Robotic system, horizontal multi-joint robot and control method thereof

Abstract

The present application provides a control device, a horizontal multi-joint robot, and a robot system, which reduce vibration of a shaft in an axial direction at a front end portion of the shaft. A control device controls a horizontal multi-joint robot including a base, a first arm provided to the base and rotating about a first axis with respect to the base, a second arm provided to the first arm and rotating about a second axis with respect to the first arm, a shaft provided to the second arm and linearly moving in a direction of a third axis, a motor driving linear movement of the shaft, a position detector detecting a position of the motor, and an inertial sensor provided to the second arm. The control device includes a control unit that feeds back an output of the inertial sensor to control of the motor to drive the motor.

Description

[0001] This application is a divisional application of patent application filed on July 19, 2019, with application number 201910657380.9 and entitled "Control Device, Horizontal Multi-Joint Robot and Robot System", the entire contents of which are incorporated herein by reference. Technical Field

[0002] This invention relates to control devices, horizontal multi-joint robots, and robot systems. Background Technology

[0003] A control device has been proposed that uses inertial sensors mounted on a horizontal articulated robot to reduce vibration, allowing for control of its position and orientation in the horizontal plane as well as its position in the vertical direction.

[0004] For example, Patent Document 1 describes a horizontal multi-joint robot comprising: a base; a first arm configured to rotate relative to the base about a first axis as a rotation center; a second arm configured to rotate relative to the first arm about a second axis as a rotation center; an axis for linear movement relative to the second arm; and an inertial sensor disposed on the second arm. The document also describes a technique for reducing vibration in the rotation direction of the arm by feeding back the output of the inertial sensor to a motor that drives the first arm.

[0005] Patent Document 1: Japanese Patent Application Publication No. 2012-171052

[0006] However, the technology described in Patent Document 1 does not take into account reducing the axial vibration of the shaft at the front end of the shaft. In this case, since it takes time for the vibration to decay naturally, there are problems such as reduced workability due to waiting for the vibration to converge and reduced work quality due to performing work before the vibration converges. Summary of the Invention

[0007] To address the aforementioned technical problems, one aspect of the present invention is a control device for controlling a horizontal multi-joint robot, the horizontal multi-joint robot comprising: a base; a first arm disposed on the base and rotating relative to the base about a first axis; a second arm disposed on the first arm and rotating relative to the first arm about a second axis; an axis disposed on the second arm and linearly moving in the direction of a third axis; a motor driving the linear movement of the axis; a position detector detecting the position of the motor; and an inertial sensor disposed on the second arm. The control device includes a control unit that feeds back the output of the inertial sensor to control the motor to drive the motor.

[0008] In addition, another aspect of the present invention is a horizontal multi-joint robot controlled by the aforementioned control device.

[0009] Another aspect of the present invention is a robot system comprising the aforementioned control device and a horizontal multi-joint robot controlled by the aforementioned control device. Attached Figure Description

[0010] Figure 1 This is a diagram showing the overall structure of the robot system according to the first embodiment.

[0011] Figure 2 This is a diagram showing the structure of the robot according to the first embodiment.

[0012] Figure 3 This is a control block diagram according to the first embodiment, in which inertial sensor information is processed in the inertial sensor information processing unit A and then fed back to the current command.

[0013] Figure 4 This is a control block diagram according to the first embodiment, in which inertial sensor information is processed in the inertial sensor information processing unit B and then fed back to the current command.

[0014] Figure 5 This is a control block diagram of proportional control according to the second embodiment, in which inertial sensor information is processed in the inertial sensor information processing unit A and then fed back to the speed control unit.

[0015] Figure 6 This is a control block diagram of proportional control according to the second embodiment, in which inertial sensor information is processed in the inertial sensor information processing unit B and then fed back to the speed control unit.

[0016] Figure 7 This is a control block diagram according to the third embodiment, in which inertial sensor information is processed in the inertial sensor information processing unit B and then fed back to the speed command.

[0017] Figure 8 This is a graph showing the vibration reduction effect of the control device according to the first embodiment.

[0018] Figure 9 This is a graph showing the relationship between the angle θ2 of the second arm and the coefficient Rgj according to the fourth embodiment.

[0019] Figure 10 This is a graph showing the relationship between the mass W of the workpiece and the coefficient Rgw according to the fifth embodiment.

[0020] Figure 11 This is a graph showing the relationship between the axis position Z and the coefficient Rgz according to the sixth embodiment.

[0021] Figure 12 This is a graph showing the relationship between the angle θ2 of the second arm and the coefficient Rfj according to the seventh embodiment.

[0022] Figure 13 This is a graph showing the relationship between the mass W of the workpiece and the coefficient Rfw according to the eighth embodiment.

[0023] Figure 14 This is a graph showing the relationship between the axis position Z and the coefficient Rfz according to the ninth embodiment.

[0024] Figure 15 This is a block diagram showing the state of the controller connected to the robot, computer, and teach pendant.

[0025] Symbol Explanation

[0026] 1. 1A…Robot system; 2…Robot; 3…Control device; 3A…Control unit; 11…Inertial sensor; 21…Base; 22…Arm; 23…First arm; 24…Second arm; 31…Axis; 32…Axis support; 33…Gripper mounting flange; 41…Gripper; 42…Workpiece; 51…First motor; 52…Second motor; 53…Third motor; 54…Fourth motor; 61…First position detector; 62…Second position detector; 63…Third position detector; 64…Fourth position detector; 71…First reducer; 72…Second reducer; 83…First synchronous belt; 84…Second synchronous belt; 93…Ball screw nut; 94…Splined outer cylinder; 100…Control block diagram; 101…Position 102… Position control unit; 103… Speed ​​control unit; 104… Current control unit; 105… Inertial sensor information processing unit A; 106… Inertial sensor information processing unit B; 111… LPF (low-pass filter); 112… DC removal unit; 113… BEF (band-stop filter); 114… HPF (high-pass filter); 121… LPF cutoff frequency adjustment unit; 122… Kgp adjustment unit; A1… First rotation axis; A2… Second rotation axis; A3… Third linear movement axis; A4… Fourth rotation axis; As… Angular velocity detection axis; Vs… Angular velocity; J1… First joint; J2… Second joint; θ1… First arm angle; θ2… Second arm angle; Z… Linear axis Movement position; U…axis rotation angle; D…displacement; S…direction of shaft support displacement; Kvp…proportional gain of velocity loop; Kvi…integral gain of velocity loop; Kgp…angular velocity feedback gain; Flpf…LPF cutoff frequency; s…differential operator; 1 / s…integral operator; Rgj…coefficient; Kgj…slope of Kgp second arm angle correction coefficient; Rgjmin…lower limit of Kgp second arm angle correction coefficient; Rgw…coefficient; Kgw1…slope of first Kgp workpiece mass correction coefficient; Kgw2…slope of second Kgp workpiece mass correction coefficient; Rgwmin…lower limit of Kgp workpiece mass correction coefficient; Rgwmax…upper limit of Kgp workpiece mass correction coefficient; Rgz…coefficient Kgz…Kgp linear movement position correction coefficient slope; Rgzmin…Kgp lower limit of linear movement position correction coefficient; Rfj…coefficient; Kfj…Flpf second arm angle correction coefficient slope; Rfjmin…Flpf second arm angle correction coefficient lower limit; Rfw…coefficient; Kfw1…first Flpf workpiece mass correction coefficient slope; Kfw2…second Flpf workpiece mass correction coefficient slope; Rfwmin…Flpf workpiece mass correction coefficient lower limit; Rfwmax…Flpf workpiece mass correction coefficient upper limit; Rfz…coefficient; Kfz…Flpf linear movement position correction coefficient slope; Rfzmin…Flpf linear movement position correction coefficient lower limit Detailed Implementation

[0027] The control device, horizontal multi-joint robot, and robot system of the present invention are described in detail based on the embodiments.

[0028] First Implementation Method

[0029] Figure 1 This is a diagram showing the overall structure of a robot system according to a first embodiment of the present invention. Figure 2 It is shown Figure 1 The diagram shows the structure of the robot. Figure 3 and Figure 4 yes Figure 1 The control block diagram shown illustrates how the control device feeds back inertial sensor information to current commands. Figure 8 It is shown Figure 1 The graph shows the effect of the control device on reducing vibration.

