Mobile body and control device

Abstract

To prevent a movable body from being increased in size by arranging motors, which are configured to drive a plurality of omnidirectional movable wheels, so as not to interfere with each other since the omnidirectional movable wheels are typically arranged in a circle such that rotation axes intersect at one point.SOLUTION: A movable body 1 comprises: three or more omnidirectional movable wheels arranged arbitrarily such that thrust directions of at least two omnidirectional movable wheels are different from each other; and a control device 2. The control device 2 includes a first calculation unit 21 configured to calculate, from a target speed and a target angular speed of the movable body 1, a target angular speed of each of the omnidirectional wheels arranged arbitrarily. As just described, the plurality of omnidirectional movable wheels can be arranged arbitrarily, and thus even when the omnidirectional movable wheels are arranged such that a plurality of motors 12 does not interfere with each other, the movable body 1 can be prevented from being increased in size.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to a mobile body or the like having a plurality of omnidirectional wheels. [Background technology]

[0002] BACKGROUND ART Conventionally, a mobile body having a plurality of omnidirectional wheels (for example, omniwheels) is known as a mobile body that can move in all directions (for example, see Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2005-047312 Summary of the Invention [Problem to be solved by the invention]

[0004] Generally, a mobile object that can move in all directions has multiple omnidirectional wheels 101 arranged as shown in Fig. 5. That is, the multiple omnidirectional wheels 101 are arranged at equal intervals on the circumference of a circle so that their rotation planes 104 are tangent to a circle 103, and straight lines 102 extending from the rotation axes of the omnidirectional wheels 101 intersect at the center of the circle 103.

[0005] In this case, the motors that rotate each omnidirectional wheel 101 would be placed near the center of the circle 103, but in order to position the motors so that they do not interfere with each other, the circle 103 would have to be made larger, which would result in the problem of the moving body becoming larger.

[0006] Furthermore, Patent Document 1 above shows an example in which the omnidirectional wheels are arranged differently from that shown in FIG. 5, but in this example, the motor and other components are arranged closer to the center of the moving body, which presents the same problem.

[0007] The present invention has been made to solve the above-mentioned problems, and aims to provide a mobile body in which multiple omnidirectional wheels can be arranged at any position, and a control device that can calculate the angular velocity of each of the arbitrarily arranged omnidirectional wheels from the target speed of the mobile body. [Means for solving the problem]

[0008] In order to achieve the above object, one aspect of the present invention provides a control device for controlling each omnidirectional wheel of a moving body having three or more omnidirectional wheels arbitrarily arranged so that the thrust directions of at least two of the omnidirectional wheels are different, and the control device includes a first calculation unit that calculates a target angular velocity of each omnidirectional wheel from a target speed and a target angular velocity of the moving body.

[0009] Furthermore, a moving body according to one aspect of the present invention has N (N is an integer of 3 or more) omnidirectional wheels arbitrarily arranged so that the thrust directions of at least two omnidirectional wheels are different. [Effects of the Invention]

[0010] According to one aspect of the present invention, a vehicle can be configured with three or more omnidirectional wheels arranged in a way that at least two of the omnidirectional wheels have different thrust directions, thereby preventing the vehicle from becoming too large. Furthermore, according to another aspect of the present invention, a control device can calculate, from the target speed and target angular velocity of the vehicle, the target angular velocities of three or more omnidirectional wheels arranged in a way that at least two of the omnidirectional wheels have different thrust directions. [Brief explanation of the drawings]

[0011] [Figure 1] FIG. 1 is a plan view showing a moving body according to an embodiment of the present invention; [Figure 2] FIG. 2 is a functional block diagram showing the configuration of a moving body according to the embodiment; [Figure 3] FIG. 10 shows the arrangement of omnidirectional wheels in the embodiment. [Figure 4]FIG. 10 is a diagram showing an example of the arrangement of omnidirectional wheels in the moving body according to the embodiment. [Figure 5] FIG. 1 shows an example of the arrangement of omnidirectional wheels in a conventional vehicle. DETAILED DESCRIPTION OF THE INVENTION

[0012] The following describes a vehicle and a control device according to the present invention using embodiments. In the following embodiments, components with the same reference numerals are the same or equivalent, and repeated explanations may be omitted. A vehicle according to an embodiment of the present invention can arbitrarily arrange three or more omnidirectional wheels so that the thrust directions of at least two of the omnidirectional wheels are different.

