JP5418491B2 - robot - Google Patents

Description

  The present invention relates to a robot having a robot arm.

  In the field of robots, it is required to avoid an excessive load on the robot itself or objects existing around the robot. For this reason, it is necessary to detect the presence or absence of contact (external force) with the robot.

  For example, in Patent Document 1, a force detector for detecting external force is attached to the base end of the robot arm, and the operation of the robot arm is stopped based on the detection result of the force detector, or excessive external force is applied. In such a case, a technique of operating the robot arm in a direction in which the external force is reduced is disclosed.

JP 2006-21287 A

  In order to improve the functionality of the robot, it is required to detect the presence or absence of contact with the robot arm with high accuracy.

  In the above prior art, a 6-axis force sensor is used as a force detector, and the magnitude of the actual external force acting on the robot arm is detected. Therefore, the response to the contact of the robot arm may be slow. It is also conceivable that sufficient detection cannot be performed in the case of light contact or momentary contact.

  The present invention has been made in view of such problems, and an object thereof is to provide a robot capable of improving the functionality of the robot.

In order to solve the above-described problems, a robot according to the present invention includes a robot arm, one or more actuators that are provided on the robot arm, and that drives the robot arm, and an actuator that is positioned on the most proximal side of the robot arm. A sensor fixing jig provided at the base, and arranged on the sensor fixing jig on substantially the same circumference, each of which is provided such that the longitudinal direction thereof is a radial direction, and from the structural material constituting the robot arm And a plurality of strain sensors having a piezoelectric body having a large natural frequency.

  The sensor fixing jig is preferably provided inside the robot arm casing or the robot casing.

  Moreover, it is preferable that at least three strain sensors are provided on the sensor fixing jig.

  Further, it is preferable that the at least three strain sensors are arranged at equal intervals on the same circumference, and the strain sensors are arranged in a radial direction.

  The sensor fixing jig is preferably formed in an annular shape having an opening in the center.

  The strain sensor is preferably a sensor using quartz as a piezoelectric body.

  According to the present invention, the functionality of the robot can be improved.

1 is a system configuration diagram conceptually showing an overall configuration of a robot system including a robot according to an embodiment of the present invention. It is a top view of the robot showing the structure of a robot. It is a functional block diagram showing the functional structure of a robot controller. It is a functional block diagram showing the function structure of an abnormality detection part. It is explanatory drawing for demonstrating the detail of a sensor part, a high-pass filter part, and a comparison determination part. It is explanatory drawing for demonstrating the predetermined | prescribed operation | movement performed with an arm without an abnormality, and the output value of the sensor in the meantime. It is explanatory drawing for demonstrating the predetermined operation | movement which an arm performs at the time of operation | movement, and the output value of the sensor in the meantime. It is explanatory drawing for demonstrating an example of the method of detecting the presence or absence of abnormality of an arm. It is a flowchart showing the control procedure which a robot controller performs. It is a schematic diagram showing the predetermined operation | movement which an arm performs at the time of operation | movement in the modification applied to the contact detection of an object.

  Hereinafter, an embodiment of the present invention will be described with reference to the drawings. The present embodiment is an example in which the robot of the present invention is applied to detecting an abnormality of a robot arm as an example.

  FIG. 1 is a system configuration diagram conceptually showing the overall configuration of a robot system including the robot of this embodiment. FIG. 2 is a top view of the robot representing the configuration of the robot according to the present embodiment.

  1 and 2, the robot system 1 according to the present embodiment includes a robot 100 provided on one side of a belt conveyor 2 that transports a plurality of articles P, and a robot controller 150 that controls the robot 100. Yes. The robot 100 is a double-arm robot, and includes a base 101, a body unit 102, two arms 103L and 103R (robot arms), and two sensor units 120L and 120R.

  The base 101 is fixed to an installation surface (floor portion or the like) by an anchor bolt or the like (not shown). The body portion 102 has a first joint portion provided with an actuator Ac1 that is driven to rotate about the rotation axis Ax1. The body portion 102 is installed so as to be able to turn with respect to the base 101 via the first joint portion, and is driven along an approximately horizontal direction with respect to the installation surface by driving an actuator Ac1 provided in the first joint portion. Turn. In addition, the body portion 102 supports the arms 103L and 103R configured as separate bodies on one side (right side in FIGS. 1 and 2) and the other side (left side in FIGS. 1 and 2), respectively.

  The arm 103L is a manipulator provided on one side of the body portion 102, and includes a shoulder portion 104L, an upper arm A portion 105L, an upper arm B portion 106L, a lower arm portion 107L, a wrist A portion 108L, a wrist B portion 109L, a flange 110L, And the hand 111L, and second to eighth joint portions provided with actuators Ac2 to Ac8 for rotationally driving the respective portions, respectively.

  The shoulder portion 104L is rotatably connected to the body portion 102 via the second joint portion, and a rotation axis Ax2 that is substantially horizontal with respect to the installation surface by driving an actuator Ac2 provided at the second joint portion. Rotate around. The upper arm A portion 105L is connected to the shoulder portion 104L through a third joint portion so as to be rotatable, and a rotation axis Ax3 orthogonal to the rotation axis Ax2 by driving an actuator Ac3 provided at the third joint portion. Turn around. The upper arm B portion 106L is rotatably connected to the tip of the upper arm A portion 105L via a fourth joint portion, and is orthogonal to the rotation axis Ax3 by driving an actuator Ac4 provided at the fourth joint portion. It rotates around the rotation axis Ax4. The lower arm portion 107L is connected to the upper arm B portion 106L via a fifth joint portion so as to be able to turn, and a rotation axis orthogonal to the rotation axis Ax4 by driving an actuator Ac5 provided at the fifth joint portion. Turn around Ax5. The wrist A portion 108L is rotatably connected to the tip of the lower arm portion 107L via a sixth joint portion, and is orthogonal to the rotation axis Ax5 by driving an actuator Ac6 provided at the sixth joint portion. It rotates around the rotation axis Ax6. The wrist B portion 109L is connected to the wrist A portion 108L through a seventh joint portion so as to be rotatable, and a rotation axis orthogonal to the rotation axis Ax6 by driving of an actuator Ac7 provided at the seventh joint portion. Turn around Ax7. The flange 110L is rotatably connected to the tip of the wrist B portion 109L via an eighth joint portion, and is a rotation axis orthogonal to the rotation axis Ax7 by driving an actuator Ac8 provided at the eighth joint portion. Rotate around Ax8. The hand 111L is attached to the tip of the flange 110L, and is rotated following the rotation of the flange 110L.

