JP2006333548A - Controller and vehicle - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a controller, which can improve the starting, braking, or turn performance of a vehicle by increasing the frictional coefficient between a wheel and a road, and the vehicle. <P>SOLUTION: This controller computes the slip speed to the road of the wheel (S2) and also reads the target slip speed out of a speed table (S3). Then, it actuates a wheel drive by means of a wheel driver actuating means, and it controls the rotational speed of the wheel so that the slip speed of the wheel may be the target slip speed. Hereby, it increases the frictional coefficient between the wheel and the road, whereby it can sharply improve the starting, braking or turn performance of the vehicle. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a control device and a vehicle for operating a wheel drive device and controlling a rotation speed of the wheel with respect to a vehicle having a wheel configured to roll and a wheel drive device that rotationally drives the wheel. In particular, the present invention relates to a control device and a vehicle that can increase the coefficient of friction between a wheel and a road surface and improve the start, braking, or turning performance of the vehicle.

  For example, anti-lock control and traction control control exist as techniques for controlling the wheels to increase the braking force and driving force (that is, improvement of vehicle start performance and braking performance). In a conventional example of anti-lock control, the braking force of a wheel caused by an excessive brake operating force (for example, brake pressure) is controlled by controlling the slip ratio of the wheel during braking of the vehicle to avoid wheel locking. Is prevented (for example, Patent Document 1).

Further, in a conventional example of traction control technology, in a structure in which driving force is transmitted to the left and right wheels (driving wheels) via a differential mechanism, when one slip (sliding) of the driving wheels becomes excessive, By braking the slipping drive wheel and destroying the drive torque, the drive torque is prevented from being transmitted to the other drive wheel (for example, Patent Document 2).
JP-A-5-155325 JP 2004-123084 A

  By the way, the above-described conventional technique is a technique for ensuring a braking force or a driving force by controlling a slip ratio of a wheel so that the wheel is not locked or excessively slipped. That is, the slip coefficient between the wheel slip ratio and the friction coefficient between the wheel and the road surface increases when the slip ratio increases from 0, and the friction coefficient decreases rapidly after passing through a non-slip region where the friction coefficient increases monotonously. There is a relationship of moving to an area. Therefore, in the conventional technique, by increasing the slip ratio within the non-slip region, the friction coefficient approaches the peak value, and the braking force or driving force of the wheel is ensured.

  On the other hand, the inventor of the present application has developed a new method for increasing the coefficient of friction between the wheel and the road surface. Specifically, the slip ratio of the wheel (in other words, the slip speed of the wheel with respect to the road surface) is a sufficiently small value (for example, a value that is 1 to 2 digits smaller than the slip ratio when shifting from the non-slip region to the slip region). This is based on the knowledge that a friction coefficient more than twice that obtained by the above-described conventional technology can be obtained (not known at the time of this application).

  The present invention has been made in order to provide a new method for increasing the friction coefficient between the wheel and the road surface as described above, and increases the friction coefficient between the wheel and the road surface. It is an object of the present invention to provide a control device and a vehicle that can improve start, braking or turning performance.

  In order to achieve this object, a control device according to claim 1 operates a wheel drive device on a vehicle having a wheel configured to be able to roll and a wheel drive device that rotationally drives the wheel. , Which controls the rotational speed of the wheel, a slip speed calculating means for calculating the slip speed of the wheel with respect to the road surface, and a slip speed for maximizing the friction coefficient between the road surface and the wheel. Storage means for storing as a sliding speed, and the rotational speed of the wheel are controlled so that the sliding speed of the wheel calculated by the sliding speed calculating means becomes the value of the target sliding speed stored in the storing means. And wheel driving device operating means for operating the wheel driving device.

  The control device according to claim 2 is the control device according to claim 1, wherein the vehicle includes a plurality of wheels that are rotationally driven by the wheel drive device, and the wheel drive device is configured by an electric motor. The electric motor is provided for each of the plurality of wheels, and the wheel driving device operating means operates the plurality of electric motors, respectively, so that the rotational speeds of the plurality of wheels can be independently controlled. It is characterized by being.

  According to a third aspect of the present invention, there is provided the control device according to the first or second aspect, further comprising: a peripheral speed calculating unit that calculates a peripheral speed of the wheel; and a ground speed calculating unit that calculates the ground speed of the vehicle. The slip speed calculation means calculates the slip speed of the wheel based on the peripheral speed of the wheel calculated by the peripheral speed calculation means and the ground speed of the vehicle calculated by the ground speed calculation means. Is.

  A control device according to a fourth aspect of the present invention is the control device according to any one of the first to third aspects, wherein the wheel driving device operating means controls the rotational speed of the wheel when the acceleration of the vehicle is instructed. Then, the wheel driving device is operated so that the value of the peripheral speed of the wheel is larger than the value of the ground speed of the vehicle and the slip speed of the wheel becomes the target slip speed, When the vehicle is instructed to decelerate, the rotational speed of the wheel is controlled so that the value of the peripheral speed of the wheel is smaller than the value of the ground speed of the vehicle, and the sliding speed of the wheel is the target speed. The wheel driving device is operated so as to achieve a sliding speed.

  A vehicle according to a fifth aspect includes the control device according to any one of the first to fourth aspects.