[0013] FIG. 1 is a plan view showing the configuration of a moving object 1 according to this embodiment, and FIG. 2 is a functional block diagram showing the configuration of the moving object 1. Note that the moving object 1 may be any object that moves using omnidirectional wheels 11a to 11d. The moving object 1 may be, for example, a cart or a robot. The robot may be, for example, an entertainment robot, a surveillance robot, a transport robot, a cleaning robot, or any other robot.

[0014] The mobile object 1 according to this embodiment includes a base 5, four omnidirectional wheels 11a-11d arranged on the bottom side of the base 5, four motors 12a-12d that drive rotation shafts 13a-13d of the omnidirectional wheels 11a-11d, respectively, and a control device 2 that controls the omnidirectional wheels 11a-11d of the mobile object 1. The control device 2 includes a first calculation unit 21, a second calculation unit 22, and a movement control unit 23. Note that controlling the omnidirectional wheels 11a-11d may also mean controlling the motors 12a-12d that rotate the omnidirectional wheels 11a-11d. The base 5 is a member to which the omnidirectional wheels 11a-11d are attached, and may be, for example, a loading platform. It is preferable that the four omnidirectional wheels 11a-11d have the same structure and size. The same applies to the four motors 12a-12d. Furthermore, when there is no need to distinguish between the omnidirectional wheels 11a to 11d, the motors 12a to 12d, and the rotating shafts 13a to 13d, they may be referred to as the omnidirectional wheel 11, the motor 12, and the rotating shaft 13. The motor 12 may drive the omnidirectional wheel 11 via a reducer.

[0015] The four omnidirectional wheels 11 can be arranged arbitrarily. "Arbitrarily arranging the omnidirectional wheels 11" may mean that the omnidirectional wheels 11 can be arranged at any position and angle. However, at least two omnidirectional wheels 11 are arranged so that their thrust directions are different. The thrust direction refers to the direction in which a propulsive force is generated by the rotation of the omnidirectional wheels 11. "The thrust directions of the multiple omnidirectional wheels 11 are different" means that the thrust directions of the multiple omnidirectional wheels 11 are not parallel. The omnidirectional wheels 11 may be, for example, omniwheels, Mecanum wheels, or other omnidirectional wheels. This embodiment will mainly describe the case where the omnidirectional wheel 11 is an omniwheel. The thrust direction of the omniwheel omnidirectional wheel 11 is the direction of the plane of rotation. Therefore, when the omnidirectional wheel 11 is an omniwheel, at least two omnidirectional wheels 11 may be arranged so that their planes of rotation are different. In other words, at least two omnidirectional wheels 11 may be arranged so that the directions of their rotation axes are different. Furthermore, the thrust direction of the omnidirectional wheels 11, which are Mecanum wheels, is a direction that forms a predetermined angle with the direction of the rotation plane. The rotation plane of the omnidirectional wheels 11 is a plane formed by the rotating wheels and is a plane perpendicular to the rotation axis. Furthermore, it is preferable that the rotation axis 13 of each omnidirectional wheel 11 is arranged so that it is parallel to the plane on which the mobile object 1 is traveling.

[0016] The omni-wheel, or omni-wheel, omnidirectional wheel 11 typically has one or more wheels with multiple barrel-shaped free rollers evenly spaced on the periphery. When the omni-wheel 11 has two or more wheels, the two or more wheels may be stacked so that the free rollers are staggered and the wheels have the same rotation axis. While FIG. 1 shows a simplified representation of the omni-directional wheel 11, the omni-directional wheel 11 may have a configuration similar to that of the omni-directional wheel 101 shown in FIG. 5. The omni-directional wheel 101 shown in FIG. 5 has two stacked wheels with four barrel-shaped free rollers. While an omni-wheel typically has two or more stacked wheels, this is not required. For example, an omni-wheel may have one wheel with multiple free rollers, as shown in JP 2001-191704 A. The rotation plane of the omnidirectional wheel 11 may be considered to be, for example, the rotation plane of one or more wheels of the omnidirectional wheel 11 caused by the motor 12 (a plane that passes through the center point of the wheel and is perpendicular to the rotation axis of the wheel), or it may be considered to be any plane within the omnidirectional wheel 11 that is parallel to that plane.

[0017] The motors 12 drive the omnidirectional wheels 11. As shown in FIG. 2, the motors 12 are controlled by a control device 2. Each motor 12 may have, for example, an encoder. If the motor 12 does not have an encoder, an encoder may be provided to acquire the angle and number of rotations of the motor 12 or the omnidirectional wheels 11.