  The arm 103R is a manipulator provided on the other side of the body portion 102, and has the same structure as the arm 103L. The arm 103R includes a shoulder portion 104R, an upper arm A portion 105R, an upper arm B portion 106R, a lower arm portion 107R, a wrist A portion 108R, a wrist B portion 109R, a flange 110R, and a hand 111R, and actuators that rotationally drive these portions. It has 9th-15th joint part in which Ac9-Ac15 was each provided.

  The shoulder portion 104R is rotatably connected to the body portion 102 via the ninth joint portion, and is driven by an actuator Ac9 provided at the ninth joint portion, so that the rotation axis Ax9 is substantially horizontal with respect to the installation surface. Rotate around. The upper arm A part 105R is connected to the shoulder part 104R through a tenth joint part so as to be able to turn, and a rotation axis Ax10 orthogonal to the rotation axis Ax9 by driving an actuator Ac10 provided at the tenth joint part. Turn around. The upper arm B portion 106R is rotatably connected to the tip of the upper arm A portion 105R via an eleventh joint portion, and is orthogonal to the rotation axis Ax10 by driving an actuator Ac11 provided at the eleventh joint portion. It rotates around the rotation axis Ax11. The lower arm portion 107R is connected to the upper arm B portion 106R through a twelfth joint portion so as to be rotatable, and a rotation axis orthogonal to the rotation axis Ax11 by driving an actuator Ac12 provided in the twelfth joint portion. Turn around Ax12. The wrist A portion 108R is rotatably connected to the tip of the lower arm portion 107R via a thirteenth joint portion, and is orthogonal to the rotation axis Ax12 by driving an actuator Ac13 provided at the thirteenth joint portion. It rotates around the rotation axis Ax13. The wrist B part 109R is connected to the wrist A part 108R through a fourteenth joint part so as to be able to turn, and a rotation axis orthogonal to the rotation axis Ax13 by driving an actuator Ac14 provided in the fourteenth joint part. Turn around Ax14. The flange 110R is rotatably connected to the tip of the wrist B portion 109R via a fifteenth joint portion, and is a rotation axis orthogonal to the rotation axis Ax14 by driving an actuator Ac15 provided at the fifteenth joint portion. Rotate around Ax15. The hand 111R is attached to the tip of the flange 110R, and is rotated following the rotation of the flange 110R.

  In this example, the arms 103L and 103R have seven joints, that is, seven degrees of freedom (redundancy degrees of freedom), but the degrees of freedom of the arms 103L and 103R are not limited to “7”.

  Shoulders 104L and 104R of these arms 103L and 103R, upper arm A portions 105L and 105R, upper arm B portions 106L and 106R, lower arm portions 107L and 107R, wrist A portions 108L and 108R, wrist B portions 109L and 109R, flanges 110L and The structural material constituting the 110R and the hands 111L and 111R is made of a metal material such as iron or aluminum.

  Further, as shown in FIG. 2, the rotation axis Ax1 of the first joint portion and the rotation axes Ax2 and Ax9 of the second and ninth joint portions are offset by a length D1 in a direction substantially horizontal to the installation surface. As described above, the body portion 102 is formed so as to protrude from the base 101 to the horizontal front from the first joint portion to the second and ninth joint portions. Accordingly, the space below the shoulders 104L and 104R can be used as a work space, and the reachable range of the arms 103L and 103R is expanded by rotating the rotation axis Ax1.

  Further, the shape of the upper arm B portion 106R is set so that the rotation axis Ax11 of the eleventh joint portion and the rotation axis Ax12 of the twelfth joint portion are offset by a length D2 in a top view. The shape of the lower arm 107R is set so that the rotational axis Ax12 of the twelfth joint and the rotational axis Ax13 of the thirteenth joint are offset by a length D3 when viewed from above. When the rotation axis Ax11 and the rotation axis Ax13 are in a substantially horizontal posture, the offset length between the rotation axis Ax11 and the rotation axis Ax13 is (D2 + D3). Thus, when the twelfth joint corresponding to the human “elbow” is bent, the upper arm A portion 105R and the upper arm B portion 106R corresponding to the human “upper arm” and the human “lower arm” are equivalent. A large clearance with the lower arm A portion 107R can be ensured, and the degree of freedom of movement of the arm 103R is increased even when the hand 111R is closer to the body portion 102.

  Further, although not explicitly shown in FIG. 2, similarly, the rotation axis Ax4 of the fourth joint part and the rotation axis Ax5 of the fifth joint part are offset by the length D2 in the same manner with respect to the arm 103L. As described above, the shape of the upper arm B portion 106L is set. The shape of the lower arm portion 107L is set so that the rotational axis Ax5 of the fifth joint portion and the rotational axis Ax6 of the sixth joint portion are offset by a length D3 when viewed from above. When the rotation axis Ax4 and the rotation axis Ax6 are in a substantially horizontal posture, the offset length between the rotation axis Ax4 and the rotation axis Ax6 is (D2 + D3).

