Motor control system, motor control method, and program

Abstract

To provide a motor control system, a motor control method, and a program capable of applying a short brake to a motor while ensuring safety by preventing the motor from driving.SOLUTION: A motor control system 100 includes an inverter circuit 111 including a switching element Q and an inverter drive circuit 112 that switches the state of the switching element Q from on to off. When a short brake is applied to a motor M, the motor control system 100 switches the power supply for supplying the power to the inverter drive circuit 112 from a first power supply P1 for supplying the power to the inverter circuit 111 to a second power supply P2 different from the first power supply P1.SELECTED DRAWING: Figure 3

Description

Technical Field

[0001] The present disclosure relates to a motor control system, a motor control method, and a program.

Background Art

[0002] Patent Document 1 describes a technique related to a braking device for a three-phase brushless motor.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] There may be a case where power supply to the braking device is cut off in an emergency or the like. In this case, since the on-state and off-state of the switching element included in the inverter circuit cannot be switched, a short brake cannot be applied.

[0005] The present disclosure has been made to solve such problems, and an object thereof is to provide a motor control system, a motor control method, and a program that can apply a short brake to a motor while ensuring the safety of the motor not being driven.

Means for Solving the Problems

[0006] The motor control system according to the present embodiment is an inverter circuit including a switching element, and an inverter drive circuit that switches the on-state and off-state of the switching element and includes When applying a short brake to the motor, the power supply that provides power to the inverter drive circuit is switched from a first power supply that supplies power to the inverter circuit to a second power supply that is different from the first power supply.

[0007] The above motor control system is When applying a short brake to the motor, the power supply from the first power source to the inverter circuit and the inverter drive circuit may be interrupted.

[0008] The above motor control system is The system may further include a control unit that applies a short-circuit brake to the motor by transmitting a control signal to the inverter drive circuit.

[0009] The second power supply of the motor control system described above may supply power to the control unit.

[0010] The second power supply of the motor control system described above may supply power to the control unit.

[0011] The above motor control system is The system further comprises a machine learning model trained to determine whether the robot arm has come into contact with or approached a human or object, based on images taken of the area surrounding the robot arm operated by the motor, or information from a contact sensor mounted on the robot arm. If the machine learning model determines that the result is positive, the power supply from the first power source to the inverter circuit and the inverter drive circuit may be cut off.

[0012] The control unit of the motor control system described above may control the braking force by short-circuiting the motor so that the back electromotive force generated between the terminals of the motor is less than a predetermined value.

[0013] The control unit of the motor control system described above may apply a short brake to the motor when lowering an item if the weight of the item grasped by the robot arm's hand is large.

[0014] The motor in the above motor control system is included in each of the multiple joints of the robot arm. The control unit may vary the braking force applied by the short brake among the multiple motors.

[0015] The motor in the above motor control system is included in the joint of the robot arm. The control unit may change the flexibility of the joint by applying a short brake to the motor.

[0016] The above motor control system is A cutoff unit that cuts off the power supply from the first power source to the inverter circuit, A switching unit that switches whether the power supply wiring of the inverter drive circuit is electrically connected to the terminal on the inverter circuit side of the break-off unit or to the positive terminal of the second power supply. Equipped with, When the interruption unit is in a connected state, the power supply wiring may be electrically connected to the terminals of the interruption unit, and when the interruption unit is in a disconnected state, the power supply wiring may be electrically connected to the positive terminal of the second power supply.

[0017] The motor control method in this embodiment is: When applying a short brake to the motor, the power supply that provides power to the inverter drive circuit that switches the switching element between the on and off states is switched from a first power supply that supplies power to the inverter circuit including the switching element to a second power supply that is different from the first power supply.

[0018] The program in this embodiment is On the computer, When applying a short brake to the motor, a process is executed to switch the power supply that supplies power to the inverter drive circuit that switches between the on state and the off state of the switching element from a first power supply that supplies power to an inverter circuit including the switching element to a second power supply different from the first power supply.

