JP2006273273A - Control device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a control device capable of realizing enhancement of braking force of a vehicle and realizing shortening of a braking distance. <P>SOLUTION: An absolute value of a slip angle of a wheel 2 is increased by firstly operating an actuator device 4 at braking. Therefore, lateral force is generated on a ground-contact surface of the wheel 2 and is utilized as the braking force of the vehicle 1. Then, a wheel drive device 3 is operated by varying rotation speed of the wheel 2 such that a deformation amount in an advancement direction of the vehicle on the ground-contact surface of the wheel becomes larger. Therefore, friction force generated on the ground-contact surface of the wheel can be increased and further enhancement of the braking force of the vehicle can be realized. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention operates an actuator device and a wheel drive device for a vehicle having a wheel configured to be steerable, an actuator device that steering-drives the wheel, and a wheel drive device that rotationally drives the wheel, The present invention relates to a control device that controls the slip angle and rotation speed of a wheel, and more particularly to a control device that can improve the braking force of a vehicle and shorten the braking distance.

As a conventional example of a technique for controlling a wheel to increase its braking force, for example, there is anti-lock control (Patent Document 1). According to this anti-lock control, when braking the vehicle, the slip ratio of the wheel is controlled so that the wheel is not locked, so that the braking force of the vehicle caused by an excessive brake operating force (for example, brake pressure) is controlled. The decline is prevented.
JP-A-5-155325

  By the way, when the slip ratio increases from 0 between the slip ratio of the wheel and the braking force, the braking force rapidly decreases after passing through a first region (for example, a linear region) in which the braking force monotonously increases. There is a relationship of shifting to the second region. And the actual value of the slip ratio when the braking force shifts from the first region to the second region is not always constant, and it is difficult to accurately detect each time.

  Therefore, in anti-lock control, based on the expected value that the braking force is expected to be surely lower than the actual value of the slip rate when the braking force shifts from the first region to the second region, the predicted value is calculated based on the estimated slip value of the wheel. The brake operating force is controlled so as not to exceed. Therefore, in anti-lock control, it is practically difficult to brake the wheel using the road surface μ fully.

  Against this background, the inventor of the present application has developed a new method for generating a braking force on a wheel in a wheel control technique for increasing the braking force of the wheel. Specifically, when braking the vehicle, the absolute value of the slip angle of the wheel is increased by the actuator device, and the lateral force generated on the ground contact surface of the wheel is used as the braking force, thereby increasing the braking force of the wheel. (However, it is not known at the time of this application).

  The present invention has been made to further improve the above-described new technique relating to the wheel control technology, and provides a control device capable of improving the braking force of the vehicle and shortening the braking distance. It is aimed.

  In order to achieve this object, a control device according to claim 1 is a vehicle having a wheel configured to be steerable, an actuator device that steering-drives the wheel, and a wheel drive device that rotationally drives the wheel. On the other hand, the actuator device and the wheel drive device are operated to control the slip angle and rotation speed of the wheel, and in order to increase the braking force of the wheel, the absolute value of the slip angle of the wheel And an actuator operating means for operating the actuator device so that a lateral force is generated on the ground contact surface of the wheel, and the rotational speed of the wheel whose absolute value of the slip angle is increased by the actuator operating means. A wheel drive device for operating the wheel drive device so that the amount of deformation in the vehicle traveling direction on the ground contact surface of the wheel is increased. And an actuating means.

  The control device according to claim 2 is the control device according to claim 1, wherein a ground speed detecting means for detecting a ground speed of the vehicle, a rotational speed detecting means for detecting a rotational speed of the wheel, and a slip of the wheel. A slip angle detecting means for detecting an angle; and the vehicle on the ground contact surface of the wheel based on the ground speed, the rotational speed and the slip angle detected by the ground speed detecting means, the rotational speed detecting means and the slip angle detecting means. A deformation amount calculating means for calculating a deformation amount in the traveling direction; and a storage means for storing a deformation limit value in the vehicle traveling direction on the ground contact surface of the wheel, and the operation of the wheel driving device by the wheel driving device operating means. The amount of deformation in the vehicle traveling direction on the ground contact surface of the wheel becomes larger within a range not exceeding the deformation limit value stored in the storage means. Sea urchin, thereby changing the rotational speed of the wheel.