  As shown in FIG. 2, each of the sensor units 120L and 120R is provided inside a casing (in this example, a casing configuring the outer shell of the body unit 102) that forms the outer shape of the robot 100, and has an annular shape. The sensor fixing jig 121 is formed and at least three (three in this example) substantially rectangular parallelepiped sensors 122 (strain sensors). The sensor fixing jig 121 of the sensor unit 120L is attached to the base of the stator of the actuator Ac2 located on the most proximal side of the arm 103L, and the three sensors 122 provided on the sensor fixing jig 121 are It is possible to detect the force applied to 103L (specifically, not the magnitude of the force itself but the amount of strain due to vibration or the like caused by the impact force applied to the arm 103L). The sensor fixing jig 121 of the sensor unit 120R is attached to the base of the stator of the actuator Ac9 located on the most proximal side of the arm 103R, and the three sensors 122 provided on the sensor fixing jig 121 are It is possible to detect the force applied to 103R (specifically, not the magnitude of the force itself, but the amount of strain caused by vibration or the like caused by the impact force applied to the arm 103R). Details of the sensor units 120L and 120R will be described later.

  In this example, the sensor fixing jigs 121 of the sensor units 120L and 120R are provided inside the casing of the body unit 102. However, the present invention is not limited to this, and the sensor fixing jigs 121 are provided inside the casings of the arms 103L and 103R, respectively. You may make it provide. In this example, three sensors 122 are provided in the sensor fixing jig 121, but the present invention is not limited to this, and four or more (for example, four or five) may be provided in the sensor fixing jig 121. .

  The robot 100 configured as described above is configured so that the arms 103L and 103R operate inward from both sides of the article P on the belt conveyor 2 so that the articles P are gripped by the hands 111L and 111R. The operation of each drive part including Ac1 to Ac15 is controlled by the robot controller 150. The actuators Ac1 to Ac15 are each constituted by a reduction gear integrated servo motor having a hollow portion through which a wiring (not shown) can be inserted, and the rotation positions of the actuators Ac1 to Ac15 are the actuators Ac1 to Ac15. As a signal from an encoder (not shown) built in the robot controller 150, the signal is input to the robot controller 150 via wiring.

  FIG. 3 is a functional block diagram showing the functional configuration of the robot controller 150.

  In FIG. 3, the robot controller 150 is configured by a computer including an arithmetic unit, a storage device, an input device, and the like (not shown), and is connected to each drive part of the robot 100 and each sensor 122 so as to be able to communicate with each other via wiring. Has been. The robot controller 150 includes an operation command unit 151, a position command blocking unit 152, a smoothing processing unit 153, a servo unit 154, an abnormality detection unit 155, a gripping torque compensation unit 156, and a gravity torque compensation unit 157.

  The operation command unit 151 sends position commands (operation commands) to the actuators Ac1 to Ac15 based on teaching information (information of operation start positions and operation completion positions) for the arms 103L and 103R taught via the input device. Each is calculated and pooled in the smoothing processing unit 153 via the position command blocking unit 152.

  The smoothing processing unit 153 sequentially outputs the pooled position commands to the servo unit 154 every predetermined calculation cycle.

  For each actuator Ac1 to Ac15, the servo unit 154 includes a joint angle feedback circuit Fp based on a detection value of the encoder of each actuator Ac1 to Ac15 and a joint angle based on a detection value of the angular velocity obtained from the detection value of the encoder of each actuator Ac1 to Ac15. And a feedback circuit Fv. The servo unit 154 generates and outputs a torque command Tref for each of the actuators Ac1 to Ac15 at each predetermined calculation cycle based on the position command sequentially input from the smoothing processing unit 153.

  The abnormality detection unit 155 is based on the aging of the rotating members such as the actuators Ac2 to Ac15 and the reduction gears provided in the arms 103L and 103R based on the output value V (output signal) of each sensor 122 of the sensor units 120L and 120R. Detect the presence or absence of abnormalities. In addition, it is not restricted to this, The presence or absence of abnormality of arm 103L, 103R itself (including abnormality due to aged deterioration of rotating members such as actuators Ac2 to Ac15 and a reduction gear, abnormality of the housing of arms 103L, 103R, etc.) You may make it detect. Details of the abnormality detection unit 155 will be described later.

  The position command cut-off unit 152 cuts off the output of the position command from the operation command unit 151 to the smoothing processing unit 153 when the abnormality detection unit 155 detects an abnormality in the actuators Ac2 to Ac15 of the arms 103L and 103R. Then, the position command transmitted to the servo unit 154 is blocked. When the position command to the servo unit 154 is interrupted, the value of the torque command Tref output by feedback decreases, and the arms 103L and 103R immediately enter a stop operation.

  The gripping torque compensation unit 156 adds gripping compensation torque for the arms 103L and 103R to grip the article P to the torque command Tref generated by the servo unit 154 for each of the actuators Ac1 to Ac15.

  The gravity torque compensator 157 adds gravity compensation torque corresponding to its own weight to the torque command Tref generated by the servo unit 154 for each of the actuators Ac1 to Ac15.

  FIG. 4 is a functional block diagram illustrating a functional configuration of the abnormality detection unit 155.

  In FIG. 4, the abnormality detection unit 155 includes a high-pass filter unit 161, a section setting unit 162, a reference waveform recording unit 163, an output waveform recording unit 167, a comparison determination unit 164, a zero point adjustment unit 165, and a threshold setting unit 166. ing.

  The high-pass filter unit 161 removes a frequency component (for example, a frequency component caused by disturbance) other than the frequency caused by the abnormality of the arms 103L and 103R included in the output signals of the sensors 122 of the sensor units 120L and 120R. In addition, the high-frequency vibration component of the output signal of each sensor 122 is extracted. Details of the high-pass filter unit 161 will be described later.

  The section setting unit 162 records the time history of the output value V of the sensor 122 as a reference waveform expressed as a waveform by the reference waveform recording unit 163 based on the input information input via the input device (hereinafter simply referred to as appropriate). (Referred to as “recording section”).

