Robotic system

Abstract

A robot system (1) comprises: a robot (20) which operates on a workpiece (W); a camera device (30) which moves relative to the workpiece and photographs the workpiece; and a control device (40) which controls the camera device and the robot, wherein the control device and the camera device respectively have clocks (41) and (31) whose zero points are consistent or offset by a known amount, and the control device causes the shooting instruction to be sent to the camera device to include a predetermined waiting time (Td) from the sending time (To) of the shooting instruction to the shooting time (Tc), or a required time (T) obtained by subtracting the difference time (Δt) between the receiving time (Ti) of the shooting instruction and the sending time from the waiting time, and after the required time has passed from the receiving time, the camera device sends image information obtained by photographing the workpiece to the control device, and the control device controls the robot based on the position information of the robot obtained after the waiting time has passed from the sending time and the image information sent from the camera device.

Description

Technical Field

[0001] The present disclosure relates to robotic systems. Background Art

[0002] A robot control device has been disclosed that controls a robot based on image information of a workpiece acquired by a CCD camera fixed to the front end of the robot arm and position information of the robot when the workpiece is imaged (see, for example, Patent Document 1).

[0003] In this robot control device, when image information acquired by the CCD camera is taken into the control device, the control device acquires position information of the robot.

[0004] Prior art literature

[0005] Patent Literature

[0006] Patent Document 1: Japanese Patent Application Laid-Open No. 2001-212777 Summary of the Invention

[0007] Problems to be solved by the invention

[0008] In reality, there is a time difference between the time the camera captures the image and when the image information is received by the control device due to image information communication delay. Therefore, when the robot is moving while capturing the image, the robot's position information at the time the image information is acquired will differ from the position information at the time the control device acquires the image.

[0009] Therefore, it is desired to accurately acquire the position information of the robot at the time of camera imaging even if a communication delay occurs.

[0010] Solutions for solving problems

[0011] One aspect of the present disclosure is a robot system comprising: a robot that performs work on a workpiece; an imaging device that moves relative to the workpiece and images the workpiece; and a control device that controls the imaging device and the robot, the control device and the imaging device each having a clock with a consistent zero point or a clock with a known offset, the control device causing a shooting instruction to be sent to the imaging device to include a prescribed standby time from the time the shooting instruction is sent to the shooting time, or a required time obtained by subtracting the difference between the time the shooting instruction is received and the time the shooting instruction is sent from the standby time, the imaging device images the workpiece at a time when the required time has elapsed from the time of reception, and transmits image information obtained by the shooting to the control device, the control device obtaining position information of the robot at a time when the standby time has elapsed from the time of sending, and controlling the robot based on the position information and the image information sent from the imaging device. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] Figure 1 This is a diagram showing the overall configuration of a robot system according to one embodiment of the present invention.

[0013] Figure 2 It shows Figure 1 A block diagram of a camera device and a control device included in a robot system.

[0014] Figure 3 This is an example Figure 1 A diagram showing the data transmission timing between the imaging device and the control device of the robot system.

[0015] Figure 4 This is an example Figure 1 A diagram showing data transmission timing between an imaging device and a control device included in a first variation of the robot system.

[0016] Figure 5 This is an example Figure 1 A diagram showing data transmission timing between an imaging device and a control device included in a second variation of the robot system. DETAILED DESCRIPTION

[0017] Hereinafter, a robot system 1 according to an embodiment of the present disclosure will be described with reference to the drawings.

[0018] like Figure 1 As shown in FIG. 1 , the robot system 1 of this embodiment includes: a robot 20 that operates on a workpiece W; an imaging device 30 fixed to the front end of an arm 21 of the robot 20; and a control device 40. Figure 1In the drawing, reference numeral 10 denotes a conveying device such as a conveyor for conveying a workpiece W.

[0019] exist Figure 1 In the illustrated example, the robot 20 is a vertical six-axis articulated robot and includes a hand 22 capable of gripping a workpiece W at the distal end of a wrist disposed at the distal end of an arm 21 .

[0020] The control device 40 includes one or more processors (not shown) including hardware, and controls the robot 20 and the imaging device 30 according to a plurality of commands included in the operating program by executing a pre-taught operating program.

[0021] like Figure 2 as well as Figure 3 As shown, the control device 40 includes a first timing unit (clock) 41 that measures time in the control device 40 , and a first communication unit 42 that sends a shooting instruction to the imaging device 30 and receives image information from the imaging device 30 .

