JP2014000959A - Vehicle - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a vehicle capable of making a pivot turn through easy operation.SOLUTION: A vehicle includes a plurality of wheels including two front wheels 21, 31, steering actuators 23, 33 which are coupled to the front wheels respectively and steer the front wheels, a steering operation tool 62 for instructing operation of the steering actuator, control means 100 of calculating a steering angle of the front wheels for a turn on the center of swivel determined based upon a manipulated variable of the steering operation tool, and then placing the steering actuator in operation so that the steering angle of the front wheels reaches the calculated steering angle, a driving actuator which can drive one or each of the plurality of driving wheels defined among the plurality of wheels including the two front wheels while coupled to the one or each of the plurality of driving wheels, and a driving operation tool which sets a target speed.

Description

  The present invention relates to a vehicle technology capable of independently steering a pair of left and right front wheels, and more particularly to a vehicle technology capable of performing a super turn by steering only the front wheels.

  Conventionally, the technique of the vehicle which can steer a pair of left and right wheels independently is publicly known. As such a vehicle technology, a vehicle described in Patent Document 1 is known.

  The vehicle described in Patent Document 1 includes a pair of main drive wheels (rear wheels), a pair of hydraulic transmission devices that individually drive the pair of main drive wheels, and a pair that individually operates the pair of hydraulic transmission devices. The operation lever is provided. In such a configuration, the vehicle can drive the pair of main drive wheels in opposite directions by operating the pair of operation levers in opposite directions. Therefore, the vehicle can turn around the center of the left and right of the main drive wheel (super turning).

  However, the vehicle described in Patent Document 1 is disadvantageous in that it is complicated to operate because it is necessary to turn each of the pair of operation levers.

JP 2005-343283 A

  The present invention has been made in view of the situation as described above, and provides a vehicle capable of performing a super turn by a simple operation.

  The problem to be solved by the present invention is as described above. Next, means for solving the problem will be described.

  That is, in claim 1, a plurality of wheels including two front wheels, a steering actuator coupled to each of the front wheels for steering the front wheels, a steering operation tool for instructing an operation of the steering actuator, A steering angle of the front wheel capable of turning around a turning center determined based on an operation amount of the steering operation tool is calculated, and the steering angle is set so that the steering angle of the front wheel becomes the calculated steering angle. Control means for operating an actuator and one or a plurality of wheels out of a plurality of wheels including the two front wheels as drive wheels, and drive capable of being connected and driven for each of the one or plurality of drive wheels And a driving operation tool for setting a target speed.

  According to a second aspect of the present invention, the steering actuator is capable of steering the front wheels by 90 degrees or more.

  According to a third aspect of the present invention, the control means turns around the turning center without slipping the drive wheel with respect to the road surface based on the operation amount of the steering operation tool and the operation amount of the drive operation tool. The speed of the driving wheel capable of being calculated is calculated, and the driving actuator is operated so that the speed of the driving wheel becomes the calculated speed.

  According to a fourth aspect of the present invention, the control means limits the calculated speed so as not to exceed a predetermined value.

  As effects of the present invention, the following effects can be obtained.

In claim 1, it is possible to easily turn around an arbitrary turning center. In addition, since the two front wheels can be steered independently, the steering angle of the two front wheels is not mechanically limited, and the vehicle can turn with a small turning radius.
Further, based on the operation amount of the driving operation tool, the speed of the driving wheel can be adjusted so that the driving wheel does not slide on the road surface.

  In claim 2, the front wheel is steered by 90 degrees or more to turn around the center of the vehicle body width (reliable turn), or turn around the center position of the vehicle body width (super-trust). Slewing).

  According to the third aspect of the present invention, the speed of the driving wheel can be adjusted based on the operation amount of the driving operation tool so that the driving wheel does not slide with respect to the road surface. Thus, it is possible to stably perform the super-revolution without damaging the lawn, the field, etc.) and preventing damage to the drive wheels.