  The control device according to claim 3 is the control device according to claim 2, wherein friction coefficient detection means for detecting a friction coefficient of a portion of the road surface on which the wheel travels corresponds to the ground contact surface of the wheel, and the friction Correction means for correcting the deformation limit value stored in the storage means based on the friction coefficient detected by the coefficient detection means, and the operation of the wheel drive device by the wheel drive device operation means is The rotational speed of the wheel is changed so that the amount of deformation in the vehicle traveling direction on the ground contact surface of the wheel becomes larger within a range not exceeding the deformation limit value after being corrected by the correcting means.

  The control device according to claim 4 is the control device according to any one of claims 1 to 3, wherein the wheel includes a left wheel and a right wheel disposed on the left and right of the vehicle, and the actuator operating means. When increasing the absolute value of the slip angle of at least one of the left wheel and the right wheel in order to increase the braking force of at least one of the left wheel and the right wheel, The actuator device is operated so that the relationship becomes toe-in.

  The control device according to claim 5 is the control device according to claim 4, wherein the actuator actuating means is configured such that the absolute value of the slip angle of the left wheel and the absolute value of the slip angle of the right wheel are the same amount. Further, the actuator device is operated.

  According to the control device according to claim 1, the slip angle of the wheel with respect to a vehicle having a wheel configured to be steerable, an actuator device that steering-drives the wheel, and a wheel drive device that rotationally drives the wheel. The actuator actuating means is provided to actuate the actuator device so that the lateral force is generated on the ground contact surface of the wheel, so that the lateral force generated on the wheel can be used as the braking force of the vehicle. There is an effect that can be done.

  Here, when the wheel rolls on the road surface with a non-zero slip angle, not only rolling resistance but also lateral force is generated on the ground contact surface of the wheel. Of the total frictional force that is the resultant force of the rolling resistance and the lateral force, the component acting in the vehicle traveling direction is the frictional force that contributes to the braking of the wheel, and this frictional force increases according to the lateral force.

  That is, the cornering force acting on the wheel has a characteristic of increasing from 0 and saturating when the slip angle increases from 0, whereas the lateral force has a characteristic of continuously increasing monotonously although the gradient gradually decreases. . Therefore, if the absolute value of the slip angle of the wheel is increased, the wheel braking can be performed using the lateral force having such characteristics. As a result, by using the lateral force generated in the wheel as in the present invention, the braking force of the wheel can be increased without depending on the wheel braking device.

  Furthermore, according to the control device of the present invention, the rotational speed of the wheel whose absolute value of the slip angle is increased by the actuator operating means is changed, and the deformation amount in the vehicle traveling direction on the ground contact surface of the wheel becomes larger. Since the wheel drive device actuating means for actuating the wheel drive device is provided, the frictional force generated on the ground contact surface of the wheel can be increased, and the braking force of the wheel can be further improved.

  As a result, compared with the case where only the control for increasing the absolute value of the slip angle of the wheel is performed, even when the ground speed of the vehicle is the same, the deformation amount in the vehicle traveling direction on the ground contact surface of the wheel is increased. Thus, since a large frictional force can be generated on the ground contact surface of the wheel, there is an effect that the braking effect can be further enhanced by increasing the absolute value of the slip angle of the wheel. As a result, the braking force of the vehicle is synergistically improved and the braking distance can be further shortened.

  According to the control device of the second aspect, in addition to the effect produced by the control device of the first aspect, the deformation amount calculating means for calculating the deformation amount of the wheel contact surface in the vehicle traveling direction, and the wheel contact surface Storage means for storing a deformation limit value in the vehicle traveling direction, and the operation of the wheel drive device by the wheel drive device operating means is within the range not exceeding the deformation limit value stored in the storage means, Since the rotational speed of the wheel is changed so that the amount of deformation in the vehicle traveling direction becomes larger, the frictional force is surely generated on the ground contact surface of the wheel to increase the braking force of the wheel with high efficiency. There is an effect that can be.

  That is, if the deformation amount calculated by the deformation amount calculation means has not yet reached the deformation limit value, the wheel contact surface is changed by changing the rotational speed of the wheel so that the deformation amount approaches the deformation limit value. Thus, a large frictional force can be efficiently generated, and the braking force of the wheel can be improved.