  According to the control device of the first aspect, the rotational speed of the wheel can be controlled by operating the wheel driving device by the wheel driving device operating means so that the sliding speed of the wheel becomes the target sliding speed. Here, the target sliding speed stored in the storage means of the present invention is a sliding coefficient that provides a friction coefficient that is obtained at other sliding speeds, that is, a friction coefficient that is at least twice that obtained by the above-described conventional technique. Since the speed is high, the friction coefficient between the wheel and the road surface can be increased as compared with the conventional technique, and the vehicle start, braking or turning performance can be greatly improved.

  According to the control device of the second aspect, in addition to the effect produced by the control device of the first aspect, the wheel drive device is constituted by an electric motor, so that the rotational speed of the wheel is compared with the case of the conventional internal combustion engine. Can be controlled with high responsiveness and high accuracy. As a result, it is possible to increase the coefficient of friction between the wheel and the road surface by controlling the slipping speed of the wheel to become the target sliding speed, and as a result, the vehicle start, braking or turning performance is greatly improved. Can be achieved.

  That is, since the target slip speed of the present invention is an extremely small value (for example, about 10 cm / s), it is impossible for a conventional internal combustion engine to control the wheel to such a slip speed. As described above, the wheel drive device can be controlled for the first time by an electric motor. As a result, it is possible to control the slipping speed of the wheel to become the target slipping speed, and as a result, the friction coefficient between the wheel and the road surface is increased, and the vehicle start, braking or turning performance is greatly improved. Can be planned.

  Furthermore, in this invention, since the electric motor was provided for every some wheel, there exists an effect that the rotational speed of these some wheels can be controlled independently, respectively. Usually, when the vehicle is running, the ground contact state between the road surface and each wheel is different for each wheel. Therefore, if the same rotational driving force is applied to each wheel, the sliding speed of each wheel varies.

  On the other hand, if each wheel can be controlled independently as in the present invention, each wheel can be controlled with high precision so that the sliding speed of each wheel becomes the target sliding speed. There is an effect that the coefficient can be improved efficiently. As a result, it is possible to further improve the starting, braking or turning performance of the vehicle as a whole.

  According to the control device of claim 3, in addition to the effect of the control device of claim 1 or 2, the peripheral speed calculation means and the ground speed calculation means are provided, the peripheral speed calculation means and the ground speed calculation means. Since the slip speed of the wheel is calculated by the slip speed calculation means based on the peripheral speed of the wheel and the ground speed of the vehicle calculated by the above, the effect that the slip speed of the wheel can be calculated with high accuracy is obtained. is there.

  According to the control device of the fourth aspect, in addition to the effect produced by the control device according to any one of the first to third aspects, the wheel drive device operating means can accelerate the vehicle by, for example, an operation of the driver or Regardless of the driver's operation, when instructed, the wheel drive is performed so that the wheel peripheral speed value is greater than the vehicle ground speed value and the wheel slip speed is the target slip speed. Since the device is operated, there is an effect that the friction coefficient between the road surface and the wheel can be increased while avoiding that the vehicle is decelerated even though the acceleration of the vehicle is instructed. .

  On the other hand, when deceleration of the vehicle is instructed by, for example, the driver's operation or regardless of the driver's operation, the wheel drive device operating means is configured such that the wheel peripheral speed value is the vehicle ground speed value. Since the wheel drive device is operated so that the wheel slip speed becomes the target slip speed, the vehicle is prevented from accelerating despite being instructed to decelerate the vehicle. However, there is an effect that the coefficient of friction between the road surface and the wheel can be increased.

  According to the vehicle of the fifth aspect, the same effect as that of the vehicle including the control device according to any one of the first to fourth aspects is achieved.

  Hereinafter, preferred embodiments of the present invention will be described with reference to the accompanying drawings. FIG. 1 is a schematic diagram schematically showing a vehicle 1 on which a control device 100 according to an embodiment of the present invention is mounted. An arrow FWD in FIG. 1 indicates the forward direction of the vehicle 1. Moreover, in FIG. 1, the state by which the predetermined rudder angle was provided to all the wheels 2 is shown in figure.

  First, a schematic configuration of the vehicle 1 will be described. As shown in FIG. 1, the vehicle 1 includes a vehicle body frame BF, a plurality of (four wheels in this embodiment) wheels 2 supported by the vehicle body frame BF, and wheels that rotate and drive these wheels 2 independently. A driving device 3 and an actuator device 4 for steering and driving each wheel 2 independently are mainly provided. During traveling, the sliding speed of the wheel 2 relative to the road surface is controlled by a control device 100 described later, whereby the wheel 2 and the road surface are The friction coefficient is increased so that the start performance, braking performance, or turning performance can be improved.

  Next, the detailed configuration of each part will be described. As shown in FIG. 1, the wheel 2 includes four wheels, that is, left and right front wheels 2FL and 2FR positioned on the front side in the traveling direction of the vehicle 1 and left and right rear wheels 2RL and 2RR positioned on the rear side in the traveling direction. The front and rear wheels 2FL to 2RR are configured to be steerable by the steering devices 20 and 30.

  The wheel 2 includes a tire mainly composed of a rubber material, and a wheel composed of a metal material such as steel, aluminum alloy, or magnesium alloy while holding the tire, and the wheel is a wheel driving device. 3 is connected to the driving shaft 3, and the rotational driving force is transmitted from the wheel driving device 3 to the wheel (wheel 2) via the driving shaft.