  According to the fourth aspect, by limiting the calculated speed to a predetermined value or less, it is possible to prevent the occurrence of problems due to the over-rotation of the driving actuator.

1 is a perspective view illustrating an overall configuration of a vehicle according to an embodiment of the present invention. The perspective view which showed the left front wheel mechanism. Schematic which showed the structure regarding control of a vehicle. Schematic which showed the relationship between the turning radius of a vehicle, the steering angle of a front wheel, and the speed of each wheel. The figure which shows an example of the map showing the relationship between a turning radius and the steering angle of a front wheel. The figure which shows an example of the map showing the relationship between a turning radius and each wheel speed coefficient. The figure which shows the steering angle map showing the relationship between the turning angle of a steering wheel, and the steering angle of a front wheel. The figure which shows the wheel speed coefficient map showing the relationship between the rotation angle of a steering, and each wheel speed coefficient. Schematic which shows the control aspect of each steering motor and each drive motor by a controller.

  Below, vehicle 1 which is one embodiment of a vehicle concerning the present invention is explained. The vehicle according to the present invention is not limited to the vehicle 1 according to the present embodiment, and may be various vehicles such as a construction vehicle, an agricultural vehicle, and an industrial vehicle.

  As shown in FIG. 1, the vehicle 1 travels with power generated by an electric motor. The vehicle 1 includes a vehicle main body 10, a left front wheel mechanism 20, a right front wheel mechanism 30, a left rear wheel mechanism 40, a right rear wheel mechanism 50, an operation unit 60, and a controller 100 (see FIG. 3).

  The vehicle main body 10 constitutes a main structure of the vehicle 1. The vehicle body 10 is configured by combining plate materials, pipe members, and the like. The vehicle main body 10 is provided with a capacitor and the like for supplying electric power to each member included in the vehicle 1.

  As shown in FIGS. 1 to 3, the left front wheel mechanism 20 is for causing the vehicle 1 to travel in an arbitrary direction. The left front wheel mechanism 20 is disposed below the left front end of the vehicle body 10. The left front wheel mechanism 20 mainly includes a left front wheel 21, a left front wheel drive motor 22, and a left front wheel steering motor 23.

  The left front wheel 21 is an embodiment of a front wheel and a drive wheel, and supports the vehicle main body 10 and moves the vehicle main body 10 by being rotationally driven.

  As shown in FIGS. 2 and 3, the left front wheel drive motor 22 is an embodiment of a drive actuator, and rotates the left front wheel 21. An output shaft (not shown) of the left front wheel drive motor 22 is connected to the left front wheel 21. The driving force of the left front wheel drive motor 22 is transmitted to the left front wheel 21 via the output shaft of the left front wheel drive motor 22, and the left front wheel 21 is rotationally driven by the driving force.

  The left front wheel steering motor 23 is an embodiment of a steering actuator, and steers the left front wheel 21. An output shaft (not shown) of the left front wheel steering motor 23 is disposed vertically downward, and is connected to the upper end of the bracket 23a (see FIG. 2) via a speed reduction mechanism (not shown). The lower end of the bracket 23 a is connected to the left front wheel 21 and the left front wheel drive motor 22. The driving force of the left front wheel steering motor 23 is transmitted to the bracket 23a via the output shaft of the left front wheel steering motor 23 and the speed reduction mechanism. The bracket 23a is rotated around the vertical axis by the driving force. The left front wheel 21 and the left front wheel 21 are steered when the left front wheel 21 and the left front wheel drive motor 22 rotate integrally with the vehicle body 10 together with the bracket 23a.

  As shown in FIGS. 1 and 3, the right front wheel mechanism 30 is for causing the vehicle 1 to travel in an arbitrary direction. The right front wheel mechanism 30 is disposed below the right front end of the vehicle body 10. The right front wheel mechanism 30 mainly includes a right front wheel 31, a right front wheel drive motor 32, and a right front wheel steering motor 33. The right front wheel 31 is an embodiment of a front wheel and a drive wheel, the right front wheel drive motor 32 is an embodiment of a drive actuator, and the right front wheel steering motor 33 is an embodiment of a steering actuator. In addition, since the structure and operation | movement aspect of the right front wheel mechanism 30 are the same as that of the left front wheel mechanism 20, description is abbreviate | omitted.