  On the other hand, when the deformation amount calculated by the deformation amount calculation means has already exceeded the deformation limit value, the current rotational speed of the wheel is inappropriate and the ground contact surface of the wheel is in an inefficient deformation state. Therefore, not only the braking force of the wheel cannot be generated efficiently, but there is also a possibility that the driving force is generated. Therefore, the braking force of the wheel can be efficiently improved by changing the rotational speed of the wheel and bringing the deformation amount close to the deformation limit value.

  According to the control device according to claim 3, in addition to the effect of the control device according to claim 2, the friction coefficient detection for detecting the friction coefficient of the portion of the road surface on which the wheel travels corresponding to the ground contact surface of the wheel. And a correcting means for correcting the deformation limit value stored in the storage means based on the friction coefficient detected by the friction coefficient detecting means, so that the deformation limit value corrected by the correcting means is obtained. There is an effect that highly reliable control can be performed by changing the rotation speed of the wheel so that the deformation amount in the vehicle traveling direction on the ground contact surface of the wheel becomes larger within a range not exceeding.

  That is, the deformation limit value on the ground contact surface of the wheel is proportional to the friction coefficient of the road surface on which the wheel travels, and therefore changes every moment according to the road surface condition while the vehicle is traveling. For this reason, if the rotation limit of the wheel is controlled on the assumption that the deformation limit value is a constant value, the braking control of the wheel cannot be performed properly. On the other hand, the braking control according to the actual road surface condition can be appropriately performed by providing the correction means as in the present invention.

  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 actuator operating means increases the braking force of at least one of the left wheel and the right wheel. Therefore, when increasing the absolute value of the slip angle of at least one of the left wheel and the right wheel, the actuator device is operated so that the relationship between the left wheel and the right wheel becomes toe-in. There is an effect that the braking force can be improved while securing the above.

  According to the control device of the fifth aspect, in addition to the effect produced by the control device according to the fourth aspect, the actuator operating means has the same amount of the absolute value of the slip angle of the left wheel and the absolute value of the slip angle of the right wheel. Since the actuator device is operated so that the steering stability of the vehicle is further ensured, there is an effect that the braking force can be improved, and particularly in the braking control from the straight traveling state. Has an effect.

  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 braking, a slip angle θ and a rotational speed of the wheel 2 are controlled by a control device 100 described later, respectively. The power is improved and the braking distance can be shortened.

  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 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.

  The actuator device 4 is also driven when the driver operates the brake pedal 52, and the braking control of the wheels 2 is performed by giving each wheel 2 a slip angle θ corresponding to the operation amount of the brake pedal 52. Done. Details of the braking control will be described later.

  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). When the driver operates the accelerator pedal 53, a rotational driving force is applied to each wheel 2 from each wheel driving device 3, and each wheel 2 is rotated at a rotational speed corresponding to the operation amount of the accelerator pedal 53.

  The wheel driving device 3 is also drive-controlled when the driver operates the brake pedal 52, and each wheel 2 is driven to rotate at a rotational speed corresponding to the amount of operation of the brake pedal 52. The braking control is performed. Details of the braking 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 rotate the wheel 2 at a rotational speed or a slip angle θ. By controlling the above, braking 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 nonvolatile memory storing a control program executed by the CPU 71, fixed value data, and the like, and the RAM 73 is a memory for storing various data in a rewritable manner when the control program is executed. . The ROM 72 stores the deformation limit value Llim illustrated in FIG. 4 and a flowchart (braking control) program illustrated in FIG. 5.

  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 (virtual line d2, see FIG. 3) and the reference line of the vehicle 1 (body frame BF). This is an angle determined independently of the traveling direction of the vehicle 1 (virtual line d1, see FIG. 3). On the other hand, the slip angle θ (see FIG. 3) described later is an angle formed by the center line of each wheel 2 and the traveling direction of the vehicle 1, and is detected by the steering angle sensor device 31 and the vehicle speed sensor device 32 described later. Is calculated based on A method for calculating the slip angle θ will be described later.

  The vehicle speed sensor device 32 is a device for detecting the ground speed (absolute value and traveling direction) Vc of the vehicle 1 with respect to the road surface and outputting the detection result to the CPU 71, and the longitudinal and lateral acceleration sensors 32a and 32b. And a processing circuit (not shown) that processes the detection results of the acceleration sensors 32a and 32b and outputs the result to the CPU 71.