[0018] The first calculation unit 21 of the control device 2 calculates the target angular velocity of each omnidirectional wheel 11 from the target speed and target angular velocity of the moving object 1. The target speed and target angular velocity of the moving object 1 may be, for example, a command speed and command angular velocity of the moving object 1. The angular velocity of the moving object 1 may also be the angular velocity of the turning of the moving object 1. Details of this calculation will be described later. This calculation makes it possible to know the angular velocity and rotational speed of each omnidirectional wheel 11 required for the moving object 1 to move as desired.

[0019] The second calculation unit 22 calculates the actual speed and actual angular speed of the moving object 1 from the actual angular speed of each omnidirectional wheel 11. This calculation will be described in detail later. This calculation makes it possible to know the current speed and current angular speed of the moving object 1 from the angular speed and rotational speed of each omnidirectional wheel 11.

[0020] The movement control unit 23 controls the movement of the mobile object 1 by controlling the rotation of each omnidirectional wheel 11, i.e., by controlling each motor 12. The movement control may include, for example, control of the direction of movement of the mobile object 1, the start and stop of movement, the speed of the mobile object 1, and the angular velocity of the mobile object 1 when turning. For example, if a movement path is set, the movement control unit 23 may control the motors 12 so that the mobile object 1 moves along the movement path. The movement control unit 23 may control the movement of the mobile object 1 using the current position of the mobile object 1 acquired by a current position acquisition unit (not shown). More specifically, the movement control unit 23 may control each motor 12 so that the current position acquired by the current position acquisition unit is along the movement path. The current position acquisition unit may acquire the current position of the mobile object 1 using, for example, the calculation result of the second calculation unit 22, or may acquire the current position of the mobile object 1 using a method such as GPS or SLAM, or may acquire the current position of the mobile object 1 by other methods. The movement control unit 23 may also control the movement using, for example, a map. The control of movement by the movement control unit 23 is well known, and therefore a detailed description thereof will be omitted.

[0021] The movement control unit 23 may use the target angular velocity of the omnidirectional wheels 11 calculated by the first calculation unit 21 in controlling the movement of the moving object 1. For example, when it is desired to move the moving object 1 at a certain target speed and turn at a certain target angular velocity, the movement control unit 23 may pass the target speed and target angular velocity to the first calculation unit 21, receive from the first calculation unit 21 the target angular velocity of each omnidirectional wheel 11 corresponding to the target speed and target angular velocity, and control the motors 12 that drive each omnidirectional wheel 11 so that the wheels rotate at the target angular velocity.

[0022] Furthermore, in controlling the movement of the moving object 1, the movement control unit 23 may obtain the actual angular velocity of each omnidirectional wheel 11 from the value of the encoder, pass the obtained value to the second calculation unit 22, and receive the actual velocity and actual angular velocity of the moving object 1 corresponding to the actual angular velocity. Note that the encoder may be, for example, an encoder included in the motor 12, or may be another encoder. The movement control unit 23 may perform feedback control regarding the movement of the moving object 1, for example, using the actual velocity and actual angular velocity of the moving object 1 and the target velocity and target angular velocity. Furthermore, as described above, the actual velocity and actual angular velocity calculated by the second calculation unit 22 may be used to calculate the current position of the moving object 1.

[0023] Next, the calculation by the first calculation unit 21 will be described. Here, it is assumed that the four omnidirectional wheels 11 are arranged as shown in FIG. 3. The xy Cartesian coordinate system is a coordinate system provided on the moving body 1. The origin of the xy coordinate system may be, for example, the center of gravity of the moving body 1. Furthermore, the positive direction of the x axis may be, for example, the forward direction of the moving body 1. Furthermore, as shown in FIG. 3, the component of the velocity of the moving body 1 in the positive direction of the x axis is defined as V x The component of the velocity of moving body 1 in the positive direction of the y-axis is V y Let Ω be the angular velocity of the rotation around the origin of the xy coordinate system. As shown in FIG. 3, the angular velocity Ω is set so that the counterclockwise direction is positive. As shown in FIG. 3, let r be the radius of each omnidirectional wheel 11. Let ω be the angular velocity of the n-th (n=1, 2, 3, 4) omnidirectional wheel 11. n The velocity component in the direction of the rotation plane is V n The coordinates of the representative point are (x n ,y n ) and the angle between the x-axis and the direction of the rotation plane is θ n The representative point of the omnidirectional wheel 11 may be the center or center of gravity of the omnidirectional wheel 11. For example, (x n ,y n ) is the position of the n-th omnidirectional wheel 11, and θ nIt can be considered that V is the arrangement angle indicating the direction of the rotation plane of the n-th omnidirectional wheel 11. Therefore, at least two of θ1 to θ4 are different values. n =r×ω n In this case, the target velocity and the target angular velocity (V x ,V y , Ω), the target angular velocity (ω1, ω2, ω3, ω4) of each omnidirectional wheel 11 can be calculated. Therefore, the first calculation unit 21 may calculate the angular velocity of each omnidirectional wheel 11 using the following equation. Note that the following matrix for calculating the target angular velocity of the omnidirectional wheel 11 from the target velocity of the moving object 1 etc. will be referred to as the calculation matrix.

