Drive device

Abstract

To provide a drive device capable of initializing an accurate position of an object to be driven.SOLUTION: In a drive device, a first input stage encoder initializes the number of rotation of a first input stage gear based on a reference position of a drive target set by a setting unit and initializes a rotation angle of the first input stage gear based on the rotation angle of a first output stage gear measured by a first output stage encoder at the time of activation, and a second input stage encoder initializes the number of rotation of a second input stage gear based on the reference position of the drive target set by the setting unit and initializes the rotation angle of the second input stage gear based on the rotation angle of a second output stage gear measured by a second output stage encoder at the time of activation.SELECTED DRAWING: Figure 4

Description

Technical Field

[0001] The present disclosure relates to a drive device.

Background Art

[0002] Generally, in order to achieve high-precision operation by a driven object driven by a motor or the like, it is required to accurately identify the position of the driven object. For example, Patent Document 1 discloses a device that detects by electrical or optical means that a diaphragm body movable within a predetermined range along one direction is disposed at a reference position.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] By the way, in a machine such as a work robot, a mechanism may be provided that rotates a set of input stage gears using a set of motors and slides a driven object along a reference axis by rotating a set of output stage gears meshed with the set of input stage gears. In such a mechanism, at the time of startup, the rotation speed of any one of the gears measured by an incremental encoder that measures the rotation speed and rotation angle of each gear becomes indefinite, so that it is difficult to identify the exact position of the driven object, that is, to initialize the exact position of the driven object.

[0005] The present disclosure has been made in view of the above background, and an object thereof is to provide a drive device capable of initializing the exact position of a driven object.

Means for Solving the Problems

[0006] The drive device according to the present disclosure includes a first input stage gear, a second input stage gear disposed opposite to the first input stage gear, a first actuator that rotates the first input stage gear, a second actuator that rotates the second input stage gear, a first input stage encoder that is an incremental encoder for measuring the rotation angle and rotation speed of the first input stage gear, a second input stage encoder that is an incremental encoder for measuring the rotation angle and rotation speed of the second input stage gear, a first output stage gear that is directly or indirectly meshed with the first input stage gear, a second output stage gear that is directly or indirectly meshed with the second input stage gear, a first output stage encoder that is an absolute encoder for measuring the rotation angle of the first output stage gear, a second output stage encoder that is an absolute encoder for measuring the rotation angle of the second output stage gear, a drive object configured to be slidable and rotatable by the rotation of the first output stage gear and the rotation of the second output stage gear, and a detection object installed on one of the housing to which the drive object is attached, a sensor installed on the other of the drive object and the housing and capable of detecting the detection object, and a setting unit configured to set a reference position of the drive object in the housing according to a detection state of the detection object by the sensor. The drive device is characterized in that the first input stage encoder initializes the rotation speed of the first input stage gear based on the reference position of the drive object set by the setting unit at startup, and initializes the rotation angle of the first input stage gear based on the rotation angle of the first output stage gear measured by the first output stage encoder. The second input stage encoder initializes the rotation speed of the second input stage gear based on the reference position of the drive object set by the setting unit at startup, and initializes the rotation angle of the second input stage gear based on the rotation angle of the second output stage gear measured by the second output stage encoder. This drive device can perform accurate initialization of the position of the drive object even when the rotation speed of the gear measured by the incremental encoder becomes indefinite at startup.

Effects of the Invention

[0007] According to the present disclosure, it is possible to provide a driving device capable of initializing the exact position of an object to be driven.

Brief Description of the Drawings

[0008]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Modes for Carrying Out the Invention

[0009] Hereinafter, the present invention will be described through embodiments of the invention, but the invention according to the claims is not limited to the following embodiments. Also, not all of the configurations described in the embodiments are necessarily essential as means for solving the problems. For clarity of explanation, the following description and drawings have been appropriately omitted and simplified. In each drawing, the same elements are denoted by the same reference numerals, and duplicate explanations are omitted as necessary.

[0010] <Embodiment 1> FIG. 1 is a schematic perspective view showing the appearance of the transport robot according to Embodiment 1. FIGS. 2 and 3 are schematic perspective views showing a part of the transport robot according to Embodiment 1. The transport robot according to the present embodiment is an autonomous mobile robot capable of automatically placing a tray arranged on a shelf or the like installed at a starting point on a top plate, transporting it to a destination, and transferring it to a shelf or the like installed at the destination.