  The longitudinal acceleration sensor 32a is a sensor that detects the acceleration in the longitudinal direction (the vertical direction in FIG. 1) of the vehicle 1 (body frame BF), and the lateral acceleration sensor 32b is the lateral direction of the vehicle 1 (body frame BF) ( FIG. 1 is a sensor that detects acceleration in the left-right direction. In the present embodiment, each of the acceleration sensors 32a and 32b is configured as a piezoelectric sensor using a piezoelectric element.

  The CPU 71 time-integrates the detection results (acceleration values) of the respective acceleration sensors 32a and 32b input from the vehicle speed sensor device 32 to calculate speeds in two directions (front and rear and left and right directions), respectively. By synthesizing the components, the ground speed (absolute value and traveling direction) Vc of the vehicle 1 can be obtained.

  In addition, when the traveling direction of the vehicle 1 is obtained in this way, the CPU 71 determines each traveling direction based on the traveling direction of the vehicle 1 and the steering angle of each wheel 2 detected by the steering angle sensor device 31 described above. The slip angle θ of the wheel 2, that is, the angle formed by the center line (virtual line d2) of each wheel 2 and the traveling direction of the vehicle 1 (virtual line d1) can be obtained (see FIG. 3).

  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 actual peripheral speed Vr (see FIG. 3) of each wheel 2 from the rotation speed of each wheel 2 input from the wheel rotation speed sensor device 33 and the outer diameter of each wheel 2. .

  The ground load sensor device 34 is a device for detecting the ground load generated between each wheel 2 and the road surface and outputting the detection result to the CPU 71. The FL detects the ground load of each wheel 2 respectively. To RR load sensors 34FL to 34RR, and a processing circuit (not shown) that processes the detection results of the load sensors 34FL to 34RR and outputs them to the CPU 71.

  In the present embodiment, each of the load sensors 34FL to 34RR is configured as a piezoresistive triaxial load sensor. Each of the load sensors 34FL to 34RR is disposed on a suspension shaft (not shown) of each wheel 2 and detects the above-described ground load in the front-rear direction, the left-right direction, and the vertical direction of the vehicle 1.

  The CPU 71 can obtain the friction coefficient μ of the road surface on the ground contact surface of each wheel 2 from the detection results (ground load) of the load sensors 34FL to 34RR input from the ground load sensor device 34.

  For example, when focusing on the front wheel 2FL, when the loads in the front-rear direction, the left-right direction, and the vertical direction of the vehicle 1 detected by the FL load sensor 34FL are Fx, Fy, and Fz, respectively, they correspond to the ground contact surface of the front wheel 2FL. The friction coefficient μ of the road surface of the portion is calculated by using Fx / Fz as the friction coefficient μx in the traveling direction of the vehicle 1 and Fy / Fz as the friction coefficient μy in the left-right direction of the vehicle 1.

  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 brake pedal 52 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 actuator device 4 to increase the absolute value of the slip angle θ of each wheel 2 and starts braking control (see FIG. 5).

  Next, the braking control of the present invention will be described with reference to FIGS. 3 is a diagram schematically showing the state of the wheel 2 during braking control, FIG. 3 (a) is a top view of the wheel 2, and FIG. 3 (b) is a portion of FIG. 3 (a). It is an enlarged view.

  3 shows a state where the vehicle 1 is traveling at the ground speed Vc and the slip angle θ of the wheel 2 is not 0, and the outer shape and the ground contact surface of the wheel 2 are solid lines, and the traveling direction of the vehicle 1 is shown. Is the imaginary line d1, and the center line of the wheel 2 is imaginary line d2. Further, as shown in FIG. 3A, the ground contact surface of the wheel 2 is in contact with the road surface with a length Le in the center line direction (the imaginary line d2 direction).

  In the state shown in FIG. 3, if it is assumed that the wheel 2 is free rolling (that is, rolling in a state where no slip occurs between the wheel 2 and the road surface), the free rolling of the wheel 2 is assumed. The peripheral speed Vrf at that time is expressed by Vrf = Vc / cos θ. However, the actual peripheral speed Vr of the wheel 2 is influenced by the braking force generated by the road surface state, the slip angle θ, or the driving torque from the wheel driving device 3 (see FIG. 1), etc. during free rolling. It is different from the peripheral speed Vrf.