  The steering devices 20 and 30 are steering devices for steering each wheel 2, and as shown in FIG. 1, a king pin 21 that supports each wheel 2 so as to be swingable, and a knuckle arm (not shown) of each wheel 2. 1) and a transmission mechanism 23 for transmitting the driving force of the actuator device 4 to the tie rod 22 is mainly provided.

  As described above, the actuator device 4 is a steering drive device for independently driving the wheels 2 and includes four actuators (FL to RR actuators 4FL to 4RR) as shown in FIG. It is configured. When the driver operates the handle 51, a part (for example, only the front wheels 2FL and 2FR) or all of the actuator device 4 is driven, and a steering angle corresponding to the operation amount of the handle 51 is given.

  Here, in the present embodiment, the FL to RR actuators 4FL to 4RR are constituted by electric motors, and the transmission mechanism portion 23 is constituted by a screw mechanism. When the electric motor is rotated, the rotational motion is converted into a linear motion by the transmission mechanism 23 and transmitted to the tie rod 22. As a result, each wheel 2 is driven to swing around the king pin 21 as a swing center, and a predetermined steering angle is given to each wheel 2.

  The wheel driving device 3 is a rotation driving device for independently rotating and driving each wheel 2, and four electric motors (FL to RR motors 3FL to 3RR) are provided for each wheel 2 as shown in FIG. (Ie, as an in-wheel motor). Thereby, the rotational speed of each wheel 2 can be independently controlled.

  When the driver operates the accelerator pedal 53, a rotational driving force is applied to each wheel 2 from the wheel driving device 3, and each wheel 2 is rotated at a rotational speed corresponding to the operation amount of the accelerator pedal 53. In the present invention, in this case, rotation control is performed in order to make the slip speed of each wheel 2 relative to the road surface coincide with (or approach) a target slip speed described later. Details of the rotation control will be described later.

  The control device 100 is a control device for controlling each part of the vehicle 1 configured as described above. For example, the wheel drive device 3 and the actuator device 4 are operated to control the rotation speed of the wheel 2. Then, rotation control of the wheel 2 is performed. Here, with reference to FIG. 2, the detailed structure of the control apparatus 100 is demonstrated.

  FIG. 2 is a block diagram showing an electrical configuration of the control device 100. As shown in FIG. 2, the control device 100 includes a CPU 71, a ROM 72, and a RAM 73, which are connected to an input / output port 75 via a bus line 74. A plurality of devices such as the wheel drive motor 3 are connected to the input / output port 75.

  The CPU 71 is an arithmetic unit that controls each unit connected by the bus line 74. The ROM 72 is a non-rewritable non-volatile memory that stores a control program (for example, flowcharts of processes shown in FIGS. 5 to 7) executed by the CPU 71 and fixed value data. The RAM 73 is a control program. Is a memory for storing various work data, flags, and the like in a rewritable manner.

  The ROM 72 is provided with a sliding speed table 72a as shown in FIG. The sliding speed table 72a is a table that stores the value of the target sliding speed. The target slip speed is a target value when the rotation control of the wheel 2 is performed, and the CPU 71 sets each wheel so that the slip speed with respect to the road surface of each wheel 2 becomes the target slip speed while the vehicle 1 is traveling. 2 is controlled.

  Here, the relationship between the sliding speed and the friction coefficient will be described with reference to FIG. FIG. 3 is a diagram showing the relationship between the sliding speed and the friction coefficient, and illustrates the result of measurement using the physical properties of the wheel 2 (tire) in the present embodiment. In FIG. 3, the horizontal axis indicates the sliding speed of the wheel 2 with respect to the road surface, and the vertical axis indicates the friction coefficient between the wheel 2 and the road surface.

  As shown in FIG. 3, the coefficient of friction between the wheel 2 and the road surface changes according to the value of the sliding speed, and reaches a maximum value at a predetermined sliding speed (1 cm / s in the present embodiment). Have.

  Therefore, in the present invention, the sliding speed at which the friction coefficient is maximized is measured in advance, and this measured value is stored as a target sliding speed in the ROM 72 (sliding speed table 72a), and the sliding speed of the wheel 2 with respect to the road surface is determined. The rotational speed of the wheel 2 is controlled so as to be the value of the target sliding speed. Thereby, the coefficient of friction between the wheel 2 and the road surface can be increased, so that the braking / acceleration performance and the turning performance can be improved.

  In the conventional antilock control, as described above, control is performed so that the slip rate of the wheel 2 takes a value immediately before the transition from the non-slip region to the slip region. In this case, the target slip rate is usually It is about 0.2 to 0.3. On the other hand, the target slip speed in the rotation control of the present invention corresponds to a value smaller by one to two digits than the conventional target slip ratio when converted into a slip ratio. A technique for increasing the coefficient of friction by controlling the rotational speed (sliding speed) of the wheel 2 in such a region is a novel technique that has not been conventionally used.

  Returning to FIG. As shown in FIG. 2, the ROM 72 includes a drive release table 72b and a drive return table 72c.

  Here, in the present invention, the ground speed of the vehicle 1 is calculated from the peripheral speed of the wheel 2 by freely rolling any of the wheels 2 while the vehicle 1 is traveling. Therefore, it is necessary to release the rotational driving force applied from the wheel driving device 3 in order to freely roll the wheel 2.

