JP6672637B2 - Sensor position determination method, robot - Google Patents

Description

  The present invention relates to a method for determining a sensor position when installing a sensor for detecting vibration of a robot, and a robot.

  In the field of robot control, it is common practice to simulate the behavior of a modeled robot in advance and apply a desired simulation result, for example, a control content having a desired vibration suppression effect, to an actual robot. . Also, various studies have been made on vibration suppression control for suppressing the vibration of the robot. For example, Patent Documents 1 and 2 propose a control device that can operate the robot while suppressing the vibration.

Japanese Patent No. 4038659 Japanese Patent No. 5411687

  By the way, in a simulation, when a control content that has obtained a desired vibration suppression effect is applied to an actual robot, performance as simulated may not be exhibited. Specifically, vibrations that did not appear in the simulation may occur at a level that is too large to be treated as an error. Here, the vibration of the hand of the robot, for example, in the case of a 4-axis horizontal articulated robot (SCARA (Selective Compliance Assembly Robot Arm) type robot), the vibration of the tip of the shaft such as a ball screw spline is assumed. .

  At this time, if a sensor for detecting the vibration can be provided at the hand of the robot, the vibration can be detected directly, so that it is considered that the control for suppressing the vibration can be performed correctly. Note that any sensor that detects vibration, such as acceleration, speed, inclination, and inertia, may be used as long as it can directly or indirectly detect vibration.

However, providing a sensor at the hand of the robot is more difficult than generally imagined.
For example, when a wired sensor is provided at the hand of the robot, since the hand is located at the tip of the shaft as described above, it is necessary to wire a sensor cable via the arm and the shaft. At this time, it is not only necessary to simply wire the cable, but a protection member such as a so-called cable reel is required to protect the cable from rotation of each arm, rotation of the shaft, and vertical movement. That is, even if it is relatively easy to provide the sensor at the hand, there is a problem that the wiring structure such as the routing of the cable and the installation of the protection member is complicated.

  On the other hand, if a wireless sensor is used, it is considered that the wiring structure can be prevented from becoming complicated. However, when a wireless sensor is provided at the user's hand, it is not easy to supply or charge the sensor during operation of the robot, and wireless communication may be interrupted due to noise. Then, if the communication is interrupted, there is a problem that the robot itself cannot be controlled.

  And as a fundamental problem, it is not clear what mechanism causes the vibration of the hand of the robot to occur, so if any physical quantity is detected at which position of the robot, the vibration related to the vibration of the hand will be detected. It is not clear whether it can be detected.

  The present invention has been made in view of the above circumstances, and an object of the present invention is to detect a vibration of a robot that does not appear in a conventional simulation while preventing a wiring structure when a sensor is provided from becoming complicated. It is an object of the present invention to provide a sensor position determining method and a robot that can perform the method.

  In the field of robot control, a so-called two-inertial-system simulation that takes into account a vibration mode caused by a spring element existing in a speed reducer between a motor and an arm is used. This vibration mode is vibration caused by rigidity in the operation direction of a power transmission mechanism that transmits power such as a speed reducer. In addition, the simulation of the two-inertia system is widely used, and its effectiveness is considered to be recognized.

  At this time, mechanical values such as the rigidity of the arm are naturally included in the simulation conditions, and the actual robot is designed within a range of the mechanical values satisfying the simulation conditions. Nevertheless, the fact that vibration occurs in the robot is considered that there is a vibration mode different from the vibration mode considered in the conventional two inertial system.

  As a result of repeated investigations into the causes of the vibration, the inventors have found that in an actual robot, the vibration due to the rigidity in the operation direction of the power transmission mechanism in the vibration mode of the two inertial system (hereinafter referred to as the operation direction vibration for convenience) In addition to the above, it has been found that there is vibration (the above-mentioned non-operation direction vibration) different from the operation direction of the power transmission mechanism. In other words, it is possible to determine that non-operating direction vibration in a direction different from the operating direction is the cause of vibration that did not appear in the simulation, and that the non-operating direction vibration caused the movable part side of the robot to oscillate as a whole in directions other than the operating direction. As a result, they found that the hands were vibrating.