  Therefore, at a predetermined position (for example, position P1) on the ground contact surface of the wheel 2, as shown in FIG. 3B, the speed difference (Vr−) between the peripheral speed Vrf during free rolling and the actual peripheral speed Vr. Vrf) as a speed relative to the road surface. A speed Vd obtained by decomposing this speed in the traveling direction of the vehicle 1 is represented by Vd = (Vr−Vrf) · cos θ.

  Further, since the vehicle 1 is traveling at the ground speed Vc, the position P1 on the ground contact surface of the wheel 2 has a speed Vc as a speed with respect to the road surface as shown in FIG. Therefore, among the speeds that the position P1 has with respect to the road surface, the speed component in the traveling direction of the vehicle 1 (in the direction of the imaginary line d1) is represented by Vc−Vd = Vc− (Vr−Vrf) · cos θ.

  That is, if it is assumed that the wheel 2 is rolling freely, the position P1 moves along the center line (virtual line d2) and reaches the position P2, as shown in FIG. As described above, since the ground contact surface of the wheel 2 has a speed component in the traveling direction of the vehicle 1 (in the direction of the imaginary line d1), it reaches the position P3.

  Therefore, of the deformation amounts at the position P1, the deformation amount Lc in the traveling direction of the vehicle 1 (the direction of the imaginary line d1) is Lc = (Vc− (Vr−Vrf) · cos θ) · t = (Vc− (Vr−Vrf). ) · Cos θ) · Le / Vr. Since Vrf = Vc / cos θ, the amount of deformation Lc in the traveling direction of the vehicle 1 on the ground contact surface of the wheel 2 is eventually expressed by Lc = (2 · Vc−Vr · cos θ) · Le / Vr.

  As described above, the amount of deformation Lc in the traveling direction of the vehicle 1 on the ground contact surface of the wheel 2 depends on the actual peripheral speed Vr of the wheel 2 if the ground speed Vc and the slip angle θ of the vehicle 1 are assumed to be fixed values. . Therefore, as will be described later, when the vehicle 1 is braked, the actual circumferential speed Vr (rotational speed) of the wheel 2 is controlled, so that the vehicle traveling direction on the ground contact surface of the wheel 2 is the same even at the same ground speed Vc. The deformation amount Lc can be further increased. As a result, a large frictional force (braking force) is generated on the ground contact surface of the wheel 2 and the braking force of the vehicle 1 can be improved, and the braking distance can be shortened accordingly.

  Here, the slip ratio s of the wheel 2 is expressed as follows using the peripheral speed Vrf of the wheel 2 at the time of free rolling and the actual peripheral speed Vr of the wheel 2 described above. That is, when Vrf> Vr, it is expressed by s = (Vr−Vrf) / Vrf, while when Vr> Vrf, it is expressed by s = (Vr−Vrf) / Vr. Note that Vrf = Vc / cos θ.

  Thus, the slip ratio s can also be expressed as a function of the ground speed Vc of the vehicle 1, the slip angle θ, and the actual peripheral speed Vr of the wheel 2 as in the case of the deformation amount Lc described above.

  Therefore, the values of the ground speed Vc and the slip angle θ of the vehicle 1 are fixed, and the relationship between the slip rate s of the wheel 2 and the deformation amount Lc in the vehicle traveling direction on the ground contact surface of the wheel 2 is illustrated. The graph of FIG. 4 can be obtained with the peripheral speed Vr as a parameter.

  FIG. 4 shows six patterns in which the ground speed Vc of the vehicle 1 is fixed at 60 km / h and the slip angle θ is changed at 15 ° (or 14 °) intervals in the range of 15 ° to 89 °. Yes. Further, the length Le of the ground contact surface of the wheel 2 is a fixed value determined by the profile of the wheel 2 (tire size, air pressure, etc.). In the wheel 2 used in the present embodiment, Le = 0.2 m. is there.

  A two-dot chain line Llim in FIG. 4 is a deformation limit value in the traveling direction of the vehicle 1 on the contact surface of the wheel 2 (approximately 0.05 m for the wheel 2 used in the present embodiment). The value of the deformation limit value Llim depends on the physical properties of the wheel 2 itself and the road surface condition, and is measured in advance by a preliminary test using the wheel 2, and the maximum value is stored in the ROM 72 (see FIG. 2). ing. In the present embodiment, as will be described later, the value of the deformation limit value Llim is corrected according to the value of the friction coefficient μ of the road surface.