  Therefore, in the drive release table 72b, a release speed for releasing the rotational driving force applied to the wheel 2 from the wheel drive device 3 is defined in order to measure the ground speed of the vehicle 1. On the other hand, in the drive return table 72c, the application speed when the measurement of the ground speed of the vehicle 1 is completed and the application of the rotational driving force from the wheel drive device 3 to the wheel 2 is resumed is defined.

  Details of the drive release table 72b and the drive return table 72c will be described with reference to FIG. FIG. 4A is a schematic diagram schematically showing the contents of the drive release table 72b, and FIG. 4B is a schematic diagram schematically showing the contents of the drive return table 72c.

  4 (a) and 4 (b), the horizontal axis indicates the elapsed time since the start or release of the rotational driving force, and the vertical axis is applied from the wheel driving device 3 to the wheel 2. The magnitude of the rotational driving force is shown.

  For example, when the rotational driving force applied to the wheel 2 is released, the CPU 71 reads the release speed (that is, the rate of change of the rotational driving force with respect to the elapsed time) from the drive release table 72b shown in FIG. By controlling the wheel driving device 3 based on the read release speed, the rotational driving force applied to the wheel 2 is gradually reduced.

  In this way, when the rotational driving force already applied to the wheel 2 is to be released, the rotational driving force is not released all at once, but is gradually reduced so that the inertial force acting on the wheel 2 is affected. Can be reduced, and the follow-up characteristic with respect to the road surface can be improved. Thereby, the synchronization between the wheel 2 and the road surface can be stabilized and accelerated, and as a result, the ground speed of the vehicle 1 can be measured with high efficiency and high accuracy.

  On the other hand, when resuming the application of the rotational driving force to the wheels 2, the CPU 71 reads the application speed (that is, the rate of change of the rotational driving force with respect to the elapsed time) from the drive return table 72c shown in FIG. Based on the read application speed, the wheel driving device 3 is controlled to gradually increase the rotational driving force applied to the wheel 2.

  As described above, when the application of the rotational driving force to the wheel 2 is resumed, the rotational driving force is not applied all at once, but is gradually increased to act on the wheel 2 as described above. The following characteristic with respect to the road surface can be improved by reducing the influence of inertial force. As a result, the behavior of the vehicle 1 can be stabilized. In addition, since it is not necessary to cause the wheel drive device 3 to exhibit an excessive rotational driving force, it is possible to suppress the drive load and improve durability, and it is also possible to reduce the size of the wheel drive device 3. .

  Returning to FIG. As described above, the wheel drive device 3 is a device for rotationally driving each wheel 2 (see FIG. 1), and includes four FL to RR motors 3FL to 3RR that apply a rotational driving force to each wheel 2. And a drive circuit (not shown) for driving and controlling each of the motors 3FL to 3RR based on a command from the CPU 71.

  Further, as described above, the actuator device 4 is a device for steering and driving each wheel 2, and includes four FL to RR actuators 4FL to 4RR that apply a steering driving force to each wheel 2, and each of these actuators. 4FL to 4RR are provided with a drive circuit (not shown) for driving and controlling based on a command from the CPU 71.

  The steering angle sensor device 31 is a device for detecting the steering angle of each wheel 2 and outputting the detection result to the CPU 71. The four FL to RR steering angles for detecting the steering angle of each wheel 2 respectively. Sensors 31FL to 31RR and a processing circuit (not shown) for processing the detection results of the steering angle sensors 31FL to 31RR and outputting the results to the CPU 71 are provided.

  In this embodiment, each steering angle sensor 31FL to 31RR is provided in each transmission mechanism unit 23, and the transmission mechanism unit 23 detects the number of rotations when the rotational motion is converted into linear motion. It is configured as a rotary angle sensor of the type. Since this rotational speed is proportional to the amount of displacement of the tie rod 22, the CPU 71 can obtain the steering angle of each wheel 2 based on the detection result (the rotational speed) input from the steering angle sensor device 31.

  Here, the rudder angle detected by the rudder angle sensor device 31 is an angle formed by the center line of each wheel 2 and the reference line of the vehicle 1 (body frame BF), regardless of the traveling direction of the vehicle 1. It is a fixed angle.

  The wheel rotation speed sensor device 33 is a device for detecting the rotation speed of each wheel 2 and outputting the detection result to the CPU 71. Four FL to RR rotations for detecting the rotation speed of each wheel 2 respectively. Speed sensors 33FL to 33RR and a processing circuit (not shown) that processes the detection results of the rotational speed sensors 33FL to 33RR and outputs them to the CPU 71 are provided.

  In this embodiment, each rotation sensor 33FL-33RR is provided in each wheel 2, and detects the angular velocity of each wheel 2 as a rotation speed. That is, each rotation sensor 33FL-33RR is an electromagnetic pickup provided with a rotating body that rotates in conjunction with each wheel 2 and a pickup that electromagnetically detects the presence or absence of a large number of teeth formed in the circumferential direction of the rotating body. It is configured as a sensor of the type.

  The CPU 71 can obtain the peripheral speed of each wheel 2 from the rotational speed of each wheel 2 input from the wheel rotational speed sensor device 33 and the outer diameter of each wheel 2. In the present invention, the ground speed of the vehicle 1 is calculated based on the peripheral speed of the wheel 2 as described later. A method for calculating the ground speed of the vehicle 1 will be described later.