  As described above, the left front wheel 21 and the right front wheel 31 are steered by the left front wheel steering motor 23 and the right front wheel steering motor 33, respectively. That is, the steering angles of the left front wheel 21 and the right front wheel 31 are not mechanically limited to each other, and can be steered to arbitrary steering angles. Further, the left front wheel 21 and the right front wheel 31 are respectively steered by the left front wheel steering motor 23 and the right front wheel steering motor 33, whereby each front wheel can be steered until the steering angle becomes 90 degrees or more.

  The left rear wheel mechanism 40 is for causing the vehicle 1 to travel in an arbitrary direction. The left rear wheel mechanism 40 is disposed below the left rear end of the vehicle body 10. The left rear wheel mechanism 40 mainly includes a left rear wheel 41 and a left rear wheel drive motor 42. The left rear wheel 41 is an embodiment of a drive wheel, and the left rear wheel drive motor 42 is an embodiment of a drive actuator. The left rear wheel mechanism 40 is different from the left front wheel mechanism 20 in that it does not include a steering actuator such as the left front wheel steering motor 23. Since other configurations and operation modes are the same as those of the left front wheel mechanism 20, the description thereof is omitted.

  The right rear wheel mechanism 50 is for causing the vehicle 1 to travel in an arbitrary direction. The right rear wheel mechanism 50 is disposed below the right rear end of the vehicle body 10. The right rear wheel mechanism 50 mainly includes a right rear wheel 51 and a right rear wheel drive motor 52. The right rear wheel 51 is an embodiment of a drive wheel, and the right rear wheel drive motor 52 is an embodiment of a drive actuator. The right rear wheel mechanism 50 is different from the left front wheel mechanism 20 in that it does not include a steering actuator such as the left front wheel steering motor 23. Since other configurations and operation modes are the same as those of the left front wheel mechanism 20, the description thereof is omitted.

  Hereinafter, for convenience of explanation, the left front wheel 21 and the right front wheel 31 are collectively referred to simply as “front wheels”, and the left rear wheel 41 and the right rear wheel 51 are collectively referred to simply as “rear wheels”. Collectively, they are simply referred to as “each wheel”. Further, the left front wheel drive motor 22, the right front wheel drive motor 32, the left rear wheel drive motor 42, and the right rear wheel drive motor 52 are collectively referred to simply as “each drive motor”, the left front wheel steering motor 23, and the right front wheel steering motor. 33 is collectively referred to as “each steering motor”.

  As shown in FIG. 1, the operation unit 60 is a space for an operator to get on and operate the vehicle 1. The operation unit 60 is disposed at a substantially central portion in the front and rear direction of the vehicle body 10. The operation unit 60 mainly includes a seat 61, a steering wheel 62, and an accelerator pedal 63.

  The seat 61 is for an operator to sit on. The seat 61 is disposed at the rear of the operation unit 60.

  The steering wheel 62 is an embodiment of a steering operation tool, and is an operation tool for steering the vehicle 1. The steering wheel 62 is formed in a substantially circular shape and is turned by an operator. The steering wheel 62 is disposed in a front portion of the operation unit 60 at a position where an operator seated on the seat 61 can operate.

  The accelerator pedal 63 is an embodiment of a driving operation tool, and is an operation tool for causing the vehicle 1 to travel. The accelerator pedal 63 is a front portion of the operation unit 60 and is disposed below the steering wheel 62 and at a position where an operator seated on the seat 61 can operate with his / her foot.