  The reference waveform recording unit 163 extracts a predetermined operation corresponding to the recording section set by the section setting unit 162 by the high-pass filter unit 161 while the arms 103L and 103R perform while there is no abnormality in the arms 103L and 103R. The time history of the output value V of each sensor 122 based on the high frequency vibration component thus recorded is recorded as a reference waveform (see FIG. 6B described later) for each sensor 122. Here, the state in which there is no abnormality in the arms 103L and 103R means that the housings of the arms 103L and 103R (including structural members, cover members, wirings, etc.) and actuators Ac2 to Ac15 provided on the arms 103L and 103R, This means a state in which the speed reducer or the like is free from structural and functional defects and operates normally, and no unintended contact or interference occurs in the arms 103L and 103R. For example, the state immediately after checking that the housings of the arms 103L and 103R and the actuators Ac2 to Ac15 and the speed reducers provided on the arms 103L and 103R operate normally, or during initial operation without initial failure. The state etc. correspond. The predetermined operation is an operation according to the position command calculated by the operation command unit 151 based on teaching information (information on the operation start position and operation completion position) taught via the input device. .

  The output waveform recording unit 167 stores the time history of the output value V of each sensor 122 based on the high-frequency vibration component extracted by the high-pass filter unit 161 while the arms 103L and 103R perform the predetermined operation during operation. Each sensor 122 is recorded as an output waveform (see FIG. 7B described later). In the present embodiment, the arms 103L and 103R perform a predetermined operation when there is no article P to be gripped within the movable range during operation (for example, immediately after the start of conveyance of the article P or at the time of inspection performed by interrupting conveyance). The time history of the output value V of each sensor 122 during recording is recorded as an output waveform for each sensor 122. The time history of the output value V of each sensor 122 while the arms 103L and 103R perform the predetermined operation when there is an article P to be gripped within the movable range during operation is not limited to this. May be recorded as an output waveform for each sensor 122.

  The threshold value setting unit 166 sets a threshold value Dth that is a determination value for the presence or absence of abnormality in the comparison determination unit 164 based on input information input via the input device.

  The comparison determination unit 164 compares the reference waveform recorded for each sensor 122 in the reference waveform recording unit 163 and the output waveform recorded for each sensor 122 in the output waveform recording unit 167 for each sensor 122. By doing this, the difference (specifically, the absolute value of the difference) | D | between the reference waveform and the output waveform is calculated for each sensor 122. The difference | D | calculated for each sensor 122 is a threshold value Dth preset by the threshold value setting unit 166 for a certain period of time (in this example, while the arms 103L and 103R perform the predetermined operation once). Is counted for each sensor 122 (hereinafter referred to as “excess number N” as appropriate). Note that the fixed time is not limited to the time when the arms 103L and 103R perform a predetermined operation once, but may be a time set via an input device, for example. Then, by determining whether or not the excess number N counted for each sensor 122 exceeds the predetermined determination number Nj for each sensor 122, the presence or absence of abnormality of the actuators Ac2 to Ac15 of the arms 103L and 103R, etc. Determine. Details of the comparison determination unit 164 will be described later.

  The zero point adjustment unit 165 is a recording set by the section setting unit 162 in order to suppress the influence of the temperature drift of each sensor 122 caused by the fluctuation of the ambient temperature due to the heat generation of the actuators Ac2 to Ac15 of the arms 103L and 103R and the self-heating. Each time the arms 103L and 103R execute the predetermined operation corresponding to the section, a reset signal is output to each sensor 122, and zero adjustment of each sensor 122 is performed.

  FIG. 5 is an explanatory diagram for explaining details of the sensor units 120L and 120R, the high-pass filter unit 161, and the comparison determination unit 164. In FIG. 5, the reference waveform recording unit 163, the output waveform recording unit 167, and the like are not shown.

  In FIG. 5, as described above, the sensor portions 120 </ b> L and 120 </ b> R are provided on the inner side of the casing of the body portion 102, and the sensor fixing jig 121 and the sensor fixing jig 121 are formed in an annular shape. It is composed of three substantially rectangular parallelepiped sensors 122 provided. The sensor fixing jigs 121 of the sensor units 120L and 120R have openings 121A through which wires such as the actuators Ac2 to Ac15 provided on the arms 103L and 103R can be inserted at substantially the center. The three sensors 122 of the sensor unit 120L are the inner surface of the sensor fixing jig 121, that is, the surface that is not the mounting surface of the actuator Ac2 to the base of the stator (the left surface in FIG. 2, the paper surface in FIG. 5). Are arranged at substantially equal intervals on the substantially same circumference, and the sensors 122 are arranged in a radial direction. The three sensors 122 of the sensor unit 120R are the inner surface of the sensor fixing jig 121, that is, the surface that is not the mounting surface to the base of the stator of the actuator Ac9 (the right surface in FIG. 2, the paper surface in FIG. 5). Are arranged at substantially equal intervals on the substantially same circumference, and the sensors 122 are arranged in a radial direction.

  In the present embodiment, each sensor 122 is a force sensor having a piezoelectric body made of a material having a natural frequency (or rigidity) larger than that of the metal material, which is a structural material constituting each part of the arms 103L and 103R. Sensors using quartz as the body are used. In general, a force sensor having a larger natural frequency can detect a fluctuating force including a higher frequency component, and the crystal is more than the metal material that is a structural material constituting each part of the arms 103L and 103R. This is because the natural frequency (or rigidity) is large. Therefore, even minute high-frequency vibration (fast deformation) transmitted to the structural material of each part of the arms 103L and 103R can be detected.

  Each sensor 122 is not limited to a sensor using quartz as a piezoelectric body, and may be a force sensor having a piezoelectric body having a natural frequency larger than that of the structural material constituting each part of the arms 103L and 103R. Here, one sensor 122 detects a unidirectional strain generated in the sensor fixing jig 121, whereas abnormal vibrations caused by abnormalities in the actuators Ac2 to Ac15 of the arms 103L and 103R or a rotating member such as a speed reducer. The impact or the like is transmitted from a plurality of directions to the sensor fixing jig 121 through the structural material of each part of the arms 103L and 103R. Therefore, by providing the three sensors 122 in each sensor fixing jig 121 as described above, it is possible to detect strain in three directions generated in each sensor fixing jig 121. Each sensor 122 of the sensor unit 120L detects the amount of strain in the radial direction of the sensor fixing jig 121 caused by the force applied to the arm 103L as a voltage, and each sensor 122 of the sensor unit 120R is applied to the arm 103R, respectively. The amount of strain in the radial direction of the sensor fixing jig 121 caused by such force is detected as a voltage. The voltage obtained by each sensor unit 122 is amplified through the amplifier unit 123 and input to each high-pass filter 161A (described later) of the high-pass filter unit 161.