  By the way, if the existence of the non-operating direction vibration has been recognized so far, a control method for dealing with the non-operating direction vibration should be considered. However, in practice, no consideration has been given to suggesting the existence of non-operational direction vibration, nor to a control method or the like for suppressing non-operational direction vibration. That is, it is considered that the non-motion direction vibration has not been recognized until now. Therefore, the inventors considered why non-movement-direction vibration has not been considered.

  The first industrial robots were much thicker and sturdier than arms in recent years, such as arms, gears, and bearing members, but the overall weight of the arms and movable parts was relatively large. Was. In the case of a two-inertia system, the resonance frequency is proportional to the square root of the reciprocal of the inertia (that is, weight), so that the resonance frequency of the operation direction vibration is low. On the other hand, it is considered that the members and the like constituting the arm are formed with extremely high rigidity, and the resonance frequency has been increased even if non-operational resonance exists.

  In general, when there are a plurality of resonances, the influence of resonance having a low resonance frequency is often dominant. In other words, it is considered that the resonance in the non-operating direction has a relatively high resonance frequency, so that the influence on the position response and the speed response of the arm is negligibly small. In addition, as a result of the inventors' research, it has been found that the cause of the non-moving direction vibration is the presence of a force applied in the non-moving direction, such as a centrifugal force. It is considered that the influence of the centrifugal force was so small that it could be ignored because the operation speed was relatively slow as compared with.

  On the other hand, in recent robots, the design has been changed from a direction in which the arm is made thick and sturdy to a direction in which the arm is made thinner and lighter. That is, while the arm has been reduced in weight, the members constituting the arm have a lower rigidity than the first robot. Although the rigidity has been reduced, the arm itself, which is called a flexible arm, is not twisted.For example, a minute vibration is generated in a direction other than the rotation axis by a shaft supporting portion such as a cross roller. It is happening.

  For this reason, the dominant resonance has been replaced with the earliest robot in the state where there are multiple resonances, or the resonances of both have become close to the resonance frequency and have come to a state where they influence each other Conceivable. Furthermore, in the case of recent robots, the operation speed is significantly higher than that of the earliest robots, and it is considered that the effect of the centrifugal force proportional to the square of the speed has appeared more remarkably.

  For example, in the case of a four-axis horizontal articulated robot, a support part that directly moves the third axis (corresponding to the shaft) in the vertical direction (Z direction) is, for example, the second axis (corresponds to the second arm). It has been confirmed that it vibrates in conjunction with the movement of ()). In this case, vibration different from vibration in the movement direction of the shaft (included in the operation direction vibration), such as vibration due to inter-axis interference, specifically, the circumferential direction of the second arm (the operation direction of the second arm) ) And a vibration in the diameter direction of the second arm (the direction of the centrifugal force applied to the second arm). In addition, in a robot of another configuration such as a 6-axis vertical articulated robot (PUMA (Programmable Universal Manipulation Arm) type robot) or a so-called 7-axis robot, a non-motion direction vibration occurs due to a similar phenomenon. doing.

  Further, in an industrial robot, a plurality of arms are often connected to form a robot. As a result, a phenomenon occurs in which one axis vibrates and another axis interferes and vibrates. For this reason, the vibration characteristics themselves are not as clear as a simple two-mass system model, and multiple resonance vibrations appear in the frequency specification, and the resonance frequency that appears in the frequency characteristics and the actual vibration waveform There may be a slight difference from the resonance frequency that appears in For this reason, it is considered that it was difficult to find out that the non-operation direction vibration caused the non-operation direction vibration even if the non-operation direction vibration was present.

  Furthermore, although the vibration frequency is often different between the operating direction vibration and the non-operating direction vibration, if, for example, a wave gear device is used as the speed reducer, its rigidity may change according to the input torque. Since there are various factors that cause a modeling error, such as being known, it is considered that no one came to the non-operational direction vibration and was simply treated as an error.

  Under these circumstances, among the vibrations that appeared on the simulation, the one with the greatest influence was treated as the operating direction vibration, and the others were treated as errors such as interference from other axes. It is probable that no consideration has been given to this. In other words, the non-operating direction vibration was not so remarkable in the earliest robots, and the non-operating direction vibration was treated as an error in recent robots, which is the reason that the non-operating direction vibration was not recognized. It was speculated.

