the left rear wheel 3l and the right rear wheel. 3r is a driven wheel. That is, traveling device 100a is a so-called FF (Front Wheel Front Drive) system. In this traveling device 100a, the driving force of the left front wheel 2l and the right front wheel 2r, which are a pair of left and right drive wheels, is independently changed by at least two drive wheels, that is, the left front motor 10l and the right front motor 10r. it can.

  The traveling device 100b mounted on the vehicle 1b shown in FIG. 1-3 uses the left front wheel 21, the right front wheel 2r, the left rear wheel 31 and the right rear wheel 3r as drive wheels. The traveling device 100b drives the left front wheel 21 and the right front wheel 2r with the front wheel drive motor 13f, and drives the left rear wheel 31 and the right rear wheel 3r with the rear wheel drive motor 13r. In the traveling device 100b, the power generated by the front wheel drive motor 13f is transmitted to the left front wheel 21 and the right front wheel 2r via the front wheel differential gear 12f, and the power generated by the rear wheel drive motor 13r is rear wheel. Is transmitted to the left rear wheel 3l and the right rear wheel 3r via the differential gear 12r. When the vehicle 1b on which the traveling device 100b is mounted turns, the rotational speed difference between the inner and outer wheels is absorbed by the front wheel differential gear 12f and the rear wheel differential gear 12r.

  In this traveling device 100b, driving is independently performed between at least two drive wheels, that is, either the left front wheel 21 or the right front wheel 2r and either the left rear wheel 31 or the right rear wheel 3r. You can change the power. That is, in this traveling device 100b, the driving force can be changed independently between the driving wheel on the front side of the vehicle 1 and the driving wheel on the rear side. The drive control according to the present embodiment can also be applied to such a travel device 100b. For example, a target rotational speed is set for the front and rear driving wheels located outside the turning direction, and the rotational speeds of the front and rear driving wheels located outside the turning direction are controlled so as to be the rotational speed. The front and rear drive wheels positioned inside the turning direction are adjusted to a rotational speed corresponding to the turning radius of the vehicle 1b by the front wheel differential gear 12f and the rear wheel differential gear 12r. Next, drive control according to the present embodiment will be described.

  FIG. 2 is a schematic diagram for explaining the drive control according to the first embodiment. FIGS. 3-1 to 3-3 are schematic views for explaining the relationship between the wheels included in the vehicle according to the first embodiment. In the driving device 100 according to the present embodiment, in the traveling device 100 that can independently control the driving force of at least two driving wheels, based on the driving conditions of the vehicle 1, the rotational speed targeted by the driving wheels is set, Power is applied to the drive wheels so as to achieve the target rotation speed, and the drive wheels are driven.

  In the present embodiment, paying attention to the fact that the traveling posture of the vehicle 1 depends on the rotational speed of each driving wheel of the traveling device 100 mounted on the vehicle 1, the target rotational speed that is the target of the driving wheel of the traveling device 100 is calculated. Then, the drive wheel is set so that the actual rotation speed of the drive wheel becomes the calculated target rotation speed, that is, the difference between the actual rotation speed of the drive wheel and the calculated target rotation speed becomes zero. The power to be applied is feedback controlled. As a result, it is possible to stably travel the vehicle while suppressing the change in the traveling posture of the vehicle 1 while ensuring the turning performance of the vehicle 1 without using a yaw sensor, a slip angle sensor, or the like. In addition, even if a disturbance occurs on the vehicle 1 such as a change in the frictional state of the road surface, the turning performance of the vehicle 1 can be ensured while suppressing a decrease in running stability of the vehicle 1.

  FIG. 2 shows a state where the vehicle 1 according to the present embodiment is turning left. A solid line shown in FIG. 2 is a turning locus of the center of gravity G of the vehicle 1 while the vehicle 1 is turning. A one-dot chain line fo is a turning locus of the front outer ring 2o, a one-dot chain line ro is a turning locus of the rear outer ring 3o, a two-dot chain line fi is a turning locus of the front inner ring 2i, and a two-dot chain line ri is turning of the rear inner ring 3i. It is a trajectory. Further, the turning radius of the center of gravity G of the vehicle 1 (hereinafter referred to as vehicle center-of-gravity turning radius) is ρ, the turning radius of the front outer wheel 2o (hereinafter referred to as front outer wheel turning radius) is ρfo, and the turning radius of the rear outer wheel 3o (hereinafter referred to as rear outer wheel turning radius). ) Is ρro, the turning radius of the front inner ring 2i (hereinafter referred to as the front inner ring turning radius) is ρfi, and the turning radius of the rear inner ring 3i (hereinafter referred to as the rear inner ring turning radius) is ρri. β is a slip angle of the vehicle 1 around the center of gravity G of the vehicle 1 (hereinafter referred to as a slip angle).

  Here, the relationship between the driving wheels of the vehicle 1 shown in FIG. 1-1 and the driving wheels of the vehicle 1 shown in FIG. 2 is that the left front wheel 21 corresponds to the front outer wheel 2o and the left rear wheel 3l corresponds to the rear outer wheel 3o. Correspondingly, the right front wheel 2r corresponds to the front inner ring 2i, and the right rear wheel 3r corresponds to the rear inner ring 3i. In this correspondence relationship, when the vehicle 1 turns to the right depending on the turning direction of the vehicle 1, the left front wheel 21 corresponds to the front inner wheel 2i, and the left rear wheel 3l corresponds to the rear inner wheel. 3i, the right front wheel 2r corresponds to the front outer wheel 2o, and the right rear wheel 3r corresponds to the rear outer wheel 3o. In the present embodiment, the left front wheel 2l, the right front wheel 2r, the left rear wheel 3l, and the right rear wheel 3r shown in FIG. 1-1 are all drive wheels of the vehicle 1, and therefore the front outer wheel 2o, the rear outer wheel 3o, the front wheel The inner wheel 2 i and the rear inner wheel 3 i are both drive wheels of the vehicle 1.