  As another input / output device 35 shown in FIG. 2, for example, in order to detect an operation state (rotation angle, stepping amount, operation speed, etc.) of the handle 51, the brake pedal 52, and the accelerator pedal 53 (all of which refer to FIG. 1). An operation state detection sensor device (not shown) is exemplified.

  For example, when the accelerator pedal 53 is operated, the operation state amount is detected by the operation state detection sensor device and output to the CPU 71. The CPU 71 drives the wheel driving device 3 to control the rotation speed of each wheel 2.

  Next, processing executed by the control device 100 will be described with reference to FIGS. FIG. 5 is a flowchart showing the rotation control process. This process is a process that is repeatedly executed by the CPU 71 (for example, at intervals of 0.2 ms) while the power of the control device 100 is turned on, so that the sliding speed of the wheels 2 with respect to the road surface becomes the target sliding speed. By controlling, the friction coefficient between the wheel 2 and the road surface is increased, and the start / braking performance and the turning performance are improved.

  Regarding the rotation control process, the CPU 71 first executes a ground speed calculation process to calculate the ground speed of the vehicle 1 (S1). Here, the ground speed calculation process will be described with reference to FIG.

  FIG. 6 is a flowchart showing the ground speed calculation process. Regarding the ground speed calculation process (S1), the CPU 71 first determines whether or not the vehicle 1 is traveling (S11). As a result, when it is determined that the vehicle 1 is not traveling (S11: No), the vehicle 1 is stopped (the ground speed is 0), and it is not necessary to calculate the ground speed. The process ends.

  On the other hand, in the process of S11, when it is determined that the vehicle 1 is traveling (S11: Yes), the vehicle 1 then rolls freely among a plurality (four wheels in the present embodiment) of the wheels 2. It is determined whether or not there is a wheel 2, that is, a wheel 2 to which no rotational driving force is applied from the wheel driving device 3 (S 12).

  That is, in the present invention, as described above, the ground speed of the vehicle 1 is calculated from the peripheral speed of the wheel 2 by freely rolling any of the wheels 2 while the vehicle 1 is traveling. Therefore, when it is determined in S12 that there is a free-rolling wheel 2 (for example, the left and right rear wheels 2RL and 2RR run only as drive wheels, and the left and right front wheels 2FL and 2FR are free-rolling). (S12: Yes), the ground speed of the vehicle 1 can be calculated using the already free-rolling wheels 2 (that is, the left and right front wheels 2FL, 2FR).

  Therefore, in this case (S12: Yes), the process from S13 to S15, which is the process for freely rolling the wheel 2, is skipped, and the process proceeds to S16.

  On the other hand, in the process of S12, when it is determined that all the wheels 2 are rotationally driven by the wheel drive device 3 and there is no free-wheeling wheel 2 (S12: No), first, each wheel 2 is detected (S13), and then the wheel 2 to be freely rolled is determined based on the detection result (S14).

  That is, when the vehicle 1 is turning, each wheel 2 has a slip angle (sliding with respect to the road surface), and therefore, in the present embodiment, the influence of the slip angle of the wheel 2 is minimized. Therefore, if there is a wheel 2 to which no steering angle is given as a result of the process of S13, the wheel 2 is determined as a wheel that freely rolls (S14). On the other hand, as a result of the process of S13, when there is no wheel 2 to which no steering angle is given, that is, when all the wheels 2 have a steering angle, the absolute value of the given steering angle is small. The wheel 2 is determined as a wheel that freely rolls (S14).

  For example, if the turning mode of the vehicle 1 is a mode in which a steering angle is given only to the front wheels 2FL and 2FR by turning the steering wheel 51 by the driver, the rear wheels 2RL and 2RR are turned more than the front wheels 2FL and 2FR. Therefore, the rear wheel 2RL, 2RR is determined as a wheel that freely rolls and rolls (S14).

  Further, if the turning mode of the vehicle 1 is a mode in which the steering angle is given to all the front and rear wheels 2FL to 2RR by turning the steering wheel 51 by the driver, the steering angle among these front and rear wheels 2FL to 2RR. A wheel having a small absolute value of is determined as a wheel for free rolling (S14). Thereby, the ground speed of the vehicle 1 can be calculated with higher accuracy.

  In the process of S14, the wheels 2 determined as the wheels to be freely rolled are two wheels, and these two wheels are the left and right wheels 2 (the left and right front wheels 2FL, 2FR or the left and right rear wheels 2RL, 2RR). In addition, when the steering angle is provided to all the wheels 2, it is preferable to set it as two right and left wheels including the wheel 2 with the smallest absolute value of a steering angle.

  That is, when all the wheels 2 are rotationally driven by the wheel driving device 3 (S12: No), only one of the wheels 2 is freely rolled (that is, the rotational driving force is released). ), The driving force acting on the vehicle 1 becomes non-uniform as a whole, so that the balance is deteriorated (a rotational moment is generated to rotate the vehicle 1) and the behavior of the vehicle 1 is destabilized. However, by using two wheels on the left and right for free rolling, it is possible to secure the balance (suppress the generation of a rotational moment to rotate the vehicle 1) and keep the behavior of the vehicle 1 stable. Because it can.