  The existence of such non-movement-direction vibrations may be caused by a two-inertia model, which is a prerequisite for the conventional simulation, or a four-inertia model described in Patent Document 1, which is an extension of the two-inertia model including interference. The control model shows that the actual vibration characteristics of the robot could not be expressed in the first place, and has extremely important technical significance.

  By the way, if the existence of the non-operating direction vibration is found, if the control to suppress the vibration caused by the non-operating direction vibration is performed, it is possible to suppress the hand-side vibration that did not appear in the simulation. It is thought that it is possible.

  In the case of a recent robot, for example, residual vibration (movement in the operating direction) that occurs in the rotational direction, such as when a stationary arm is rotated at high speed and stopped, can be detected by an encoder. The operation direction vibration can be made to converge by applying. However, even in recent robots, since the non-operation direction vibration is not taken into account, there is no means for detecting the vibration other than the rotation direction in the first place, and the non-operation direction vibration itself cannot be detected. For this reason, the configuration is such that neither the control for converging the non-operation direction vibration nor the control can be performed.

  In this case, if a sensor for detecting vibration is provided at the hand of the robot, control for converging vibration including non-operational vibration can be performed, but as described above, it is not possible to provide a sensor at the hand of the robot. It is difficult, and it is not preferable that the wiring structure is complicated due to the provision of the sensor.

  Here, it is important that the movable part side of the robot is entirely shaken by the vibration in the non-operational direction found by the inventors. That is, if the hand is vibrated due to the non-operational direction vibration, the hand-side vibration can be detected directly or indirectly by detecting the non-operational direction vibration in the movable part.

  Therefore, in the invention according to the first aspect, in the arm that is attached to a predetermined attachment position with respect to the base and that operates relatively to the base, a direction different from the operation direction when the arm operates. A first sensor and a second sensor for detecting a non-operating direction vibration generated in a direction different from the operation direction of the arm in the specified range; and attaching the second sensor to the first sensor. It is provided at a position separated from a virtual line passing through the position.

The arm attached to the base is supported at a position where the arm is attached to the base. Therefore, when the movable part side of the robot vibrates as a whole due to the non-operational direction vibration, the arm vibrates around the mounting position on the base.
Therefore, if it is on the distal end side of the arm with respect to the mounting position with respect to the base, it is possible to detect the vibration caused by the non-operational vibration. That is, a range in which the tip end side of the arm vibrates in a direction different from the operation direction with respect to the mounting position. In view of the fact that the non-operational direction vibration causes a vibration different from the operation direction at the hand, the vibration of the hand can be detected by detecting the non-operational direction vibration generated at the arm.

By the way, the arm can be considered to be supported at the mounting position. Therefore, when the arm is twisted by the operation of the robot, the twist causes an error for the sensor that detects the non-operation direction vibration. Therefore, by providing a plurality of first sensors and second sensors, it is considered that the torsion can be corrected based on data detected by each sensor.
However, since the arm is twisted around a virtual line extending along the arm passing through the mounting position when viewed from the distal end side, the correction may not be possible depending on the position where the first sensor and the second sensor are provided.

  Therefore, by making data detected when the arm is twisted different from the first sensor and the second sensor, that is, the second sensor is separated from a virtual line passing through the first sensor and the mounting position. In this case, a difference occurs between the data (eg, angular acceleration) detected by the first sensor and the data (eg, angular acceleration) detected by the second sensor. Can be corrected. That is, it is possible to improve the accuracy in detecting the non-operation direction vibration.

  The first sensor and the second sensor are provided on an arm attached to the base. For this reason, the length of the cable connecting the sensor can be shortened, and the number of joints that pass through is reduced as compared with the case where the sensor is provided at the hand, so that the number of protection members for protecting the cable can be minimized. Thereby, the routing of the cable can be facilitated and the wiring structure can be simplified.

  Therefore, by providing the sensor at the sensor position determined based on such a technical idea, it is possible to prevent the wiring structure at the time of installing the sensor from being complicated, and to prevent the hand vibration which does not appear in the conventional simulation. And the non-operational direction vibration correlated with the hand vibration can be detected.