  3-1 to 3-3, G represents the center of gravity of the vehicle 1, h represents the height of the center of gravity of the vehicle 1, Df represents the tread width of the front wheel, and Dr represents the tread width of the rear wheel. L is the distance between the left and right front wheels 21 and 2r (front wheel side axle) Zf and the left and right rear wheels 31 and 3r (rear wheel side axle) Zr (the distance between the front and rear axles). Lf represents the horizontal distance between the center of gravity G and the front wheel side axle Zf, and Lr represents the horizontal distance between the center of gravity G and the rear wheel side axle Zr.

  The vehicle center-of-gravity turning radius ρ can be obtained by Equation (1), and the slip angle β of the vehicle 1 can be obtained by Equation (2). The front outer wheel turning radius ρfo, the rear outer wheel turning radius ρro, the front inner wheel turning radius ρfi, and the rear inner wheel turning radius ρri are obtained by equations (3) to (6), respectively, using the vehicle center-of-gravity turning radius ρ and the slip angle β. be able to. Further, the turning outer speed of the front outer wheel 2o (hereinafter referred to as the front outer wheel turning peripheral speed) Vfo, the turning outer speed of the rear outer wheel 3o (hereinafter referred to as the rear outer wheel turning peripheral speed) Vro, the turning inner speed of the front inner wheel 2i (hereinafter referred to as the front inner ring turning). Vfi and the turning inner speed of the rear inner ring 3i (hereinafter referred to as the rear inner wheel turning peripheral speed) Vro can be obtained by equations (7) to (10), respectively. The turning angular velocity of the front outer wheel 2o (hereinafter referred to as the front outer wheel turning angular velocity) ωfo, the turning angular velocity of the rear outer wheel 3o (hereinafter referred to as the rear outer wheel turning angular velocity) ωro, and the turning angular velocity of the front inner wheel 2i (hereinafter referred to as the front inner wheel turning angular velocity) are ωfi. , The turning angular velocity (hereinafter referred to as the rear inner ring turning angular velocity) ωri of the rear inner ring 3i can be obtained by equations (11) to (14), respectively. The front outer wheel turning angular velocity ωfo, the rear outer wheel turning angular velocity ωro, the front inner wheel turning angular velocity ωfi, and the rear inner wheel turning angular velocity ωri are the target rotation speeds of the drive wheels. That is, the target rotational speed of the front outer wheel 2o (front outer wheel target rotational speed) is ωfo, the target rotational speed of the rear outer wheel 3o (rear outer wheel rotational speed) is ωro, and the target rotational speed of the front inner ring 2i (front inner wheel target rotational speed) is ωfi, the target rotational speed of the rear inner ring 3i (rear inner ring target rotational speed) is ωri.

  The target rotational speed may be a rotational speed difference between a pair of drive wheels. For example, the front inner / outer ring rotational speed difference Δωf or the rear inner / outer ring rotational speed difference Δωr of the vehicle 1 may be used. Here, the front inner / outer wheel rotational speed difference Δωf is ωfo (front outer wheel turning angular speed) −ωfi (front inner wheel turning angular speed), and the rear inner / outer wheel rotational speed difference Δωr is ωro (rear outer wheel turning angular speed) −ωri ( Rear inner wheel turning angular velocity). In this way, since the parameters used for control can be reduced, the control load can be reduced.

  Here, V is the speed of the vehicle 1 (referred to as a vehicle speed if necessary). For example, the lowest one of the wheel speeds (circumferential speed of the wheels) provided in the vehicle 1 is used. M is the mass of the vehicle 1, Rfo is the load radius of the front outer ring 2o, Rro is the load radius of the rear outer ring 3o, Rfi is the load radius of the front inner ring 2i, and Rri is the load radius of the rear inner ring 3i. Kf is the cornering force (lateral force) of the front wheel of the vehicle 1, and Kr is the cornering force of the rear wheel of the vehicle 1. The cornering force is generally determined by the loads on the front and rear wheels of the vehicle 1 and varies with the steering angle δ. In the present embodiment, the cornering force uses a region that changes linearly to weakly nonlinear with respect to the steering angle δ.

  As described above, in the present embodiment, each actual rotation speed of the drive wheels of the vehicle 1 is set to the target rotation speed of the drive wheels calculated based on the equations (1) to (14). Power is applied to the drive wheels. Thereby, without using a yaw sensor, a slip angle sensor or the like, it is possible to suppress a change in the running posture of the vehicle 1 and to make the vehicle run stably, and to ensure the turning performance of the vehicle 1. As a result, in the drive control in the case where at least one of the drive wheels of the vehicle 1 slips or gets stuck, the attitude of the vehicle 1 when the vehicle 1 turns, when traveling on a crossing road, etc. is intended by the driver Therefore, drivability is improved. Also, in order to reduce the power applied to the front and rear inner wheels according to the inner wheel difference of the vehicle 1 and reduce the driving force of the front and rear inner wheels, especially when the inner wheel of the vehicle 1 slips or stacks during turning at a large steering angle. In addition, the driving force can be distributed so as to maintain the turning trajectory of the vehicle 1. Next, a drive control device for realizing drive control according to the present embodiment will be described.

  FIG. 4 is an explanatory diagram illustrating a configuration example of the drive control apparatus according to the first embodiment. As shown in FIG. 4, the drive control device 30 is built into the ECU 50. The ECU 50 includes a CPU (Central Processing Unit) 50p, a storage unit 50m, an input port 55 and an output port 56, and an input interface 57 and an output interface 58.

  In addition, you may prepare the drive control apparatus 30 which concerns on this embodiment separately from ECU50, and this may be connected to ECU50. And in implement | achieving the drive control which concerns on this embodiment, you may comprise so that the said drive control apparatus 30 can utilize the control function with respect to the traveling apparatus 100 grade | etc., With which ECU50 is provided.

  The drive control device 30 includes a control condition determination unit 31, a target rotational speed calculation unit 32, an output determination unit 33, and an output control unit 34. These are the parts that execute the drive control according to this embodiment. In this embodiment, the drive control device 30 is configured as a part of the CPU 50 p that constitutes the ECU 50.