[0022] Furthermore, the control device 40 includes a first storage unit 43 that stores angle information (position information) of each joint axis detected by an encoder (not shown) of the robot 20 .

[0023] In addition, the control device 40 has an image processing unit 44, which processes the image information received from the camera device 30 to extract the workpiece W in the image and calculate the position of the workpiece W; and a driving unit 45, which controls the robot 20 based on the calculated position of the workpiece W and the angle information stored in the first storage unit 43.

[0024] like Figure 2 as well as Figure 3 As shown, the imaging device 30 includes a second timing unit (clock) 31 for timing the time in the imaging device 30, and a second communication unit 32. The second communication unit 32 receives an imaging command sent from the control device 40 and transmits image information of the workpiece W acquired by imaging to the control device 40.

[0025] The imaging device 30 also includes a camera 33 that captures images of the workpiece W in response to an imaging command from the control device 40, and a second storage unit 34 that stores a preset differential time Δt required for transmitting the imaging command. The differential time Δt is determined based on the results of previously experimentally measuring and evaluating the differential time Δt actually generated when transmitting the imaging command.

[0026] The imaging device 30 also includes a calculation unit 35 that subtracts the difference time Δt stored in the second storage unit 34 from the predetermined waiting time Td included in the imaging command from the control device 40 .

[0027] The first timer unit 41 of the control device 40 and the second timer unit 31 of the imaging device 30 are synchronized by aligning their zero points.

[0028] The synchronization between the first timekeeping unit 41 and the second timekeeping unit 31 is performed by, for example, the PTP (Peripheral Time Protocol) standardized by IEEE1588.

[0029] In this embodiment, the control device 40 includes a predetermined waiting time Td from the time To at which the shooting command is sent to the shooting time Tc in the shooting command and transmits it to the imaging device 30. The shooting command sent from the control device 40 is received by the second communication unit 32. The calculation unit 35 calculates the required time T from the time Ti at which the shooting command is received to the shooting time Tc using the following formula based on the waiting time Td included in the received shooting command and the differential time Δt stored in the second storage unit 34.

[0030] T=Td-Δt

[0031] Then, the imaging device 30 images the workpiece W at a time when a required time T has elapsed from the time Ti at which the second communication unit 32 receives the imaging command from the control device 40 .

[0032] Image information of the workpiece W obtained by imaging is transmitted to the control device 40 via the second communication unit 32 .

[0033] Next, the operation of the robot system 1 according to the present embodiment configured as described above will be described.

[0034] First, the second timer 31 in the camera 30 is synchronized with the first timer 41 in the control device 40. This causes the zero point of the second timer 31 in the camera 30 to coincide with the zero point of the first timer 41 in the control device 40.

[0035] That is, the imaging device 30 and the control device 40 are controlled based on the synchronized time axis.

[0036] Then, if Figure 2 as well as Figure 3 As shown, the first communication unit 42 of the control device 40 transmits a photographing instruction for executing photographing of the workpiece W to the imaging device 30 at the transmission time To.

[0037] Furthermore, the control device 40 stores the angle information of each joint axis detected by the encoder of the robot 20 in the first storage unit 43 at time Tc when the waiting time Td has elapsed from the transmission time To of the first timer unit 41 .

[0038] On the other hand, in the imaging device 30 , the imaging command transmitted from the control device 40 is received by the second communication unit 32 at the time Ti that is delayed by the differential time Δt from the transmission time To.

[0039] Furthermore, the calculation unit 35 calculates the required time T by subtracting the difference time Δt stored in advance in the second storage unit 34 from the waiting time Td included in the imaging command.

[0040] Next, the second timer 31 causes the camera 33 to capture the workpiece W at time Tc when the required time T has elapsed from time Ti of reception of the imaging command.

[0041] Thereafter, the image information of the workpiece W acquired by the camera 33 is transmitted to the control device 40 via the second communication unit 32 .

[0042] Therefore, the reception time Ti of the shooting command is delayed by the differential time Δt from the transmission time To. After receiving the shooting command, the imaging device 30 waits for the required time T shorter than the waiting time Td by the differential time Δt to elapse before executing shooting.

[0043] That is, even if a time difference Δt occurs between the transmission and reception of the imaging command, the imaging device 30 accurately captures the workpiece W at the time Tc after the waiting time Td has elapsed from the transmission time To of the imaging command.