number

[0024] The second calculation unit 22 may also use the following equation to calculate the actual speed and actual angular velocity of the moving object 1 from the actual angular velocity of each omnidirectional wheel 11. In this way, when calculating the actual speed and actual angular velocity of the moving object 1 from the actual angular velocity of the omnidirectional wheel 11, the inverse matrix of the operational matrix may be used. In this case, since the operational matrix is ​​not a square matrix, the inverse matrix of the operational matrix on the right side of the following equation is a pseudo-inverse matrix of the operational matrix.

number

[0025] Next, the operation of the moving body 1 according to this embodiment will be described using a specific example. In this specific example, it is assumed that the moving body 1 is moving toward a destination. During the movement, the movement control unit 23 calculates the target speed (V x ,V y ) and the target angular velocity Ω of the turn are specified. Then, the movement control unit 23 calculates the target velocity (V x ,V y) and the target angular velocity Ω to the first calculation unit 21. Upon receiving these, the first calculation unit 21 calculates the target angular velocities ω1 to ω4 of each omnidirectional wheel 11 using the operational matrix of the above equation and passes the calculated values ​​to the movement control unit 23. Upon receiving the target angular velocities ω1 to ω4, the movement control unit 23 controls each motor 12 so that each omnidirectional wheel 11 has the target angular velocities ω1 to ω4.

[0026] The movement control unit 23 also receives encoder values ​​for each omnidirectional wheel 11 from the motor 12 and uses the encoder values ​​to obtain the actual angular velocity of each omnidirectional wheel 11, which it then passes to the second calculation unit 22. Upon receiving the actual angular velocity, the second calculation unit 22 calculates the actual velocity and actual angular velocity of the moving object 1 using the inverse matrix of the operational matrix in the above equation, and passes these values ​​to a current position acquisition unit (not shown). Upon receiving the actual velocity and actual angular velocity of the moving object 1, the current position acquisition unit uses the actual velocity and actual angular velocity of the moving object 1 to calculate the current position and current angle of the moving object 1, and passes these values ​​to the movement control unit 23. Upon receiving the current position and current angle, the movement control unit 23 uses the current position and current angle to determine the target velocity and target angular velocity of the moving object 1 so that the moving object 1 moves to the destination along a predetermined route. By repeating this process, the moving object 1 moves to the destination along the route. The calculation results of the second calculation unit 22 may be used, for example, for feedback control by the movement control unit 23.

[0027] As described above, in the mobile object 1 according to this embodiment, even if the multiple omnidirectional wheels 11 are arbitrarily arranged so that at least two omnidirectional wheels 11 have different rotational plane directions, the multiple omnidirectional wheels 11 can be controlled so that the mobile object 1 moves at a desired speed and turns at a desired angular velocity. Therefore, even if the multiple omnidirectional wheels 11 are arranged so that the multiple motors do not interfere with each other, the size of the mobile object 1 can be kept small. Furthermore, the multiple omnidirectional wheels 11 can be arranged so that the space inside the multiple omnidirectional wheels 11 can be used effectively. Furthermore, the actual speed and actual angular velocity of the mobile object 1 can be calculated from the actual angular velocities of the multiple omnidirectional wheels 11, and the calculation results can be used to perform feedback control for movement and calculate the current position.

[0028] In this embodiment, the case where the number of omnidirectional wheels 11 is four has been mainly described, but this is not essential. The number of omnidirectional wheels 11 possessed by the moving object 1 is not limited as long as it is three or more. When the moving object 1 has n omnidirectional wheels 11, the first calculation unit 21 may calculate the target angular velocity of each omnidirectional wheel 11 by the following formula, where n is an integer equal to or greater than three.

number

[0029] Furthermore, the second calculation unit 22 may calculate the actual velocity and the actual angular velocity of the turning of the moving object 1 by the following equation. Note that the inverse matrix of the operational matrix on the right side of the following equation is a pseudo-inverse matrix of the operational matrix when n is 4 or more.

number

[0030] Furthermore, the first and second calculation units 21 and 22 may perform calculations using other equations that are substantially the same as the above-described equations. For example, when an oblique coordinate system is used instead of the xy orthogonal coordinate system, the first and second calculation units 21 and 22 may calculate the target speed, the actual speed, and the like using equations corresponding to the oblique coordinate system.