  The invention described in claim 2 is based on a technical idea common to the invention described in claim 1 described above, and includes an arm attached to a base and operating relatively to the base. , And a first sensor and a second sensor for detecting non-operational vibration generated in a direction different from the operation direction of the arm. The second sensor is provided at a position separated from a virtual line passing through the first sensor and the mounting position.

  This makes it possible to accurately detect non-operational vibration occurring in a direction different from the operation direction of the arm and to reduce the possibility that the wiring structure is complicated, and the like. The same effect as described above can be obtained. At this time, the robot can adopt any configuration such as a 6-axis vertical articulated robot, a so-called 7-axis robot, or a 4-axis horizontal articulated robot.

  In this case, by providing the first sensor and the second sensor at positions symmetrical with respect to a virtual line extending in the direction along the arm passing through the mounting position, as in the invention described in claim 3. Since the numerical values used in the calculation are shared, the calculation for correcting the error due to the torsion can be simplified, and the processing speed in controlling the robot can be expected to be improved.

  More specifically, in the horizontal articulated robot, for example, in the horizontal articulated robot, the first sensor and the second sensor are located on the second arm side of the first arm with respect to the first axis. With this arrangement, it is possible to detect a non-operational vibration generated in a direction different from the operation direction of the first arm. Further, since the first arm is attached to the base, the cable length for connecting each sensor can be shortened, and the joint portion through which the cable passes is only the first axis, so that the wiring structure is reduced. Complexity can be prevented.

FIG. 1 is a diagram schematically illustrating a configuration of a robot system according to a first embodiment. Diagram schematically showing sensor position The figure which shows typically the Ry rotation which occurs in a 1st arm, and the detail of a sensor position. The figure which shows typically an example of the operation direction detected when a sensor axis | shaft is shifted. The figure which shows the example of another sensor position typically Diagram showing an example of a sensor position where correction due to torsion is difficult

Hereinafter, embodiments of the present invention will be described with reference to FIGS. 1 to 6.
As shown in FIG. 1, the robot system 1 includes a robot 2 and a control device 3 for controlling the robot 2. In the present embodiment, as the robot 2, a base 4, a first arm 5 attached to the base 4 and rotating about a first axis (J1) with respect to the base 4, attached to the first arm 5, A second arm 6 that rotates about a second axis (J2) with respect to the first arm 5; a shaft 7 that is attached to the second arm 6 and that moves up and down and rotates with respect to the second arm 6; A horizontal articulated robot having

  In this embodiment, the shaft 7 is assumed to be a ball screw spline. In this case, the hand of the robot 2 corresponds to a lower end side of the shaft 7, that is, a portion that moves relatively vertically with respect to the second arm 6 and rotates relatively with respect to the second arm 6. I do. Note that the shaft 7 is designed to have extremely high rigidity, and it is unlikely that the shaft 7 itself bends or deforms.

  Hereinafter, as shown in FIG. 1, the vertical direction coaxial with the first axis (J1) is the Z axis (Z direction), the direction orthogonal to the Z axis is the X axis (X direction), and the Y axis (Y direction), respectively. It will be described as. In addition, rotation around the Z axis shown in FIG. 1 is referred to as Rz rotation, rotation around the X axis is referred to as Rx rotation, and rotation around the Y axis is referred to as Ry rotation.

  In this case, when the first arm 5 is taken as an example, the Rx rotation means a state in which the first arm 5 rotates around the X axis around the connection position with the base 4 in the state shown in FIG. , The first arm 5 corresponds to a twisted state. Further, in the case of the first arm 5 as an example, the Ry rotation means that the first arm 5 rotates around the Y axis with the connection position with the base 4 as the center of rotation (C1; see FIG. 3) in the state shown in FIG. This state corresponds to a state in which the tip of the first arm 5 bows, more simply. When the posture of the robot 2 changes from the state shown in FIG. 1, the correspondence between the X axis and the Y axis also changes, but in this specification, the state shown in FIG. The rotation in which the tip of the first arm 5 bows will be described as Ry rotation.

  As shown in FIG. 2, the robot 2 has a sensor 8 (corresponding to a first sensor) and a sensor 9 (corresponding to a second sensor). In the present embodiment, the sensor 8 and the sensor 9 use a wired acceleration sensor connected by a cable, although not shown. These sensors 8 and 9 indirectly detect the vibration of the first arm 5 (more precisely, the non-operating direction vibration) by detecting the acceleration applied in a direction different from the operation direction of the first arm 5. I do. In the case of the present embodiment, the sensor 8 and the sensor 9 detect acceleration applied to the first arm 5 in the Z direction as a direction different from the operation direction of the first arm 5 (non-operation direction).