[0044] When the image information of the workpiece W is transmitted to the control device 40 , the image processing unit 44 processes the image information of the workpiece W, extracts the workpiece W in the image, and detects the position and posture of the workpiece W.

[0045] The drive unit 45 calculates the angles of the joint axes of the robot 20 for gripping the workpiece W with the hand 22 based on the position information of the robot 20 at time Tc and the information of the workpiece W imaged at the same time.

[0046] This allows the robot 20 to perform accurate work on the workpiece W.

[0047] In addition, in this embodiment, the control device 40 includes the waiting time Td in the shooting instruction, but instead, the control device 40 may include the required time T obtained by subtracting the difference Δt between the reception time Ti and the sending time To of the shooting instruction from the waiting time Td in the shooting instruction.

[0048] In this case, the difference time Δt is stored together with the waiting time Td in the first storage unit 43 of the control device 40. Furthermore, the control device 40 subtracts the difference time Δt from the waiting time Td to calculate the required time T. The calculated required time T is then included in a shooting command and transmitted to the imaging device 30.

[0049] In the imaging device 30 , imaging of the workpiece W is performed by the camera 33 at time Tc after the required time T included in the imaging command has elapsed from the time Ti at which the imaging command was received.

[0050] That is, in this case, the imaging device 30 does not need to calculate the required time T, and therefore the second storage unit 34 for storing the differential time Δt can be omitted, thereby simplifying the structure of the imaging device 30.

[0051] Furthermore, in this embodiment, the control device 40 includes only the waiting time Td in the shooting command transmitted to the imaging device 30. Alternatively, the transmitted shooting command may include the transmission time To in addition to the waiting time Td. In this case, the differential time Δt need not be pre-stored in the second storage unit 34.

[0052] like Figure 4 As shown, in the imaging device 30 , when the second communication unit 32 receives a shooting instruction including the waiting time Td and the transmission time To, the second timing unit 31 acquires the reception time Ti′ of the shooting instruction.

[0053] Next, the calculation unit 35 subtracts the transmission time To from the reception time Ti′ to calculate the actual differential time Δt′, thereby accurately calculating the imaging time Tc. This allows imaging of the workpiece W at the accurately calculated imaging time Tc, and accurately acquires the position information of the robot 20 at the imaging time Tc.

[0054] In addition, in this embodiment, Figure 5 As shown, the imaging device 30 may also transmit the actual imaging time Tc′ to the control device 40. Furthermore, the control device 40 may use the received actual imaging time Tc′ and the time Tc at which the position information of the robot 20 is acquired to correct the waiting time Td included in the next imaging command.

[0055] Specifically, upon receiving the actual imaging time Tc′ from the imaging device 30, the control device 40 calculates the offset time (difference) x between the received imaging time Tc′ and the time Tc at which the control device 40 acquired the position information of the robot 20. The control device 40 then calculates the standby time Td′ after correcting for the offset time x using the following formula.

[0056] Td′=Td+x

[0057] Here, Td′ is the corrected standby time.

[0058] Furthermore, the imaging device 30 subtracts the difference time Δt stored in the second storage unit 34 from the corrected standby time Td′ included in the imaging command. This allows the imaging device 30 to capture the workpiece W at the correct imaging time Tc′ after correcting the offset time x during the next imaging.

[0059] The standby time Td can be corrected using only the most recent capture time Tc' or by averaging multiple past capture times Tc'. The former correction method is effective when the actual differential time Δt' changes gradually, while the latter correction method is effective when the actual differential time Δt' varies from time to time.

[0060] In addition, in the present embodiment, the control device 40 may correct the required time T included in the next imaging command based on the actual imaging time Tc′ received from the imaging device 30 .

[0061] In this case, the control device 40 calculates the offset time x between the actual imaging time Tc′ received from the imaging device 30 and the time Tc at which the position information of the robot 20 was acquired. Next, the control device 40 calculates the differential time Δt′ after correcting the offset time x based on the offset time x and the differential time Δt stored in the first storage unit 43.

[0062] Thereafter, the control device 40 corrects the required time T by the offset time x by subtracting the corrected differential time Δt′ from the waiting time Td stored in the first storage unit 43 .

[0063] Thereby, in the next imaging, the workpiece W can be imaged at the correct imaging time Tc′ after the offset time x is corrected.

[0064] The required time T can be corrected using only the most recent capture time Tc' or by averaging multiple past capture times Tc'. The former correction method is effective when the actual differential time Δt' changes gradually, while the latter correction method is effective when the actual differential time Δt' varies from time to time.