[0011] The transport robot 100 according to this embodiment includes at least a housing 101, wheels 102, a top plate 103, a storage unit 104, and a calibration device described later. Further, the transport robot 100 includes, for each drive object, a motor (actuator) that drives the drive object and an encoder that measures angle information of the motor.

[0012] The housing 101 supports the top plate 103 and the storage unit 104, and stores a battery, a motor that rotates the wheels 102, a control device that controls the operation of the transport robot 100, and the like.

[0013] The top plate 103 is supported by the housing 101 via a lifting shaft 107 whose axial direction is the vertical direction (z-axis direction). Here, the top plate 103 is configured to be slidable along the vertical direction by the lifting shaft 107 extending and contracting along the vertical direction. That is, the top plate 103 is configured to be liftable. The transport robot 100 is provided with a first motor and a first encoder for the vertical expansion and contraction process of the lifting shaft 107. The first motor drives the lifting shaft 107 to expand and contract in the vertical direction. The first encoder measures angle information and the like of the first motor.

[0014] Further, the top plate 103 is configured to be rotatable along the horizontal plane (xy plane) with the lifting shaft 107 as the rotation axis. The transport robot 100 is provided with a second motor and a second encoder for the rotation process of the lifting shaft 107. The second motor drives the lifting shaft 107 to rotate. The second encoder measures angle information and the like of the second motor.

[0015] Furthermore, the top plate 103 is configured to be slidable along the horizontal direction by a linear motion shaft 110 for sliding the top plate 103 moving along the horizontal direction. The transport robot 100 is provided with a third motor and a third encoder for the horizontal movement process of the linear motion shaft 110. The third motor drives the linear motion shaft 110 to move in the horizontal direction. The third encoder measures angle information and the like of the third motor.

[0016] The top plate 103 has a rectangular planar shape and is formed to be able to place conveyed objects such as trays. An entrance / exit of the hook 108 is provided on one of the four side surfaces of the top plate 103. The hook 108 is configured to be able to protrude in a direction perpendicular to the side surface with the entrance / exit from this entrance / exit. The transfer robot 100 hooks the conveyed object on the hook 108 and moves the linear motion shaft 109 with the hook 108 attached to its tip in the horizontal direction, thereby moving the conveyed object hooked on the hook 108 from the top plate 103 to the storage unit 104 or an external shelf, or moving it from the storage unit 104 or an external shelf to the top plate 103. Further, the transfer robot 100 can hook the hook 108 on the conveyed object or remove the hook 108 from the conveyed object by rotating the hook 108 with the linear motion shaft 109 as the rotation axis. Hereinafter, among the four sides of the top plate 103, the side with the entrance / exit of the hook 108 provided on the side surface is referred to as the transfer port of the conveyed object on the top plate 103.

[0017] For example, when the transfer of the conveyed object is performed between the top plate 103 and an external shelf, first, the top plate 103 moves up and down according to the height of the external shelf. Then, by rotating the top plate 103, the transfer port of the top plate 103 is directed toward the external shelf. Then, by sliding the top plate 103 toward the external shelf side, the top plate 103 and the external shelf are connected. Then, the transfer of the conveyed object is performed between the top plate 103 and the external shelf using the hook 108.

[0018] Also, when the transfer of the conveyed object is performed between the top plate 103 and the storage unit 104, first, the top plate 103 moves up and down according to the height of the storage unit 104. Then, by rotating the top plate 103, the transfer port of the top plate 103 is directed toward the storage unit 104. Then, by sliding the top plate 103 toward the storage unit 104 side, the top plate 103 and the storage unit 104 are connected. Then, the transfer of the conveyed object is performed between the top plate 103 and the storage unit 104 using the hook 108.

[0019] FIG. 4 is a schematic plan view showing a part of the transfer robot 100. FIG. 4 shows a top plate 103, a hook 108, a linear motion shaft 109, and a calibration device 120. The calibration device 120 includes a detection object 121, a sensor 122, and a setting unit 123. Further, FIG. 4 shows, as a driving device for driving the linear motion shaft 109 which is a driving object, a motor (actuator) 131, an input stage gear 132, an output stage gear 133, an input stage encoder 134, an output stage encoder 135, a motor (actuator) 141, an input stage gear 142, an output stage gear 143, an input stage encoder 144, and an output stage encoder 145. This driving device also includes the calibration device 120.