The control condition determination unit 31, the target rotation speed calculation unit 32, the output determination unit 33, and the output control unit 34 of the drive control device 30 include a bus 54 ₁ , a bus 54 ₂ , an input port 55, and an output port 56. Connected through. As a result, the control condition determination unit 31, the target rotational speed calculation unit 32, the output determination unit 33, and the output control unit 34 that constitute the drive control device 30 exchange control data with each other, or issue commands to one side. It can be put out. Further, the drive control device 30 provided in the CPU 50p, and the storage unit 50m, are connected via a bus 54 _3. As a result, the drive control device 30 can acquire the operation control data of the traveling device 100 included in the ECU 50 and use it. Moreover, the drive control apparatus 30 can interrupt the drive control which concerns on this embodiment in the drive control routine with which ECU50 is equipped beforehand.

  An input interface 57 is connected to the input port 55. The input interface 57 includes a left front resolver 40l, a right front resolver 40r, a left rear resolver 41l, a right rear resolver 41r, an accelerator opening sensor 42, a steering angle sensor 43, a left front wheel rotational speed sensor 44l, and a right front wheel rotational speed. Sensors such as a sensor 44r, a left rear wheel rotational speed sensor 45l, and a right rear wheel rotational speed sensor 45r are connected to acquire information necessary for drive control of the traveling device 100. Signals output from these sensors are converted into signals that can be used by the CPU 50 p by the A / D converter 57 a and the digital input buffer 57 d in the input interface 57 and sent to the input port 55. Thereby, CPU50p can acquire the information required for the drive control of the traveling apparatus 100, and the drive control which concerns on this embodiment.

An output interface 58 is connected to the output port 56. A control target necessary for drive control according to the present embodiment is connected to the output interface 58. In this embodiment, a left front motor 10l, a right front motor 10r, a left rear motor 11l, an inverter 6 for controlling the right rear motor 11r, and a controller 8C for controlling the actuator 8A are connected to the output interface 58. ing. The output interface 58 includes control circuits 58 ₁ , 58 _{2 and the} like, and operates the control target based on a control signal calculated by the CPU 50p. With such a configuration, based on the output signals from the sensors, the CPU 50p of the ECU 50 can control the driving forces of the left front motor 101, the right front motor 10r, the left rear motor 11l, and the right rear motor 11r. it can.

  The storage unit 50m stores a computer program including a control procedure for drive control according to this embodiment, a control map, data used for drive control according to this embodiment, and the like. Here, the storage unit 50m can be configured by a volatile memory such as a RAM (Random Access Memory), a nonvolatile memory such as a flash memory, or a combination thereof.

  The computer program may be capable of realizing the drive control processing procedure according to this embodiment in combination with a computer program already recorded in the CPU 50p. Further, the drive control device 30 uses the dedicated hardware instead of the computer program to realize the functions of the control condition determination unit 31, the target rotation speed calculation unit 32, the output determination unit 33, and the output control unit 34. It may be a thing. Next, drive control according to this embodiment will be described. In the following description, please refer to FIGS.

  FIG. 5 is a flowchart illustrating a drive control procedure according to the first embodiment. The drive control according to the present embodiment includes steps S101 to S109, and returns to START when reaching RETURN. When RETURN is reached from START, it is counted that the control is finished once. In executing the drive control according to the present embodiment, in step S101, the control condition determination unit 31 of the drive control device 30 determines whether or not the vehicle 1 is turning.

  As described above, the drive control according to the present embodiment obtains the target rotational speed of each drive wheel based on the vehicle center-of-gravity turning radius ρ, the front outer wheel turning radius ρfo, the rear inner wheel turning radius ρri, and the like. When the vehicle 1 is not turning, the drive control according to the present embodiment is not executed. Whether or not the vehicle 1 is turning can be determined from the magnitude of the steering angle δ of the steering wheel of the vehicle 1 acquired from the steering angle sensor 43, for example. For example, when the steering angle δ_n at the time of determination is not 0, or when the steering angle δ_n is larger than a predetermined angle, it can be determined that the vehicle 1 is turning.

  When it determines with No by step S101, ie, when the control condition determination part 31 determines with the vehicle 1 not turning, it returns to START without performing the drive control which concerns on this embodiment, and the control condition determination part 31 Continues monitoring the running state of the vehicle 1. When it is determined Yes in step S101, that is, when the control condition determination unit 31 determines that the vehicle 1 is turning, the control condition determination unit 31 determines the steering angle δ_n at the time of determination in step S101 and the previous time. The steering angle δ_l at the time of the determination is compared.

  If it is determined No in step S102, that is, if the control condition determination unit 31 determines that δ_n = δ_l, the vehicle 1 is turning and the turning radius of the vehicle 1 changes in a transient state. It can be determined that there is. In this case, the rotational speed of each driving wheel of the vehicle 1 is set to each driving wheel of the vehicle 1 such that the rotational speed of each driving wheel of the vehicle 1 is calculated using the above formulas (1) to (14). Control the power to be applied.

  In calculating the target rotation speed of each drive wheel of the vehicle 1, in step S103, the target rotation speed calculation unit 32 of the drive control device 30 steers the steering angle δ of the vehicle 1 used for calculation at the time of determination in step S101. Let it be an angle δ_n. Next, in step S <b> 104, the target rotational speed calculation unit 32 acquires information necessary for calculating the target rotational speed from the sensors of the vehicle 1. Then, the target rotation speed calculation unit 32 calculates the turning radii ρfo, ρfi, ρro, ρri of each drive wheel using the above formulas (1) to (6), and the actual rotation speed ω_n of each drive wheel. (Ω_nfo, ω_nfi, ω_nro, ω_nri) is calculated. In step S105, the target rotation speed calculation unit 32 uses the turning radius of each drive wheel calculated in step S104 and the expressions (7) to (14) to target rotation speed ω (ωfo of each drive wheel. , Ωfi, ωro, ωri).