  In the process of S14, after the wheels to be freely rolled are determined, a drive release and return process (S15) is executed to freely roll the determined wheels 2, and the rotation given from the wheel driving device 3 is performed. Release the driving force. Here, with reference to FIG. 7, the drive release and return processing will be described.

  FIG. 7 is a flowchart showing drive release and return processing. In this drive release and return processing (S15), the release of the rotational drive force applied to the wheel 2 and the restart of the application of the rotational drive force to the wheel 2 are performed.

  The CPU 71 first determines whether or not the drive is to be released regarding the drive release and return processing (S15) (S21). That is, it is determined whether to release the rotational driving force applied to the wheel 2 or to resume the application of the rotational driving force to the wheel 2.

  This time, it is a process executed after the process of S14, for releasing the application of the rotational driving force applied to the wheel 2 in order to freely roll the wheel 2 determined in the process of S14. Since this is a process, it is determined that the drive has been released (S21: Yes).

  Therefore, in this case (S21: Yes), the process proceeds to S22. First, the release speed is read from the drive release table 72b, and then the rotational driving force applied to the wheel 2 at the read release speed. The wheel drive device 3 is controlled so as to gradually decrease (S22), and the drive release and return processing is terminated.

  Thereby, the application of the rotational driving force to the wheels 2 is released, and the wheels 2 roll (freely roll) without sliding on the road surface. In addition, by gradually reducing the rotational driving force in this way, as described above, the follow-up characteristic with respect to the road surface of the wheel 2 that has caused free rolling is improved, so that the synchronization between the wheel 2 and the road surface is stabilized. The ground speed of the vehicle 1 can be measured with high efficiency and high accuracy.

  Returning to FIG. After the wheel 2 is freely rolled by the drive release and return processing (S15), or when there is already a wheel 2 that freely rolls (S12: Yes), first, the wheel 2 that freely rolls. Is detected (S16), and then the ground speed of the vehicle 1 is calculated based on the detected rotational speed of the wheel 2 (S17).

  Specifically, the rotational speed of the wheel 2 is detected by the wheel rotational speed sensor device 33 (S16), and the wheel 2 is calculated from the detected rotational speed of the wheel 2 and the outer diameter of the wheel 2 stored in the ROM 72 in advance. 2 is calculated, that is, the ground speed of the vehicle 1 is calculated (S17).

  In addition, when there are two free rolling wheels, it is preferable to calculate the ground speed of the vehicle 1 based on the peripheral speed (for example, average value) of the two wheels. Further, when the freely rolling wheel 2 has a steering angle, the slip angle is estimated, and the peripheral speed of the wheel 2 is corrected based on the slip angle to calculate the ground speed of the vehicle 1. Is preferred.

  After the ground speed of the vehicle 1 is calculated by the process of S17, the drive release and return are performed in order to resume the application of the rotational driving force to the wheel 2 from which the rotational driving force has been applied for free rolling. A process (S18) is performed and this ground speed calculation process (S1) is complete | finished.

  This will be described with reference to FIG. Regarding the drive release and return processing (S18), the CPU 71 first determines whether or not the drive is released (S21). This time, the process is executed after the process of S17, and the process of restarting the application of the rotational driving force to the wheel 2 from which the application of the rotational driving force has been released to allow free rolling is performed. It is determined that there is not (S21: No).

  Therefore, in this case (S21: No), the process proceeds to S23, where the return speed is first read from the drive return table 72c, and then the rotational driving force applied to the wheel 2 at the read return speed is obtained. The wheel drive device 3 is controlled so as to increase gradually (S23), and the drive release and return processing is terminated.

  If the rotational driving force is not released by the process of S15 (that is, if S12 is Yes), it is not necessary to execute the process of resuming the application of the rotational driving force, so the process of S23 is performed. Skipping and ending this drive release and return processing.

  By the process of S23, the application of the rotational driving force to the wheel 2 is resumed, and the wheel 2 functions as a driving wheel. In addition, by gradually increasing the rotational driving force as described above, the behavior of the vehicle 1 can be stabilized as described above, and the driving load of the wheel driving device 3 can be suppressed and durability can be reduced. The wheel drive device 3 can also be reduced in size.

  Returning to FIG. After the ground speed calculation process (S1) is executed and the ground speed of the vehicle 1 is calculated, the sliding speed of the wheels 2 is then calculated based on the calculated ground speed of the vehicle 1 (S2).

  Specifically, as described above, the peripheral speed of the wheel 2 can be obtained from the rotational speed of the wheel 2 detected by the wheel rotational speed sensor device 33 and the outer diameter of the wheel 2 stored in the ROM 72 in advance. The slip speed of the wheel 2 can be calculated by taking the difference between the peripheral speed and the ground speed of the vehicle 1.

  Next, the target slip speed is read from the slip speed table 72a (S3), and after detecting the operation state of the accelerator pedal 53 (S4), the slip speed of the wheel 2 that is the drive wheel becomes the target slip speed. The wheel drive device 3 is controlled (S5), and this rotation control process is terminated.

  Thereby, the coefficient of friction between the wheel 2 and the road surface can be increased, and the start performance, braking performance or turning performance of the vehicle 1 can be improved.