[0030] Figure 1 The robot system 1 shown includes a robot 2 and a control device 3 for controlling the robot 2. The robot system 1 has no limited applications; for example, it can be used for tasks such as the transfer, assembly, and inspection of electronic components.

[0031] Robot 2 is a horizontal multi-joint robot, comprising: a base 21; a first arm 23 configured to rotate relative to the base 21 about a first axis A1 as the rotation center; a second arm 24 configured to rotate relative to the first arm 23 about a second axis A2 as the rotation center; an axis 31 configured to move linearly along a third axis A3 relative to the second arm 24 and to rotate about a fourth axis A4 as the rotation center; and an inertial sensor 11 disposed on the second arm 24 and detecting the angular velocity of an angular velocity detection axis As, which is orthogonal to the plane formed by the second axis A2 and the third axis A3, as the rotation axis.

[0032] The base 21 is fixed to the mounting surface of the robot (not shown) by bolts or the like. The first arm 23 is rotatably driven by the first motor 51 via a reducer 71 and rotates around the first axis A1 as the rotation center. The first position detector 61 is disposed on the first motor 51 to detect the rotational position of the first arm 23.

[0033] The second arm 24 is rotatably driven by the second motor 52 via the reducer 72, and rotates around the second shaft A2 as the rotation center. The second position detector 62 is disposed on the second motor 52 to detect the rotational position of the second arm 24.

[0034] In this embodiment, shaft 31 is a ball screw spline shaft capable of linear movement and rotation. The outer rings of the ball screw nut 93 and the spline outer cylinder 94 are fixed to the second arm 24, forming shaft support 32. The ball screw nut 93 is driven to rotate by the third motor 53 via the first synchronous belt 83, and shaft 31 moves linearly along the direction of the third axis A3. A third position detector 63 is provided on the third motor 53 to detect the position of the linear movement of shaft 31.

[0035] The splined outer cylinder 94 is driven to rotate by the fourth motor 54 via the second synchronous belt 84, and the shaft 31 rotates around the fourth shaft A4 as the rotation center. The fourth position detector 64 is installed on the fourth motor 54 to detect the rotation angle of the shaft 31.

[0036] It should be noted that in this embodiment, a ball screw spline shaft with the third axis A3 and the fourth axis A4 configured on the same axis is used, but the mechanism can also have different configurations of the third axis A3 and the fourth axis A4. Furthermore, in this embodiment, shaft 31 is provided on the second arm 24, but shaft 31 can be provided on the arm 22 that includes the first arm 23 and the second arm 24. For example, if the arm 22 has a third arm provided on the second arm 24, shaft 31 can also be provided on the third arm.

[0037] The inertial sensor 11 is preferably disposed near the shaft support portion 32 of the second arm 24. However, in this embodiment, although the inertial sensor 11 is disposed on the second arm 24, it is sufficient that the inertial sensor 11 is disposed on the arm 22, which includes the first arm 23 and the second arm 24. For example, if the arm 22 has a third arm disposed on the second arm 24, the inertial sensor 11 may also be disposed on the third arm.

[0038] In this embodiment, the inertial sensor 11 is an angular velocity sensor, such as... Figure 2 As shown, it is configured to detect the angular velocity Vs of the angular velocity detection axis As, which is orthogonal to the plane containing the second axis A2 and the third axis A3.

[0039] The first arm 23 is cantilevered to the base 21 via the first joint J1, and the second arm 24 is cantilevered to the first arm 23 via the second joint J2. Therefore, as Figure 2 As shown, the shaft support portion 32 is displaced in the direction S, which includes a rotational component, due to the flexural deformation of the first joint J1 and the second joint J2, as well as the bending and torsional deformation of the first arm 23 and the second arm 24. Since the direction S has a rotational motion component, the inertial sensor 11 can detect the change in the displacement D of the shaft support portion 32 as the angular velocity Vs around the angular velocity detection axis As.

[0040] The control device 3 is electrically connected to the robot 2 and has a control unit 3A for controlling the robot 2. The robot 2 and the control device are electrically connected via a cable. Alternatively, part or all of the control device 3 may be built into the robot 2.

[0041] The control device 3 includes, for example, a controller 200, which includes: a computing unit consisting of a processor such as a microprocessor for processing operations for controlling the robot, a memory, and a storage device; a current amplifier for controlling the current of the drive motor; and an interface (I / F) for exchanging information with peripheral devices. Furthermore, a computer 201 serving as a human-machine interface and a teach pendant 202 for teaching the robot can be connected to the control device 3 (see [link to relevant documentation]). Figure 15 ).

[0042] It should be noted that the processor can also be composed of multiple processors. For example, the processor is not only present in the controller 200, but also in places different from the controller 200 (such as the computer 201, the teach pendant 202, the server used in cloud services provided via a network environment such as a LAN, etc.), and some or all of these processors can be used to implement the control device 3.

[0043] The control unit 3A of the control device 3 uses a processor to control the first motor 51, the second motor 52, the third motor 53, and the fourth motor 54 based on the position information of the first position detector 61, the second position detector 62, the third position detector 63, and the fourth position detector 64. Furthermore, the control unit 3A feeds back the angular velocity detected by the inertial sensor 11 to the control of the third motor 53 to reduce the vibration of the shaft support 32 in the vertical direction.

[0044] like Figure 2 As shown, the gripper mounting flange 33 is located at the lower end of the shaft 31. The gripper 41 is mounted on the gripper mounting flange 33. The gripper 41 grasps the workpiece 42, and the robot 2 performs conveying and assembly operations.

[0045] In this robot 2 with this structure, when the linear movement of axis 31 is accelerated / decelerated, or when an external force in the vertical direction is applied to axis 31, the axis support 32 vibrates in the vertical direction. The vibration of the aforementioned axis support 32 in the vertical direction has a long decay time.

[0046] Next, use Figure 3 and Figure 4 The control block diagram describes a control method that feeds back angular velocity information detected by inertial sensor 11 to a current command to reduce the vibration of shaft support 32. The angular velocity information filtering method includes using... Figure 3 Inertial sensor information processing unit A and Figure 4 The two types are: inertial sensor information processing unit B.

[0047] Figure 3 The control unit 3A includes: a position command generation unit 101, a position control unit 102, a speed control unit 103, a current control unit 104, and an inertial sensor information processing unit A105 for controlling the third motor 53 that moves the shaft 31 linearly. The inertial sensor information processing unit A105 filters the angular velocity information detected by the inertial sensor 11 and feeds it back to the current command.

[0048] The position command generation unit 101 generates a position command for the third motor 53 to move the shaft 31 linearly at control cycle intervals. The position control unit 102 generates a speed command in a manner that matches the position command generated by the position command generation unit 101 with the position of the third motor 53 detected by the third position detector 63. As an example, the speed control unit 103 is configured with proportional-integral control and generates a current command in a manner that matches the speed calculated based on the position detected by the third position detector with the speed command. The current control unit 104 controls the current in a manner that matches the current driving the third motor 53 with the current command.

[0049] The aforementioned inertial sensor information processing unit A105 includes an inertial sensor 11, an LPF (low-pass filter) 111, a DC removal unit 112, and a feedback gain Kgp multiplication processing unit.

[0050] In this embodiment, the inertial sensor 11 uses an angular velocity sensor to detect the vibration of the shaft support 32 in the vertical direction as a change in angular velocity.

[0051] The LPF111 removes high-frequency sensor noise, mechanical resonance, and detuning noise from the inertial sensor 11 from the angular velocity information detected by the inertial sensor 11. The cutoff frequency of the LPF111 is preferably set to 20Hz or higher and 200Hz or lower, so as not to reduce the quality of the low-frequency angular velocity information required to detect the vibration of the shaft support 32, while removing noise that causes control instability with a high attenuation rate.