  Next, in step S106, the output determining unit 33 of the drive control device 30 calculates the actual rotational speed ω_n of each driving wheel calculated in step S104 and the target rotational speed ω of each driving wheel calculated in step S105. Δω (= | ω_n−ω |) is calculated. In the present embodiment, the rotational speed deviation is represented by the absolute value of the difference between ω_n and ω. In step S107, the output determination unit 33 calculates the power to be applied to each drive wheel so that the rotation speed deviation Δω calculated in step S106 is zero. That is, the output of power generation means (in this embodiment, an electric motor) that drives each drive wheel is calculated.

  In the present embodiment, based on the rotational speed deviation Δω of each driving wheel calculated in step S106, that is, the driving current value of the motor that drives each driving wheel such that the rotational speed deviation Δω of each driving wheel becomes zero. The output determining unit 33 calculates I. Since the drive current value I of the motor driving each drive wheel is proportional to the drive force of each drive wheel, the motor is driven with a drive current value I such that the rotational speed deviation Δω of each drive wheel becomes zero. For example, the rotational speed deviation Δω of each drive wheel becomes zero. Therefore, if the driving current value I is calculated such that the rotational speed deviation Δω of each driving wheel is zero, the power (driving force) of each driving wheel is calculated so that the rotational speed deviation Δω of each driving wheel is zero. Will do. In step S108, the output control unit 34 of the drive control device 30 drives each drive wheel with the drive current value I of the electric motor driving each drive wheel calculated in step S107. Thus, power is applied to each drive wheel so that the rotational speed deviation Δω of each drive wheel becomes 0, and each drive wheel is driven at the target rotational speed.

  When it is determined Yes in step S102, that is, when the control condition determination unit 31 determines that δ_n = δ_l, the vehicle 1 is turning and the turning radius of the vehicle 1 does not change. Can be determined. In this case, in step S109, the target rotation speed calculation unit 32 calculates the actual rotation speed ω_n of each drive wheel based on information acquired from the sensors of the vehicle 1. Since the turning radius of the vehicle 1 has not changed, the value at the previous determination is used as the target rotational speed ω.

  In step S106, the output determination unit 33 calculates the rotational speed deviation Δω between the actual rotational speed ω_n of each driving wheel calculated in step S109 and the target rotational speed ω of each driving wheel calculated in the previous step S105. Calculate. In step S107, the output determining unit 33 calculates the drive current value I of the motor that drives each drive wheel such that the rotational speed deviation Δω of each drive wheel calculated in step S106 becomes zero. The output control unit 34 drives each drive wheel with the drive current value I of the electric motor that drives each drive wheel calculated in step S107.

(Modification)
FIG. 6 is a schematic diagram for explaining drive control according to a modification of the first embodiment. In the drive control according to this modification, in the drive control according to the first embodiment described above, the turning posture of the vehicle 1 is in a so-called neutral steer state, that is, the slip angle β is zero. Different. For this reason, in this modification, the target rotational speeds of the drive wheels on the same side surface of the vehicle 1 are the same. As a result, the turning state of the vehicle 1 can be brought close to neutral steering, and a good turning feeling can be given to the driver of the vehicle 1. Here, the neutral steer means that the vehicle 1 turns with the traveling direction of the vehicle 1 facing the tangential direction of the turning radius of the vehicle 1.

  As shown in the equation (2), the slip angle β of the vehicle 1 is a value determined from the speed of the vehicle 1, the steering angle δ, and the specifications of the vehicle 1, and therefore usually does not become zero. Here, on the same side surface of the vehicle 1, ω_f> ω_r when understeering, and ω_f <ω_r when oversteering. That is, when understeering, the lateral force margin of the front driving wheel is smaller than the lateral force margin of the rear driving wheel, and when oversteering, the lateral force margin of the rear driving wheel is equal to the lateral force margin of the front driving wheel. Smaller than you can afford. Note that f means the front wheel of the vehicle 1 and r means the rear wheel of the vehicle 1.

  Therefore, in this modification, the angular velocities at the time of turning, which are obtained by the equations (11) to (14), are the same on the same side surface of the vehicle 1, that is, the inner wheel side or the outer wheel side. More specifically, on the same side surface side of the vehicle 1, the smaller one of the target rotational speeds ω obtained by Expressions (11) to (14) is set as the target rotational speed of each drive wheel. Thereby, the turning state of the vehicle 1 can be brought close to the neutral steer. In addition, since the target is set in a direction in which the lateral force margin of each drive wheel can be recovered to the maximum, the safety margin of the vehicle 1 can be further expanded.

  Here, in a normal vehicle, since Df / 2 and Dr / 2 are negligibly small with respect to the turning radius of the vehicle 1, the turning radius (outer ring turning radius) ρo of the outer ring of the vehicle 1 and the vehicle When obtaining the turning radius (inner ring turning radius) ρi of one inner ring, for example, an average value D / 2 (= (Df + Dr) / 4) of Df / 2 and Dr / 2 may be used. In this case, the outer ring turning radius ρo is (ρ + H / 2), and the inner ring turning radius ρi is (ρ−H / 2). Here, ρ is the vehicle center-of-gravity turning radius determined by Equation (1). In this way, the calculation when calculating the inner ring turning radius ρi and the like can be simplified, and the calculation load can be reduced.

  In the present embodiment and the modification thereof, an example in which the turning control of the vehicle is executed without using a sensor such as a yaw sensor or a slip angle sensor that detects the running posture or running state of the vehicle has been described. However, the present embodiment and its modifications can also be applied to the case where the turning control of the vehicle is executed using a sensor that detects the running posture or running state of the vehicle such as a yaw sensor or a slip angle sensor. In this case, the drive control according to the present embodiment and its modification is used for backup, and for example, when a failure of a sensor that detects the running posture or running state of the vehicle is detected, this embodiment and its modification. The vehicle turning control is executed using the driving control according to the above. Thereby, reliability is improved.