  As shown in FIG. 3, the controller 100 is an embodiment of the control means, and controls the driving and steering of each wheel based on the operation of each operating tool. The controller 100 is disposed at an appropriate position of the vehicle main body 10. Specifically, the controller 100 may be configured such that a CPU, ROM, RAM, HDD, or the like is connected by a bus, or may be configured by a one-chip LSI or the like. The controller 100 stores various programs and data for controlling the driving and steering of each wheel, and controls the driving and steering of each wheel based on the program and the like. The controller 100 is connected to an accelerator operation amount detection sensor 101, a steering operation amount detection sensor 102, each drive motor, and each steering motor.

The accelerator operation amount detection sensor 101 detects the operation amount A of the accelerator pedal 63. The controller 100 can acquire a detection signal of the operation amount A of the accelerator pedal 63 by the accelerator operation amount detection sensor 101. Further, the controller 100 can calculate a target speed v _t that is a target speed of the vehicle 1 based on the operation amount A of the accelerator pedal 63.

  The steering operation amount detection sensor 102 detects the operation amount of the steering wheel 62, more specifically, the rotation angle θ of the steering wheel 62 rotated by the operator. The controller 100 can acquire a detection signal of the rotation angle θ of the steering wheel 62 by the steering operation amount detection sensor 102. Here, if the value of the rotation angle θ of the steering wheel 62 is determined, the value of the turning radius r when the vehicle 1 turns is determined. In the present embodiment, the turning radius r refers to the distance from the turning center Z to the midpoint between the left rear wheel 41 and the right rear wheel 51 (see FIG. 4).

  The controller 100 is connected to each drive motor, and can control the drive of each drive motor, more specifically, the rotation direction and the rotation speed of each drive motor. With this control, the controller 100 can control the driving of each wheel, and consequently, the vehicle 1 can travel at an arbitrary speed.

  The controller 100 is connected to each steering motor, and can control the driving of each steering motor, more specifically, the rotation direction and the number of rotations of each steering motor. With this control, the controller 100 can control the steering of each wheel, and consequently, the vehicle 1 can be steered in an arbitrary direction.

  In the vehicle 1 configured as described above, the controller 100 can independently control the steering of the front wheels based on the operation of the steering wheel 62. Further, the controller 100 can independently control the driving of each wheel based on the operation of the accelerator pedal 63.

  Here, as described above, the vehicle 1 turns by steering only the front wheels. Accordingly, as shown in FIG. 4, the turning center Z is located on a straight line connecting the ground point of the left rear wheel 41 and the ground point of the right rear wheel 51, and is based on the rotation angle θ of the steering wheel 62. If the turning radius r is calculated, the position of the turning center Z is determined based on the calculated turning radius r.

  Hereinafter, a method for calculating the steering angle of the front wheels and the speed of each wheel when the vehicle 1 turns with the turning radius r will be described with reference to FIGS. 4 to 8.

As shown in FIG. 4, in order for the vehicle 1 to turn smoothly at the turning radius r, the trajectory between the left front wheel 21 and the right front wheel 31 at the time of turning needs to draw a concentric circle. Steering angle [delta] _FR of the steering angle [delta] _FL and the right front wheel 31 of the left front wheel 21 for this purpose, respectively represented by the relationship expressed by a number 1 and number 2 below.

  Here, T represents the tread of the vehicle 1 (distance between the center of the left front wheel 21 and the center of the right front wheel 31), and L represents the wheel base (distance between the front wheel and the rear wheel) of the vehicle 1. . In the present embodiment, the front tread T and the rear tread T are the same.

  Since the vehicle 1 steers only the front wheels as described above, the steering angles of the left rear wheel 41 and the right rear wheel 51 are both zero.

As can be seen from Equations 1 and 2, since the tread T and the wheel base L are predetermined values depending on the specifications of the vehicle 1, if the target turning radius r is determined, the tread T and the wheel base L are based on the turning radius r. A steering angle δ _FL and a steering angle δ _FR are calculated.