[0020] The motor 131 rotates the input stage gear 132. The output stage gear 133 is directly or indirectly meshed with the input stage gear 132 via an intermediate gear and rotates in conjunction with the input stage gear 132. The input stage encoder 134 is an incremental encoder and measures the rotation angle and rotation speed of the input stage gear 132. The output stage encoder 135 is an absolute encoder and measures the rotation angle of the output stage gear 133. Here, the rotation angle of the gear refers to the angle of the gear in the range of 0 to 2π (so-called single-turn information). Also, the rotation speed of the gear refers to the cumulative rotation speed of the gear (so-called multi-rotation information).

[0021] The motor 141 rotates the input stage gear 142 disposed opposite to the input stage gear 132. The output stage gear 143 is directly or indirectly meshed with the input stage gear 142 via an intermediate gear and rotates in conjunction with the input stage gear 142. The input stage encoder 144 is an incremental encoder and measures the rotation angle and rotation speed of the input stage gear 142. The output stage encoder 145 is an absolute encoder and measures the rotation angle of the output stage gear 143.

[0022] The linear motion shaft 109 slides horizontally or rotates about the linear motion shaft 109 as the rotation axis according to the rotation of each of the output stage gears 133 and 143. For example, when the output stage gears 133 and 143 rotate in the same direction, the linear motion shaft 109 slides horizontally along the linear motion shaft 109, and when the output stage gears 133 and 143 rotate in different directions, the linear motion shaft 109 rotates about the linear motion shaft 109 as the rotation axis. The horizontal movement amount of the linear motion shaft 109 can be calculated from the rotation angle and rotation speed of the input stage gears 132 and 142, the rotation angle of the output stage gears 133 and 143, and the like.

[0023] By the way, when the power supply of the transfer robot 100 is shut down, the rotation angle and rotation speed of the input stage gears 132 and 142 measured by the input stage encoders 134 and 144 of the incremental encoder become indefinite. Here, the rotation angle of the input stage gears 132 and 142 can be calculated from the rotation angle of the output stage gears 133 and 143 measured by the output stage encoders 135 and 145. Therefore, at power-on (start-up), the input stage encoders 134 and 144 calculate the rotation angle of the input stage gears 132 and 142 from the rotation angle of the output stage gears 133 and 143 measured by the output stage encoders 135 and 145 and use it as the initial value. In other words, at power-on (start-up), the input stage encoders 134 and 144 initialize the rotation angle of the input stage gears 132 and 142 based on the rotation angle of the output stage gears 133 and 143 measured by the output stage encoders 135 and 145.

[0024] On the other hand, the rotation speed of the input stage gears 132 and 142 cannot be calculated from the measurement results of the output stage encoders 135 and 145. Therefore, at power-on, the input stage encoders 134 and 144 use the calibration result of the linear motion shaft 109 by the calibration device 120 to initialize the rotation speed of the input stage gears 132 and 142. In other words, at power-on, the input stage encoders 134 and 144 initialize the rotation speed of the input stage gears 132 and 142 at the reference position of the linear motion shaft 109 set by the calibration device 120 to "0".

[0025] FIG. 5 is a schematic plan view for explaining the operation of the calibration device 120. The object to be detected 121 has, for example, a specific shape, pattern, or color, and is attached to the rear end of the linear motion axis 109. The sensor 122 is, for example, a photo-reflector, and is attached to the top plate 103 (housing side). The sensor 122 is configured to be able to detect the object to be detected 121 located within the detection range A1. Note that the attachment positions of the sensor 122 and the object to be detected 121 may be reversed.

[0026] For example, in the calibration device 120, the setting unit 123 uses the motors 131, 141 to slide the linear motion axis 109, which is the calibration target, in the direction of housing the hook 108 into the top plate 103 (minus direction of the y-axis) at a speed v1. Then, the setting unit 123 sets the position of the linear motion axis 109 at the timing when the transition from non-detection to detection of the object to be detected 121 by the sensor 122 is detected as the reference position. Note that the setting unit 123 may slide the linear motion axis 109 in the reverse direction (plus direction of the y-axis) and set the position of the linear motion axis 109 at the timing when the transition from detection to non-detection of the object to be detected 121 by the sensor 122 is detected as the reference position.