[0052] The DC removal unit 112 removes the offset component included in the angular velocity information. In this embodiment, when the robot 2 stops, the offset component is detected as a moving average of the angular velocity information. The method of removing the offset component by using the moving average of the angular velocity information only removes the DC component included in the angular velocity information, without degrading the quality of the low-frequency angular velocity information used to reduce vibration. Therefore, compared to the method using an HPF (high-pass filter), it has a higher ability to reduce vertical vibration. Furthermore, since this process is relatively simple, it prevents an increase in the computational processing of the control unit 3A.

[0053] The aforementioned feedback gain Kgp multiplication processing unit filters the angular velocity information detected by the inertial sensor 11 and multiplies it by the angular velocity feedback gain Kgp to create the input for the current command.

[0054] If this control method is applied to the control of the third motor, the vibration of the shaft support 32 can be reduced.

[0055] Next, use as follows Figure 3 The control method described herein reduces the vibration of the shaft support 32. The reaction force of the linear movement of the shaft 31 acts on the shaft support 32. This invention utilizes this reaction force to reduce the vibration of the shaft support 32. Figure 2 As shown, the position Z of shaft 31, the angular velocity Vs detected by inertial sensor 11, and the direction of displacement D of shaft support 32 are defined. Figure 3 As shown, if the output of the inertial sensor information processing unit A105 is added to the current command, the acceleration of the shaft 31 is adjusted, causing the angular velocity of the shaft support 32 to decrease, thereby reducing the vibration of the shaft support 32. According to this control method, since the vibration of the shaft support 32 is reduced by adjusting the current command used to drive the shaft 31, the vibration of the shaft support 32 can be reduced while the shaft 31 is being moved.

[0056] According to such Figure 3 The control method described above feeds back angular velocity information to a current command, directly controlling the reaction force that suppresses vibration of the shaft support 32 in the vertical direction. Therefore, it exhibits high responsiveness and achieves high vibration suppression capability. Furthermore, it can reduce the vibration of the shaft support 32 while simultaneously moving the shaft 31. Moreover, the DC removal unit 112 removes only the DC component contained in the angular velocity information, preventing distortion in the low-frequency angular velocity information and thus eliminating positioning delays. Additionally, even if a DC component remains in the output of the DC removal unit 112, it is eliminated as interference through integral control by the speed control unit, preventing positional deviation of the shaft 31.

[0057] like Figure 8 The charts show the changes in vertical vibration when workpiece 42 is positioned with and without vibration reduction control A. According to control device 3, vibration is reduced in case A, compared to case B without control to reduce vertical vibration.

[0058] Next, the description is as follows: Figure 4 The control method using the inertial sensor information processing unit B as described herein. (And...) Figure 3 Similarly, as Figure 4The control unit 3A includes: a position command generation unit 101, a position control unit 102, a speed control unit 103, a current control unit 104, and a [missing information - likely a component name or component]. Figure 3 Different inertial sensor information processing units B106. The aforementioned inertial sensor information processing unit B106 includes: inertial sensor 11, LPF (low-pass filter) 111, BEF (band-stop filter) 113, HPF (high-pass filter) 114, and feedback gain Kgp multiplication processing unit.

[0059] In this embodiment, the inertial sensor 11 uses an angular velocity sensor to detect the vibration of the shaft support 32 in the vertical direction as a change in angular velocity and outputs angular velocity information.

[0060] The LPF111 removes sensor noise and mechanical resonance in the high-frequency region contained in the angular velocity information detected by the inertial sensor 11. The cutoff frequency of the LPF111 is preferably set to be above 20Hz and below 200Hz so as not to reduce the quality of the low-frequency angular velocity information required to detect the vibration of the shaft support 32 in the vertical direction, while removing sensor noise and mechanical resonance in the high-frequency region that cause unstable sound generation and control with a high attenuation rate.

[0061] The aforementioned BEF113 removes detuning noise from the output of the inertial sensor 11. Since the frequency of this detuning noise varies depending on the type of inertial sensor 11, the frequency band for removing detuning noise can be set according to the characteristics of the inertial sensor 11 used.

[0062] The HPF114 described above removes the offset component from the angular velocity information. When an appropriate cutoff frequency is set, the HPF can completely remove time-varying offsets. Preferably, the cutoff frequency of the HPF is set to 20Hz or lower.

[0063] The aforementioned feedback gain Kgp multiplication processing unit multiplies the angular velocity information (after removing low-frequency noise and DC components) detected by the inertial sensor 11 with the angular velocity feedback gain Kgp to create an input for the current command.

[0064] According to such Figure 4 The inertial sensor information processing unit B106 can use inertial sensors with different characteristics because BEF113 can be used to remove detuning noise based on the characteristics of inertial sensor 11. Furthermore, since HPF114 can completely remove the DC component contained in the angular velocity information, inertial sensor 11 with large offset variations can be used.

[0065] It should be noted that this embodiment shows an example of using an angular velocity sensor for the inertial sensor 11, but velocity information obtained by integrating the acceleration detected by the accelerometer can also be used.

[0066] The above describes an embodiment of the control device 3 in the robot system 1, characterized in that the control unit 3A feeds back the angular velocity information detected by the inertial sensor 11 to the current command in the control method. According to this embodiment, the following effects can be obtained.

[0067] The control device according to embodiments of the present invention controls a horizontal multi-joint robot, which includes: a base; a first arm disposed on the base and rotating about a first axis relative to the base; a second arm disposed on the first arm and rotating about a second axis relative to the first arm; an axis disposed on the second arm and moving linearly in the direction of a third axis; a motor driving the linear movement of the axis; a position detector detecting the position of the motor; and an inertial sensor disposed on the second arm. The control device includes a control unit that feeds back the output of the inertial sensor to the control of the motor to drive the motor.

[0068] In existing technologies, to prevent vertical vibration of the shaft support, it is necessary to increase the torque rigidity of the bearings in the support arm and improve the bending and torsional rigidity of the arm. In recent years, in order to improve the operational capabilities of robots, while seeking to increase the movable weight and operating speed of robots, the rigidity of the aforementioned mechanical components of robots has been increased. Consequently, there are problems such as the increasing size, weight, and cost of robots.

[0069] According to this embodiment, the vibration of the shaft support caused by the tilting of the support portions of the first and second arms of the horizontal articulated robot, as well as the bending and torsion of the first and second arms, can be reduced. Problems of existing horizontal articulated robots, such as reduced work capacity due to the time required for vibration at the lower end of the shaft to naturally decay after deformation of the arm support portions and the arm itself, damage to the work object caused by working before vibration convergence, decreased work quality due to uneven work positions, larger robot size, increased weight, and increased cost, can be solved.

[0070] According to this embodiment, the increased vibration of the shaft support caused by increasing the acceleration for linear movement of the axis to increase the robot speed, increasing the mass of the workpiece to expand the corresponding operation, and extending the length of the arm to expand the operation range can be suppressed, thereby improving the robot's working ability.

[0071] The control unit according to the embodiments of the present invention includes: a position command generation unit that generates position commands, a position control unit that generates speed commands based on the position commands, a speed control unit that generates current commands based on the speed commands, and a current control unit that controls the current driving the motor, and feeds back the output of the inertial sensor to the current commands.

[0072] According to this embodiment, since the output of the inertial sensor is fed back to the control current command of the motor that drives the shaft to move linearly, the response is fast and the vibration suppression capability is high. Even if the output of the inertial sensor contains offset, no positional deviation will occur, and the vibration of the shaft support in the vertical direction can be reduced.

[0073] The control unit according to the embodiments of the present invention removes noise contained in the output of the aforementioned inertial sensor by using a low-pass filter.

[0074] According to this embodiment, since mechanical resonance in the high-frequency region that causes instability in control and detuning noise contained in the output of the inertial sensor can be removed, it is not easily affected by individual differences and environmental changes, and the vibration of the shaft support in the vertical direction can be reduced.

[0075] The cutoff frequency of the low-pass filter involved in the embodiments of the present invention is above 20Hz and below 200Hz.

[0076] According to this embodiment, by removing noise that causes control instability without reducing the quality of information in the low-frequency region required to suppress vibration of the shaft support in the vertical direction, control with high suppression effect on vibration of the shaft support in the vertical direction can be achieved.

[0077] The control unit according to the embodiments of the present invention removes the detuning noise contained in the output of the inertial sensor by means of a band-stop filter.