  The high-pass filter unit 161 includes a plurality of high-pass filters 161A (or a band-pass filter having a high-frequency band as a pass band) that can extract a high-frequency vibration component of the output signal of the sensor 122. The high-frequency vibration component of the output signal of each sensor 122 amplified through the amplifier unit 123 is extracted by 161A. Each high-pass filter 161A is cut so as to remove frequency components other than the frequency due to the abnormalities of the arms 103L and 103R (for example, frequency components due to events other than contact such as the operation of the actuators Ac2 to Ac15). The off frequency has been determined.

  As described above, the comparison determination unit 164 determines, for each sensor 122, whether or not the excess number N counted for each sensor 122 exceeds the determination number Nj, whereby the actuators Ac2- of the arms 103L and 103R. The presence / absence of an abnormality such as Ac15 is determined. Specifically, out of the excess number N related to each sensor 122, when the excess number N related to all the sensors 122 is within the determination number Nj, it is determined that there is no abnormality in the actuators Ac2 to Ac15, etc. When the excess number N related to any one of the sensors 122 exceeds the determination number Nj, it is determined that there is an abnormality in the actuators Ac2 to Ac15 and the like.

  The comparison determination unit 164 performs the determination while changing the determination number Nj according to the operating speed of the arms 103L and 103R. That is, when there are abnormalities due to deterioration over time in the rotating members such as the actuators Ac2 to Ac15 of the arms 103L and 103R and the speed reducer, and when the arms 103L and 103R are operated, periodic abnormal vibrations and impacts occur, the arm 103L , 103R when the operation speed is high, the number of periodic abnormal vibrations increases, and when the operation speed is low, the number of periodic abnormal vibrations decreases. For this reason, when the determination number Nj is set to a constant value, an erroneous detection of an abnormality may be caused depending on the operation speed. Therefore, in the present embodiment, the comparison determination unit 164 prevents the erroneous detection by making the above determination while changing the determination number Nj according to the operating speed of the arms 103L and 103R.

  FIG. 6 is an explanatory diagram for explaining a predetermined operation executed in a state in which the arms 103L and 103R are not abnormal and an output value V of the sensor 122 during that time.

  FIG. 6A schematically illustrates an example of a predetermined operation that is performed in a state where the arms 103L and 103R are not abnormal. In the example shown in FIG. 6A, the arms 103L and 103R are in a state where there is no abnormality in the arms 103L and 103R at the time of teaching, for example, and there is no article P to be grasped, and the surroundings of the robot 100 (arm 103L , 103R within a movable range) in an environment where no obstacle exists, that is, in a state where there is no object contact with the arms 103L, 103R, a predetermined operation according to the position command from the robot controller 150, that is, teaching The operation from the operation start position (position shown on the left side in FIG. 6A) to the taught operation completion position (position shown on the right side in FIG. 6A) is executed. The operation completion position is set to a position where the hands 111L and 111R can grip the smallest article P among the articles P conveyed by the belt conveyor 2.

  In FIG. 6B, the horizontal axis is time t, and the vertical axis is the output value V of the sensor 122, which is recorded in the reference waveform recording unit 163 corresponding to the operation shown in FIG. This shows an example of the reference waveform. In the example shown in FIG. 6 (b), the reference waveform recording unit 163 performs the operation shown in FIG. 6 (a) corresponding to the above-described recording section once while the arms 103L and 103R are not abnormal. A time history of the output value V of the sensor 122 is recorded as a reference waveform. The reference waveform can be recorded at any time as long as there is no abnormality in the arms 103L and 103R. However, in the present embodiment, a case of recording at the time of teaching a predetermined operation to the robot 100 will be described as an example.

  FIG. 7 is an explanatory diagram for explaining a predetermined operation performed by the arms 103L and 103R during operation and an output value V of the sensor 122 during the operation.

  FIG. 7A schematically illustrates an example of a predetermined operation performed by the arms 103L and 103R during operation. In the example shown in FIG. 7A, the arms 103L and 103R are in operation when there is no article P to be gripped within the movable range (for example, immediately after the start of conveyance of the article P or at the time of inspection performed by interrupting conveyance). Etc.) in the state where there is an abnormality due to aging deterioration in the rotating members such as the actuators Ac2 to Ac15 of the arms 103L and 103R and the speed reducer, the predetermined operation according to the position command from the robot controller 150, that is, the taught The operation from the operation start position (position shown on the left side in FIG. 7A) to the taught operation completion position (position shown on the right side in FIG. 7A) is executed. In the example shown in FIG. 7A, the arms 103L and 103R perform the predetermined operation when the article P to be grasped does not exist within the movable range as described above. Therefore, the operation is executed up to the operation completion position similar to FIG. 6A without holding the article P with the hands 111L and 111R. Although not shown, when there is an article P to be gripped, the arms 103L and 103R operate from the operation start position toward the inside from both sides of the article P on the belt conveyor 2, When the article P comes into contact with the arms 103L and 103R, the operation is stopped at that position, and the article P is held by the hands 111L and 111R.