  As described above, in the present embodiment and the modification thereof, attention is paid to the fact that the rotation speed of the driving wheel represents a trajectory that the vehicle is going to travel, and therefore the attitude of the vehicle is determined by the rotation speed of the driving wheel. The driving force of at least two drive wheels can be changed independently, and the actual rotational speed of the drive wheels becomes a target rotational speed that the drive wheels target when the vehicle is driven. As described above, power is applied to the drive wheels. Note that the target rotation speed is determined based on vehicle running conditions such as the turning radius of the vehicle and the speed of the vehicle, for example. In this way, since the rotation speed of the drive wheel that greatly affects the attitude and behavior of the vehicle during traveling is controlled to the target rotation speed, even if a disturbance such as a change in the frictional state of the road surface occurs, the attitude of the vehicle Changes and behavior changes can be minimized. As a result, the planned turning performance of the vehicle can be exhibited while suppressing a decrease in running stability of the vehicle.

  In the drive control in which the driving force of each driving wheel becomes the target driving force, when there is no sensor for detecting the running posture or running state of the vehicle such as a yaw sensor or a slip angle sensor, the target vehicle posture is set. It is extremely difficult to determine the driving force of the vehicle, and when a disturbance to the vehicle occurs, the stability of the vehicle may be reduced. This is because there is no sensor for detecting the running posture or running state of the vehicle, and as a result of changing the driving force of the driving wheel, it is impossible to grasp the posture of the vehicle. Because it becomes unstable.

  However, in the present embodiment and its modified examples, the rotational speed of the driving wheel that greatly affects the posture and behavior of the vehicle during traveling becomes the target rotational speed based on the rotational speed of each driving wheel, the vehicle speed, and the steering angle. Thus, feedback control is performed on the power applied to the drive wheels. As a result, the turning performance of the vehicle can be improved and the stability against disturbance can be improved without using a sensor that detects the running posture or running state of the vehicle such as a yaw sensor or a slip angle sensor. As described above, in the present embodiment and the modified example thereof, sensors already mounted on the vehicle can be used, and expensive sensors such as a yaw sensor and a slip angle sensor are not necessary. There is also an advantage that can be reduced. Note that the configuration of the first embodiment can also be applied as appropriate in the following embodiments.

(Embodiment 2)
The second embodiment is similar to the first embodiment in that power is applied to each drive wheel so that the rotation speed of the drive wheel becomes the target rotation speed, but is required for the power generation means that drives the drive wheel. When the output exceeds the limit of the power generation means, the driving wheel is driven at a rotational speed that can be realized within the range of output that can be generated by the power generation means, and the other driving wheels are rotated. The difference is that the rotational speed is reduced at the same rate of reduction as the drive wheels with reduced speed. The drive control according to the present embodiment can be applied to the traveling device 100 and the like provided in the vehicle 1 according to the first embodiment shown in FIG. Next, the vehicle 1 shown in FIG. 1-1 and the traveling device 100 included in the vehicle 1 will be described as an example.

  FIG. 7 is a schematic diagram for explaining drive control according to the second embodiment. FIG. 8 is a schematic diagram showing an iso-output line of an electric motor that is an example of power generation means. FIG. 7 shows a state in which the inner wheel and the outer wheel pass on road surfaces having different friction coefficients while the vehicle 1 is turning. The road surface through which the outer wheel of the vehicle 1 passes, that is, the front outer wheel 2o and the rear outer wheel 3o is a low friction coefficient road surface, and has a lower friction coefficient than the inner wheel of the vehicle 1, that is, the road surface through which the front inner wheel 2i and the rear inner wheel 3i pass. In the state shown in FIG. 7, for example, sand floats outside the road surface to form a low friction coefficient road surface, and the front outer ring 2o and the rear outer ring 3o of the vehicle 1 pass over the sand, but the front inner ring 2i. And the rear inner ring 3i is in a state of passing over a paved road surface on which no sand floats.

  In such a case, in order to achieve the target rotational speed ω of the front outer wheel 2o and the rear outer wheel 3o of the vehicle 1 passing on the low friction coefficient road surface SL, the road surface having a higher friction coefficient than the low friction coefficient road surface SL is used. Less power than the front inner wheel 2i and the rear inner wheel 3i of the vehicle 1 that passes is sufficient. On the other hand, in order to realize the target rotational speed ω of the front inner wheel 2i and the rear inner wheel 3i of the vehicle 1 that passes on the road surface having a higher friction coefficient than the low friction coefficient road surface SL, the vehicle that passes on the low friction coefficient road surface SL. More power than the front outer ring 2o and the rear outer ring 3o is required. This is because it is necessary to generate a driving force for maintaining the speed of the vehicle 1 and a moment necessary for turning with the driving wheels of the vehicle 1 passing on the road surface having a higher friction coefficient.

  Here, there is a limit to the output that can be generated by the power generation means that drives each drive wheel of the vehicle 1 (in this embodiment, the electric motor included in the traveling device 100 shown in FIG. 1-1). It is not always possible to realize the target rotational speed of each drive wheel obtained in (14). In the present embodiment, the output generated by the electric motor that drives the front inner ring 2i of the vehicle 1 exceeds the output required for the electric motor. In this case, in the present embodiment, the target rotational speed of each drive wheel of the vehicle 1 is reduced at the same rate within an output range that can be generated by the electric motor that drives the drive wheel of the vehicle 1. As a result, the speed of the vehicle 1 is reduced, but the rotational speed of each drive wheel is reduced at the same rate, and the rotational speed ratio between the drive wheels can be maintained, so that the vehicle 1 remains in the previous turning posture. , Can turn stably. For example, when the vehicle 1 is turned by neutral steer, neutral steer can be maintained even when the driving wheels of the vehicle 1 pass through road surfaces having different friction coefficients.

  As shown in FIG. 8, it is assumed that the target rotational speed of the front inner ring 2i is ωfi. The solid line shown in FIG. 8 is an equal output line of the electric motor that drives the front inner ring 2i. Even if the torque and the rotational speed are different, the output generated by the electric motor is the same as long as it is on the equal output line. When the target rotational speed is ωfi, the driving torque required to drive the front inner wheel 2i, which is determined from the mass, speed, and steering angle of the vehicle 1, is T_l. However, as can be seen from the iso-output line shown in FIG. 8, the electric motor that drives the front inner ring 2i cannot generate the drive torque T_l at the target rotational speed ωfi. That is, the output that can be generated by the electric motor that drives the front inner ring 2i has been exceeded.