  Although not shown, the first arm 5 provided with the sensor 8 and the sensor 9 is formed in a hollow shape, and a structure such as a wiring and a bearing is provided therein. The sensor 8 and the sensor 9 are provided on the bottom surface of the hollow portion in the first arm 5. The sensors 8 and 9 are not limited to the acceleration sensors, but may be any sensors that can directly or indirectly detect vibration, such as a speed sensor, a tilt sensor, and an inertial sensor.

  As shown in FIG. 2 (side view), the sensor 8 and the sensor 9 are arranged such that the sensor 8 is located at a distance L1 and the sensor 9 is located at a distance L2 (from the first axis (J1) to the distal end of the first arm 5) In the present embodiment, they are provided at positions separated by L1 = L2). In the present embodiment, the distance L1 is defined as the distance to the center of the sensor 8. That is, the sensor 8 and the sensor 9 are located on the tip side of the arm (here, the first arm 5) relative to the mounting position with the base 4 (here, the first axis (J1)) (more specifically, the arm). The second shaft is located closer to the second shaft than the first shaft. In the present embodiment, the distances L1 and L2 are defined as distances to the center lines (SL) of the sensors 8 and 9.

  Further, as shown in FIG. 2 (in plan view), the sensor 8 and the sensor 9 pass through a first axis (J1) and a second axis (J2), and extend in a virtual direction along the longitudinal direction of the first arm 5. It is provided at a position symmetrical with respect to the line (the straight line CL1 in the present embodiment) (a position where θ1 = θ2 in FIG. 3 (plan view) described later). Although the first axis (J1) is shown as a point or a line in FIG. 2 for simplicity, the first axis is actually configured by a shaft member such as a shaft member. Therefore, in the present embodiment, the virtual line passing through the first axis (J1) is assumed to pass through the range of the diameter of the shaft member.

Next, the operation of the above configuration will be described.
As described above, when a simulation is performed using a conventional two-inertia model, even if a desired vibration suppression effect is obtained in the simulation, vibrations may occur at the hands of the actual robot 2. Therefore, first, at which position of the robot 2 can observe the hand vibration, more specifically, the vibration (non-operating direction) generated in a direction different from the operating direction instead of the vibration (operating direction vibration) generated in the operating direction. Let's consider

  The non-operating direction vibration is a state in which not only the shaft 7 is vibrating but also the whole operating part of the robot 2 is shaking in a direction other than the operating direction. Therefore, it is considered that the hand vibration is correlated with the local vibration that can be observed at each part of the robot 2. However, since the base 4 is firmly fixed to the installation surface and is considered to be a fixed end, it is unlikely that hand vibration is detected. Therefore, in order to detect hand vibrations, it is considered necessary to provide a sensor closer to the hand than the first axis (J1) where the first arm 5 is attached.

  Now, when the robot 2 is vibrating as a whole, it is also the hand, that is, the tip of the shaft 7, that can most accurately detect the hand vibration. However, as described above, since the shaft 7 moves relatively to the second arm 6, if a sensor is provided on the shaft 7, the cable may expand and contract or may be rubbed. From a viewpoint, it is not preferable to provide a sensor on the shaft 7. Therefore, it is considered desirable to provide a sensor on the first arm 5 or the second arm 6.

  Here, the case where a sensor is provided on the first arm 5 and the case where a sensor is provided on the second arm 6 will be compared. Since the first arm 5 is closer to the base 4 than the second arm 6, by providing a sensor on the first arm 5, the cable length can be reduced. Further, since the second arm 6 rotates relatively to the first arm 5, when a sensor is provided on the second arm side, a protection structure such as a cable reel for protecting the cable from the rotation operation of the second arm 6 is provided. Is required. Usually, a motor for driving the second arm 6 is often provided in the second arm 6 to secure a working area below the first arm 5. There is a concern that it is difficult to secure a space for installing reels and the like.