  As described above, the amount of deformation Lc in the traveling direction of the vehicle 1 on the contact surface of the wheel 2 is a function of the ground speed Vc of the vehicle 1, the slip angle θ of the wheel 2, and the actual peripheral speed Vr of the wheel 2. Therefore, the current deformation amount Lc of each wheel 2 can be obtained by calculating these values Vc, θ, Vr based on the detection values of the sensor devices 31 to 33 (see FIG. 2).

  Therefore, by controlling the peripheral speed Vr of each wheel 2 by the wheel driving device 3 (see FIG. 2) so that the current deformation amount Lc approaches the deformation limit value Llim, even if the ground speed Vc is the same, the wheel A large deformation amount Lc can be given to the second grounding surface, and a larger frictional force (braking force) can be generated.

  For example, when the vehicle 1 is braked and the deformation amount Lc generated at the current peripheral speed Vr of the wheel 2 has already exceeded the deformation limit value Llim (for example, position Pa in FIG. 4), the wheel 2 While the actual circumferential speed Vr is decelerated, when the deformation amount Lc does not reach the deformation limit value Llim (for example, the position Pb in FIG. 4), the actual circumferential speed Vr of the wheel 2 is accelerated, thereby deforming. The amount Lc is controlled so as to approach the deformation limit value Llim (position Pc in FIG. 4).

  Thereby, even if it is the same ground speed Vc, deformation amount Lc can be enlarged more. As a result, a large frictional force (braking force) is generated on the ground contact surface of the wheel 2 and the braking force of the vehicle 1 can be improved, and the braking distance can be shortened accordingly.

  Next, processing executed by the control device 100 will be described with reference to FIG. FIG. 5 is a flowchart showing the braking 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 control device 100 is powered on.

  Regarding the braking control process, the CPU 71 first determines whether braking control is necessary, that is, whether the brake pedal 52 has been operated by the driver (S1). When the driver does not detect the operation of the brake pedal 52, or when it is detected that the operation is performed but is less than a predetermined operation amount (depression amount), it is determined that the braking control is not necessary (S1: No), this braking control process is terminated. After the end, the process proceeds to another process (not shown).

  On the other hand, in the process of S1, when the operation of the brake pedal 52 by the driver is detected and it is determined that the braking control is necessary (S1: Yes), first, the detected operation state of the brake pedal 52 is set. Accordingly, the target value of the slip angle θ is determined for each wheel 2 (S2), and the process proceeds to S3. In the present embodiment, the target value (0 ° to 90 °) of the slip angle θ is determined as a proportional value of the depression amount (0% to 100%) of the brake pedal 52.

  In the process of S3, each actuator device 4 is driven and each wheel 2 is steered to control the slip angle θ of each wheel 2 so as to approach the target value (S3). As a result, the absolute value of the slip angle θ of each wheel 2 is increased, and a lateral force is generated on the ground contact surface of each wheel 2. As a result, the lateral force acts as a braking force for the wheel 2 (vehicle 1).

  After the slip angle θ is given to each wheel 2 by the process of S3, the ground speed Vc of the vehicle 1 is detected by the vehicle speed sensor device 32 (S4), and the rotational speed of each wheel 2 by the wheel rotational speed sensor device 33 ( That is, the actual circumferential speed Vr) is detected (S5), the slip angle θ of each wheel 2 is detected by the rudder angle sensor device 31 (S6), and the road surface friction coefficient μ is detected by the ground load sensor device 34 (S7). ), Respectively, and the process proceeds to S8 and S9.

  In the process of S8, based on the ground speed Vc, the rotation speed (circumferential speed Vr) and the slip angle θ detected by the processes of S4 to S6, the current deformation amount Lc on the ground contact surface of each wheel 2 is calculated (S8). ).

  On the other hand, in the process of S9, the deformation limit value Llim on the ground contact surface of each wheel 2 is corrected based on the road surface friction coefficient μ detected in the process of S7 (S9). As described above, the deformation limit value Llim of the wheel 2 is stored in the ROM 72 in the maximum value (that is, the value when the friction coefficient μ of the road surface is maximum), and the deformation limit value Llim is a friction value. A value obtained by multiplying the coefficient μ is a correction value.