Advantages of the Invention

[0019] According to the present disclosure, it is possible to provide a motor control system, a motor control method, and a program that can apply a short brake to a motor while ensuring the safety of the motor not being driven.

Brief Description of the Drawings

[0020] [Figure 1] It is a diagram for explaining the configuration of the motor control system according to the comparative example. [Figure 2] It is a diagram for explaining the configuration of the motor control system according to the comparative example. [Figure 3] It is a diagram for explaining the configuration of the motor control system according to Embodiment 1. [Figure 4] It is a diagram for explaining an example of the configuration of the switching unit. [Figure 5] It is a diagram for explaining an example of the configuration of the switching unit. [Figure 6] It is a diagram for explaining the configuration of the robot arm according to Embodiment 2. [Figure 7] It is a diagram for explaining the configuration of the motor control system according to Embodiment 2. [Figure 8] It is a diagram for explaining an example of the operation of the robot arm according to Embodiment 2.

Modes for Carrying Out the Invention

[0021] Hereinafter, the present invention will be described through embodiments of the invention, but the invention according to the claims is not limited to the following embodiments. Also, not all of the configurations described in the embodiments are essential as means for solving the problems.

[0022] Consideration leading to the implementation First, we will specifically explain the problems identified by the inventors regarding the motor control system of the comparative example. Figure 1 is a diagram illustrating the configuration of the motor control system 50 of the comparative example. In the following drawings, the same elements are denoted by the same reference numerals, and redundant explanations are omitted where necessary.

[0023] The motor control system 50 includes a motor M, a first power supply P1, a circuit breaker R1, a drive circuit 110, a second power supply P2, and a control unit 120. The first power supply P1 is also called the power supply. The second power supply P2 is also called the control supply. The motor M is a motor such as a three-phase brushless motor. The motor M has terminals for the U phase, V phase, and W phase.

[0024] The first power supply P1 supplies power to the drive circuit 110. The first power supply P1 supplies power to both the inverter circuit 111 and the inverter drive circuit 112, which will be described later. The first power supply P1 may be a battery or a power supply provided via a power cord.

[0025] The interruption unit R1 is configured to interrupt the power supply from the first power source P1 to the drive circuit 110. The interruption unit R1 may also interrupt the power supply when it receives an interruption signal from the control unit 120 or an emergency stop button (not shown). One end of the interruption unit R1 is electrically connected to the positive terminal of the first power source P1, and the other end of the interruption unit R1 is electrically connected to the power supply wiring of the inverter circuit 111 and the inverter drive circuit 112, which will be described later. A step-down circuit may be placed in the path between the interruption unit R1 and the inverter drive circuit 112. The interruption unit R1 may be, for example, an electromagnetic mechanical relay. The interruption unit R1 may be configured to be manually turned on and off by a human.

[0026] The drive circuit 110 drives the motor M. The drive circuit 110 includes an inverter circuit 111 and an inverter drive circuit 112.

[0027] The inverter circuit 111 includes multiple switching elements Q1 to Q6. Switching element Q1 is located in the path between the U-phase terminal of the motor M and the circuit breaker R1. Switching element Q2 is located in the path between the V-phase terminal of the motor M and the circuit breaker R1. Switching element Q3 is located in the path between the W-phase terminal of the motor M and the circuit breaker R1.

[0028] Switching element Q4 is located in the path between the U-phase terminal of motor M and ground. Switching element Q5 is located in the path between the V-phase terminal of motor M and ground. Switching element Q6 is located in the path between the W-phase terminal of motor M and ground. Although not shown in the diagram, the gates of switching elements Q1 to Q6 are electrically connected to the inverter drive circuit 112.

[0029] Switching elements Q1 to Q6 may be MOSFETs (Metal Oxide Semiconductor Field Effect Transistors). Switching elements Q1 to Q6 may also be IGBTs (Insulated Gate Bipolar Transistors) or thyristors.