  Further, since members such as a motor and a bearing are provided in a concentrated manner at the joint portion, the wiring structure becomes more complicated as the joint passes. At this time, if two sensors 8 and 9 are provided as in the present embodiment, the wiring structure may be further complicated. Therefore, from the viewpoint of simplifying the wiring structure when providing the sensor, it is considered desirable to provide the sensor 8 and the sensor 9 on the first arm 5.

Next, when the sensor 8 and the sensor 9 are provided on the first arm 5, consideration will be given to where to provide the sensor 8 and the sensor 9 on the first arm 5.
As shown in FIG. 3 (side view), when the first arm 5 rotates Ry (vibrates in the non-operating direction), the displacement amount (Z), that is, the magnitude of the acceleration increases. Therefore, when only the first arm 5 is viewed, it is considered that the acceleration can be detected with higher accuracy as the distance L between the sensors 8 and 9 and the first axis (J1) increases. In FIG. 3, the rotation angle of the first arm 5 is indicated as Ry.

  Now, since the first arm 5 is attached to the base 4 with the first axis (J1), it can be considered that the first axis (J1) is a fixed end. In this case, when the first arm 5 is twisted, the sensors 8 and 9 respectively detect the torsional component (displacement due to torsion). Then, the torsion component becomes an error when detecting the acceleration caused by the Ry rotation.

  Here, as shown in FIG. 4, the angle θ3 formed by a line segment passing through the sensor 8 and the first axis with respect to the virtual line (CL1), and the sensor 9 with respect to the virtual line (CL1). Let us consider a case where the angle θ4 formed by a line segment passing through the first axis is different. In this case, the actual Rx rotation direction of the first arm 5 is the direction shown by the arrow F1, and the actual Ry rotation direction is the direction shown by the arrow F2. However, since the sensor axis (SL, a straight line passing through the center between the sensor 8 and the sensor 9) is deviated from the virtual line (CL1), what is directly detected from the data of the sensors 8 and 9 is that , Rx rotation direction is the direction shown by arrow F10, and the Ry rotation direction is the direction shown by arrow F20.

  In this case, although the data can be corrected based on the information on the installation positions of the sensors 8 and 9 such as the distance from the first axis and the above-described θ3 and θ4, processing time is required for the correction. Become.

  Therefore, in the present embodiment, as shown in FIG. 3 (in plan view), the angle θ1 formed by a line segment passing through the sensor 8 and the first axis with respect to the virtual line (CL1) and the virtual line (CL1) has the same value (the same absolute value) as the angle θ2 formed by the line segment passing through the sensor 9 and the first axis, and the distance D1 from the virtual line (CL1) to the sensor 8 is the same as the angle D2. The distance D2 from the typical line (CL1) to the sensor 8 has the same value (the same absolute value).

  As a result, it is not necessary to perform correction due to the deviation of the sensor axis (SL), so that the processing time can be shortened and data loss due to the correction (that is, a decrease in accuracy) can be prevented.

Here, it is defined as follows.
Z1: displacement amount of the sensor 8 on the circumference of a circle having a radius of L1 when the first arm 5 rotates around the Y direction as a rotation axis.
Z2: displacement of the sensor 9 on the circumference of a circle having a radius of L2 when the first arm 5 rotates around the Y direction as a rotation axis.
Ry1: a rotation angle of the sensor 8 when the first arm 5 rotates around the Y direction as a rotation axis.
Ry2: a rotation angle of the sensor 9 when the first arm 5 rotates around the Y direction as a rotation axis.
Ry: a rotation angle of the first arm 5 when the first arm 5 rotates around the Y direction as a rotation axis.
Rx: the rotation angle of the first arm 5 when the first arm 5 rotates about the X direction as the rotation axis (the torsion component of the first arm 5).

At this time, since L1 and L2 are sufficiently larger than Z1 and Z2, the following equations (1) to (3) are established.
In equation (1) and each of the equations described later, the differentiation is expressed in Newton's notation. One dot symbol (“•”) indicates the first derivative with respect to time and two dot symbols. Shows the second derivative with respect to time. Due to the available character types, for example, the left side of equation (1) is referred to as "second derivative of Z" or "Z" for convenience. explain. The "second derivative of Z" corresponds to the second derivative of the displacement amount, that is, the angular acceleration in the present embodiment. In each formula, in order to clarify the formula, for example, the distance L1 is represented as “L ₁ ” with “1” as a subscript, and D2 is represented with “2” as a subscript. It is shown as “D ₂ ” as a character.