[0078] According to this embodiment, by removing the detuning noise contained in the output of the inertial sensor that cannot be removed by a low-pass filter in accordance with the characteristics of the inertial sensor, it is possible to use inertial sensors with different detuning noise characteristics to suppress the vibration of the shaft support in the vertical direction.

[0079] The control unit according to the embodiments of the present invention calculates the offset component contained in the output of the inertial sensor by means of a moving average, and removes the offset component from the output of the inertial sensor.

[0080] According to this embodiment, the offset contained in the inertial sensor is obtained by a moving average that can be achieved with simple calculations, and the offset is eliminated. Therefore, the information in the low-frequency range of the output of the inertial sensor required to suppress vibration is not distorted, so the positioning is not delayed. The increase in the amount of computation of control processing can be suppressed, and the vibration of the shaft support in the vertical direction can be suppressed.

[0081] The control unit according to the embodiments of the present invention removes the offset component contained in the output of the inertial sensor by means of a high-pass filter.

[0082] According to this embodiment, since the offset contained in the inertial sensor can be completely removed by a high-pass filter, the vibration of the shaft support in the vertical direction can be suppressed by using an inertial sensor 11 with a large offset variation.

[0083] The inertial sensor involved in the embodiments of the present invention is an angular velocity sensor that detects the angular velocity around an angular velocity detection axis orthogonal to a plane including the second axis and the third axis.

[0084] According to this embodiment, by configuring the angular velocity sensor to detect the angular velocity around an angular velocity detection axis orthogonal to a plane including the second and third axes, the angular velocity equivalent to the vibration of the shaft support in the vertical direction can be detected with high sensitivity.

[0085] The horizontal multi-joint robot involved in the embodiments of the present invention is a horizontal multi-joint robot controlled by the above-described control device.

[0086] According to this embodiment, a horizontal multi-joint robot that suppresses vibration of the shaft support in the vertical direction can be realized.

[0087] The robot system according to the embodiments of the present invention includes the above-described control device and a horizontal multi-joint robot controlled by the above-described control device.

[0088] According to this embodiment, a robot system including a horizontal multi-joint robot and a control device for suppressing vibration of the shaft support in the vertical direction can be realized.

[0089] Second Implementation Method

[0090] Figure 5 and Figure 6 This is related to the second embodiment of the present invention. Figure 1 The control block diagram shown illustrates the proportional control mechanism that feeds back inertial sensor information to the speed control unit.

[0091] The robot system 1 described in this embodiment is identical to the robot system 1 of the first embodiment, except for the control method of the control unit 3A of the control device 3. It should be noted that in the following description, the robot system 1 of the second embodiment will be described focusing on the differences from the first embodiment; identical details will be omitted.

[0092] Next, use Figure 5 and Figure 6 The control block diagram describes a control method that reduces the vibration of the shaft support 32 by feeding back angular velocity information detected by the inertial sensor 11 to the velocity control unit via proportional control. The angular velocity information filtering method includes using... Figure 5 Inertial sensor information processing unit A and Figure 6 The two types are: inertial sensor information processing unit B.

[0093] Figure 5 The control unit 3A includes: a position command generation unit 101, a position control unit 102, a speed control unit 103, a current control unit 104, and an inertial sensor information processing unit A105 for controlling the third motor 53 that moves the shaft 31 linearly. The inertial sensor information processing unit A105 filters the angular velocity information detected by the inertial sensor 11 and feeds it back to the speed control unit for proportional control.

[0094] The aforementioned inertial sensor information processing unit A105 includes an inertial sensor 11, an LPF (low-pass filter) 111, a DC removal unit 112, and a feedback gain Kgp multiplication processing unit.

[0095] In this embodiment, the inertial sensor 11 uses an angular velocity sensor to detect the vibration of the shaft support 32 in the vertical direction as a change in angular velocity.

[0096] If this control method is applied to the control of the third motor, the vibration of the shaft support 32 in the vertical direction can be reduced.

[0097] Next, use Figure 2 Description via, for example Figure 5 The control method described herein reduces the vibration of the shaft support 32 in the vertical direction.

[0098] The axis support 32 moves towards the displacement D at a velocity in the positive direction. Figure 2 In the case of upward displacement, inertial sensor 11 detects the angular velocity Vs in the + direction. In the case of... Figure 5In the aforementioned control method, the angular velocity Vs is filtered in the LPF and DC removal units, multiplied by the angular velocity feedback gain Kgp, and added to the proportional control of the speed control unit to generate a speed command that increases the speed of the third motor 53 in the positive direction. Therefore, when shaft 31 is in Figure 2 When the Z-coordinate is accelerated in the + direction, the reaction force in the D- direction acts on the shaft support 32, suppressing the displacement of the shaft support 32 in the D+ direction.

[0099] Since the reaction force driving the shaft 31 acts on the shaft support 32, the angular velocity of the shaft support 32 is attenuated, thereby reducing the vibration of the shaft support 32.

[0100] Furthermore, since the aforementioned reaction force is processed in conjunction with the control that drives the shaft 31 in accordance with the position command, the vibration of the shaft support 32 can be reduced simultaneously with the position control of the shaft 31.

[0101] According to such Figure 5 The control method described above exhibits high stability and robust control against environmental changes or disturbances because it feeds back angular velocity information to the proportional control unit of the speed control unit and obtains a reaction force to suppress the vertical vibration of the shaft support 32 by changing the speed command. Furthermore, it can reduce the vibration of the shaft support 32 while controlling the position of the shaft 31. Moreover, the DC removal unit 112 only removes the offset component contained in the angular velocity information and does not degrade the quality of the low-frequency angular velocity information required to reduce the vibration of the shaft support 32, thus achieving control with high vibration suppression effect. Additionally, even if the offset component remains in the angular velocity information output from the DC removal unit 112, it is eliminated as interference by the integral control of the speed control unit, thus preventing positional deviation of the shaft 31.

[0102] Next, in the second embodiment of the present invention, an embodiment using the inertial sensor information processing unit B will be described.

[0103] Figure 6 The feature is that the inertial sensor information is filtered by the inertial sensor information processing unit B, which includes LPF111, BEF113, HPF114 and feedback gain Kgp multiplication processing unit.

[0104] In this embodiment, the inertial sensor 11 uses an angular velocity sensor to detect the vibration of the shaft support 32 in the vertical direction as a change in angular velocity and outputs angular velocity information.

[0105] If this control method is applied to the control of the third motor, the vibration of the shaft support 32 in the vertical direction can be reduced.

[0106] According to such Figure 6 The control method described above, which reduces the vibration of the shaft support 32 in the vertical direction, is the same as the control method using the inertial sensor information processing unit A, and therefore is omitted.

[0107] According to such Figure 6 The inertial sensor information processing unit B106 can use inertial sensors with different characteristics because it can use BEF113 to remove detuning noise based on the characteristics of the inertial sensor 11. Furthermore, since HPF114 can remove the time-varying offset component contained in the angular velocity information, it can use an inertial sensor 11 with a large offset variation.

[0108] It should be noted that this embodiment shows an example of using an angular velocity sensor for the inertial sensor 11, but velocity information obtained by integrating the acceleration detected by the accelerometer can also be used.

[0109] The above describes an embodiment of the control device 3 in the robot system 1, characterized in that the control unit 3A feeds back the angular velocity information detected by the inertial sensor 11 to the speed control unit for proportional control. According to this embodiment, the following effects can be obtained.

[0110] The control unit according to the embodiments of the present invention includes: a position command generation unit that generates position commands, a position control unit that generates speed commands based on the position commands, a speed control unit that generates current commands based on the speed commands, and a current control unit that controls the current driving the motor, and provides proportional control by feeding back the output of the inertial sensor to the speed control unit.

[0111] According to this embodiment, since the output of the inertial sensor is fed back to the proportional control of the speed control unit that drives the motor that makes the shaft move linearly, it is not easily affected by environmental changes. Even if there is a offset in the output of the inertial sensor, no positional deviation will occur, and the vibration of the shaft support in the vertical direction can be reduced.