FIG. 5 shows an example of a map representing the relationship between the turning radius r, the steering angle δ _FL, and the steering angle δ _FR when the vehicle 1 is turned to the left (see FIG. 4). The horizontal axis (turning radius r) in FIG. 5 is a logarithmic axis. It can be seen that the steering angle δ _FL and the steering angle δ _FR increase as the turning radius r decreases, and the steering angle δ _FL and the steering angle δ _FR decrease as the turning radius r increases. It can also be seen that the steering angle δ _FL of the left front wheel 21 located on the inner side in the turning direction is larger than the steering angle δ _FR of the right front wheel 31 located on the outer side in the turning direction. By using such a map, the steering angle of the front wheels can be calculated from the turning radius r.

Further, when the vehicle 1 (vehicle main body 10) turns at a speed v, in order for each wheel to turn without slipping on the ground, it is necessary to determine the speed of each wheel to an optimum value.
The speed of each wheel for this is as follows: the turning radius r is (1) T / 2 ≦ r,
(2) It is expressed by the following relational expressions separately for the case of 0 <r ≦ T / 2.
Note that the speed _{v FL} of the left front wheel 21, the speed and the _{v FR} of the right front wheel 31, the speed and the _{v RL} of the left rear wheel 41, and the speed of the right rear wheel 51 _{v RR,} representing respectively. Moreover, the speed of each wheel represents the speed with respect to the ground-contact surface of each wheel (refer FIG. 4).

  When (1) T / 2 ≦ r, that is, when the turning center Z is located outside the width of the rear wheel, the speed of each wheel is expressed by the following relational expressions shown in the following equations 3 to 6. expressed.

  When (2) 0 <r ≦ T / 2, that is, when the turning center Z is located on the inner side of the rear wheel, the speeds of the respective wheels are expressed by the following relational expressions shown in Equations 7 to 10, respectively. expressed.

As can be seen from Equations 3 to 10, since the tread T and the wheel base L are predetermined values depending on the specifications of the vehicle 1, if the target vehicle speed 10 is determined, the speed v Based on the above, the speeds (v _FL , v _FR , v _RL , and v _RR ) of each wheel are calculated.

Here, each wheel speed coefficient (left front wheel speed coefficient C _FL , right front wheel speed coefficient C _FR , left rear wheel speed coefficient C _RL , and right rear wheel speed coefficient C _RR ) that is a generalized coefficient and the accelerator pedal 63 When the target speed v _t calculated based on the manipulated variable A is used, the speed of each wheel is expressed by the relational expressions shown in the following equations 11 to 14.

If the turning radius r is determined, the ratio between the wheel speed coefficients is determined. Further, as can be seen from Expressions 11 to 14, if the wheel speed coefficients and the target speed v _t are determined, the speed of each wheel is calculated.

6 shows a turning radius r and each wheel speed coefficient (left front wheel speed coefficient C _FL , right front wheel speed coefficient C _FR , left rear wheel speed coefficient C when the vehicle 1 is turned leftward (see FIG. 4). An example of the map showing the relationship between _RL and the right rear wheel speed coefficient C _RR ) is shown. The horizontal axis (turning radius r) in FIG. 6 is a logarithmic axis.

FIG. 6 shows a case where the right front wheel speed coefficient C _FR is set to be always 1. If the turning radius r is determined, the ratio of the other wheel speed coefficients (the left front wheel speed coefficient C _FL , the left rear wheel speed coefficient C _RL , and the right rear wheel speed coefficient C _RR ) to the right front wheel speed coefficient C _FR is also determined. The relationship between the turning radius r and each wheel speed coefficient is as shown in FIG. As can be seen from Equation 12, when the right front wheel speed coefficient C _FR is always set to 1, the speed v _FR of the right front wheel 31 is always the target speed v _t . By using such a map and Equations 11 to 14, the speed of each wheel can be calculated from the turning radius r.