  In addition, the following equation (4) holds.

  From the expressions (1) to (4), the relationship of the following expression (5) is obtained.

  When this equation (5) is expanded, the following equations (6) and (7) are obtained.

  In the case of this embodiment, L1 and L2 have the same value (the same absolute value), and D1 and D2 also have the same value (the same absolute value). Expression is found.

  Therefore, as shown in the following equations (11) and (12), the second derivative of Rx (angular acceleration of Rx rotation) and the second derivative of Ry (angular acceleration of Ry) are obtained from the difference between the data detected by the sensors 8 and 9. Ry rotation angular acceleration).

Then, by integrating the angular acceleration of the Ry rotation, the angular velocity at the time of the Ry rotation and further, the rotation angle (Ry) at the time of the Ry rotation can be obtained. That is, the sensors 8 and 9 can detect non-operational vibrations in the first arm 5 that are correlated with hand vibrations.
By now, the sensors 8 and 9 are provided in the regions S1 and S2 on the distal end side with respect to the second axis (J2) as shown in FIG. In this case, as shown in FIG. 3, since the displacement amount in the Z direction becomes large, it is expected that the accuracy is further improved if the sensor has the same resolution.

  However, since a bearing is provided in the first arm 5 at a position corresponding to the second shaft, it may be difficult to route a cable around the bearing. In such a case, for example, as shown in FIG. 5B, the sensors 8 and 9 are provided in the regions S3 and S4 on the near side (between the first axis and the second axis) with respect to the second axis. Is also good. Accordingly, it is not necessary to bypass the bearing of the second shaft, and the wiring structure can be simplified.

  In addition, since the structure inside the first arm 5 may be different depending on the robot 2, for example, if the structure can secure a space below the virtual line (CL 1) in the drawing, FIG. As shown in (1), the sensors 8 and 9 may be provided below the virtual line (CL1) in the figure. In addition, if the configuration is such that a space for wiring can be secured by avoiding the bearing above the virtual line (CL1) in the figure, as shown in FIG. It may be provided in the area S1. Further, as shown in FIG. 5E, both the sensor 8 and the sensor 9 may be provided in the region S4.

According to the embodiment described above, the following effects can be obtained.
In the embodiment, the first arm 5 attached to the base 4 at a predetermined attachment position (rotation center (C1) on the first axis) and operating relatively to the base 4 includes the first arm 5. When the arm 5 operates, a range in which the arm 5 vibrates in a direction different from the operation direction (a range closer to the tip end than the first axis (J1)) is specified. A sensor 8 (first sensor) and a sensor 9 (second sensor) for detecting non-operational direction vibrations generated in different directions are provided, and the sensor 9 is separated from a virtual line passing through the sensor 8 and the mounting position. Is provided.

The first arm 5 attached to the base 4 is supported at a position where the first arm 5 is attached to the base 4. Therefore, when the movable portion side of the robot 2 vibrates as a whole due to the non-operational direction vibration, the first arm 5 vibrates about the position of attachment to the base 4.
Therefore, if it is on the distal end side of the mounting position with respect to the base 4, it is possible to detect the vibration caused by the non-operational vibration. That is, the distal end side of the first arm 5 from the attachment position vibrates in a direction different from the operation direction. In consideration of the fact that the non-operational direction vibration causes a vibration different from the operation direction at the hand, the vibration of the hand can be detected by detecting the non-operational direction vibration generated at the first arm 5. .

  When the first arm 5 is twisted, the twist causes an error in detecting the non-operating direction vibration. However, by providing a plurality of sensors 8 and sensors 9 at different positions, the twist is corrected based on the data. be able to. However, since the arm is twisted around a virtual line extending along the arm passing through the mounting position when viewed from the distal end side, the correction may not be possible depending on the position where the first sensor and the second sensor are provided. Specifically, as shown in FIG. 6, a state in which the sensor 8 and the sensor 9 are arranged on a straight line, that is, an angle formed by a line segment passing through the sensor 8 and the first axis, and a virtual line When the angle formed by the line segment passing through the sensor 9 and the first axis with respect to (CL1) is both θ5, it cannot be corrected from the data difference.