  After the current deformation amount Lc and the deformation limit value Llim of each wheel 2 are calculated and corrected by the processing of S8 and S9, the corrected deformation limit value Llim is not exceeded by driving the wheel drive device 3. Within the range, the peripheral speed Vr (rotational speed) of each wheel 2 is controlled so that the deformation amount Lc of each wheel 2 becomes maximum, that is, approaches the corrected deformation limit value Llim (S10), This braking control process is terminated.

  As a result, the deformation amount Lc in the vehicle traveling direction on the ground contact surface of each wheel 2 can be increased to generate a larger frictional force, so that the braking force of the vehicle 1 is improved and the braking distance is shortened. be able to.

  Further, the driving of the wheel driving device 3 is performed so that the peripheral speed Vr of each wheel 2 is set so that the deformation amount Lc in the vehicle traveling direction on the ground contact surface of each wheel 2 becomes larger within a range not exceeding the deformation limit value Llim. Since it is changed, it is possible to reliably generate a frictional force on the ground contact surface of each wheel 2 and increase the braking force with high efficiency.

  Further, the deformation limit value Llim is corrected according to the friction coefficient μ of the road surface, and the deformation amount Lc in the vehicle traveling direction on the ground contact surface of each wheel 2 is more within a range not exceeding the corrected deformation limit value Llim. Since the peripheral speed Vr of each wheel 2 is controlled so as to increase, highly reliable control can be performed.

  In the flowchart (braking control process) shown in FIG. 5, the process of S3 is performed as the actuator operation means according to claim 1, the process of S10 is performed as the wheel drive apparatus operation means, and the ground speed detection means according to claim 2. The processing of S4 as the rotational speed detection means, the processing of S6 as the slip angle detection means, the processing of S8 as the deformation amount calculation means, and the friction coefficient detection means as claimed in claim 3. Corresponds to the processing of S7, and the processing of S9 corresponds to the correction 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.

  Moreover, although the said embodiment demonstrated the case where the slip angle (theta) of each wheel 2 was determined in proportion to the operation amount (depression amount) of the brake pedal 52 by a driver | operator (refer S2 and S3 of FIG. 5). However, the present invention is not necessarily limited to this, and it is naturally possible to determine the slip angle θ of each wheel 2 based on other state quantities.

  Here, as another state quantity, for example, the operation speed of the brake pedal 52, the deceleration of the vehicle 1, or the friction coefficient μ of the road surface is exemplified. For example, even when the amount of depression of the brake pedal 52 is the same, when the operation speed is fast (slow), the slip angle θ may be controlled to be larger (smaller).

  Further, for example, even when the depression amount and the operation speed of the brake pedal 52 are the same, when the deceleration of the vehicle 1 is small (large), the slip angle θ may be controlled to be larger (smaller). good. Further, for example, even if the operation amount of the brake pedal 52 is the same, when the friction coefficient μ of the road surface is small (large), the slip angle θ may be controlled to be larger (smaller).

  These state quantities may be used alone or in combination as a reference value for determining the slip angle θ. As a result, the operation state of the driver is accurately reflected in the braking force control, and the operational feeling can be improved, the braking force of the vehicle 1 is improved, and the braking distance can be further shortened.

  In the above embodiment, the control means for changing the circumferential speed Vr (rotational speed) of each wheel 2 has been described as the control means for bringing the deformation amount Lc on the ground contact surface of each wheel 2 closer to the deformation limit value Llim. Instead of this control means, or together with this control means, control means for changing the slip angle θ of each wheel 2 to bring the deformation amount Lc closer to the deformation limit value Llim may be adopted.

  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 addition, although explanation is omitted in the above embodiment, when a slip angle θ is given to each wheel 2, only a part of each wheel 2 (for example, only front wheels 2FL and 2FR or rear wheels 2RL and 2RR). Only) or may be given to all the wheels 2. That is, the slip angles θ of the wheels 2 do not have to be the same.

  In this case, for example, the operation angle of the handle 51 may be detected, and if the angle is equal to or greater than the predetermined operation angle, the control may be performed so that the slip angle θ is given only to the wheels 2 outward or inward in the turning direction. Or you may comprise so that slip angle (theta) may be provided to some or all of the wheel 2 only when the operation angle of the handle | steering-wheel 51 is below a predetermined operation angle. The slip angle θ may be given so as to be toe-in or toe-out, or may be given so that the steering angles of the left and right wheels 2 are in the same direction.