  In FIG. 7B, the horizontal axis represents time t, and the vertical axis represents the output value V of the sensor 122, which is recorded in the output waveform recording unit 167 corresponding to the operation shown in FIG. An example of the output waveform is shown. In the example shown in FIG. 7B, the output waveform recording unit 167 includes the arms 103L and 103R in the state shown in FIG. 7A when the rotating members such as the actuators Ac2 to Ac15 and the speed reducer are abnormal due to aging. A time history of the output value V of the sensor 122 during one operation shown is recorded as an output waveform. Here, as shown in this example, when there is an abnormality due to deterioration over time in the rotating members such as the actuators Ac2 to Ac15 of the arms 103L and 103R and the speed reducer, the abnormal part periodically appears in the rotation phase. When 103L and 103R operate, periodic abnormal vibrations and impacts are likely to occur. Generally, when an abnormal vibration or impact occurs in the arms 103L and 103R, an impact force due to the abnormal vibration or impact is transmitted to the arms 103L and 103R, so that no abnormal vibration or impact occurs. In comparison, the output value V of the sensor 122 tends to increase. Therefore, when there is an abnormality or the like due to aging deterioration in the rotating members such as the actuators Ac2 to Ac15 and the speed reducer, there are periodically intervals in the output waveform where the output value V of the sensor 122 increases. In the output waveform shown in FIG. 7B, there are four sections in which the output value V of the sensor 122 increases periodically.

  FIG. 8 is an explanatory diagram for explaining an example of a method for detecting the presence / absence of an abnormality in the arms 103L and 103R. In FIG. 8 (a), the horizontal axis represents time t, the vertical axis represents the output value V of the sensor 122, and the reference waveform corresponding to FIG. 6 (b) is represented, and FIG. The output waveform corresponding to is shown. In FIG. 8B, time t is plotted on the horizontal axis and the difference | D | is plotted on the vertical axis, and the time series change of the difference | D | is represented by a waveform.

  8A and 8B, as described above, when the arms 103L and 103R are abnormal, there are periodically intervals in the output waveform where the output value V of the sensor 122 increases. Therefore, the two waveforms of the teaching reference waveform recorded in the reference waveform recording unit 163 and the output waveform during operation recorded in the output waveform recording unit 167 are compared with each other without any abnormality in the arms 103L and 103R. Thus, since it is possible to detect periodic fluctuations in the output waveform with respect to the reference waveform, it is possible to detect whether or not there is an abnormality in the actuators Ac2 to Ac15 of the arms 103L and 103R. That is, the number N of times that the difference | D | between the reference waveform and the output waveform exceeds the threshold value Dth while the arms 103L and 103R perform the predetermined operation once depends on the operating speed of the arms 103L and 103R. In addition, by determining whether or not the above-described determination number Nj has been exceeded, it is possible to determine whether there is an abnormality in the actuators Ac2 to Ac15. Specifically, when the excess number N is within the determination number Nj, it is determined that there is no abnormality in the actuators Ac2 to Ac15, and when the excess number N exceeds the determination number Nj, the actuators Ac2 to Ac15, etc. Can be determined to be abnormal. In the example shown in FIGS. 8A and 8B, the excess number N is “4” as shown in FIG. 8B. Therefore, when the determination number Nj is “3” or less, the actuator Ac2 It is determined that there is an abnormality in ~ Ac15 and the like.

  FIG. 9 is a flowchart showing a control procedure executed by the robot controller 150.

  In FIG. 9, the process shown in this flow is started by performing a predetermined operation start operation via an input device, for example. First, in step S10, the robot controller 150 determines whether the operation mode of the robot 100 is “teaching mode” in which teaching is performed or “operating mode” in which operation is performed based on input information input via the input device. It is determined whether or not the “teach mode” is set. If the operation mode of the robot 100 is the “teaching mode”, the determination in step S10 is satisfied, and the process proceeds to step S20.

  In step S20, the robot controller 150 sets the above-described recording section in the section setting unit 162 based on the input information input via the input device.

  Thereafter, in step S30, the robot controller 150 outputs the reset signal to each sensor 122 in the zero point adjustment unit 165 to adjust the zero point of each sensor 122.

  Then, the process proceeds to step S40, where the robot controller 150 calculates the motion command unit 151 based on the teaching information (information on the motion start position and motion completion position) for each of the arms 103L and 103R taught via the input device. Position commands for the actuators Ac1 to Ac15 are output to the actuators Ac1 to Ac15, so that the arms 103L and 103R are in an abnormal state and an object is not in contact with the arms 103L and 103R. 103R is caused to start a predetermined operation (see FIG. 6A) according to the position command.

  Thereafter, in step S50, the robot controller 150 starts recording the reference waveform for each sensor 122 in the reference waveform recording unit 163. Therefore, while the arms 103L and 103R perform the predetermined operation started in step S40 corresponding to the recording section set in step S20 in a state where there is no abnormality in the arms 103L and 103R and no object contact, The reference waveform recording unit 163 obtains the time history of the output value V of each sensor 122 based on the high-frequency vibration component amplified by the amplifier unit 123 and extracted by the high-pass filter 161A for each sensor 122. Record as.

  When the arms 103L and 103R move to the operation completion position, the process proceeds to step S60, and the robot controller 150 causes the arms 103L and 103R to complete the operation.

  Thereafter, in step S70, the robot controller 150 completes the recording of the reference waveform for each sensor 122 in the reference waveform recording unit 163. Then, the process shown in this flow ends. The process shown in this flow is executed by the robot controller 150 every time a predetermined operation start operation is performed via the input device.

  On the other hand, if the operation mode of the robot 100 is “operation mode” in step S10, the determination in step S10 is not satisfied, and the process proceeds to step S80.

  In step S80, the robot controller 150 sets the above-described threshold value Dth in the threshold value setting unit 166 based on the input information input via the input device.

  Then, the process proceeds to step S90, and the robot controller 150 performs the zero point adjustment of each sensor 122 in the zero point adjustment unit 165, similarly to step S30.

  Thereafter, in step S100, the robot controller 150 calculates each of the motion command units 151 calculated based on the teaching information (information of the motion start position and motion completion position) for each of the arms 103L and 103R taught via the input device. Position commands for the actuators Ac1 to Ac15 are output to the actuators Ac1 to Ac15, and when there is no article P to be gripped within the movable range of the arms 103L and 103R, the position commands are sent to the arms 103L and 103R. A predetermined operation (see FIG. 7 (a)) corresponding to is started.