[0030] The inverter drive circuit 112 drives the inverter circuit 111. In other words, the inverter drive circuit 112 switches the switching elements Q1 to Q6 between the ON and OFF states. The ON state refers to a conduction state, and the OFF state refers to a disconnection state.

[0031] The second power source P2 supplies power to the control unit 120. The second power source P2 may be a battery or a power source supplied via a power cord.

[0032] The control unit 120 is composed of a microcomputer centered around a CPU (Central Processing Unit), ROM (Read Only Memory), and RAM (Random Access Memory). The control unit 120 inputs a PWM (Pulse Width Modulation) signal to the inverter drive circuit 112. The inverter drive circuit 112 controls the rotation of the motor M by switching the on and off states of switching elements Q1 to Q6 based on the PWM signal. The functions of the control unit 120 may be realized by the CPU loading a computer program from ROM into RAM and executing the computer program.

[0033] The control unit 120 may also have a function to transmit a shutoff signal to the shutoff unit R1. For example, the control unit 120 may transmit a shutoff signal to the shutoff unit R1 when an emergency stop button (not shown) is pressed, or when a person or object comes into contact with or approaches the machine operated by the motor M.

[0034] After the interruption unit R1 cuts off the power supply from the first power source P1, the motor M continues to rotate due to inertia. When the switching elements Q4, Q5, and Q6 are turned on, a short circuit occurs between the U-phase terminals, V-phase terminals, and W-phase terminals of the motor M, applying a short-circuit brake to the motor M. However, since the power supply to the inverter drive circuit 112 is also cut off, there is a problem that the inverter drive circuit 112 cannot turn on the switching elements Q4, Q5, and Q6.

[0035] Referring to Figure 2, a modified example of the motor control system 50a is shown. Comparing Figure 1 and Figure 2, the motor control system 50a further includes switching elements Q7, Q8, and Q9. Switching element Q7 is located in the path between the U-phase terminal of the motor M and ground. Switching element Q8 is located in the path between the V-phase terminal of the motor M and ground. Switching element Q9 is located in the path between the W-phase terminal of the motor M and ground. The gates of switching elements Q7 to Q9 are electrically connected to the control unit 120.

[0036] When applying a short-circuit brake to the motor M, the control unit 120 turns on the switching elements Q7, Q8, and Q9. Even when the circuit breaker R1 is tripped, the control unit 120 can apply a short-circuit brake to the motor M by turning on the switching elements Q7, Q8, and Q9.

[0037] The motor control system 50a can apply a short brake to the motor M. However, it requires switching elements Q7 to Q9, which increases the circuit area.

[0038] Based on the above considerations, the inventors arrived at the present invention.

[0039] Embodiment 1 The motor control system according to Embodiment 1 will now be described with reference to the drawings. Figure 3 is a diagram illustrating the configuration of the motor control system 100 according to Embodiment 1. The motor control system 100 includes a motor M, a first power supply P1, a cutoff unit R1, a drive circuit 110, a second power supply P2, a control unit 120, and a switching unit 130. The drive circuit 110 includes an inverter circuit 111 and an inverter drive circuit 112.

[0040] The motor control system 100 controls, for example, the motors included in the joints of the robot arm. In this case, part of the motor control system 100 may be located outside the robot arm. However, a system consisting only of a single robot arm may also be included in the motor control system 100 according to Embodiment 1.

[0041] Comparing Figure 1 and Figure 3, the motor control system 100 further includes a switching unit 130. Also, the electrical connection relationship between the interruption unit R1 and the drive circuit 110 has been changed.

[0042] The circuit breaker R1 interrupts the power supply from the first power source P1 to the inverter circuit 111. The first terminal of the circuit breaker R1 is electrically connected to the positive terminal of the first power source P1, and the second terminal of the circuit breaker R1 is electrically connected to the power supply wiring of the inverter circuit 111.