Up to this point, the method for calculating the steering angle of the front wheels and the wheel speed coefficients based on the turning radius r and the maps illustrated in FIGS. 5 and 6 has been described. However, since the turning radius r is determined based on the turning angle θ of the steering wheel 62, the steering angle of each front wheel and each wheel speed coefficient are actually calculated based on the turning angle θ instead of the turning radius r. become. FIG. 7 shows an example of a map (hereinafter simply referred to as “steering angle map M1”) _showing the relationship between the rotation angle θ of the steering wheel 62, the steering angle δ _FL, and the steering angle δ _{FR in} this case. FIG. 8 shows an example of a map representing the relationship between the rotation angle θ of the wheel 62 and each wheel speed coefficient (hereinafter simply referred to as “wheel speed coefficient map M2”).

In the steering angle map M1 shown in FIG. 7, the steering angle δ _FL and the steering angle δ _FR when the steering wheel 62 is rotated to the left, that is, when the front wheels are steered to the left, are set to positive values. When the wheel 62 is rotated to the right, that is, when the front wheels are steered to the right, the steering angle δ _FL and the steering angle δ _FR are shown as negative values, respectively. By using such a steering angle map M1, the steering angle of the front wheels can be calculated from the rotation angle θ.

In the wheel speed coefficient map M2 shown in FIG. 8, the right front wheel speed coefficient _CFR is always 1 when the steering wheel 62 is rotated to the left, and the left front wheel speed coefficient when the steering wheel 62 is rotated to the right. A case where C _FL is always set to 1 is shown. By using such a wheel speed coefficient map M2 and Expressions 11 to 14, the speed of each wheel can be calculated from the rotation angle θ.

  Below, the control aspect of each drive motor and each steering motor by the controller 100 is demonstrated using FIGS. 7-9.

As shown in FIG. 9, the controller 100 acquires the rotation angle θ of the steering wheel 62 detected by the steering operation amount detection sensor 102, and the steering angle corresponding to the rotation angle θ based on the steering angle map M1. δ _FL and steering angle δ _FR are respectively calculated.

The controller 100, as the steering angle [delta] _FL and the steering angle [delta] _FR of the left front wheel 21 and the right front wheel 31, a steering angle [delta] _FL and the steering angle [delta] _FR calculated on the basis of the steering angle map M1, the left front-wheel steering The driving of the motor 23 and the right front wheel steering motor 33 is controlled.

In this way, by controlling the values of the steering angle δ _FL and the steering angle δ _FR to be values calculated based on the steering angle map M1, the trajectory between the left front wheel 21 and the right front wheel 31 during turning is determined. Will draw concentric circles, and the vehicle 1 can turn smoothly with the turning radius r. Further, since the left front wheel 21 and the right front wheel 31 are independently steered by the left front wheel steering motor 23 and the right front wheel steering motor 33, the steering angles (δ _FL and δ _FR ) are mechanically limited by a link mechanism or the like. It will not be done. For this reason, even when the turning center Z is located inside the width of the rear wheel, it is possible to turn around the turning center Z, particularly when the turning center Z is located at the middle point of the rear wheel. Even turn (super turning) can be performed.

Further, the controller 100 determines the target speed v _t based on the operation amount A of the accelerator pedal 63 detected by the accelerator operation amount detection sensor 101 and the appropriate map M3 showing the relationship between the operation amount A and the target speed v _t. Is calculated.

The controller 100 acquires the rotation angle θ of the steering wheel 62, and each wheel speed coefficient (C _FL , C _FR , C _RL , and C _RR ) corresponding to the rotation angle θ based on the wheel speed coefficient map M2. Are calculated respectively.

The controller 100 uses the target speed v _t calculated based on the map M3 and each wheel speed coefficient calculated based on the wheel speed coefficient map M2, and from the relational expressions shown in Expression 11 to Expression 14, Velocity (v _FL , v _FR , v _RL , and v _RR ) is calculated respectively.

The controller 100 controls the drive of each drive motor so that the speed of each wheel becomes the calculated speed (v _FL , v _FR , v _RL , and v _RR ).