  Then, the process proceeds to step S <b> 110, and the robot controller 150 starts recording the output waveform for each sensor 122 in the output waveform recording unit 167. Therefore, when the article P to be grasped does not exist within the movable range of the arms 103L and 103R, while the arms 103L and 103R perform the predetermined operation started in step S40, the output waveform recording unit 167 The time history of the output value V of each sensor 122 based on the high-frequency vibration component amplified through the amplifier unit 123 and extracted by the high-pass filter 161A is recorded as an output waveform for each sensor 122.

  Thereafter, when the arms 103L and 103R move to the operation completion position, the process proceeds to step S120, and the robot controller 150 causes the arms 103L and 103R to complete the operation.

  Then, the process proceeds to step S <b> 130, and the robot controller 150 completes the recording of the output waveform for each sensor 122 in the output waveform recording unit 167.

  Thereafter, in step S140, the robot controller 150 records the reference waveform recorded for each sensor 122 in the reference waveform recording unit 163 and the output waveform recording unit 167 for each sensor 122 in the comparison determination unit 164. The aforementioned difference | D | is calculated for each sensor 122 by comparing the output waveform for each sensor 122. The difference | D | calculated for each sensor 122 is equal to the threshold value Dth set in step S80 while the arms 103L and 103R perform the predetermined operation started in step S100 and completed in step S120 once. The excess number N of times exceeded is counted for each sensor 122. Then, by determining for each sensor 122 whether the excess number N counted for each sensor 122 exceeds the determination number Nj set according to the operating speed of the arms 103L, 103R, the arm 103L, 103R The presence or absence of abnormality of the actuators Ac2 to Ac15 is determined. Specifically, when the excess number N related to all the sensors 122 is within the determination number Nj, it is determined that there is no abnormality in the actuators Ac2 to Ac15 and the excess number N related to any one sensor 122 is When the number of determinations Nj is exceeded, it is determined that there is an abnormality in the actuators Ac2 to Ac15 and the like.

  Then, the process proceeds to step S150, and the robot controller 150 determines whether it is determined in step S140 that there is an abnormality in the actuators Ac2 to Ac15. If it is determined that there is no abnormality in the actuators Ac2 to Ac15, etc., the determination in step S150 is not satisfied, and the processing shown in this flow is terminated. On the other hand, if it is determined that there is an abnormality in the actuators Ac2 to Ac15, etc., the determination in step S150 is satisfied, and the process proceeds to step S160.

  In step S160, the robot controller 150 cuts off the output of the position command from the operation command unit 151 to the smoothing processing unit 153 in the position command cut-off unit 152, and generates the torque command Tref generated by the servo unit 154. Is output to each of the actuators Ac1 to Ac15 to stop the operation taught to the arms 103L and 103R, and the notifying unit (not shown) notifies the abnormality of the arms 103L and 103R to the outside. Thereafter, the processing shown in this flow is terminated.

  As described above, the robot 100 of this embodiment has the arms 103L and 103R, and the sensor fixing treatment provided at the bases of the actuators Ac2 and Ac9 located at the most proximal ends of the arms 103L and 103R. The tool 121 includes a sensor 122 having a piezoelectric body having a natural frequency higher than the structural material (metal material such as iron and aluminum in the above example) constituting each part of the arms 103L and 103R (in the above example, there are three sensors 122). ) Is provided. By using the sensor 122 as a sensor having a piezoelectric body having a natural frequency larger than that of the structural material constituting each part of the arms 103L and 103R, the following effects can be obtained. That is, when there is an abnormality due to deterioration over time in the actuators Ac2 to Ac15 of the arms 103L and 103R and a rotating member such as a speed reducer, periodic abnormal vibrations and impacts may occur when the arms 103L and 103R operate. . Therefore, by providing a sensor 122 having a piezoelectric body having a higher natural frequency than the structural material of each part of the arms 103L and 103R, high-frequency abnormal vibration and impact generated in the structural material of each part of the arms 103L and 103R due to the above abnormality. And the presence / absence of abnormality of the actuators Ac2 to Ac15 of the arms 103L and 103R can be detected, so that the functionality of the robot 100 can be improved.

  Furthermore, since the sensor 122 is provided at the base of the actuators Ac2 and Ac9 located on the most proximal side of the arms 103L and 103R, abnormal vibrations caused by all the actuators Ac2 to Ac15 and rotating members such as speed reducers on the distal end side, etc. Can be detected. That is, an abnormality can be detected for the entire arms 103L and 103R.

  In the present embodiment, the sensor fixing jig 121 is provided inside the casing of the body portion 102. Thereby, since each sensor 122 can be provided in a housing | casing, the damage of the sensor 122 by the contact of an object outside a housing | casing, a collision, etc. can be prevented. Further, there is an effect that the sensor 122 can be protected from droplets or dust outside the housing.

  In the present embodiment, in particular, three sensors 122 are provided in the sensor fixing jig 121. And three sensors are arrange | positioned at equal intervals on the same periphery, and each sensor 122 is arrange | positioned so that it may become radial direction. By providing three sensors 122, it is possible to detect strains in three directions generated in the sensor fixing jig 121, and to detect abnormal vibrations, impacts, and the like with high accuracy. In addition, by arranging the three sensors 122 on the same circumference at equal intervals and in a radial direction, the detection sensitivity of the sensors 122 is substantially uniform in the circumferential direction without biasing the detection sensitivity in one direction. can do. Accordingly, it is possible to detect abnormal vibrations, shocks, and the like transmitted from a plurality of directions to the sensor fixing jig 121 through the structural material of each part of the arms 103L and 103R with high accuracy.

  In the present embodiment, in particular, the sensor fixing jig 121 is formed in an annular shape having an opening 121A in the approximate center. The sensor fixing jig 121 located on the base end side of the arms 103L and 103R is formed in an annular shape having an opening 121A in the approximate center, thereby wiring the actuators Ac2 to Ac15 and the like of the arms 103L and 103R. The tool 121 can be inserted into the opening 121A (toward the body portion 102) and drawn. As a result, the wiring can be routed without being exposed to the outside of the housing, so that the wiring can be protected and the appearance of the robot 100 can be improved.