[0043] The switching unit 130 switches whether the power supply wiring of the inverter drive circuit 112 is electrically connected to the second terminal of the circuit breaker R1 or to the positive terminal of the second power supply P2. When the circuit breaker R1 is connected, the power supply wiring of the inverter drive circuit 112 is electrically connected to the second terminal of the circuit breaker R1. When the circuit breaker R1 is disconnected, the power supply wiring of the inverter drive circuit 112 is electrically connected to the positive terminal of the second power supply P2. The switching unit 130 may also switch the connection destination of the power supply wiring of the inverter drive circuit 112 in response to a switching signal received from the control unit 120. Alternatively, the connection destination of the power supply wiring of the inverter drive circuit 112 may be automatically switched in response to the disconnection of the circuit breaker R1.

[0044] Furthermore, the voltages of the first power supply P1 and the second power supply P2 may be different. For example, the voltage of the first power supply P1 may be higher than the voltage of the second power supply P2. In this case, the motor control system 100 may include a boost circuit to increase the voltage of the second power supply P2.

[0045] Figure 4 illustrates a first configuration example of the switching unit 130. The switching unit 130 includes interruption units R2 and R3. The state of interruption units R2 and R3 can be controlled by the control unit 120. The interruption units R2 and R3 are, for example, electromagnetic mechanical relays. One end of interruption unit R2 is electrically connected to the second terminal of interruption unit R1. One end of switch R3 is electrically connected to the positive terminal of the second power supply P2. The other end of interruption unit R2 and the other end of interruption unit R3 are electrically connected to the power supply wiring of the inverter drive circuit 112.

[0046] When circuit breaker R1 is in the connected state, circuit breaker R2 is set to the connected state and circuit breaker R3 is set to the disconnected state. When circuit breaker R1 is in the disconnected state, circuit breaker R2 is set to the disconnected state and circuit breaker R3 is set to the connected state. This switches the connection destination of the power supply wiring of the inverter drive circuit 112. Circuit breakers R2 and R3 switch between connected and disconnected states in response to a switching signal from the control unit 120, for example. The control unit 120 may, for example, monitor the voltage in the path between circuit breaker R1 and circuit breaker R2, and if the voltage drops, set circuit breaker R2 to the disconnected state and circuit breaker R3 to the connected state. Alternatively, the control unit 120 may set circuit breaker R2 to the disconnected state and circuit breaker R3 to the connected state when it receives a signal indicating that the emergency stop button has been pressed.

[0047] Figure 5 illustrates a second configuration example of the switching unit 130. In Figure 4, the interruption unit R2 is replaced with diode D1, and the interruption unit R3 is replaced with diode D2. For example, suppose the voltage of the first power supply P1 is higher than the voltage of the second power supply P2. When the interruption unit R1 is connected, the voltage in the path between the interruption unit R1 and diode D1 is higher than the voltage in the path between the second power supply P2 and diode D2 (i.e., the voltage of the second power supply P2). Therefore, diode D1 becomes conductive and diode D2 becomes non-conductive. When the interruption unit R1 is disconnected, the voltage in the path between the interruption unit R1 and diode D1 is lower than the voltage in the path between the second power supply P2 and diode D2 (i.e., the voltage of the second power supply P2). Therefore, diode D1 becomes non-conductive and diode D2 becomes conductive. The control unit 120 does not need to transmit a control signal to the switching unit 130.

[0048] The configuration of the switching unit 130 is not limited to the examples shown in Figure 4 and Figure 5. For example, the switching unit 130 may be composed of a single changeover switch.

[0049] The control unit 120 has the function of controlling the rotation of the motor M by transmitting a control signal to the inverter drive circuit 112. In particular, the control unit 120 has the function of applying a short brake to the motor M. When the control unit 120 applies a short brake to the motor M, the power supply of the inverter drive circuit 112 is switched from the first power supply P1 to the second power supply P2. Also, when the short brake is applied to the motor M, the cutoff unit R1 is in the cutoff state, and the power supply from the first power supply P1 to the inverter circuit 111 and the inverter drive circuit 112 is cut off.