[0112] Third Implementation Method

[0113] Figure 7 This is relevant to the third embodiment of the present invention. Figure 1 The control block diagram shown in control device 3 feeds back inertial sensor information to speed commands.

[0114] The robot system 1 described in this embodiment is identical to the robot system 1 of the first embodiment, except for the control method of the control unit 3A of the control device 3. It should be noted that in the following description, the robot system 1 of the third embodiment will be described focusing on the differences from the first embodiment, and descriptions of identical items will be omitted.

[0115] based on Figure 7 The control block diagram describes the control method of the control unit 3A, which feeds back the inertial sensor information detected by the inertial sensor 11 to the speed command to reduce the vibration of the shaft support 32 in the vertical direction.

[0116] Figure 7 The control unit 3A includes: a position command generation unit 101, a position control unit 102, a speed control unit 103, a current control unit 104, and an inertial sensor information processing unit B106 for controlling the third motor 53 that moves the shaft 31 linearly. The inertial sensor information processing unit B106 filters the angular velocity information detected by the inertial sensor 11 and feeds it back to the speed command.

[0117] The present invention is characterized in that the angular velocity information obtained by the inertial sensor information processing unit B, which includes LPF111, BEF113, HPF114 and the feedback gain Kgp multiplication processing unit, is fed back to the velocity command.

[0118] In this embodiment, the inertial sensor 11 uses an angular velocity sensor to detect the vibration of the shaft support 32 in the vertical direction as a change in angular velocity and outputs angular velocity information.

[0119] If this control method is applied to the control of the third motor, the vibration of the shaft support 32 in the vertical direction can be reduced.

[0120] According to such Figure 7 The control method described above, which reduces the vibration of the shaft support 32 in the vertical direction, is the same as the control method in the second embodiment, and therefore is omitted.

[0121] According to such Figure 7 The inertial sensor information processing unit B106 can improve control stability by using BEF113 to remove detuning noise based on the characteristics of the inertial sensor 11. Furthermore, since HPF114 can completely remove the time-varying offset component contained in the angular velocity information, an inertial sensor 11 with large offset variations can be used.

[0122] It should be noted that this embodiment shows an example of using an angular velocity sensor for the inertial sensor 11, but velocity information obtained by integrating the acceleration detected by the accelerometer can also be used.

[0123] The above describes an embodiment of the control device 3 in the robot system 1, characterized in that the control unit 3A feeds back the angular velocity information detected by the inertial sensor 11 to the speed command. According to this embodiment, the following effects can be obtained.

[0124] The control unit according to the embodiments of the present invention includes: a position command generation unit that generates position commands, a position control unit that generates speed commands based on the position commands, a speed control unit that generates current commands based on the speed commands, and a current control unit that controls the current driving the motor, and feeds back the output of the inertial sensor to the speed commands.

[0125] According to this embodiment, since the output of the inertial sensor is fed back to the speed command of the motor that drives the shaft to move linearly, it is less susceptible to changes in conditions, and the vibration of the shaft support in the vertical direction can be reduced.

[0126] Fourth Implementation Method

[0127] The control device 3 according to the fourth embodiment of the present invention adjusts the angular velocity feedback gain Kgp based on the angle θ2 of the second arm 24.

[0128] The embodiments described herein involve, for example, Figure 1 The control device 3 of the robot system 1 has the effect of improving and reducing the vibration of the shaft support 32 in the vertical direction and stabilizing the control. It should be noted that in the following description, the differences from the first to third embodiments are described, and descriptions of the same points are omitted.

[0129] In the robot system 1 according to this embodiment, such as Figures 3 to 7 As shown, the control unit 3A has a Kgp adjustment unit 122, which changes the angular velocity feedback gain Kgp based on the angle θ2 of the second arm 24 relative to the first arm 23. When the angle θ2 changes, the vertical rigidity of the shaft support 32 relative to the base 21 and the inertia of the shaft support 32 that holds the first arm 23 and the second arm 24 together change. Specifically, when the second arm bends and the angle θ2 increases, the rigidity decreases and the inertia decreases. Therefore, if the angular velocity feedback gain Kgp is fixed regardless of the angle θ2, the control may be unstable and the vibration reduction effect may not be sufficient. Therefore, the control device 3 of this embodiment is configured to adjust the angular velocity feedback gain Kgp according to the angle θ2, thus solving the above problems.

[0130] As an example of this control method Figure 9 A graph showing the relationship between the angle θ2 of the second arm and the coefficient Rgj is presented. Figure 9 The vertical axis of the graph represents the coefficient Rgj for adjusting Kgp based on the angle θ2 of the second arm. Furthermore, the lower limit of Rgj is set to Rgjmin. Additionally, the slope of Rgj relative to the angle θ2 of the second arm is defined symmetrically by ±Kgj with θ2 = 0°. Based on... Figure 9 The adjustment method for Rgj is to adjust the angular velocity feedback gain Kgp relative to angle θ2 using two parameters: slope Kgj and lower limit value Rgjmin.

[0131] Angular velocity feedback gain Kgp will be based on Figure 9 The coefficient Rgj is obtained by multiplying the base value Kgpb of Kgp by equation (1).

[0132] Kgp=Rgj×Kgpb···(1)

[0133] As described above, near the extended position of the second arm 24 relative to the first arm 23 (θ2 = 0), the inertia of the shaft support portion 32 formed by the first arm 23 and the second arm 24 is large, and the vertical rigidity of the shaft support portion 32 relative to the base 21 is high. Therefore, the control system tends to be stable. In this case, Rgj can be increased to improve the effect of reducing vertical vibration.

[0134] On the other hand, when the second arm 24 is bent relative to the first arm 23, the inertia formed by the first arm 23 and the second arm 24 is reduced, and the rigidity of the shaft support 32 relative to the base 21 decreases, which tends to cause control instability. In this case, Rgj can be reduced to improve control stability.

[0135] The control unit involved in the embodiments of the present invention increases the gain of feeding back the output of the inertial sensor to the control of the motor based on the angle adjustment of the second arm.

[0136] According to this embodiment, by adjusting the feedback gain of the output of the inertial sensor in conjunction with the changes in the vertical rigidity of the shaft support and the inertia around the shaft support caused by the change in the angle of the second arm, it is possible to prevent instability in the control of suppressing the vibration of the shaft support in the vertical direction.

[0137] Fifth Implementation Method

[0138] The control device 3 according to the fifth embodiment of the present invention adjusts the angular velocity feedback gain Kgp based on the mass W of the workpiece.

[0139] The embodiments described herein involve, for example, Figure 1 The control device 3 of the robot system 1 has the effect of improving and reducing the vibration of the shaft support 32 in the vertical direction and stabilizing the control. It should be noted that in the following description, the differences from the first to third embodiments are described, and descriptions of the same points are omitted.

[0140] In the robot system 1 of this embodiment, as Figures 3 to 7 As shown, the control unit 3A includes a Kgp adjustment unit 122, which adjusts the angular velocity feedback gain Kgp based on the workpiece's mass W. When the workpiece's mass W changes, the magnitude of the reaction force acting on the shaft support 32 changes as the shaft 31 is driven. Specifically, when the workpiece's mass W is large, the reaction force caused by the shaft 31's drive increases, thus having the same effect as increasing the angular velocity feedback gain Kgp. Therefore, if the angular velocity feedback gain Kgp is fixed regardless of the workpiece's mass W, the control may be unstable, and sufficient vibration reduction effect may not be obtained. Therefore, the control device 3 of this embodiment is configured to adjust the angular velocity feedback gain Kgp according to the workpiece's mass W, thus solving the above-mentioned problem.

[0141] As an example of this control method Figure 10 This is a graph showing the relationship between the mass W of a standardized workpiece and the coefficient Rgw. Figure 10 The vertical axis of the graph represents the coefficient Rgw for adjusting Kgp based on the workpiece mass W. The lower limit of Rgw is set as Rgwmin, and the upper limit as Rgwmax. The horizontal axis represents the standardized workpiece mass W. The slope of the graph is defined as Kgw1 when the workpiece mass W is less than 1, and as Kgw2 when the workpiece mass W is greater than 1. Based on... Figure 10 The adjustment method for Rgw is to adjust the angular velocity feedback gain Kgp relative to the mass W of the workpiece using four parameters: slope Kgw1, Kgw2, Rgwmax, and Rgwmin.

