JP2013202762A - Robot system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a robot system capable of suppressing the loss of regeneration energy while maintaining the accuracy of the motion trajectory of a robot.SOLUTION: A robot system 10 includes a power source unit 20 which adjusts the height of a power supply voltage supplied from a power source 14 to power source lines 15a, 15b, a motor 52 to which the power supply voltage is supplied through the power source lines 15a, 15b, and a robot 11 having an arm 50 driven by the motor 52. The robot system 10 is provided with a capacitor 21 connected to the power source lines 15a, 15b in parallel, and a control part 60 which generates the regenerative power by the motor 52 during deceleration of the motor 52 and supplies the regenerative current to the power source lines 15a, 15b, and raises the power source voltage by the power source unit 20 based on the deviation of the position of the arm 50 detected by an encoder 53 from a target position.

Description

  The present invention relates to a robot system that controls a power supply voltage supplied to a robot.

  Conventionally, when a robot having an arm is in an acceleration section or a constant speed section, a deviation between the hand position calculated by the hand position calculation unit and a straight line that is a target trajectory is obtained, and when this deviation is greater than or equal to an allowable value, Some output a discrimination signal (see, for example, Patent Document 1). In such a case, the trajectory of the hand position is generally corrected by correcting the position command value and the speed command value.

JP 2001-216008 A JP2002-218676

  By the way, in the deceleration section of the robot, there is one that performs regenerative power generation by a motor that drives the robot and accumulates regenerative energy generated by the regenerative power generation in a capacitor (for example, see Patent Document 2). At the time of regenerative power generation, if the voltage of the power supply line to which the capacitor is connected rises above the upper limit value, it is necessary to flow the regenerative resistor to consume regenerative energy. In this case, since energy loss occurs, it is desirable to increase the regenerative energy accumulated in the capacitor.

  The present invention has been made in view of such circumstances, and a main object of the present invention is to provide a robot system that can suppress the loss of regenerative energy while maintaining the accuracy of the motion trajectory of the robot.

  The present invention employs the following means in order to solve the above problems.

  The first means is a robot system, comprising: a voltage adjusting unit that adjusts a level of a power supply voltage supplied from a power supply to a power supply line; a motor to which the power supply voltage is supplied through the power supply line; and the motor. A series connection body in which a robot having an arm to be driven, a position detection unit for detecting the position of the arm, a capacitor connected in parallel to the power supply line, and a regenerative resistor and a switch unit are connected in series; Based on the series connection body connected in parallel to the power supply line, a voltage detection unit for detecting the voltage of the power supply line, and the position of the arm detected by the position detection unit, the arm is moved to a target position. And controlling the driving of the motor so that the motor generates regenerative power when the motor decelerates, and the regenerative current is supplied to the power line. A control unit that closes the switch unit when the voltage of the power supply line detected by the voltage detection unit is higher than a predetermined voltage, and the control unit is detected by the position detection unit. The power supply voltage is raised by the voltage adjusting unit based on a deviation between the arm position and the target position.

  According to the above configuration, the height of the power supply voltage supplied from the power supply to the power supply line is adjusted by the voltage adjustment unit. In the robot, a power supply voltage is supplied to the motor through the power supply line, and the arm is driven by the motor. The control unit controls driving of the motor so as to move the arm to the target position based on the position of the arm detected by the position detection unit. Further, the control unit causes the motor to generate regenerative power when the motor decelerates and supplies the regenerative current to the power supply line. For this reason, the capacitor connected in parallel to the power supply line is charged by the regenerative current, and the regenerative energy is stored in the capacitor. At this time, when the voltage of the power supply line detected by the voltage detection unit is higher than a predetermined voltage, the switch unit is closed. For this reason, excessive regenerative energy is consumed by regenerative resistance, and it can control that a voltage regulation part is damaged by regenerative current.

  Here, the higher the power supply voltage supplied to the motor, the better the response of the motor. Therefore, the higher the power supply voltage, the higher the accuracy of the arm trajectory. However, when the power supply voltage is set high, the difference between the power supply voltage and the predetermined voltage becomes small, and when the regenerative current is supplied to the power supply line, the voltage of the power supply line easily rises to the predetermined voltage. For this reason, the opportunity to consume regenerative energy by regenerative resistance increases, and energy loss will increase. In this regard, the control unit causes the voltage adjustment unit to increase the power supply voltage supplied to the power supply line based on the deviation between the arm position detected by the position detection unit and the target position. For this reason, the responsiveness of the motor, and thus the accuracy of the arm trajectory can be improved based on the deviation. Therefore, the power supply voltage can be set low, the chance of consuming the regenerative energy with the regenerative resistor can be reduced, and the regenerative energy accumulated in the capacitor can be increased. As a result, the loss of regenerative energy can be suppressed while maintaining the accuracy of the arm motion trajectory.

  In the second means, the controller adjusts the power supply voltage by the voltage adjuster on condition that a deviation between the position of the arm detected by the position detector and the target position exceeds a first threshold. To raise.