[0050] The timing at which the motor control system 100 applies a short brake is not limited to the timing of an emergency stop for the motor M. For example, the motor M may be short-bripped when applying a braking force to the rotation of the shoulder or elbow joints due to gravity, or when controlling the mechanical impedance (flexibility of each joint) of the robot arm.

[0051] The control unit 120 may further have the function of switching the connection destination of the power supply wiring of the inverter drive circuit 112 by transmitting a switching signal to the switching unit 130. When the interruption unit R1 is interrupted, the control unit 120 switches the connection destination of the power supply wiring of the inverter drive circuit 112 to the second power supply P2. The control unit 120 may also switch the connection destination of the power supply wiring of the inverter drive circuit 112 when it receives a signal indicating that the emergency stop button has been pressed, for example. In addition, the control unit 120 may monitor the voltage in the path between the second terminal of the interruption unit R1 and the switching unit 130, and switch the connection destination of the power supply wiring of the inverter drive circuit 112 when the voltage drops.

[0052] The control unit 120 may further have a function to transmit a shut-off signal to the shut-off unit R1. For example, if a person or object comes into contact with or approaches a machine (e.g., a robot arm) operated by the motor M, the control unit 120 transmits a shut-off signal to the shut-off unit R1. When the control unit 120 transmits a shut-off signal to the shut-off unit R1, it may also transmit a switching signal to the switching unit 130.

[0053] For example, if a contact sensor is provided on the surface of the robot arm, the control unit 120 may send a cutoff signal to the cutoff unit R1 if the output of the contact sensor exceeds a threshold. The control unit 120 may also store a machine learning model that has been trained to determine whether the robot arm is approaching a person or an object based on images taken of the area around the robot arm or information from the contact sensor mounted on the robot arm. In this case, the control unit 120 may send a cutoff signal to the cutoff unit R1 if the determination result by the machine learning model is positive. The control unit 120 may also send a cutoff signal to the cutoff unit R1 at any timing when short-circuiting the motor M.

[0054] When the interruption unit R1 is interrupted and the connection destination of the power supply wiring of the inverter drive circuit 112 is switched, the control unit 120 applies a short-circuit brake to the motor M. Since the power supply wiring of the inverter drive circuit 112 is electrically connected to the power supply (second power supply P2), the inverter drive circuit 112 is operational and the control unit 120 can apply a short-circuit brake to the motor M. Since the inverter circuit 111 is not electrically connected to any power supply, it is guaranteed that the motor M will not be driven.

[0055] The control unit 120 may control the braking force due to short-circuit braking based on the duty cycle of the PWM signal. Alternatively, the control unit 120 may control the braking force due to short-circuit braking based on the duty cycle ratio, which indicates the proportion of time that the switching element Q is ON.

[0056] When a short-circuit brake is applied to the motor M, a back electromotive force (EMF) is generated between the U-phase, V-phase, and W-phase terminals of the motor. If the generated back EMF exceeds a predetermined value, dielectric breakdown may occur on the circuit board on which the drive circuit 110 is mounted. The back EMF generated between the terminals of the motor M changes depending on the magnitude of the braking force applied by the short-circuit brake. For example, the greater the braking force applied by the short-circuit brake, the greater the back EMF generated between the terminals of the motor M. Therefore, the control unit 120 may control the braking force applied by the short-circuit brake so that the generated back EMF is less than a predetermined value. This prevents dielectric breakdown from occurring due to the back EMF. The control unit 120 may also determine the magnitude of the braking force based on the current rotational speed of the motor.

[0057] Furthermore, the second power supply P2 is not limited to a power supply that provides power to the control unit 120. The second power supply P2 can be a different power supply from the first power supply P1. However, if the second power supply P2 is a power supply that provides power to the control unit 120, there is the advantage that there is no need to prepare another power supply (e.g., a battery).