[0142] As mentioned above, in robot system 1, the larger the mass W of the workpiece, the greater the reaction force of the drive shaft 31, thus having the same effect as increasing the angular velocity feedback gain Kgp. Figure 10 As shown, in the region where the workpiece mass W is greater than 1, Rgw is reduced by the slope Kgw2, thereby maintaining a constant control stability. Furthermore, in the region where the workpiece mass W is less than 1, Rgw is increased by the slope Kgw1, thereby improving the vibration reduction effect.

[0143] Angular velocity feedback gain Kgp will be based on Figure 10The coefficient Rgw is obtained by multiplying the base value Kgpb of Kgp by equation (2).

[0144] Kgp=Rgw×Kgpb…(2)

[0145] As mentioned above, in robot system 1, the larger the mass W of the workpiece, the greater the reaction force, thus the control tends to be unstable. In this case, such as Figure 10 As shown, Rgw can be reduced to improve control stability.

[0146] As described above, the control unit according to the embodiments of the present invention feeds back the output of the inertial sensor to the control gain of the motor based on the mass adjustment of the workpiece attached to the shaft.

[0147] According to this embodiment, by adjusting the feedback gain of the inertial sensor output in accordance with changes in the mass of the workpiece, instability in the control of suppressing vibration of the shaft support in the vertical direction can be prevented.

[0148] Sixth Implementation Method

[0149] The control device 3 according to the sixth embodiment of the present invention adjusts the angular velocity feedback gain Kgp based on the axis position Z.

[0150] The embodiments described herein involve, for example, Figure 1 The control device 3 of the robot system 1 has the effect of improving and reducing the vibration of the shaft support 32 in the vertical direction and stabilizing the control. It should be noted that in the following description, the differences from the first to third embodiments are described, and descriptions of the same points are omitted.

[0151] In the robot system 1 of this embodiment, as Figures 3 to 7 As shown, the control unit 3A has a Kgp adjustment unit 122, which changes the angular velocity feedback gain Kgp based on the shaft position Z. When the shaft position Z changes, the resonant frequency of the bending mode of the shaft 31 changes. Specifically, when the shaft 31 is lowered, the resonant frequency of the bending mode of the shaft 31 decreases, which may sometimes interfere with the control that reduces vertical vibration, causing the control to become unstable. Therefore, the control device 3 of this embodiment is configured to change the angular velocity feedback gain Kgp according to the shaft position Z, thus solving the above-mentioned problem.

[0152] As an example of this control method Figure 11 A graph showing the relationship between axis position Z and coefficient Rgz. Figure 11The vertical axis of the chart represents the coefficient Rgz, with a maximum value of 1 and a minimum value set as Rgzmin. The horizontal axis represents the axis position Z. The slope of the coefficient Rgz relative to the Z position is represented by Kgz. Based on... Figure 11 The adjustment method for Rgz can be achieved by adjusting the angular velocity feedback gain Kgp relative to the axis position Z through two parameters: the minimum value Rgzmin and the coefficient Rgz.

[0153] Angular velocity feedback gain Kgp will be based on Figure 11 The coefficient Rgz is obtained by multiplying the base value Kgpb of Kgp by equation (3).

[0154] Kgp=Rgz×Kgpb…(3)

[0155] As described above, in robot system 1, the lower the axis position Z becomes, the lower the resonant frequency of the axis's bending mode, leading to a tendency for unstable control. In this case, such as Figure 11 As shown, Rgz can be reduced to improve control stability.

[0156] As described above, the control unit according to the embodiments of the present invention adjusts the gain of the control of the motor by feeding back the output of the inertial sensor based on the position of the linear movement.

[0157] According to this embodiment, by adjusting the feedback gain of the inertial sensor output in conjunction with the position of the linear movement of the shaft, instability in the control of suppressing vibration of the shaft support in the vertical direction can be prevented.

[0158] Seventh Implementation Method

[0159] The control device 3 according to the seventh embodiment of the present invention adjusts the LPF cutoff frequency Flpf based on the angle θ2 of the second arm 24.

[0160] The embodiments described herein involve, such as Figure 1 The control device 3 of the robot system 1 has the function of improving and reducing the vibration of the shaft support 32 in the vertical direction and stabilizing the control. It should be noted that in the following description, the differences from the first to third embodiments are described, and descriptions of the same points are omitted.

[0161] In the robot system 1 of this embodiment, as Figures 3 to 7As shown, the control unit 3A has an LPF adjustment unit 121 that changes the LPF cutoff frequency Flpf based on the angle θ2 of the second arm 24 relative to the first arm 23. When the angle θ2 changes, the vertical rigidity of the shaft support 32 relative to the base 21 and the inertia around the shaft support 32 that joins the first arm 23 and the second arm 24 change. Specifically, when the second arm bends and the angle θ2 increases, the rigidity decreases and the inertia decreases. Therefore, if the LPF cutoff frequency Flpf is fixed regardless of the angle θ2, the control may be unstable and insufficient vibration reduction may not be achieved. Therefore, the control device 3 of this embodiment is configured to adjust the LPF cutoff frequency Flpf according to the angle θ2, thus solving the above problems.

[0162] As an example of this control method Figure 12 A graph showing the relationship between the angle θ2 of the second arm and the coefficient Rfj is presented. Figure 12 The vertical axis of the graph represents the coefficient Rfj of Flpf adjusted according to θ2. Furthermore, the lower limit of Rfj is set to Rfjmin. Additionally, the slope of Rfj relative to the angle θ2 of the second arm is defined symmetrically by ±Kfj with θ2 = 0°. Based on... Figure 12 The method for adjusting Rfj is to adjust the LPF cutoff frequency Flpf using two parameters: the slope Kfj and the lower limit value Rfjmin, for the angle θ2.

[0163] The LPF cutoff frequency Flpf is determined by... Figure 12 The coefficient Rfj is obtained by multiplying the base value Flpfb of Flpf by equation (4).

[0164] F1pf=Rfj×Flpfb…(4)

[0165] As described above, near the extended position of the second arm 24 relative to the first arm 23 (θ2 = 0), the inertia of the shaft support portion 32 formed by the first arm 23 and the second arm 24 is large, and the vertical rigidity of the shaft support portion 32 relative to the base 21 is high. Therefore, the control system tends to be stable. In this case, Flpf can be increased to improve the effect of reducing vertical vibration.

[0166] On the other hand, when the second arm 24 is bent relative to the first arm 23, the inertia formed by the first arm 23 and the second arm 24 is reduced, and the rigidity of the shaft support 32 relative to the base 21 decreases, which tends to cause control instability. In this case, Flpf can be reduced to improve control stability.

[0167] As described above, the control unit involved in the embodiments of the present invention adjusts the cutoff frequency of the low-pass filter based on the angle of the second arm.

[0168] According to this embodiment, by adjusting the cutoff frequency of the low-pass filter in conjunction with the angle of the second arm, instability in the control of suppressing vibration of the shaft support in the vertical direction can be prevented.

[0169] Eighth Implementation Method

[0170] exist Figure 13 In the eighth embodiment of the present invention, the control device 3 adjusts the LPF cutoff frequency Flpf based on the mass W of the workpiece.

[0171] The embodiments described herein involve, for example, Figure 1 The control device 3 of the robot system 1 has the effect of improving and reducing the vibration of the shaft support 32 in the vertical direction and stabilizing the control. It should be noted that in the following description, the differences from the first to third embodiments are described, and descriptions of the same points are omitted.

[0172] In the robot system 1 of this embodiment, as Figures 3 to 7 As shown, the control unit 3A includes an LPF adjustment unit 121, which changes the LPF cutoff frequency Flpf based on the workpiece mass W. When the workpiece mass W changes, the resonant frequency of the bending mode of the shaft 31 changes, sometimes interfering with the control of reducing the vibration of the shaft support 32 in the vertical direction. Therefore, if the LPF cutoff frequency Flpf is fixed regardless of the workpiece mass W, the control may be unstable and insufficient vibration reduction effect may not be obtained. Therefore, the control device 3 of this embodiment is configured to change the LPF cutoff frequency Flpf according to the workpiece mass W, thus solving the above-mentioned problem.