  Here, it can be seen from the iso-output line shown in FIG. 8 that the rotational speed at which the drive torque T_l can be generated is ωfi_c. Therefore, the rotational speed at which the electric motor that drives the front inner ring 2i can generate the driving torque T_l is ωfi_c. In the present embodiment, the rotational speed ωfi_c capable of generating the drive torque T_l is set as a target rotational speed (referred to as a corrected target rotational speed) of the electric motor that drives the front inner ring 2i. Then, the target rotational speed correction coefficient α is obtained from the initial target rotational speed ωfi and the corrected target rotational speed ωfi_c. Here, the target rotational speed correction coefficient α is a value obtained by dividing the corrected target rotational speed ωfi_c by the initial target rotational speed ωfi, and α = ωfi_c / ωfi. As can be seen from this relationship, α <1.

  When the target rotational speed of the front inner ring 2i is corrected to ωfi_c, the target rotational speed ωri of the rear inner ring 3i, the target rotational speed ωfo of the front outer ring 2o, and the target rotational speed ωro of the rear outer ring 3o are also corrected. Decrease at the same rate. That is, the target rotational speed ωri of the rear inner wheel 3i, the target rotational speed ωfo of the front outer wheel 2o, and the target rotational speed ωro of the rear outer wheel 3o are multiplied by the target rotational speed correction value α to obtain the corrected target rotational speed of the rear inner wheel 3i. α × ωri, corrected target rotational speed α × ωfo of the front outer wheel 2o, and corrected target rotational speed α × ωro of the rear outer wheel 3o. The rotational speed of the front inner ring 2i is ωfi_c, the rotational speed of the rear inner ring 3i is α × ωri, the rotational speed of the front outer ring 2o is α × ωfo, and the rotational speed of the rear outer ring 3o is α × ωro. The power generated by the electric motor that drives each drive wheel is controlled. Next, a procedure example of drive control according to the second embodiment will be described.

  FIG. 9 is a flowchart illustrating a drive control procedure according to the second embodiment. The drive control according to the second embodiment can be realized by the drive control device 30 according to the first embodiment shown in FIG. In executing the drive control according to the second embodiment, in step S201, the control condition determination unit 31 of the drive control device 30 illustrated in FIG. 4 executes the drive control of the traveling device 100 included in the vehicle 1 illustrated in FIG. It is determined whether or not. For example, it is determined that the drive control of the travel device 100 is being executed when the vehicle 1 is turning or when the vehicle 1 is traveling on the low friction coefficient road surface SL.

  When it determines with No by step S201, ie, when the control condition determination part 31 determines with not performing the drive control of the traveling apparatus 100, it returns to START, without performing the drive control which concerns on this embodiment, The control condition determination unit 31 continues to monitor the traveling state of the vehicle 1.

  When it is determined Yes in step S201, that is, when the control condition determination unit 31 determines that drive control of the traveling device 100 included in the vehicle 1 is being performed, in step S202, the control condition determination unit 31 It is determined whether there is a motor whose output has reached a limit among the motors included in the apparatus 100. For example, the determination is made based on whether or not there is a request output W_d for the motor of each drive wheel included in the traveling device 100 shown in FIG. 1-1 exceeding the maximum output W_max of the motor.

  When it is determined No in step S202, that is, when the control condition determining unit 31 determines that there is no output that has reached the limit among the electric motors included in the traveling device 100, the drive control according to the present embodiment is performed. Returning to START without executing, the control condition determination unit 31 continues to monitor the running state of the vehicle 1.

  When it is determined Yes in step S202, that is, when the control condition determining unit 31 determines that there is an electric motor included in the traveling device 100 that has reached the limit, the process illustrated in FIG. The target rotation speed calculation unit 32 of the drive control device 30 sets the corrected target rotation speed of the drive wheel driven by the electric motor whose output has reached the limit by the above-described procedure. That is, the target rotational speed calculation unit 32 sets a rotational speed at which the drive torque required for the motor can be generated from the iso-output line of the motor as the corrected target rotational speed.

  For example, the equal output line of the electric motor is stored in the storage unit 50m of the ECU 50 shown in FIG. 4 as a corrected target rotational speed setting map, and when the corrected target rotational speed is set, the target rotational speed calculation unit 32 A drive torque required for the electric motor is applied to the corrected target rotational speed setting map to obtain a corresponding corrected target rotational speed. Here, when it is determined in step S202 that there are a plurality of required outputs W_d exceeding the maximum output W_max of the motor, the drive torque required for the motor with respect to the motor having the largest required output. Is set as the corrected target rotation speed.

  Next, in step S204, the target rotational speed calculation unit 32 calculates a target rotational speed correction coefficient α from the initial target rotational speed and the corrected target rotational speed set in step S203. In step S205, the target rotational speed calculation unit 32 uses the calculated target rotational speed correction coefficient to drive the corrected target rotational speed based on the drive torque required for the other drive wheels, that is, the electric motor. The corrected target rotational speed of the drive wheels other than the wheels is calculated. That is, the currently set target rotational speed of the other driving wheel is multiplied by the target rotational speed correction coefficient calculated in step S204 to obtain the corrected target rotational speed of the other driving wheel.

  Next, in step S206, the output determining unit 33 provided in the drive control device 30 shown in FIG. 4 sets the rotation speed of each drive wheel provided in the traveling device 100 mounted in the vehicle 1 in step S203 and step S205. The power to be applied to each drive wheel is calculated so that the corrected target rotation speed is obtained. More specifically, the driving of the motor that drives each driving wheel such that the rotational speed deviation between the actual rotational speed of each driving wheel and the corrected target rotational speed set in steps S203 and S205 is zero. Calculate the current value. In step S207, the output control unit 34 included in the drive control device 30 shown in FIG. 4 drives each drive wheel with the drive current value of the motor that drives each drive wheel calculated in step S206.