[0058] The motor control system according to Embodiment 1 can apply a short brake to the motor while ensuring safety by preventing the motor from being driven. This eliminates the need for a dedicated switching element for the short brake and prevents an increase in the area of ​​the drive circuit.

[0059] Embodiment 2 Embodiment 2 is a specific example of Embodiment 1. Embodiment 2 includes a robot arm operated by a motor. Figure 6 is a diagram illustrating the configuration of a robot arm 20 provided by the motor control system according to Embodiment 2. The robot arm 20 comprises a hand 21, a first link 22, a second link 23, a wrist joint 24, an elbow joint 25, a shoulder joint 26, and a body 27.

[0060] The hand 21 grasps an object. One end of the first link 22 is rotatably connected to the hand 21 via a wrist joint 24. One end of the second link is rotatably connected to the other end of the first link 22 via an elbow joint 25. The other end of the second link 23 is rotatably connected to a shoulder joint 26. The shoulder joint 26 is connected to the body 27. The configuration of the body 27 is arbitrary and may include a head and legs. Figure 6 shows a simplified configuration of the body 27. The configuration of the robot arm 20 described is an example. The configuration of the robot arm 20 is not limited thereto, and for example, the number of links and joints may differ.

[0061] Each of the wrist joint 24, elbow joint 25, and shoulder joint 26 has a built-in motor (not shown). Each of the wrist joint 24, elbow joint 25, and shoulder joint 26 may also be further provided with a rotation sensor (e.g., a rotary encoder) (not shown). The rotation sensor outputs information indicating the rotation angle to a control unit, which will be described later. The control unit may be located in the main body 27. The motors rotate the wrist joint 24, elbow joint 25, and shoulder joint 26 in response to control signals from the control unit, thereby controlling the posture of the robot arm 20.

[0062] When the hand 21 lowers an object it is grasping, the control unit may apply a short brake to the motor to apply an appropriate braking force to the rotation of the shoulder joint 26 and elbow joint 25 due to gravity. Furthermore, by applying the short brake, the control unit can change the mechanical impedance (flexibility of each joint) of each joint of the robot arm 20. Controlling the mechanical impedance can improve the robot arm 20's ability to cooperate with humans.

[0063] Furthermore, in the event of an emergency stop of the robot arm 20, the control unit may apply a short-circuit brake to the motor. Applying a short-circuit brake to the motor reduces the speed at which each joint rotates due to gravity.

[0064] Figure 7 illustrates an example of the configuration of the motor control system 100a according to Embodiment 2. In Figure 7, dotted lines indicate the main control flow.

[0065] The motor control system 100a comprises multiple motors M, multiple inverter circuits 111, multiple inverter drive circuits 112, and a control unit 220. The control unit 220 corresponds to the control unit 120 described above. The control unit 220 comprises multiple shaft control units 121 and a main control unit 122.

[0066] Each of the multiple joints contains a motor M. Each motor M is provided with an inverter circuit 111, an inverter drive circuit 112, and an axis control unit 121. The axis control unit 121 controls the drive of the motor M by transmitting a control signal to the inverter drive circuit 112.

[0067] The main control unit 122 controls the overall movement of the robot arm 20. The main control unit 122 is a CPU that is more advanced than the CPU that makes up the axis control unit 121.

[0068] The motor control system 100a, like Embodiment 1, includes a first power supply P1, a second power supply P2, a circuit breaker R1, and a switching unit 130. The main control unit 122 is supplied with power from the second power supply P2. The switching unit 130 switches the connection destination of the power supply wiring of the inverter drive circuit 112.