  Thus, by calculating the speed of each wheel using each wheel speed coefficient calculated based on the wheel speed coefficient map M2, and controlling the speed of each wheel so as to be the calculated speed, Each wheel can turn without sliding against the ground. Thus, when the vehicle 1 turns, the road surface (turf, farm field, etc.) is not damaged, and damage due to friction with the road surface of each wheel can be prevented.

In the present embodiment, the wheel speed coefficient map M2 is moved to the right so that the right front wheel speed coefficient _CFR is always 1 when the steering wheel 62 is rotated to the left (when turning to the left). When turning (when turning to the right), the left front wheel speed coefficient _CFL is set to 1 at all times. That is, the control is performed so that the speed v _FR of the right front wheel 31 is always v _t when turning left, and the speed v _FL of the left front wheel 21 is always v _t when turning right. Is done.

Here, when the vehicle 1 turns to the left, the radius of the circle drawn by the right front wheel 31 is the largest among the circles drawn by the wheels (see FIG. 4). Accordingly, the speed v _FR of the right front wheel 31 is the highest among the speeds of the wheels. Therefore, as described above, by controlling the speed v _FR of the right front wheel 31 to always become the target speed v _t , the speeds of the other wheels (v _FL , v _RL , and v _RR ) are made equal to or lower than the target speed v _t . Can be suppressed. In this way, by suppressing the speed of each wheel to a predetermined value (the target speed v _t in the present embodiment) or less, it is possible to prevent the occurrence of problems (damage or the like) due to over-rotation of each drive motor. For example, it is possible to prevent over-rotation of each drive motor by selecting each drive motor that can drive each wheel comfortably at the target speed v _t or more.

When the vehicle 1 turns to the right, the radius of the circle drawn by the left front wheel 21 is the largest among the circles drawn by the wheels. Accordingly, the speed v _FL of the left front wheel 21 is the highest among the speeds of the wheels. Therefore, as in the case of turning to the left as described above, by controlling the speed v _FL of the left front wheel 21 to always become the target speed v _t , the speed of each wheel is set to a predetermined value (in this embodiment, The target speed v _t ) or less can be suppressed, and the occurrence of malfunctions (damage or the like) due to excessive rotation of each drive motor can be prevented.

In the present embodiment, each wheel speed coefficient is set so as not to exceed 1. However, the present invention is not limited to this, and each wheel speed coefficient has a value exceeding 1. It is also possible. For example, it is possible to configure the vehicle body 10 so that the speed of the vehicle main body 10 always becomes the target speed v _t .

  In the present embodiment, each wheel is driven by each drive motor, but the present invention is not limited to this. For example, a configuration in which only the front wheels are driven, a configuration in which only the rear wheels are driven, or a configuration in which only one of the wheels is driven may be employed.

However, when only one of the rear wheels is driven, when the ground contact point of the wheel coincides with the turning center Z, the speed of the driven wheel becomes zero. For example, in the wheel speed coefficient map M2 shown in FIG. 8, and left rear wheel speed coefficient C _RL during rotation angle theta _1, a right rear wheel speed coefficient C _RR during rotation angle theta _2. In such a case, since the vehicle 1 cannot travel with the configuration in which only the wheel is driven, it cannot be configured to drive only one of the rear wheels.

As described above, the vehicle 1 according to this embodiment includes a plurality of wheels including two front wheels (the left front wheel 21 and the right front wheel 31), and a steering actuator (left front wheel steering) that is connected to the front wheels and steers the front wheels. The motor 23 and the right front wheel steering motor 33), the steering wheel 62 for instructing the operation of the steering actuator, and the turning center Z determined based on the turning angle θ of the steering wheel 62. And a controller 100 that calculates the steering angles (δ _FL and δ _FR ) of the front wheels and operates the steering actuator so that the steering angles of the front wheels become the calculated steering angles. With this configuration, it is possible to easily turn around the arbitrary turning center Z by a simple operation of turning the steering wheel 62. In addition, since the two front wheels can be steered independently, the steering angle of the two front wheels is not mechanically limited, and the vehicle can turn with a small turning radius. Furthermore, since the sense of turning operation of the steering wheel 62 is similar to that of a general automobile, an operator accustomed to the sense of automobile operation can easily operate the vehicle 1. Furthermore, since the turning radius r can be reduced without steering the rear wheel, there is no need for a separate member (steering actuator, etc.) for steering the rear wheel, and the number of parts and part cost can be reduced. Can do.