  According to the above configuration, since the power supply voltage is increased when the deviation exceeds the first threshold, it is possible to suppress the deviation from exceeding the first threshold. On the other hand, since the power supply voltage cannot be increased until the deviation exceeds the first threshold value, priority can be given to accumulating regenerative energy in the capacitor.

  In the third means, the voltage adjustment unit may control the control unit on condition that a change speed of a deviation between the arm position detected by the position detection unit and the target position exceeds a second threshold value. The power supply voltage is increased.

  According to the above configuration, since the power supply voltage is increased when the deviation change rate exceeds the second threshold, it is possible to suppress the deviation from increasing when the deviation is likely to increase. On the other hand, since the power supply voltage cannot be increased until the deviation change rate exceeds the second threshold value, priority can be given to storing regenerative energy in the capacitor.

  In the fourth means, the control unit increases the power supply voltage by the voltage adjustment unit as the change rate of the deviation between the arm position detected by the position detection unit and the target position increases.

  According to the above configuration, since the power supply voltage is greatly increased as the change rate of the deviation is increased, the motor response can be appropriately improved as necessary. As a result, it is possible to further increase the regenerative energy accumulated in the capacitor while improving the accuracy of the arm trajectory.

  As in the fifth means, the arm includes a plurality of rotating portions and a plurality of motors, each rotating portion is driven by each motor, and the position detecting portion is a rotational position of each motor. And the control unit controls driving of each motor to operate each motor to a target rotation position based on the rotational position of each motor detected by the position detection unit, and the position detection unit A configuration in which the power supply voltage is increased by the voltage adjustment unit based on a deviation between the detected rotational position of the predetermined motor and the target rotational position may be employed. According to such a configuration, in a robot that includes a plurality of rotating units and a plurality of motors, and each rotating unit is driven by each motor, the loss of regenerative energy can be reduced while maintaining the accuracy of the arm motion trajectory. Can be suppressed.

  In a sixth means, the predetermined motor is a motor that drives the rotating unit farthest from the tip of the arm, and the control unit detects the rotation position of the predetermined motor detected by the position detecting unit and the On the condition that the deviation from the target rotation position exceeds the third threshold value, the power supply voltage is raised by the voltage adjusting unit.

  In an arm including a plurality of rotating parts and a plurality of motors, the rated output of the motor that drives the rotating part farthest from the tip of the arm is generally the largest. And since the electric power which arises by regenerative power generation becomes large as the motor with a large rated output, the effect which suppresses the loss of regenerative energy becomes high.

  In this regard, according to the above configuration, in the motor that drives the rotating part farthest from the tip of the arm, the power supply voltage is increased when the deviation exceeds the third threshold, and the deviation exceeds the third threshold. Until the power supply voltage cannot be raised. Therefore, the regenerative energy stored in the capacitor can be further increased. Furthermore, the rotating part that is farthest from the tip of the arm has a greater influence on the motion trajectory of the arm. Therefore, in the motor that drives the rotating part farthest from the tip of the arm, it is possible to effectively improve the accuracy of the arm trajectory by suppressing the deviation from exceeding the third threshold value. .

  In a seventh means, the predetermined motor includes a plurality of the motors, and the control unit has a deviation between a rotational position of the predetermined motor detected by the position detection unit and the target rotational position exceeding a third threshold value. As a result, the power supply voltage is increased by the voltage adjusting unit, and the third threshold value is set to be larger as the motor drives the rotating unit away from the tip of the arm.

  As described above, a motor with a large rated output, that is, a motor that drives a rotating portion that is distant from the tip of the arm has a larger electric power generated by regenerative power generation, so that the effect of suppressing the loss of regenerative energy becomes higher. In this regard, according to the above-described configuration, the third threshold value is set to be larger as the motor drives the rotating unit far from the tip of the arm. Therefore, the motor having a higher rated output allows a larger deviation. Can do. Therefore, when the opportunity to consume the regenerative energy with the regenerative resistor is reduced, the regenerative energy accumulated in the capacitor can be effectively increased.

  In an eighth means, the predetermined motor includes a plurality of the motors, and the control unit detects that a deviation between the rotation position of the predetermined motor detected by the position detection unit and the target rotation position exceeds a third threshold value. As a result, the power supply voltage is increased by the voltage adjusting unit, and the third threshold value is set to be smaller as the motor drives the rotating unit away from the tip of the arm.

  As described above, since the rotating part farther from the tip of the arm has a greater influence on the arm trajectory, the accuracy of the arm trajectory can be improved by suppressing the deviation from exceeding the third threshold. The effect to improve becomes high. In this regard, according to the above-described configuration, the third threshold value is set to be smaller as the motor drives the rotating unit far from the tip of the arm. The tolerance of becomes smaller. Therefore, when the deviation is suppressed from exceeding the third threshold value, the accuracy of the arm motion trajectory can be effectively improved.