  In this case, it is preferable to apply the slip angle θ to all the wheels 2 and to apply the slip angle θ so that the left and right wheels 2 are toe-in. Most preferably, a slip angle θ is given to all the wheels 2 so that the front wheels 2FL, 2FR and the rear wheels 2RL, 2RR are both toe-in. Thereby, the braking force as a whole can be increased, the braking distance can be shortened, and the steering stability during deceleration can be ensured.

  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 natural that such a brake device is further provided in the vehicle 1. Is possible.

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. (A) is a top view of a wheel, (b) is the elements on larger scale of Fig.3 (a). It is the figure which showed the relationship between the slip ratio of a wheel and the deformation | transformation amount of the vehicle advancing direction in the contact surface of a wheel. It is a flowchart which shows a braking control 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)
4 Actuator device 4FL to 4RR FL to RR actuator (actuator device)
31 Rudder angle sensor device (part of slip angle detection means)
31FL to 31RR FL to RR rudder angle sensor (part of slip angle detection means)
32 Vehicle speed sensor device (a part of ground speed detection means and slip angle detection means)
32a Longitudinal acceleration sensor (part of ground speed detection means, part of slip angle detection means)
32b Lateral acceleration sensor (part of ground speed detection means, part of slip angle detection means)
33 Wheel rotation speed sensor device (rotation speed detection means)
33FL to 33RR FL to RR rotational speed sensor (rotational speed detecting means)
34 Ground load sensor device (friction coefficient detection means)
34FL to 34RR FL to RR load sensor (friction coefficient detection means)
72 ROM (storage means)
θ Slip angle Vr Actual peripheral speed (rotational speed) of wheel
Lc Deformation amount Vc in the vehicle traveling direction on the wheel contact surface Vc Ground speed Llim of the vehicle Deformation limit value in the vehicle traveling direction on the wheel contact surface

Claims (5)

For the vehicle having a wheel configured to be steerable, an actuator device for steering and driving the wheel, and a wheel driving device for rotationally driving the wheel, the actuator device and the wheel driving device are operated, and the wheel A control device for controlling the slip angle and rotation speed of
An actuator actuating means for actuating the actuator device such that a lateral force is generated on the ground contact surface of the wheel by increasing an absolute value of a slip angle of the wheel in order to increase a braking force of the wheel;
The wheel driving device is operated so that the amount of deformation in the vehicle traveling direction on the ground contact surface of the wheel is increased by changing the rotational speed of the wheel whose absolute value of the slip angle is increased by the actuator operating means. And a wheel drive device operating means. Ground speed detection means for detecting the ground speed of the vehicle;
Rotation speed detection means for detecting the rotation speed of the wheel;
Slip angle detecting means for detecting a slip angle of the wheel;
A deformation amount for calculating a deformation amount in the vehicle traveling direction on the ground contact surface of the wheel based on the ground speed, the rotation speed, and the slip angle detected by the ground speed detection unit, the rotation speed detection unit, and the slip angle detection unit. A calculation means;
Storage means for storing a deformation limit value in the vehicle traveling direction on the contact surface of the wheel,
The operation of the wheel driving device by the wheel driving device operating means is such that the amount of deformation in the vehicle traveling direction on the ground contact surface of the wheel becomes larger within a range not exceeding the deformation limit value stored in the storage means. 2. The control device according to claim 1, wherein the rotation speed of the wheel is changed. Friction coefficient detection means for detecting a friction coefficient of a portion of the road surface on which the wheel travels corresponding to the ground contact surface of the wheel;
Correction means for correcting the deformation limit value stored in the storage means based on the friction coefficient detected by the friction coefficient detection means,
The operation of the wheel driving device by the wheel driving device operating means is such that the amount of deformation in the vehicle traveling direction on the ground contact surface of the wheel is larger within a range not exceeding the deformation limit value after being corrected by the correcting means. The control apparatus according to claim 2, wherein the rotation speed of the wheel is changed. The wheel includes a left wheel and a right wheel disposed on the left and right of the vehicle,
When the actuator operating means increases the absolute value of the slip angle of at least one of the left wheel and the right wheel in order to increase the braking force of at least one of the left wheel and the right wheel, The control device according to any one of claims 1 to 3, wherein the actuator device is operated so that a relationship with a right wheel is toe-in.   The actuator actuating means operates the actuator device so that the absolute value of the slip angle of the left wheel and the absolute value of the slip angle of the right wheel are equal. 4. The control device according to 4.

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