  As described above, in the second embodiment, when the output required for the power generation means for driving the drive wheels exceeds the output that can be generated by the power generation means, the rotational speed of the drive wheels driven by the power generation means. And the rotational speeds of the other drive wheels are reduced at the same rotational speed reduction rate. Thus, for example, even when the road surface friction state is different between the drive wheels on the inner side and the drive wheels on the outer side, the vehicle can stably turn while maintaining the turning posture. Note that the configuration of the second embodiment can also be applied as appropriate in the following embodiments.

(Embodiment 3)
The third embodiment is substantially the same as the second embodiment, but when the output required for the power generation means of the drive wheels exceeds the maximum output that can be generated by the power generation means, The difference is that the change in the turning radius of the vehicle with respect to the decrease in the vehicle speed is suppressed by reducing the rotational speed at the same rate and correcting the steering angle of the vehicle. Other configurations are the same as those of the second embodiment. The drive control according to the present embodiment can be applied to the traveling device 100 and the like provided in the vehicle 1 according to the first embodiment shown in FIG. Next, the vehicle 1 shown in FIG. 1-1 and the traveling device 100 included in the vehicle 1 will be described as an example.

  It can be seen that the vehicle center-of-gravity turning radius ρ determined by the equation (1) is a function of the vehicle speed V and changes as the vehicle speed V changes. In the case of understeer, LfKf−LrKr <0, and as the vehicle speed V decreases, the vehicle center-of-gravity turning radius ρ increases with the same steering angle δ. On the other hand, in the case of oversteering, LfKf−LrKr> 0, and if the steering angle δ is the same as the vehicle speed V decreases, the vehicle center-of-gravity turning radius ρ decreases.

  In the drive control according to the second embodiment described above, the vehicle 1 can be turned while maintaining the posture of the vehicle 1 by reducing the rotational speed of each drive wheel at the same rate. If the steering angle δ of the vehicle 1 is the same as a result of the change in the vehicle center-of-gravity turning radius ρ with the decrease, the turning radius of the vehicle 1 changes. In this case, the turning radius of the vehicle 1 is changed, and the output of the power generation means included in the traveling device 100 has reached the limit. Therefore, the change in the turning radius of the vehicle 1 cannot be corrected.

  In the present embodiment, in order to avoid this, the steering angle of the steering wheel (the left front wheel 21 and the right front wheel 2r) of the vehicle 1 is changed, and the vehicle center-of-gravity turning radius ρ determined by Expression (1) is The change of the turning radius of the vehicle 1 is suppressed so that it does not change even if the speed of 1 decreases. Here, the steering angle of the steered wheels of the vehicle 1 is changed while the operation amount of the handle 4 is kept constant by the steering reduction device 8 provided in the traveling device 100 mounted on the vehicle 1 shown in FIG. Can do.

  In order to make the turning radius of the vehicle 1 constant before and after the vehicle speed V decreases, the vehicle center-of-gravity turning radius ρ ′ after the vehicle speed V decreases calculated by the equation (15) and the equation (1) It is assumed that the obtained vehicle center-of-gravity turning radius ρ before the vehicle speed V decreases is equal. Then, the corrected steering angle δ ′ is calculated by the expression (16) in which the expression ρ ′ = ρ is arranged with respect to the steering angle (hereinafter referred to as a corrected steering angle) δ ′ after the vehicle speed V is decreased, and the vehicle 1 Is controlled to a corrected steering angle δ ′. Thereby, the change of the turning radius of the vehicle 1 due to the decrease in the vehicle speed V can be suppressed. Next, a drive control procedure according to the present embodiment will be described.

  FIG. 10 is an explanatory diagram illustrating a configuration example of a drive control device that realizes drive control according to the third embodiment. FIG. 11 is a flowchart illustrating a drive control procedure according to the third embodiment. First, a drive control device 30a that realizes drive control according to the third embodiment will be described. This drive control device 30a is obtained by adding a steering angle control unit 35 for controlling the steering angle of the steering wheel of the vehicle 1 to the drive control device 30 according to the first embodiment shown in FIG. These are the same as those of the drive control device 30 according to the first embodiment. And the drive control apparatus 30a which concerns on Embodiment 3 shown in FIG. 10 is also integrated in ECU50 similarly to the drive control apparatus 30 which concerns on Embodiment 1 shown in FIG.

  Since step S301 to step S306 of the drive control according to the third embodiment are the same as step S201 to step S206 according to the second embodiment, description thereof will be omitted. When the power to be applied to each drive wheel is calculated in step S306, the steering angle control unit 35 of the drive control device 30a shown in FIG. 10 calculates the post-deceleration steering angle, that is, the corrected steering angle δ ′ in step S307. To do. In step S306, in this embodiment, the drive current value of the electric motor that drives each drive wheel is calculated such that the rotation speed deviation between the actual rotation speed of each drive wheel and the corrected target rotation speed becomes zero. Is done.

  In step S307, the current vehicle speed V, the steering angle δ, and the target rotational speed correction coefficient α calculated in step S304 are given to equation (16), and the corrected steering angle δ ′ is calculated. When the corrected steering angle δ ′ is calculated, in step S308, the output control unit 34 of the drive control device 30a drives each drive wheel with the drive current value of the motor that drives each drive wheel calculated in step S306. . At the same time, in step S308, the steering angle control unit 35 controls the steering angle of the vehicle 1 to the corrected steering angle δ ′ calculated in step S307. Thereby, the change of the turning radius of the vehicle 1 can be suppressed before and after the vehicle speed V is decelerated.

  As described above, in the third embodiment, when the output required for the power generation means of the drive wheels exceeds the maximum output that can be generated by the power generation means, the rotational speed of each drive wheel is reduced at the same rate. At the same time, the steering angle of the vehicle is corrected. As a result, a change in the turning radius of the vehicle with respect to a decrease in the vehicle speed can be suppressed, so that drivability is improved.

  As described above, the traveling device and the drive control device according to the present invention are useful for improving the turning performance of the vehicle, and are particularly suitable for devices that can independently change the driving force of at least two drive wheels. ing.