  In a ninth means, the control unit raises the power supply voltage by the voltage adjusting unit, and then a deviation between the rotation position of the predetermined motor detected by the position detection unit and the target rotation position is The increase in the power supply voltage by the voltage adjustment unit is canceled on the condition that the voltage is less than the fourth threshold set smaller than the third threshold.

  According to the above configuration, after the power supply voltage is increased by the voltage adjustment unit, the increase of the power supply voltage by the voltage adjustment unit is not canceled until the deviation is less than the fourth threshold value set to be smaller than the third threshold value. . And when the said deviation becomes less than a 4th threshold value, the raise of the power supply voltage by a voltage adjustment part is cancelled | released. Therefore, it is possible to suppress the increase and release of the power supply voltage by the voltage adjusting unit, and to improve the accuracy of the arm operation trajectory more reliably.

  In the tenth means, the control unit sets the operation locus when the arm is moved to the target position, and the PTP control does not set the operation locus when the arm is moved to the target position. When the switching unit switches to the PTP control, the voltage adjustment unit makes the power supply voltage constant at an initial voltage lower than the predetermined voltage, and the switching unit switches the CP When switched to control, the voltage adjustment unit causes the power supply voltage to be the initial voltage, and a deviation between the arm position and the target position detected by the position detection unit exceeds a first threshold value. On the condition that the power supply voltage is raised by the voltage adjusting unit.

  The inventor of the present application consists of a combination of assembly / picking work (CP control) that requires the accuracy of the motion trajectory and transport / moving work (PTP control) that requires simple movement. Focused on that. In this regard, according to the above configuration, the switching unit switches between the CP control that sets the operation locus when the arm is moved to the target position and the PTP control that does not set the operation locus when the arm is moved to the target position. It is done.

  When the switching unit switches to the PTP control, the voltage adjustment unit makes the power supply voltage constant at an initial voltage lower than the predetermined voltage. For this reason, in PTP control that does not set an operation trajectory when the arm is moved to the target position, that is, transfer / moving work that requires only simple movement, the regenerative energy accumulated in the capacitor is reduced by reducing the chance of regenerative energy consumption. Can be increased.

  On the other hand, when the switching unit is switched to the CP control, the power supply voltage is set to the initial voltage by the voltage adjusting unit, and the deviation between the arm position detected by the position detecting unit and the target position is the first threshold value. The power supply voltage is raised by the voltage adjustment unit on the condition that the voltage exceeds. For this reason, in the CP control that requires the accuracy of the motion trajectory, the accuracy of the arm motion trajectory can be improved.

  Therefore, in the PTP control where the accuracy of the operation trajectory is not required, priority is given to increasing the regenerative energy accumulated in the capacitor, and in the CP control where the accuracy of the operation trajectory is required, the regenerative energy accumulated in the capacitor is increased while the operation trajectory is increased. Accuracy can be maintained.

The block diagram which shows a robot system. The time chart which shows the relationship between a power supply voltage and regenerative energy loss. The time chart which shows the change of a positional deviation and a power supply voltage. The graph which shows the relationship between the rotational speed of a motor, and a torque. A time chart showing a target speed and an actual speed. The time chart which shows the change speed of a deviation, and the change of a power supply voltage. The time chart which shows a rotation deviation and the change of a power supply voltage. The time chart which shows the change of the work content of robot, power supply voltage, and regenerative electric power.

  Hereinafter, an embodiment will be described with reference to the drawings. This embodiment is embodied as a robot system that controls the operation of an articulated robot.

  FIG. 1 is a block diagram showing a robot system 10. The robot system 10 includes a robot 11, a power supply unit 20, an inverter circuit 30, a control unit 60, and the like. The robot 11 includes an arm 50 and the like. The power supply unit 20, the inverter circuit 30, and the control unit 60 constitute a robot controller.

  The power supply unit 20 (voltage adjusting unit) is connected to a three-phase 200 V commercial AC power supply 14 (external power supply). The power supply unit 20 includes a rectifier circuit, a coil, a capacitor 21, switching elements 22, 23, and the like. The capacitor 21 is connected in parallel to the power supply lines 15a and 15b. The switching elements 22 and 23 are formed of a field effect transistor (FET) or the like. The switching element 22 is connected in series to the power supply lines 15a and 15b, and the switching element 23 is connected in parallel to the power supply lines 15a and 15b. Then, the power supply unit 20 performs the PWM control (duty control) of the switching element 23 with the switching element 22 turned on, thereby increasing the height of the power supply voltage Vb supplied from the power supply 14 to the power supply lines 15a and 15b. Adjust.

  A series connection body in which a resistor 25 (regenerative resistor) and a switching element 26 (switch unit) are connected in series is connected in parallel to the power supply lines 15a and 15b. The switching element 26 is formed of a field effect transistor or the like. A voltage sensor 27 is connected in parallel to the power supply lines 15a and 15b. The voltage sensor 27 (voltage detection unit) detects the power supply voltage Vb of the power supply lines 15a and 15b.