[0065] In addition, as another embodiment of the present embodiment, the control device 40 may include the shooting time Tc in the shooting command sent to the imaging device 30 .

[0066] In this case, when the imaging device 30 receives an imaging instruction from the control device 40 via the second communication unit 32 , the camera 33 images the workpiece W at the imaging time Tc measured by the second timing unit 31 .

[0067] On the other hand, the control device 40 acquires the position information of the robot 20 at the time when the imaging time Tc is measured by the first timing unit 41 and stores it in the first storage unit 43 .

[0068] Thus, the imaging device 30 and the control device 40 perform imaging of the workpiece W and acquisition of position information of the robot 20 at the common imaging time Tc.

[0069] That is, there is an advantage that the imaging device 30 can capture the workpiece W and the control device 40 can acquire the position information of the robot 20 at the same time without being affected by the differential time Δt for transmitting the imaging command.

[0070] In the present embodiment, the zero points of the first timing section 41 and the second timing section 31 are aligned, but the zero points of the first timing section 41 and the second timing section 31 may be offset by a known amount.

[0071] In this case, the imaging device 30 may increase or decrease the waiting time Td or the required time T by a time corresponding to the shift from the time.

[0072] In addition, in this embodiment, a vertical six-axis articulated robot is exemplified, but the present invention is not limited thereto and may be any other type of robot such as a horizontal articulated robot or a parallel link robot.

[0073] Description of reference numerals:

[0074] 1 Robotic System

[0075] 20 Robot

[0076] 30 Camera

[0077] 31 Second timing unit (clock)

[0078] 40 Control Device

[0079] 41 First Timing Unit (Clock)

[0080] Δt differential time

[0081] T Time required

[0082] Tc shooting time

[0083] Td standby time

[0084] Ti receiving time

[0085] To Send Time

[0086] W workpiece

[0087] X offset time (differential).

Claims

1. A robot system, characterized in that: have: a robot, which performs operations on a workpiece; a camera device that moves relative to the workpiece and photographs the workpiece; and a control device for controlling the camera device and the robot, The control device and the camera device each have a clock with a consistent zero point or a clock with a known offset. The control device sends the shooting command to the camera device including a predetermined waiting time from the time the shooting command is sent to the shooting time, or a required time obtained by subtracting the difference between the time the shooting command is received and the time the shooting command is sent from the waiting time. The imaging device images the workpiece at a time when a time obtained by subtracting the differential time from the waiting time has elapsed since the reception time, or at a time when the required time has elapsed, and transmits image information obtained by the imaging to the control device. The control device acquires the position information of the robot at a time when the waiting time has elapsed from the transmission time, and controls the robot based on the position information and the image information transmitted from the imaging device.

2. The robot system according to claim 1, wherein: The camera device sends the shooting time corresponding to the image information to the control device, The control device corrects the waiting time or the required time included in the next imaging command based on a difference between the imaging time transmitted from the imaging device and a time when the waiting time has elapsed from the transmission time.

3. A robot system, characterized in that: have: a robot, which performs operations on a workpiece; a camera device that moves relative to the workpiece and photographs the workpiece; and a control device for controlling the camera device and the robot, The control device and the camera device each have a clock with a consistent zero point or a clock with a known offset. The control device transmits the shooting command to the imaging device so that the shooting command includes a predetermined waiting time from the time the shooting command is sent to the shooting time and the sending time is included in the shooting command. The imaging device images the workpiece at a time when the waiting time obtained by subtracting the difference between the sending time and the receiving time of the imaging instruction including the sending time has passed since the receiving time, and transmits image information obtained by the imaging to the control device. The control device acquires the position information of the robot at a time when the waiting time has elapsed from the transmission time, and controls the robot based on the position information and the image information transmitted from the imaging device.

4. A robot system, characterized in that: have: a robot, which performs operations on a workpiece; a camera device that moves relative to the workpiece and photographs the workpiece; and a control device for controlling the camera device and the robot, The control device and the camera device each have a clock with a consistent zero point or a clock with a known offset. The control device notifies the imaging device of the shooting time, The imaging device images the workpiece at the imaging timing notified from the control device, and transmits image information acquired by the imaging to the control device. The control device stores the position information of the robot at the imaging time, and controls the robot based on the image information transmitted from the imaging device and the stored position information.

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