It is the schematic which shows the structure of a vehicle provided with the traveling apparatus which concerns on Embodiment 1. FIG. It is the schematic which shows the other example of the traveling apparatus which concerns on Embodiment 1. FIG. It is the schematic which shows the other example of the traveling apparatus which concerns on Embodiment 1. FIG. FIG. 3 is a schematic diagram for explaining drive control according to the first embodiment. It is a schematic diagram for demonstrating the relationship of each wheel with which the vehicle which concerns on Embodiment 1 is provided. It is a schematic diagram for demonstrating the relationship of each wheel with which the vehicle which concerns on Embodiment 1 is provided. It is a schematic diagram for demonstrating the relationship of each wheel with which the vehicle which concerns on Embodiment 1 is provided. FIG. 3 is an explanatory diagram illustrating a configuration example of a drive control device according to the first embodiment. 3 is a flowchart illustrating a procedure of drive control according to the first embodiment. FIG. 10 is a schematic diagram for explaining drive control according to a modification of the first embodiment. FIG. 10 is a schematic diagram for explaining drive control according to a second embodiment. It is a schematic diagram which shows the equal output line of the electric motor which is an example of a motive power generation means. 6 is a flowchart illustrating a procedure of drive control according to the second embodiment. It is explanatory drawing which shows the structural example of the drive control apparatus which implement | achieves the drive control which concerns on Embodiment 3. FIG. 10 is a flowchart illustrating a drive control procedure according to the third embodiment.

Explanation of symbols

1, 1a, 1b Vehicle 2l Left front wheel 2r Right front wheel 2i Front inner wheel 2o Front outer wheel 3l Left rear wheel 3r Right rear wheel 3i Rear inner wheel 3o Rear outer wheel 4 Handle 5 Accelerator 6 Inverter 7 In-vehicle power supply 8 Steering speed reducer 10l Left front motor 10r right front motor 11l left rear motor 11r right rear motor 30, 30a drive control device 31 control condition determination unit 32 target rotational speed calculation unit 33 output determination unit 34 output control unit 35 steering angle control unit 40l left front resolver 40r right front Side resolver 41l Left rear resolver 41r Right rear resolver 42 Accelerator opening sensor 43 Steering angle sensor 44l Left front wheel rotational speed sensor 44r Right front wheel rotational speed sensor 45l Left rear wheel rotational speed sensor 45r Right rear wheel rotational speed sensor 50 ECU
100, 100a, 100b traveling device

Claims (19)

A plurality of drive wheels are provided, and the vehicle is mounted on a vehicle and travels.
For at least two of the driving wheels, the driving force can be changed independently, and the rotational speed of the driving wheel capable of changing the driving force becomes the target rotational speed for running the vehicle. In addition, power is applied to the drive wheels.   The travel device according to claim 1, wherein the target rotation speed is set based on a travel radius of the vehicle.   The travel device according to claim 2, wherein the travel radius of the vehicle is set based on a steering angle of a steered wheel included in the vehicle and a travel speed of the vehicle.   The travel device according to claim 1, wherein the target rotation speed is set for each of the drive wheels.   The traveling device according to claim 1, wherein the target rotational speed is a rotational speed difference between the pair of drive wheels.   The traveling device according to any one of claims 1 to 5, wherein the target rotational speeds of the plurality of drive wheels arranged on the same side surface of the vehicle are the same.   The traveling device according to claim 6, wherein the target rotational speed is set to the smallest value in the plurality of drive wheels arranged on the same side surface side of the vehicle. When the output required for the power generation means for driving the drive wheels exceeds the output that can be generated by the power generation means,
The rotational speed of the driving wheels driven by the power generation means is reduced, and the rotational speed of the other driving wheels is reduced at the same reduction rate as that of the driving wheels reduced in rotational speed. The traveling device according to any one of? 7. The traveling device includes:
The traveling apparatus according to claim 8, further comprising a steering angle changing unit that changes a steering angle of the steering wheel of the vehicle in accordance with a decrease in the rotation speed of the drive wheel.   The power generation means for the drive wheels is an electric motor that is provided for each of the drive wheels and that individually drives each of the drive wheels. Traveling device. A plurality of driving wheels are provided, and at least two driving wheels can independently change the driving force, and are used for controlling a traveling device that is mounted on a vehicle and travels the vehicle,
A target rotational speed calculation unit for calculating a target rotational speed targeted by the drive wheels when the vehicle is driven;
An output determining unit that determines the power to be applied to the drive wheel so that the rotation speed of the drive wheel becomes the target rotation speed;
An output control unit that drives the drive wheels with the power determined by the output determination unit;
A drive control device comprising: The target rotation speed calculation unit
The drive control device according to claim 11, wherein the target rotation speed is calculated based on a running radius of the vehicle. The target rotation speed calculation unit
The drive control device according to claim 12, wherein a travel radius of the vehicle is calculated based on a steering angle of a steered wheel included in the vehicle and a travel speed of the vehicle. The target rotation speed calculation unit
The drive control apparatus according to claim 11, wherein the target rotation speed is calculated for each of the drive wheels. The target rotation speed calculation unit
The drive control device according to any one of claims 11 to 13, wherein a difference in rotation speed between the pair of drive wheels is set as the target rotation speed. The target rotation speed calculation unit
The drive control device according to any one of claims 11 to 15, wherein the target rotation speeds of the plurality of drive wheels arranged on the same side surface of the vehicle are the same. The target rotation speed calculation unit
The drive control device according to claim 16, wherein the target rotation speed is set to the smallest value among the plurality of drive wheels arranged on the same side surface of the vehicle. When the output required for the power generation means for driving the drive wheels exceeds the output that can be generated by the power generation means,
The target rotation speed calculation unit
12. The rotational speed of driving wheels driven by the power generation means is reduced, and the rotational speed of other driving wheels is reduced at the same reduction rate as that of the driving wheels reduced in rotational speed. The drive control apparatus according to any one of -17. While calculating the amount of change in the steering angle of the steering wheel of the vehicle according to the decrease in the rotational speed of the drive wheel,
The drive control device according to claim 18, further comprising a steering angle control unit that steers the steered wheels of the vehicle so that the calculated steering angle is obtained.

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