  Therefore, by providing the sensor 9 at a position separated from a virtual line passing through the sensor 8 and the mounting position, that is, by preventing the sensor 8, the sensor 9 and the first axis from being on the same straight line. In addition, it is possible to correct an error due to torsion, and it is possible to improve accuracy in detecting vibration in a non-operation direction.

  The sensors 8 and 9 are provided on the first arm 5. For this reason, the cable length when connecting to each of the sensors 8 and 9 can be shortened, and the number of joints that pass through is reduced as compared with the case where the sensor is provided at the hand, and the number of protection members for protecting the cable is minimized. It can be. Thereby, the routing of the cable can be facilitated and the wiring structure can be simplified.

  Therefore, by providing the sensor at the sensor position determined based on such a technical idea, it is possible to prevent the wiring structure at the time of installing the sensor from being complicated, and to prevent the hand vibration which does not appear in the conventional simulation. And the non-operational direction vibration correlated with the hand vibration can be detected.

  Further, according to the robot 2 having the sensors 8 and 9 at the positions determined by such a sensor position determination method, as described above, the wiring structure when installing the sensors is prevented from becoming complicated. In addition, it is possible to detect the non-operational direction vibration which is a cause of the hand vibration which does not appear in the conventional simulation and is correlated with the hand vibration.

  Similarly, in the case of a four-axis horizontal articulated robot such as the present embodiment, by providing the sensors 8 and 9 on the first arm 5, the non-operation generated in a direction different from the operation direction of the first arm 5 is similarly performed. The operation direction vibration can be detected, and since the joint portion through which the cable passes is only the first shaft portion, it is possible to prevent the wiring structure from becoming complicated.

  Further, by providing the sensor 8 and the sensor 9 at positions symmetrical with respect to a virtual line (CL1) extending in the direction along the first arm 5 through the mounting position, the error caused by torsion can be corrected. The calculation can be simplified, and an improvement in the processing speed when controlling the robot 2 can be expected.

The present invention is not limited to the embodiments described above and illustrated in the drawings, and various modifications and extensions can be made without departing from the gist thereof.
The numerical values shown in the embodiment are examples, and the present invention is not limited to this.
The number and arrangement of the sensors described in the embodiment are examples, and are not limited thereto.
Since the speed, the acceleration, and the displacement amount can be calculated by each other, the sensors 8 and 9 do not necessarily need to detect the same physical quantity.
In the embodiment, an example in which the present invention is applied to a horizontal articulated robot is shown. However, the present invention can be applied to other configurations such as a 6-axis vertical articulated robot and a so-called 7-axis robot.

  In the drawing, 2 is a robot, 4 is a base, 5 is a first arm (arm), and 8 and 9 are sensors.

Claims (3)

A method for determining a sensor position when installing an acceleration sensor that detects vibration of a robot,
In an arm attached to a predetermined attachment position with respect to the base and operating relatively to the base, when the arm operates, a range in which the arm vibrates in a direction different from the operation direction is specified.
In a specified range, a first sensor and a second sensor for detecting non-operational vibration caused by shaking and torsion occurring in a direction different from the operation direction of the arm are provided, and the second sensor is provided with the first sensor. the mounting position and Rousset capacitors location method provided is symmetrical positions with respect to a virtual a position spaced from the line and the virtual line passing through the. An arm attached to the base and operating relative to the base;
A first sensor and a second sensor that are acceleration sensors that detect non-moving direction vibrations caused by shaking and torsion occurring in directions different from the operating direction of the arm,
The second sensor is provided at a position separated from a virtual line passing through the first sensor and the mounting position ,
The robot, wherein the first sensor and the second sensor are provided at positions symmetrical with respect to a virtual line extending in a direction along the arm through the mounting position. A first arm attached to the base and rotating about a first axis with respect to the base;
A second arm attached to the first arm and rotating about a second axis with respect to the first arm;
A shaft that is attached to the second arm and that vertically moves and rotates with respect to the second arm.
The robot according to claim 2, wherein the first sensor and the second sensor are provided on the first arm at a position closer to the second axis than the first axis.

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