  A plurality of inverter circuits 30 (only one is shown) are connected in parallel to the power supply lines 15a and 15b. A plurality of motors 52 that respectively drive a plurality of rotating units 51 in the arm 50 of the robot 11 are connected to the plurality of inverter circuits 30. Each motor 52 is provided with an encoder 53 (position detection unit) that detects a rotational position.

  Each inverter circuit 30 is a known circuit in which six switching elements 31 are connected in a three-phase bridge and a flywheel diode 32 is connected in parallel with each switching element 31. The switching element 31 is formed by a bipolar power transistor or the like. In each inverter circuit 30, the switching element 31 is PWM-controlled, whereby the voltage supplied from each inverter circuit 30 to each motor 52 is controlled. A current sensor 35 detects a current supplied to each motor 52.

  The control unit 60 includes a power supply control unit 61, a trajectory generation unit 62, a position / speed control unit 63, a current control unit 64, a PWM circuit 65, a drive circuit 66, and the like.

  The output of the encoder 53 provided in each motor 52 is input to the trajectory generation unit 62, the position / speed control unit 63, and the current control unit 64, respectively. The trajectory generating unit 62 is based on the operation performed by the arm 50 and the rotational position of each motor 52 detected by each encoder 53 (the rotational position of each rotating unit 51). A target rotation position of the motor 52 (target rotation position of each rotating unit 51) is calculated. The position / speed control unit 63 determines the target rotation speed of each motor 52 (each rotation unit 51 based on the target rotation position of each motor 52 calculated by the trajectory generation unit 62 and the detected rotation position of each motor 52. Target rotation speed) and target torque of each motor 52 are calculated. The current control unit 64 is based on the target torque of each motor 52 calculated by the position / speed control unit 63, the current detected by each current sensor 35, and the detected rotational position of each motor 52. To calculate the target current to be supplied to the motor 52. The PWM circuit 65 outputs a PWM signal for controlling each switching element 31 of each inverter circuit 30 based on the target current calculated by the current control unit 64. The drive circuit 66 drives each switching element 31 of each inverter circuit 30 based on the PWM signal output from the PWM circuit. Thereby, the drive of each motor 52 is controlled so that each motor 52 (arm 50) is operated to the target rotation position (target position).

  In addition, the control unit 60 causes each motor 52 to generate regenerative power when each motor 52 is decelerated. The regenerative current generated by the regenerative power generation is supplied to the power supply lines 15 a and 15 b via the flywheel diode 32 of the inverter circuit 30. The regenerative current charges the capacitor 21 connected in parallel to the power supply lines 15a and 15b. However, the regenerative current supplied to the power supply lines 15a and 15b increases the power supply voltage Vb of the power supply lines 15a and 15b. For this reason, the power supply controller 61 turns on (closes) the switching element 26 when the power supply voltage Vb detected by the voltage sensor 27 is higher than the predetermined voltage Vr. As a result, a regenerative current flows through the resistor 25, and excessive regenerative energy is consumed as heat. Therefore, it is possible to suppress the power supply voltage Vb from rising excessively and to prevent the power supply unit 20 from being damaged.

  FIG. 2 is a time chart showing the relationship between the power supply voltage Vb and the regenerative energy loss. As indicated by the one-dot chain line in the figure, when the power supply voltage Vb is set to the initial voltage Vp by the power supply unit 20, the difference between the initial voltage Vp and the predetermined voltage Vr becomes small. For this reason, if regenerative power generation is performed during the period from time t1 to time t2, the power supply voltage Vb exceeds the predetermined voltage Vr. When the power supply voltage Vb exceeds the predetermined voltage Vr, the switching element 26 is turned on, and regenerative energy corresponding to the area S is consumed as heat. Therefore, a loss of regenerative energy occurs.

  On the other hand, as shown by the solid line in FIG. 3, when the power supply unit 20 sets the power supply voltage Vb to the initial voltage Vc lower than the initial voltage Vp, the initial voltage Vc and the predetermined voltage Vr The difference becomes larger. For this reason, even if regenerative power generation is performed during the period from time t1 to time t2, the power supply voltage Vb does not exceed the predetermined voltage Vr. Therefore, it can be avoided that the switching element 26 is not turned on and a loss of regenerative energy occurs. Therefore, in this embodiment, the power supply unit 20 sets the power supply voltage Vb to the initial voltage Vc.

  On the other hand, the higher the power supply voltage Vb supplied to each motor 52, the better the response of each motor 52. Therefore, the higher the power supply voltage Vb, the higher the accuracy of the operation trajectory of the arm 50. For this reason, it is desirable to set the power supply voltage Vb high in order to increase the accuracy of the operation trajectory of the arm 50. Therefore, in the present embodiment, the power supply control unit 61 of the control unit 60 causes the power supply unit 20 to perform power supply on the condition that the deviation ΔP between the detected tip position of the arm 50 and the target position exceeds the first threshold Th1. The voltage Vb is increased. For this reason, even if the initial voltage Vc is set low, the accuracy of the operation trajectory of the arm 50 can be maintained. Note that the tip position of the arm 50 can be calculated based on the rotational position of each motor 52 detected by each encoder 53. Then, a deviation ΔP between the calculated tip position of the arm 50 and the target position calculated by the trajectory generating unit 62 is calculated.