[0173] As an example of this control method Figure 13 It is a graph showing the relationship between the mass W of a standardized workpiece and the coefficient Rfw. Figure 13 The vertical axis of the graph represents the coefficient Rfw for adjusting Flpf based on the workpiece mass W. The lower limit of Rfw is set as Rfwmin, and the upper limit as Rfwmax. The horizontal axis represents the workpiece mass W. The slope of the graph is defined as Kfw1 when the workpiece mass W is less than 1, and Kfw2 when the workpiece mass W is greater than 1. Based on... Figure 13 The Rfw adjustment method can be achieved by adjusting the LPF cutoff frequency Flpf based on the workpiece mass W using four parameters: slope Kfwl, Kfw2, Rfwmax, and Rfwmin.

[0174] As mentioned above, in robot system 1, the larger the mass W of the workpiece, the lower the resonant frequency of the bending mode of axis 31 becomes. This can sometimes interfere with the control that reduces vertical vibration, leading to control instability. Therefore, as... Figure 13 As shown, in the region where the workpiece mass W is greater than 1, Rfw is reduced by Kfw2, thereby maintaining a constant control stability. Furthermore, in the region where the workpiece mass W is less than 1, Fjw is increased by the slope Kfwl, thereby improving the vibration reduction effect.

[0175] The LPF cutoff frequency Flpf is determined by... Figure 13 The coefficient Rfw is obtained by multiplying the base value Flpfb of Flpf by equation (5).

[0176] Flpf=Rfw×F1pfb…(5)

[0177] As mentioned above, the larger the mass W of the workpiece, the lower the resonant frequency of the bending mode of shaft 31 becomes, which can sometimes make the control for reducing vertical vibration unstable. In this case, Flpf can be reduced to stabilize the control.

[0178] As described above, the control unit according to the embodiments of the present invention adjusts the cutoff frequency of the low-pass filter based on the mass of the workpiece attached to the shaft.

[0179] According to this embodiment, by adjusting the cutoff frequency of the low-pass filter in accordance with the mass of the workpiece, it is possible to prevent and suppress the unstable control of vibration of the shaft support in the vertical direction.

[0180] Ninth Implementation Method

[0181] The control device 3 according to the ninth embodiment of the present invention adjusts the LPF cutoff frequency Flpf based on the axis position Z.

[0182] The embodiments described herein involve, for example, Figure 1 The control device 3 of the robot system 1 has the function of improving and reducing the vibration of the shaft support 32 in the vertical direction and stabilizing the control. It should be noted that in the following description, the differences from the first to third embodiments are described, and descriptions of the same points are omitted.

[0183] In the robot system 1 of this embodiment, as Figures 3 to 7As shown, the control unit 3A includes an Flpf adjustment unit 121, which changes the LPF cutoff frequency Flpf based on the shaft position Z. When the shaft position Z changes, the resonant frequency of the bending mode of the shaft 31 changes. Specifically, when the shaft 31 is lowered, the resonant frequency of the bending mode decreases, which may sometimes interfere with the control to reduce vertical vibration, causing the control to become unstable. Therefore, the control device 3 of this embodiment is configured to change the LPF cutoff frequency Flpf according to the shaft position Z, thus solving the above-mentioned problem.

[0184] As an example of this control method Figure 14 A graph showing the relationship between axis position Z and the coefficient Rfz for adjusting Flpf based on axis position Z. Figure 14 The vertical axis of the chart represents the coefficient Rfz, with a maximum value of 1 and a minimum value set as Rfzmin. The horizontal axis represents the axis position Z. The slope of the coefficient Rfz relative to the Z position is represented by Kfz. Based on... Figure 14 The Rfz adjustment method can be achieved by adjusting the LPF cutoff frequency Flpf relative to the axis position Z using two parameters: the minimum value Rfzmin and the slope Kfz.

[0185] The LPF cutoff frequency Flpf is determined by... Figure 14 The coefficient Rfz is obtained by multiplying the base value Flpfb of Flpf by equation (6).

[0186] Flpf=Rfz×Flpfb…(6)

[0187] As described above, in robot system 1, the lower the axis position Z becomes, the lower the resonant frequency of the axis's bending mode, leading to a tendency for unstable control. In this case, such as Figure 14 As shown, reducing Rfz can improve control stability.

[0188] As described above, the control unit according to the embodiments of the present invention adjusts the cutoff frequency of the low-pass filter based on the position of the linear movement.

[0189] According to this embodiment, by adjusting the cutoff frequency of the low-pass filter in conjunction with the position of linear movement, instability in the control of suppressing vibration of the shaft support in the vertical direction can be prevented.

Claims

1. A robot system, characterized in that, Equipped with a horizontal multi-joint robot and control device, The horizontal multi-joint robot comprises: a base; a first arm that rotates about a first axis relative to the base; a second arm that rotates about a second axis relative to the first arm; an axis supported by an axis support portion of the second arm and capable of linear movement in a direction parallel to the second axis; and a motor that drives the linear movement of the axis. And an inertial sensor, located in the second arm, The control device feeds back the output of the inertial sensor to the control of the motor to drive the motor. The control device includes: a position command generation unit that generates a position command; a position control unit that generates a speed command based on the position command; and a speed control unit that generates a current command based on the speed command. and a current control unit that controls the current driving the motor. The control device feeds back the output of the inertial sensor to the current command, the proportional control of the speed control unit, or the speed command.

2. A robot system, characterized in that, Equipped with a horizontal multi-joint robot and control device, The horizontal multi-joint robot comprises: a base; a first arm that rotates about a first axis relative to the base; a second arm that rotates about a second axis relative to the first arm; an axis supported by an axis support portion of the second arm and capable of linear movement in a direction parallel to the second axis; and a motor that drives the linear movement of the axis. And an inertial sensor, located in the second arm, The control device adjusts the shaft's movement based on the output of the inertial sensor, thereby reducing the shaft's vibration in the axial direction. The control device includes: a position command generation unit that generates a position command; a position control unit that generates a speed command based on the position command; and a speed control unit that generates a current command based on the speed command. and a current control unit that controls the current driving the motor. The control device feeds back the output of the inertial sensor to the current command, the proportional control of the speed control unit, or the speed command.

3. A robot system, characterized in that, Equipped with a horizontal multi-joint robot and control device, The horizontal multi-joint robot comprises: a base; a first arm that rotates relative to the base about a first axis; a second arm that rotates relative to the first arm about a second axis; an axis supported by an axis support portion of the second arm and capable of linear movement in a direction parallel to the second axis; a motor that drives the linear movement of the axis; and an inertial sensor disposed on the second arm. The inertial sensor is an angular velocity sensor configured to detect angular velocities about an angular velocity detection axis that intersects a plane including the second and third axes. The control device feeds back the output of the inertial sensor to control the motor to drive it. The control device includes: a position command generation unit that generates a position command; a position control unit that generates a speed command based on the position command; and a speed control unit that generates a current command based on the speed command. and a current control unit that controls the current driving the motor. The control device feeds back the output of the inertial sensor to the current command, the proportional control of the speed control unit, or the speed command.

4. The robot system according to any one of claims 1 to 3, characterized in that, The control device removes noise from the output of the inertial sensor using a low-pass filter.

5. The robot system according to claim 4, characterized in that, The cutoff frequency of the low-pass filter is above 20Hz and below 200Hz.

6. The robot system according to any one of claims 1 to 3, characterized in that, The control device removes detuning noise from the output of the inertial sensor using a band-stop filter.

7. The robot system according to any one of claims 1 to 3, characterized in that, The control device calculates the offset component contained in the output of the inertial sensor by using a moving average of the angular velocity information, and removes the offset component from the output of the inertial sensor.

8. The robot system according to any one of claims 1 to 3, characterized in that, The control device removes the offset component contained in the output of the inertial sensor using a high-pass filter.

9. The robot system according to any one of claims 1 to 3, characterized in that, The control device adjusts the angle of the second arm to feed back the output of the inertial sensor to the control gain of the motor.