  The steering actuator can steer the front wheels by 90 degrees or more. With this configuration, the front wheel is steered by 90 degrees or more to turn around the turning position at the inner side of the rear wheel (reliable turning), or turn around the center position of the rear wheel. (Super Shinji turn) can be.

Further, the vehicle 1 uses a plurality of wheels including a plurality of wheels including two front wheels (a left front wheel 21 and a right front wheel 31) as driving wheels (a left front wheel 21, a right front wheel 31, a left rear wheel 41, and a right rear wheel 51). ), And a driving actuator (left front wheel drive motor 22, right front wheel drive motor 32, left rear wheel drive motor 42, and right rear wheel drive motor 52) that can be connected and driven for each of the plurality of drive wheels. And an accelerator pedal 63 for setting the target speed v _t , and the controller 100 determines that the drive wheel is in relation to the road surface based on the rotation angle θ of the steering wheel 62 and the operation amount A of the accelerator pedal 63. The speeds (v _FL , v _FR , v _RL , and v _RR ) of the drive wheels that can turn around the turning center Z without slipping are calculated so that the speed of the drive wheels becomes the calculated speed. Above It is intended to operate the movement actuator. With this configuration, the speed of the driving wheel can be adjusted based on the operation amount A of the accelerator pedal 63 so that the driving wheel does not slide on the road surface. Therefore, it is possible to stably perform the super turn without damaging the road surface (turf, farm field, etc.) when turning and while preventing damage to the drive wheels.

Further, the controller 100 limits the calculated speed so as not to exceed a predetermined value (target speed v _t ). With this configuration, the calculated speed is limited to a predetermined value or less, so that it is possible to prevent the occurrence of problems due to over-rotation of the driving actuator.

1 Vehicle 21 Left front wheel (front wheel, drive wheel)
22 Front left wheel drive motor (drive actuator)
23 Left front wheel steering motor (steering actuator)
31 Right front wheel (front wheel, drive wheel)
32 Right front wheel drive motor (drive actuator)
33 Right front wheel steering motor (steering actuator)
41 Left rear wheel (drive wheel)
42 Left rear wheel drive motor (drive actuator)
51 Right rear wheel (drive wheel)
52 Right rear wheel drive motor (drive actuator)
62 Steering wheel (steering operation tool)
63 Accelerator pedal (drive operation tool)
100 controller (control means)

Claims (4)

A plurality of wheels including two front wheels;
A steering actuator coupled to each of the front wheels for steering the front wheels;
A steering operation tool for instructing the operation of the steering actuator;
A steering angle of the front wheel capable of turning around a turning center determined based on an operation amount of the steering operation tool is calculated, and the steering angle is set so that the steering angle of the front wheel becomes the calculated steering angle. Control means for operating the actuator;
One or more wheels among the plurality of wheels including the two front wheels are drive wheels,
A driving actuator capable of being connected and driven for each of the one or more driving wheels;
A drive operation tool for setting a target speed. The steering actuator is
The vehicle according to claim 1, wherein the front wheel can be steered by 90 degrees or more.   The control means is capable of turning around the turning center without slipping the drive wheel with respect to a road surface based on an operation amount of the steering operation tool and an operation amount of the drive operation tool. The vehicle according to claim 1, wherein a speed of the driving wheel is calculated, and the driving actuator is operated so that the speed of the driving wheel becomes the calculated speed.   The vehicle according to claim 3, wherein the control means limits the calculated speed so as not to exceed a predetermined value.

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