  FIG. 3 is a time chart showing changes in the deviation ΔP of the tip position of the arm 50 and the power supply voltage Vb. In (a), the solid line indicates the change in deviation ΔP in the present embodiment, and the alternate long and short dash line indicates the change in deviation ΔP when the power supply voltage Vb is not increased.

  Since the power supply voltage Vb is set to the initial voltage Vc as shown in (b), the deviation ΔP increases with the operation of the arm 50 of the robot 11 as shown in (a). When the deviation ΔP exceeds the first threshold Th1 at time t11, the power supply voltage Vb is raised from the initial voltage Vc as shown in (b). Here, the power supply controller 61 drives the switching element 23 with a duty of 100%, and raises the power supply voltage Vb to the maximum voltage Vh. Thereby, the responsiveness of each motor 52 is improved, and as shown in (a), the deviation ΔP becomes less than the first threshold Th1 at time t12. Therefore, as shown in (b), the power supply voltage Vb is lowered to the initial voltage Vc. Thereafter, as shown in (a), the deviation ΔP changes below the first threshold Th1.

  When the deviation ΔP exceeds the first threshold Th1 at time t13 with the operation of the arm 50, the power supply voltage Vb is raised from the initial voltage Vc as shown in (b). As shown in (a), when the deviation ΔP becomes less than the first threshold Th1 at time t14, the power supply voltage Vb is lowered to the initial voltage Vc as shown in (b). Thereafter, when the load on the arm 50 becomes small, the deviation ΔP changes below the first threshold Th1.

  FIG. 4 is a graph showing the relationship between the rotational speed of the motor 52 and the torque T. The solid line indicates the case where the power supply voltage Vb is increased according to the present embodiment, and the alternate long and short dash line indicates the case where the power supply voltage Vb is not increased.

  As indicated by the alternate long and short dash line, when the power supply voltage Vb is not increased from the initial voltage Vc, the torque T tends to decrease as the rotational speed of the motor 52 increases. On the other hand, as shown by the solid line, when the power supply voltage Vb is increased from the initial voltage Vc to the maximum voltage Vh, the decrease in the torque T is suppressed even if the rotation speed of the motor 52 is increased. Therefore, according to the present embodiment, the magnitude of the torque T can be maintained even in a region where the rotational speed of the motor 52 is high.

  FIG. 5 is a time chart showing the target rotation speed and the actual rotation speed of the motor 52. The broken line indicates the target rotation speed, the solid line indicates the actual rotation speed when the power supply voltage Vb is increased according to the present embodiment, and the alternate long and short dash line indicates the actual rotation speed when the power supply voltage Vb is not increased.

  As indicated by the alternate long and short dash line, when the power supply voltage Vb is not increased from the initial voltage Vc, the delay of the actual rotational speed of the motor 52 becomes larger than the target rotational speed indicated by the broken line in a region where the rotational speed is high. Yes. On the other hand, as shown by the solid line, when the power supply voltage Vb is increased from the initial voltage Vc to the maximum voltage Vh, the actual rotational speed is higher than the target rotational speed indicated by the broken line even in the high rotational speed region. The delay has not increased. Therefore, according to the present embodiment, the responsiveness of the motor 52 can be maintained even in a region where the rotational speed of the motor 52 is high.

  The embodiment described above has the following advantages.

  The power supply control unit 61 of the control unit 60 generates the power supply voltage Vb supplied to the power supply lines 15a and 15b based on the deviation ΔP between the tip position of the arm 50 calculated based on the detection value of the encoder 53 and the target position. Raised by the power supply unit 20. For this reason, based on the deviation ΔP, the responsiveness of the motor 52 and, consequently, the accuracy of the operation trajectory of the arm 50 can be improved. Therefore, the power supply voltage Vb can be set low, and the opportunity for consuming the regenerative energy by the resistor 25 can be reduced, and the regenerative energy accumulated in the capacitor 21 can be increased. As a result, the loss of regenerative energy can be suppressed while maintaining the accuracy of the operation trajectory of the arm 50.

  Since the power supply voltage Vb is raised when the deviation ΔP exceeds the first threshold Th1, it is possible to suppress the deviation ΔP from exceeding the first threshold Th1. On the other hand, since the power supply voltage Vb cannot be increased until the deviation ΔP exceeds the first threshold Th1, it is possible to give priority to accumulating regenerative energy in the capacitor 21.

  Note that the above embodiment can be modified as follows.

  FIG. 6 is a time chart showing the change rate Rp of the deviation ΔP and the change of the power supply voltage Vb. Here, the power supply control unit 61 of the control unit 60 is provided on the condition that the change speed Rp of the deviation ΔP between the tip position of the arm 50 calculated based on the detection value of the encoder 53 and the target position exceeds the second threshold Th2. The power supply voltage Vb is raised by the power supply unit 20.