  In the present embodiment, in particular, each sensor 122 is a sensor using quartz as a piezoelectric body. As a result, it is possible to reliably detect high-frequency abnormal vibrations and shocks generated in the structural materials of the respective parts of the arms 103L and 103R due to abnormalities due to aging of the rotating members such as the actuators Ac2 to Ac15 of the arms 103L and 103R and the reduction gear. Therefore, the presence or absence of abnormality of the actuators Ac2 to Ac15 of the arms 103L and 103R can be detected with higher accuracy.

  The present invention is not limited to the above-described embodiment, and various modifications can be made without departing from the spirit and technical idea of the present invention. Hereinafter, such modifications will be described.

(1) When applied to object contact detection In the above embodiment, the robot of the present invention is applied to the abnormality detection of the arms 103L and 103R. However, the present invention is not limited to this. It may be applied to contact detection.

  In this modification, a contact detection unit (not shown) of the robot controller 150 detects the presence or absence of an object contact with the arms 103L and 103R based on the output value V (output signal) of each sensor 122 of the sensor units 120L and 120R. . In this specification, an object that can be recognized as “thing” is defined as an object. Therefore, the object includes an article P to be grasped by the robot 100, the robot 100 itself, a work device such as the belt conveyor 2 described above, a part of a building such as a wall, a living body such as a human body, and the like.

  Here, as described above, the sensors 122 of the sensor units 120L and 120R detect the force applied to the arms 103L and 103R. As the force applied to the arms 103L and 103R, an internal force generated by the operation of the arms 103L and 103R itself and an external force acting on the arms 103L and 103R from the outside can be considered. While the arms 103L and 103R operate in a state where there is no object contact as shown in FIG. 6A, no external force is applied to the arms 103L and 103R, so that each sensor 122 is caused by an internal force. Only vibration is detected. On the other hand, when an object comes into contact with the arms 103L and 103R, an external force acts on the arms 103L and 103R in addition to an internal force, so that each sensor 122 detects a vibration caused by the internal force and the external force. For this reason, when an object contacts the arms 103L and 103R, the output value V of the sensor 122 increases by the amount caused by the external force. Therefore, in this modification, the contact detection unit performs the predetermined operation in a state where the arms 103L and 103R perform a predetermined operation during operation and the arms 103L and 103R are not in contact with an object. The presence or absence of contact of an object with the arms 103L and 103R is determined by comparing the reference waveform recorded in advance as the output value V of the sensor 122 during the process.

  FIG. 10 schematically illustrates an example of a predetermined operation performed by the arms 103L and 103R during operation. In the example shown in FIG. 10, the arms 103L and 103R are operated by the position command from the robot controller 150 in an environment where the obstacle B exists around the robot 100 (within the movable range of the arms 103L and 103R). A predetermined operation corresponding to the above-described operation, that is, the operation from the taught operation start position (the position shown on the left side in FIG. 10) to the taught operation completion position is executed. At this time, the contact detection unit determines whether or not an object is in contact with the arms 103L and 103R using the above-described method. Then, the arms 103L and 103R move inward from both sides of the article P on the belt conveyor 2 (not shown in FIG. 10) from the operation start position to the inside until the operation completion position is reached by the contact detection unit. When contact of an object (in this example, an obstacle B) with 103L, 103R is detected, the robot controller 150 stops the operation of the arms 103L, 103R at that position (the position shown on the right side in FIG. 10).

  In this example, the case where the contact of the obstacle B with the arms 103L and 103R is detected and control is performed so as to stop the operation when the contact is detected is described as an example. It is also possible to detect the contact of the article P with respect to the 103L and 103R, stop the operation when the contact is detected, and control the gripping of the article P with the hands 111L and 111R.

  Also in this modification, the same effect as the above embodiment can be obtained. Further, since the external force acting on the arms 103L and 103R can be detected by the sensor 122, it is possible to detect the presence or absence of an object contact with the arms 103L and 103R. Further, as described above, since the sensor 122 is provided at the base of the actuators Ac2 and Ac9 located on the most proximal side of the arms 103L and 103R, the contact at the distal end side can be detected. That is, contact can be detected for the entire arms 103L and 103R. Therefore, it is possible to avoid an excessive load on the robot 100 itself or an object existing around the robot 100.

(2) When applied to a single-arm robot In the above description, the present invention has been applied to the robot 100 which is a dual-arm robot having two arms 103L and 103R. However, the present invention is not limited to this, and the present invention is applied to one robot. You may apply to the single arm robot which has an arm. Also in this case, the same effects as those of the above embodiment and the modified example (1) can be obtained.

  In addition to those already described above, the methods according to the above-described embodiments and modifications may be used in appropriate combination.

  In addition, although not illustrated one by one, the present invention is implemented with various modifications within a range not departing from the gist thereof.

100 robot 103L, R arm (robot arm)
121 sensor fixing jig 121A opening 122 sensor (strain sensor)
Ac2-15 Actuator

Claims (6)

A robot arm,
One or more actuators provided on the robot arm for driving the robot arm;
A sensor fixing jig provided at the base of the actuator located on the most proximal side of the robot arm;
A plurality of piezoelectric bodies that are arranged on the sensor fixing jig on substantially the same circumference, are provided so that their longitudinal directions are radially oriented, and have a higher natural frequency than the structural material constituting the robot arm. And a strain sensor. The sensor fixing jig is
The robot according to claim 1, wherein the robot is provided inside a case of the robot arm or inside the case of the robot. The strain sensor is
The robot according to claim 1, wherein at least three sensor fixing jigs are provided. The at least three strain sensors are:
4. The robot according to claim 3, wherein the robot is arranged at equal intervals on the same circumference, and the strain sensors are arranged in a radial direction. The sensor fixing jig is
The robot according to any one of claims 1 to 4, wherein the robot is formed in an annular shape having an opening in the center. The strain sensor is
The robot according to any one of claims 1 to 5, wherein the sensor uses a crystal as a piezoelectric body.

Images