[0027] Alternatively, if the detection timing of the transition from non-detection to detection of the detection target 121 by the sensor 122 is delayed and the detection target 121 enters inside the detection range A1 of the sensor 122, the setting unit 123 may slide the linear motion axis 109 in the reverse direction (the positive direction of the y-axis) at a speed v2 slower than the speed v1, and set the position of the linear motion axis 109 at the timing when the transition from detection to non-detection of the detection target 121 by the sensor 122 is detected as the reference position. Here, since the speed v2 is slower than the speed v1, the deviation in the detection timing of the transition from detection to non-detection of the detection target 121 by the sensor 122 is small. Therefore, the calibration device 120 can accurately and promptly set the reference position in the horizontal direction of the linear motion axis 109 to be calibrated. That is, the calibration device 120 can accurately and promptly perform the calibration in the horizontal direction of the linear motion axis 109. The input stage encoders 134 and 144 initialize the number of rotations of the input stage gears 132 and 142 to "0" at the reference position of the linear motion axis 109 set by the calibration device 120 as described above when the power is turned on.

[0028] As described above, in the transfer robot 100 according to the present disclosure, the drive device can initialize the accurate position of the drive object even when the number of rotations of the gear measured by the incremental encoder becomes indefinite at startup.

[0029] The present invention is not limited to the above-described embodiments, and can be appropriately modified without departing from the spirit. For example, the drive device and its calibration method (initialization method) applied to the transfer robot 100 according to the present disclosure can be applied to any device or system other than the transfer robot 100.

[0030] Furthermore, the present disclosure can be realized by causing a CPU (Central Processing Unit) to execute a computer program for part or all of the control processing in the drive device.

[0031] The above-described program includes a set of instructions (or software code) for causing a computer to perform one or more functions described in the embodiments when loaded into the computer. The program may be stored in a non-transitory computer-readable medium or a tangible storage medium. By way of example and not limitation, the computer-readable medium or the tangible storage medium includes RAM (Random-Access Memory), ROM (Read-Only Memory), flash memory, SSD (Solid-State Drive) or other memory technologies, CD-ROM, DVD (Digital Versatile Disc), Blu-ray (registered trademark) disc or other optical disc storage, magnetic cassette, magnetic tape, magnetic disc storage or other magnetic storage devices. The program may be transmitted on a transitory computer-readable medium or a communication medium. By way of example and not limitation, the transitory computer-readable medium or the communication medium includes electrical, optical, acoustic, or other forms of propagated signals.

Explanation of Reference Numerals

[0032] 100 Carrier robot, 101 Housing, 102 Wheels, 103 Top plate, 104 Storage section, 107 Lifting shaft, 108 Hook, 109 Linear motion shaft, 110 Linear motion shaft, 120 Calibration device, 121 Detection object, 122 Sensor (photo-reflector), 123 Setting section, 131 Motor (actuator), 132 Input stage gear, 133 Output stage gear, 134 Input stage encoder, 135 Output stage encoder, 141 Motor (actuator), 142 Input stage gear, 143 Output stage gear, 144 Input stage encoder, 145 Output stage encoder

Claims

【Claim 1】 a first input stage gear; a second input stage gear disposed opposite to the first input stage gear; a first actuator for rotating the first input stage gear; a second actuator for rotating the second input stage gear; a first input stage encoder which is an incremental encoder for measuring the rotation angle and rotation speed of the first input stage gear; a second input stage encoder which is an incremental encoder for measuring the rotation angle and rotation speed of the second input stage gear; a first output stage gear directly or indirectly meshed with the first input stage gear; a second output stage gear directly or indirectly meshed with the second input stage gear; a first output stage encoder which is an absolute encoder for measuring the rotation angle of the first output stage gear; a second output stage encoder which is an absolute encoder for measuring the rotation angle of the second output stage gear; a detection object installed on one of a driven object configured to be slidable and rotatable by the rotation of the first output stage gear and the rotation of the second output stage gear, and a housing to which the driven object is attached; a sensor installed on the other of the driven object and the housing and capable of detecting the detection object; a setting unit for setting a reference position of the driven object in the housing according to a detection state of the detection object by the sensor; A drive device comprising: At startup, the first input stage encoder initializes the rotation speed of the first input stage gear based on the reference position of the driven object set by the setting unit, and initializes the rotation angle of the first input stage gear based on the rotation angle of the first output stage gear measured by the first output stage encoder. At startup, the second input stage encoder initializes the rotation speed of the second input stage gear based on the reference position of the driven object set by the setting unit, and initializes the rotation angle of the second input stage gear based on the rotation angle of the second output stage gear measured by the second output stage encoder. Drive device.

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