  As shown in (a), when the change speed Rp exceeds the second threshold Th2 at time t21, the power supply voltage Vb is raised from the initial voltage Vc as shown in (b). Here, the power supply voltage Vb is greatly increased as the change rate Rp of the deviation ΔP is increased. Thereby, the responsiveness of each motor 52 improves, and as shown to (a), the change speed Rp becomes less than 2nd threshold value Th2 in the time t22. Therefore, as shown in (b), the power supply voltage Vb is lowered to the initial voltage Vc. Thereafter, as shown in (a), the change rate Rp changes below the second threshold Th2.

  When the deviation ΔP exceeds the second threshold Th2 at time t23 with the operation of the arm 50, the power supply voltage Vb is raised from the initial voltage Vc as shown in (b). Here, since change rate Rp of deviation ΔP is larger than time t21, power supply voltage Vb is further increased. As shown in (a), when the change speed Rp becomes less than the second threshold Th2 at time t24, the power supply voltage Vb is lowered to the initial voltage Vc as shown in (b). Thereafter, when the load of the arm 50 becomes small, the change speed Rp changes below the second threshold Th2.

  According to the above configuration, when the change rate Rp of the deviation ΔP exceeds the second threshold Th2, the power supply voltage Vb is increased. Therefore, when the deviation ΔP is likely to increase, the deviation ΔP is increased. Can be suppressed. On the other hand, since the power supply voltage Vb cannot be increased until the change rate Rp of the deviation ΔP exceeds the second threshold Th2, it can be prioritized to accumulate the regenerative energy in the capacitor 21. Furthermore, since the power supply voltage Vb is greatly increased as the change rate Rp of the deviation ΔP is increased, the responsiveness of the motor 52 can be appropriately improved as necessary. As a result, the regenerative energy accumulated in the capacitor 21 can be further increased while improving the accuracy of the operation trajectory of the arm 50.

  FIG. 7 is a time chart showing the deviation Δθ between the rotational position of the motor 52 detected by the encoder 53 and the target rotational position, and changes in the power supply voltage Vb. Here, the power supply control unit 61 of the control unit 60 increases the power supply voltage Vb by the power supply unit 20 and then the deviation Δθ between the rotational position of the motor 52 detected by the encoder 53 and the target rotational position is the third threshold value. The increase in the power supply voltage Vb by the power supply unit 20 is canceled on condition that the power supply unit 20 is less than the fourth threshold Th4 set smaller than Th3. In (a), the solid line indicates the change in deviation Δθ in the above configuration, and the alternate long and short dash line indicates the change in deviation Δθ when the power supply voltage Vb is not increased.

  As shown in (a), when the deviation Δθ exceeds the third threshold Th3 at time t31, the power supply voltage Vb is raised from the initial voltage Vc as shown in (b). Here, the power supply controller 61 drives the switching element 23 with a duty of 100%, and raises the power supply voltage Vb to the maximum voltage Vh. As a result, as shown in (a), the deviation Δθ is less than the third threshold Th3, but the increase of the power supply voltage Vb by the power supply unit 20 is not canceled until the deviation Δθ is less than the fourth threshold Th4. When the deviation Δθ becomes less than the fourth threshold Th4 at time t32, the power supply voltage Vb is lowered to the initial voltage Vc as shown in (b). Thereafter, as shown in (a), the deviation Δθ changes below the third threshold Th3.

  When the deviation Δθ exceeds the third threshold Th3 at time t33 with the operation of the arm 50, the power supply voltage Vb is raised from the initial voltage Vc as shown in (b). As shown in (a), when the deviation Δθ becomes less than the fourth threshold Th4 at time t34, the power supply voltage Vb is lowered to the initial voltage Vc as shown in (b). Thereafter, when the load of the arm 50 becomes small, the deviation Δθ changes below the fourth threshold Th4.

  According to the above configuration, after the power supply unit 20 increases the power supply voltage Vb, the power supply voltage Vb by the power supply unit 20 is increased until the deviation Δθ becomes less than the fourth threshold Th4 set to be smaller than the third threshold Th3. Will not be released. When the deviation Δθ becomes less than the fourth threshold Th4, the increase in the power supply voltage Vb by the power supply unit 20 is cancelled. Therefore, it is possible to suppress the rise and release of the power supply voltage Vb by the power supply unit 20 and to improve the accuracy of the operation trajectory of the arm 50 more reliably.

  The increase in the power supply voltage Vb by the power supply unit 20 can be canceled on the condition that a predetermined time has elapsed after the power supply unit 20 has increased the power supply voltage Vb.

  The power control unit 61 of the control unit 60 supplies power on condition that the deviation Δθ between the rotational position of the predetermined motor 52 (predetermined motor) detected by the encoder 53 and the target rotational position exceeds the third threshold Th3. The unit 20 may raise the power supply voltage Vb.