  In addition, as a result of detecting the operation state of the accelerator pedal 53 (S4), when the acceleration of the vehicle 1 is instructed, the wheel driving device is set so that the peripheral speed of the wheel 2 is larger than the ground speed of the vehicle 1. 3 is controlled (S5). Thereby, it is possible to increase the coefficient of friction between the road surface and the wheel 2 while avoiding that the vehicle 1 is decelerated although the acceleration of the vehicle 1 is instructed.

  On the other hand, as a result of detecting the operation state of the accelerator pedal 53 (S4), when the vehicle 1 is instructed to decelerate, the wheel drive device is set so that the peripheral speed of the wheel 2 is smaller than the ground speed of the vehicle 1. 3 is controlled (S5). Accordingly, it is possible to increase the coefficient of friction between the road surface and the wheel 2 while avoiding that the vehicle 1 is accelerated even though the deceleration of the vehicle 1 is instructed.

  In the flowchart (rotation control process) shown in FIG. 5, the process of S2 is performed as the slip speed calculating means according to claim 1, and the process of S5 is performed as the wheel drive device operating means. The flowchart (ground speed) shown in FIG. In the calculation process), the processing of S16 corresponds to the peripheral speed calculation means described in claim 2, and the processing of S17 corresponds to the ground speed calculation means.

  The present invention has been described above based on the embodiments. However, the present invention is not limited to the above embodiments, and various improvements and modifications can be made without departing from the spirit of the present invention. It can be easily guessed.

  For example, the numerical values given in the above embodiment are merely examples, and other numerical values can naturally be adopted.

  In the above embodiment, the slip speed of the wheel 2 is set to the target slip speed regardless of the travel state of the vehicle 1, that is, whether the vehicle 1 is traveling at a constant speed or acceleration / deceleration. However, the present invention is not necessarily limited to this, and the rotation control may be executed only when a predetermined condition is satisfied. In addition, as a case where predetermined conditions are satisfy | filled, the case where the acceleration or deceleration of the vehicle 1 becomes more than predetermined value, for example, and the case where the vehicle 1 is turning are illustrated.

  In the above embodiment, the ground speed of the vehicle 1 is calculated regardless of the traveling state of the vehicle 1, that is, whether the vehicle 1 is traveling straight or turning. For example, the ground speed can be calculated only when the vehicle 1 is traveling straight ahead. Whether or not the vehicle 1 is traveling straight may be determined based on the steering angle of the wheel 2 as described above, or an acceleration sensor device (for example, a piezoelectric sensor using a piezoelectric element) is used. You may do it.

  In the above-described embodiment, it has been described that it is preferable that the wheels 2 to be freely rolled to calculate the ground speed of the vehicle 1 are two left and right wheels. However, the number of wheels 2 to be freely rolled is not necessarily limited. For example, it is naturally possible to freely roll only one wheel or three or more wheels. Similarly, the wheels 2 to be freely rolled are not necessarily left and right wheels, and may be front and rear wheels, for example.

  In the above embodiment, the case where the outer diameter of each wheel 2 is stored in advance in the ROM 72 as fixed value data has been described. However, the fixed value data is stored in a rewritable nonvolatile memory such as an EEPROM. The driver may be configured to arbitrarily change the value of the fixed value data while storing the value.

  Or you may provide the correction | amendment means which correct | amends the value of fixed value data (namely, make an outer diameter small according to an abrasion part) according to the frequency | count of accumulation rotation of wheel 2 (namely, wear degree). With these configurations, even when the wheel 2 is changed (so-called inch up) or the tread of the wheel 2 is worn, the peripheral speed of the wheel 2 (that is, the ground speed of the vehicle 1) is calculated with higher accuracy. Can do.

  In the above embodiment, the case where only one type of target slip speed is stored in the slip speed table 72a has been described. However, the present invention is not necessarily limited to this, and a plurality of types of target slip speeds are stored. When the sliding speed of the wheel 2 is controlled, the target sliding speed read in the process of S3 may be appropriately changed. As a result, the coefficient of friction between the wheel 2 and the road surface can be increased with higher efficiency, and the starting performance and the like can be further improved.

  For example, a plurality of types of target slip speeds are stored in the slip speed table 72a according to the temperature of the road surface or wheels (tires) 2, and the surface temperature of the road surface or wheels 2 is measured while the vehicle 1 is traveling. It is also possible to read out the target slip speed corresponding to the above and control the slip speed of the wheel 2. The surface temperature may be estimated from the outside air temperature, or may be measured by a non-contact temperature sensor (such as an infrared sensor).

  Also, a plurality of types of target slip speeds are stored in the slip speed table 72a according to the presence / absence of rainfall and the rainfall amount, and the target corresponding to the presence / absence of rainfall and the rainfall amount while measuring the rainfall amount while the vehicle 1 is traveling. The sliding speed may be read and the sliding speed of the wheel 2 may be controlled. The rainfall amount can be measured by a known rainfall sensor.

  Further, a plurality of types of target slip speeds are stored in the slip speed table 72a for each type of road surface (for example, asphalt physical properties), and the type of the road surface is monitored while the type of the road surface is monitored while the vehicle 1 is traveling. It is also possible to read out the target slip speed corresponding to the above and control the slip speed of the wheel 2.

  The road surface type may be estimated using a non-contact optical sensor device, or the road surface type information is stored in advance in the navigation system in association with the position information, and the position of the vehicle 1 obtained from the GPS is stored. Information may be acquired, and road surface type information corresponding to the position information may be acquired from the navigation system.