10. The robot system according to any one of claims 1 to 3, characterized in that, The control device feeds back the output of the inertial sensor to the control gain of the motor based on the mass adjustment of the workpiece attached to the shaft.

11. The robot system according to any one of claims 1 to 3, characterized in that, The control device adjusts the gain of the control of the motor by feeding back the output of the inertial sensor to the motor based on the position of the linear movement.

12. The robot system according to claim 4, characterized in that, The control device adjusts the cutoff frequency of the low-pass filter based on the angle of the second arm.

13. The robot system according to claim 4, characterized in that, The control device adjusts the cutoff frequency of the low-pass filter based on the mass of the workpiece attached to the shaft.

14. The robot system according to claim 4, characterized in that, The control device adjusts the cutoff frequency of the low-pass filter based on the position of the linear movement.

15. The robot system according to any one of claims 1 to 3, characterized in that, The inertial sensor is located near the shaft support of the second arm.

16. The robot system according to any one of claims 1 to 3, characterized in that, The inertial sensor is positioned between the motor and the shaft.

17. The robot system according to any one of claims 1 to 3, characterized in that, The height of the upper surface of the inertial sensor in the vertical direction is lower than the height of the upper surface of the motor in the vertical direction.

18. The robot system according to any one of claims 1 to 3, characterized in that, The second arm has a timing belt, which is positioned further down in the vertical direction than the inertial sensor.

19. The robot system according to any one of claims 1 to 3, characterized in that, The inertial sensor is positioned above the lower surface of the second arm.

20. The robot system according to claim 9, characterized in that, The gain is obtained by multiplying a reference value of the angular velocity feedback gain of the second arm by a coefficient that adjusts the angular velocity feedback gain according to the angle of the second arm, and the coefficient is increased when the second arm is in an extended posture relative to the first arm.

21. The robot system according to claim 10, characterized in that, The gain is obtained by multiplying a reference value of the angular velocity feedback gain of the second arm by a coefficient that adjusts the angular velocity feedback gain according to the mass of the workpiece; the greater the mass of the workpiece, the smaller the coefficient.

22. The robot system according to claim 11, characterized in that, The gain is obtained by multiplying a reference value of the angular velocity feedback gain of the second arm by a coefficient that adjusts the angular velocity feedback gain according to the position of the linear movement. The lower the position of the linear movement, the smaller the coefficient becomes.

23. The robot system according to claim 12, characterized in that, The cutoff frequency is obtained by multiplying a reference value by a coefficient that adjusts the cutoff frequency relative to the angle of the second arm, and the coefficient is increased when the second arm is in an extended position relative to the first arm.

24. The robot system according to claim 13, characterized in that, The cutoff frequency is obtained by multiplying a reference value by a coefficient that adjusts the cutoff frequency relative to the mass of the workpiece; the greater the mass of the workpiece, the smaller the coefficient.

25. The robot system according to claim 14, characterized in that, The cutoff frequency is obtained by multiplying a reference value by a coefficient that adjusts the cutoff frequency relative to the position of the linear movement. The lower the position of the linear movement, the smaller the coefficient becomes.

26. A horizontal multi-joint robot, characterized in that, have: A base; a first arm that rotates about a first axis relative to the base; a second arm that rotates about a second axis relative to the first arm; a shaft supported by a shaft support portion of the second arm and moving linearly in a direction parallel to a third axis; and a motor that drives the linear movement of the shaft. And an inertial sensor, located in the second arm, The horizontal multi-jointed robot has a built-in control device that feeds back the output of the inertial sensor to control the motors and drive them. The control device includes: a position command generation unit that generates a position command; a position control unit that generates a speed command based on the position command; and a speed control unit that generates a current command based on the speed command. and a current control unit that controls the current driving the motor. The control device feeds back the output of the inertial sensor to the current command, the proportional control of the speed control unit, or the speed command.

27. A horizontal multi-joint robot, characterized in that, have: The horizontal multi-joint robot comprises: a base; a first arm that rotates about a first axis relative to the base; a second arm that rotates about a second axis relative to the first arm; an axis supported by an axis support portion of the second arm and capable of linear movement in a direction parallel to the second axis; and a motor that drives the linear movement of the axis. And an inertial sensor, located in the second arm, The horizontal multi-joint robot has a built-in control device that adjusts the movement of the axis based on the output of the inertial sensor, thereby reducing the vibration of the axis in the axial direction. The control device includes: a position command generation unit that generates a position command; a position control unit that generates a speed command based on the position command; and a speed control unit that generates a current command based on the speed command. and a current control unit that controls the current driving the motor. The control device feeds back the output of the inertial sensor to the current command, the proportional control of the speed control unit, or the speed command.

28. A horizontal multi-joint robot, characterized in that, have: The horizontal multi-joint robot comprises: a base; a first arm that rotates relative to the base about a first axis; a second arm that rotates relative to the first arm about a second axis; an axis supported by an axis support portion of the second arm and capable of linear movement in a direction parallel to the second axis; a motor that drives the linear movement of the axis; and an inertial sensor disposed on the second arm. The inertial sensor is an angular velocity sensor configured to detect the angular velocity around an angular velocity detection axis that intersects a plane including the second and third axes. The horizontal jointed robot has a built-in control device that feeds back the output of the inertial sensor to control the motors to drive them. The control device includes: a position command generation unit that generates a position command; a position control unit that generates a speed command based on the position command; and a speed control unit that generates a current command based on the speed command. and a current control unit that controls the current driving the motor. The control device feeds back the output of the inertial sensor to the current command, the proportional control of the speed control unit, or the speed command.

29. A control method, characterized in that, The control method for controlling the horizontal jointed robot of any one of claims 26 to 28 includes: Generate position instructions; Generate a speed command based on the position command; Generate a current command based on the speed command; Controlling the current driving the motor; and The output of the inertial sensor is fed back to the control of the motor, and the motor is driven.

30. A control method for a horizontal multi-joint robot, characterized in that, The horizontal multi-joint robot comprises: a base; a first arm that rotates about a first axis relative to the base; a second arm that rotates about a second axis relative to the first arm; and an axis supported by an axis support portion of the second arm and capable of linear movement in a direction parallel to the second axis. The motor drives the linear movement of the shaft; And an inertial sensor, located in the second arm, The control method includes: Generate position instructions; Generate a speed command based on the position command; Generate a current command based on the speed command; Controlling the current driving the motor; and The output of the inertial sensor is fed back to the control of the motor to drive the motor. In the control method, the output of the inertial sensor is fed back to the current command, the proportional control of the speed control unit, or the speed command.

31. A control method for a horizontal multi-joint robot, characterized in that, The horizontal multi-joint robot comprises: a base; a first arm that rotates about a first axis relative to the base; a second arm that rotates about a second axis relative to the first arm; and an axis supported by an axis support portion of the second arm and capable of linear movement in a direction parallel to the second axis. The motor drives the linear movement of the shaft; And an inertial sensor, located in the second arm, The control method includes: Generate position instructions; Generate a speed command based on the position command; Generate a current command based on the speed command; Controlling the current driving the motor; and The shaft's movement is adjusted based on the output of the inertial sensor, thereby reducing the shaft's vibration in the axial direction. In the control method, the output of the inertial sensor is fed back to the current command, the proportional control of the speed control unit, or the speed command.

32. A control method for a horizontal multi-joint robot, characterized in that, The horizontal multi-joint robot comprises: a base; a first arm that rotates relative to the base about a first axis; a second arm that rotates relative to the first arm about a second axis; an axis supported by an axis support portion of the second arm and capable of linear movement in a direction parallel to the second axis; a motor that drives the linear movement of the axis; and an inertial sensor disposed on the second arm. The inertial sensor is an angular velocity sensor configured to detect the angular velocity about an angular velocity detection axis that intersects a plane containing the second axis and the third axis. The control method includes: Generate position instructions; Generate a speed command based on the position command; Generate a current command based on the speed command; Controlling the current driving the motor; and The output of the inertial sensor is fed back to the control of the motor to drive the motor. In the control method, the output of the inertial sensor is fed back to the current command, the proportional control of the speed control unit, or the speed command.

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