  In the arm 50 including the plurality of rotating parts 51 and the plurality of motors 52, the rated output of the motor 52 that drives the rotating part 51 farthest from the tip of the arm 50 is generally the largest. Since the motor 52 having a higher rated output has a larger electric power generated by regenerative power generation, the effect of suppressing the loss of regenerative energy becomes higher.

  Therefore, as the predetermined motor 52, a motor 52 that drives the rotating portion 51 farthest from the tip of the arm 50 may be employed. According to such a configuration, in the motor 52 that drives the rotating portion 51 farthest from the tip of the arm 50, the power supply voltage Vb is raised when the deviation Δθ exceeds the third threshold Th3, and the deviation Δθ The power supply voltage Vb cannot be increased until the threshold value Th3 is exceeded. Therefore, the regenerative energy accumulated in the capacitor 21 can be further increased. Furthermore, the rotating part 51 farthest from the tip of the arm 50 has a greater influence on the motion trajectory of the arm 50. Therefore, in the motor 52 that drives the rotating portion 51 farthest from the tip of the arm 50, the accuracy of the motion trajectory of the arm 50 is effectively reduced by suppressing the deviation Δθ from exceeding the third threshold Th3. Can be improved.

  The predetermined motor 52 includes a plurality of motors 52, and the third threshold Th <b> 3 is set to be larger as the motor 52 drives the rotating unit 51 away from the tip of the arm 50. May be. As described above, the motor 52 having a large rated output, that is, the motor 52 that drives the rotating unit 51 that is distant from the tip of the arm 50, has a large effect of suppressing the loss of regenerative energy because the electric power generated by regenerative power generation increases. Become. In this regard, according to the above configuration, the third threshold value Th3 is set to be larger as the motor 52 drives the rotating unit 51 far from the tip of the arm 50. Therefore, the motor 52 having a higher rated output has the above deviation. Δθ can be greatly allowed. Therefore, when the opportunity to consume the regenerative energy with the resistor 25 is reduced, the regenerative energy accumulated in the capacitor 21 can be effectively increased.

  Further, a configuration is adopted in which a plurality of motors 52 are included as the predetermined motor 52, and the third threshold value Th3 is set to be smaller as the motor 52 drives the rotating unit 51 away from the tip of the arm 50. May be. As described above, since the rotating part 51 farther from the tip of the arm 50 has a larger influence on the operation trajectory of the arm 50, the arm 50 is suppressed by suppressing the deviation Δθ from exceeding the third threshold Th3. The effect of improving the accuracy of the motion trajectory becomes higher. In this regard, according to the above configuration, the third threshold value Th3 is set to be smaller as the motor 52 drives the rotating unit 51 farther from the tip of the arm 50. The larger the motor 52, the smaller the tolerance of the deviation Δθ. Therefore, when the deviation Δθ is suppressed from exceeding the third threshold Th3, the accuracy of the motion trajectory of the arm 50 can be effectively improved.

  The values of the threshold values Th1 to Th4 can be made variable. When emphasizing the accuracy of the motion trajectory of the arm 50, the values of the threshold values Th1 to Th4 may be decreased, and when emphasizing the suppression of regenerative energy loss, the values of the threshold values Th1 to Th4 may be increased.

  Specifically, the following configuration can be employed. In other words, the control unit 60 switches between CP control that sets an operation locus when the tip position of the arm 50 is moved to the target position and PTP control that does not set an operation locus when the arm 50 is moved to the target position. A part. When the switching unit is switched to PTP control, the control unit 60 causes the power supply unit 20 to keep the power supply voltage Vb constant at the initial voltage Vc lower than the predetermined voltage Vr, and the switching unit switches to CP control. In this case, the power supply unit 20 sets the power supply voltage Vb to the initial voltage Vc, and the deviation ΔP between the tip position of the arm 50 calculated based on the detection value of the encoder 53 and the target position exceeds the first threshold Th1. As a condition, the power supply unit 20 increases the power supply voltage Vb.

  As shown in FIG. 8, the inventor of the present application performs assembly / picking work (CP control) in which the operation of one cycle of the robot 11 requires the accuracy of the motion trajectory, and transport / moving work (PTP control) that requires only movement. We focused on the fact that it is composed of In this regard, according to the above configuration, the control unit sets the operation locus when the arm 50 is moved to the target position, and the PTP control does not set the operation locus when the arm 50 is moved to the target position. Is switched.

  When the switching unit switches to PTP control, the power supply unit 20 makes the power supply voltage Vb constant at the initial voltage Vc lower than the predetermined voltage Vr. For this reason, in the PTP control in which the movement locus is not set when the arm 50 is moved to the target position, that is, in the transfer / moving work that only requires movement, the opportunity for consuming the regenerative energy by the resistor 25 is reduced and accumulated in the capacitor 21. Regenerative energy can be increased.

  On the other hand, when the control unit is switched to CP control, the power supply unit 20 sets the power supply voltage Vb to the initial voltage Vc, and the deviation ΔP between the position of the arm 50 detected by the encoder 53 and the target position is The power supply voltage Vb is raised by the power supply unit 20 on condition that the first threshold Th1 is exceeded. For this reason, in the CP control that requires the accuracy of the motion trajectory, the accuracy of the motion trajectory of the arm 50 can be improved.