[0031] As described above, in the vehicle 1 according to this embodiment, as long as the thrust directions of at least two omnidirectional wheels 11 are different, each omnidirectional wheel 11 can be positioned anywhere. In this case, for example, as shown in FIG. 4, four omnidirectional wheels 11 may be positioned at one end of each side of a rectangular shape 7, whose plane of rotation is indicated by a dashed line, so that the four omnidirectional wheels 11 are aligned along each side. That is, one omnidirectional wheel 11 may be positioned at each vertex of the rectangular shape 7, and the two omnidirectional wheels 11 positioned at both ends of each side of the rectangular shape 7 may be positioned so that the directions of the planes of rotation of the wheels form a 90-degree angle. FIG. 4 is a plan view of the vehicle 1. Although the motor 12 and other components are omitted in FIG. 4, the motor 12 may be positioned on the back side of the base 5 of the vehicle 1. This positioning of the omnidirectional wheels 11 prevents the motor 12 from being located near the center of the vehicle 1. This allows for a larger space to be secured near the center of the vehicle 1, allowing for other components, such as a battery, to be located there. Moreover, it becomes possible to make the moving body 1 smaller.

[0032] 4, two adjacent omnidirectional wheels 11, i.e., two omnidirectional wheels 11 at both ends of each side of the rectangular shape 7, are arranged so that one end of one omnidirectional wheel 11 in the direction of the plane of rotation (for example, the right end of omnidirectional wheel 11d in FIG. 4) is aligned on a straight line with one end of the other omnidirectional wheel 11 in the direction of the rotation axis (for example, the right end of omnidirectional wheel 11a in FIG. 4), but this does not have to be the case. In this way, when four omnidirectional wheels 11 are arranged on one end of each side of the rectangular shape 7 whose plane of rotation is indicated by the dashed dotted lines so that they are aligned along each side, the four straight lines in the direction of the rotation axes of the four omnidirectional wheels 11 do not intersect at a single point as in the conventional example, but rather form a rectangle.

[0033] Furthermore, in the above embodiments, each process or function may be realized by centralized processing by a single device or a single system, or may be realized by distributed processing by multiple devices or multiple systems.

[0034] In the above embodiments, each component may be configured with dedicated hardware, or components that can be realized by software may be realized by executing a program. For example, each component may be realized by a program execution unit such as a CPU reading and executing a software program recorded on a recording medium such as a hard disk or semiconductor memory. During execution, the program execution unit may execute the program while accessing a storage unit or recording medium. The program may also be executed by being downloaded from a server or the like, or by being read from a predetermined recording medium. The program may also be executed by a single computer or multiple computers. That is, centralized processing or distributed processing may be performed.

[0035] Furthermore, the present invention is not limited to the above-described embodiment, and various modifications are possible, and it goes without saying that these modifications are also included within the scope of the present invention. [Explanation of symbols]

[0036] 1 moving body, 2 control device, 11, 11a to 11d omnidirectional moving wheel, 21 first calculation unit, 22 second calculation unit, 23 movement control unit

Claims

1. A moving body, three or more omnidirectional wheels arranged arbitrarily so that at least two of the omnidirectional wheels have thrust directions different from each other; three or more motors for driving the three or more omnidirectional wheels, respectively; a first calculation unit that calculates a target angular velocity of each of the omnidirectional wheels from a target velocity and a target angular velocity of the moving body; a second calculation unit that calculates an actual velocity and an actual angular velocity of the moving body from the actual angular velocities of the omnidirectional wheels; a current position acquisition unit that acquires a current position of the moving object using a calculation result of the second calculation unit; a movement control unit that specifies a target speed and a target angular speed of the moving body using the current position acquired by the current position acquisition unit so that the moving body moves to a destination along a predetermined route, receives from the first calculation unit target angular speeds of each of the omnidirectional wheels corresponding to the specified target speed and target angular speed, and controls each of the motors.

2. A swivelable mobile body having four omnidirectional wheels arranged arbitrarily so that the thrust directions of at least two omnidirectional wheels are different, The four omnidirectional wheels are arranged on one end of each side of a rectangular shape so that the rotation surfaces thereof are aligned along the respective sides of the rectangular shape.

Images