  In addition, a plurality of types of target slip speeds are stored in the slip speed table 72a for each type of wheel (tire) 2 (for example, by physical property of the rubber material constituting the tread of the tire) and mounted on the vehicle 1. The target slip speed corresponding to the wheel 2 may be read to control the slip speed of the wheel 2. The type of wheel 2 is preferably configured to be input by the driver.

  Further, the various target slip speeds described above may be used alone or in combination.

  In the above embodiment, the case where the release speed and the return speed (that is, the slope of the straight line shown in FIG. 4) stored in the drive release table 72b and the drive return table 72c are constant values has been described. The present invention is not limited to this, and it is naturally possible to change the release speed and the return speed.

  For example, the case where it changes according to the acceleration / deceleration of the vehicle 1, the case where it changes according to a road surface state, etc. are illustrated. Specifically, for example, the greater the acceleration / deceleration of the vehicle 1, the greater the influence of the inertial force that acts on the wheel 2 when the rotational driving force is released, and so on. Reduce the effect of force. Similarly, the greater the frictional resistance of the road surface, the greater the influence of the inertial force acting on the wheel 2 when releasing the rotational driving force, etc., so the influence of the inertial force is reduced by setting the release speed etc. slower. Let

  Moreover, although the said embodiment demonstrated the case where the vehicle 1 was comprised with 4 wheels of front-and-rear wheels 2FL-2RR, the number of the wheels 2 is not necessarily restricted to this, For example, it is 3 wheels. There may be five or more wheels.

  Further, in the above-described embodiment, the case where the actuator device 4 is configured by an electric motor and the transmission mechanism unit 23 is configured by a screw mechanism has been described. However, the configuration is not necessarily limited thereto. -You may comprise a pneumatic cylinder. Thereby, since the transmission mechanism part 23 can be abbreviate | omitted, a structure can be simplified and weight reduction and reduction of component cost can be aimed at.

  In the above embodiment, the case where the brake device (for example, a drum brake or a disc brake using frictional force) is not provided in the vehicle 1 has been described, but it is naturally possible to provide such a brake device in the vehicle 1. It is.

  Further, the wheel drive device 3 (FL to RR motors 3FL to 3RR) may be configured as a so-called regenerative brake. You may comprise so that the electric power which generate | occur | produces by operating a regenerative brake may be charged to the battery apparatus (not shown) for driving the wheel drive device 3. FIG.

It is the schematic diagram which showed typically the vehicle by which the control apparatus in one embodiment of this invention is mounted. It is the block diagram which showed the electric constitution of the control apparatus. It is a figure which shows the relationship between a sliding speed and a friction coefficient. (A) And (b) is a schematic diagram which illustrates typically the content of a drive cancellation | release table and a drive return table. It is a flowchart which shows a rotation control process. It is a flowchart which shows a ground speed calculation process. It is a flowchart which shows drive cancellation | release and a return process.

Explanation of symbols

100 Control device 1 Vehicle 2 Wheel 2FL Front wheel (wheel, left wheel)
2FR Front wheel (wheel, right wheel)
2RL Rear wheel (wheel, left wheel)
2RR Rear wheel (wheel, right wheel)
3 Wheel drive device 3FL-3RR FL-RR motor (wheel drive device)
72a Sliding speed table (storage means)

Claims (5)

A control device for operating a wheel drive device for a vehicle having a wheel configured to be rollable and a wheel drive device that rotationally drives the wheel, and controlling a rotation speed of the wheel,
Sliding speed calculating means for calculating the sliding speed of the wheel with respect to the road surface;
Storage means for storing a slip speed for maximizing a coefficient of friction between the road surface and the wheel as a target slip speed;
A wheel that controls the rotational speed of the wheel and operates the wheel driving device so that the slip speed of the wheel calculated by the slip speed calculating means becomes a value of the target slip speed stored in the storage means. A control device comprising drive device operating means. The vehicle includes a plurality of the wheels that are rotationally driven by the wheel driving device,
The wheel driving device is constituted by an electric motor, and the electric motor is provided for each of the plurality of wheels.
The control device according to claim 1, wherein the wheel driving device operating unit operates each of the plurality of electric motors so that rotation speeds of the plurality of wheels can be independently controlled. A peripheral speed calculating means for calculating a peripheral speed of the wheel;
Ground speed calculating means for calculating the ground speed of the vehicle,
The slip speed calculation means calculates the slip speed of the wheel based on the peripheral speed of the wheel calculated by the peripheral speed calculation means and the ground speed of the vehicle calculated by the ground speed calculation means. The control device according to claim 1, wherein the control device is a control device. The wheel drive device operating means is
When acceleration of the vehicle is instructed, the rotational speed of the wheel is controlled, the value of the peripheral speed of the wheel is larger than the value of the ground speed of the vehicle, and the sliding speed of the wheel is While operating the wheel drive device to achieve the target sliding speed,
When the vehicle is instructed to decelerate, the rotational speed of the wheel is controlled, the value of the peripheral speed of the wheel is smaller than the value of the ground speed of the vehicle, and the slip speed of the wheel is The control device according to any one of claims 1 to 3, wherein the wheel driving device is operated so as to achieve a target sliding speed.   A vehicle comprising the control device according to claim 1.

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