  Therefore, in PTP control in which the accuracy of the operation trajectory is not required, priority is given to increasing the regenerative energy accumulated in the capacitor 21, and in CP control in which the accuracy of the operation trajectory is required, while increasing the regenerative energy accumulated in the capacitor 21, The accuracy of the motion trajectory can be maintained.

  DESCRIPTION OF SYMBOLS 10 ... Robot system, 11 ... Robot, 14 ... Commercial alternating current power supply (power supply), 15a ... Power supply line, 15b ... Power supply line, 20 ... Power supply unit (voltage adjustment part), 21 ... Capacitor, 25 ... Resistance (regenerative resistance), DESCRIPTION OF SYMBOLS 26 ... Switching element (switch part), 27 ... Voltage sensor (voltage detection part), 50 ... Arm, 51 ... Rotation part, 52 ... Motor, 53 ... Encoder (position detection part), 60 ... Controller.

Claims (10)

A voltage adjustment unit for adjusting the height of the power supply voltage supplied from the power supply to the power supply line;
A motor supplied with the power supply voltage through the power supply line, and a robot having an arm driven by the motor;
A position detector for detecting the position of the arm;
A capacitor connected in parallel to the power line;
A series connection body in which a regenerative resistor and a switch unit are connected in series, and the series connection body connected in parallel to the power supply line,
A voltage detector for detecting the voltage of the power line;
Based on the position of the arm detected by the position detector, the drive of the motor is controlled so as to move the arm to a target position, and regenerative power is generated by the motor during deceleration of the motor. A control unit that closes the switch unit when the voltage of the power line detected by the voltage detection unit is higher than a predetermined voltage.
With
The said control part raises the said power supply voltage by the said voltage adjustment part based on the deviation of the position of the said arm detected by the said position detection part, and the said target position, The robot system characterized by the above-mentioned.   The control unit increases the power supply voltage by the voltage adjustment unit on condition that a deviation between the position of the arm detected by the position detection unit and the target position exceeds a first threshold. The robot system described in 1.   The control unit increases the power supply voltage by the voltage adjustment unit on condition that a change speed of a deviation between the position of the arm detected by the position detection unit and the target position exceeds a second threshold value. The robot system according to claim 1 or 2.   The said control part raises the said power supply voltage largely by the said voltage adjustment part, so that the change speed of the deviation of the position of the said arm detected by the said position detection part and the said target position is large. The robot system according to claim 1. The arm includes a plurality of rotating parts and a plurality of the motors, and each rotating part is driven by each motor,
The position detector detects the rotational position of each motor,
The control unit controls driving of each motor so as to operate each motor to a target rotation position based on the rotation position of each motor detected by the position detection unit, and is detected by the position detection unit. The robot system according to any one of claims 1 to 4, wherein the power supply voltage is increased by the voltage adjustment unit based on a deviation between a rotational position of a motor and the target rotational position. The predetermined motor is a motor that drives the rotating part farthest from the tip of the arm,
The control unit increases the power supply voltage by the voltage adjustment unit on condition that a deviation between the rotation position of the predetermined motor detected by the position detection unit and the target rotation position exceeds a third threshold value. The robot system according to claim 5. The predetermined motor includes a plurality of the motors,
The control unit increases the power supply voltage by the voltage adjustment unit on condition that a deviation between the rotation position of the predetermined motor detected by the position detection unit and the target rotation position exceeds a third threshold. ,
The robot system according to claim 5, wherein the third threshold value is set to be larger as the motor drives the rotating unit that is farther from the tip of the arm. The predetermined motor includes a plurality of the motors,
The control unit increases the power supply voltage by the voltage adjustment unit on condition that a deviation between the rotation position of the predetermined motor detected by the position detection unit and the target rotation position exceeds a third threshold. ,
The robot system according to claim 5, wherein the third threshold value is set to be smaller as the motor drives the rotating unit away from the tip of the arm.   The controller raises the power supply voltage by the voltage regulator, and then a deviation between the rotational position of the predetermined motor detected by the position detector and the target rotational position is smaller than the third threshold value. 9. The robot system according to claim 7, wherein the increase in the power supply voltage by the voltage adjustment unit is canceled on condition that the voltage is less than a set fourth threshold value. The controller is
A switching unit that switches between CP control that sets an operation locus when the arm is moved to the target position and PTP control that does not set an operation locus when the arm is moved to the target position;
When the switching unit is switched to the PTP control, the voltage adjustment unit makes the power supply voltage constant at an initial voltage lower than the predetermined voltage,
When the switching unit switches to the CP control, the voltage adjustment unit causes the power supply voltage to be the initial voltage, and a deviation between the arm position detected by the position detection unit and the target position The robot system according to any one of claims 1 to 9, wherein the power supply voltage is increased by the voltage adjustment unit on the condition that exceeds a first threshold value.

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