[0069] When applying a short brake to each motor M, the control unit 220 sends, for example, a cutoff signal to the cutoff unit R1 and a switching signal to the switching unit 130. Applying a short brake is, for example, when stiffening the mechanical impedance of each joint of the robot arm 20. The control unit 220 may also determine whether or not to apply a short brake based on images taken of the area around the robot arm 20 or the output of contact sensors provided on the surface of the robot arm 20.

[0070] The control unit 220 may change the flexibility of each joint by applying a short brake to the motor M. By using a short brake, the flexibility of each joint can be changed with minimal energy loss.

[0071] The control unit 220 may decide whether or not to apply a short brake to the motor M when lowering an item grasped by the hand of the robot arm 20. For example, the control unit 220 may apply a short brake to the motor M if the weight of the item grasped by the hand of the robot arm 20 exceeds a predetermined value. The control unit 120 may also apply a short brake to the motor M if there are people or objects around the robot arm 20. The control unit 220 can reduce the operating speed of the robot arm 20 when there is a high need to ensure safety.

[0072] The control unit 220 can change the braking force by appropriately setting the duty cycle. For example, the control unit 220 may set a larger duty cycle and increase the braking force as the weight of the object grasped by the robot arm 20's hand increases. Also, the control unit 220 may set a larger duty cycle and increase the braking force as the number of objects surrounding the robot arm 20 increases. This allows for optimization of the robot arm 20's operating speed.

[0073] The braking force applied to the motor M may differ between joints. For example, the control unit 220 may apply different braking forces to the motor M in the shoulder joint and the motor M in the elbow joint. The control unit 220 may optimize the braking force applied to multiple motors M when a person is present around the robot arm.

[0074] Assume that the posture of the robot arm 20 is such that both the elbow joint 25 and the shoulder joint 26 are rotatable by gravity, as shown in the upper part of Figure 8. The control unit 220, for example, increases the braking force applied to the motor of the shoulder joint 26 and decreases the braking force applied to the motor of the elbow joint 25. In this case, the elbow joint 25 rotates mainly, and the posture of the robot arm 20 becomes the posture shown in the lower part of Figure 8. By appropriately determining the braking forces applied to multiple motors, the control unit 220 can change the posture of the robot arm 20.

[0075] The process of determining the braking force to be applied to multiple motors may be performed by the main control unit 122, which is a higher-level CPU. The moment of inertia around each axis changes depending on the weight of the object gripped by the hand. By issuing braking instructions from the main control unit 122, which understands the state of all axes, to the axis control unit 121, an appropriate braking force is applied to each axis.

[0076] The main control unit 122 can determine the braking force based on the current posture of the robot arm. The main control unit 122 determines the magnitude of the allowable braking force based on the current posture. The braking force may be determined based on the relationship between the external force applied to the motor, the braking force, and the back electromotive force generated between the motor terminals. The duty cycle is determined according to the braking force.

[0077] The motor control system 100a according to Embodiment 2 can apply a short-circuit brake to the motors included in each joint of the robot arm while ensuring safety by preventing each joint from being driven. Furthermore, by controlling the impedance of each joint through the short-circuit brake, safety can be improved, and the robot's ability to cooperate with humans can be enhanced.

[0078] In the examples described above, the program includes a set of instructions (or software code) that, when loaded into a computer, cause the computer to perform one or more of the functions described in the embodiments. The program may be stored on a non-temporary computer-readable medium or a physical storage medium. Examples, but not limited to, include random-access memory (RAM), read-only memory (ROM), flash memory, solid-state drive (SSD) or other memory technologies, CD-ROM, digital versatile disc (DVD), Blu-ray® disc or other optical disc storage, magnetic cassette, magnetic tape, magnetic disk storage or other magnetic storage devices. The program may be transmitted over a temporary computer-readable medium or a communication medium. Examples, but not limited to, include temporary computer-readable medium or a communication medium that includes electrically, optically, acoustically or otherwise propagating signals.

[0079] It should be noted that the present invention is not limited to the embodiments described above, and can be modified as appropriate without departing from the spirit of the invention. [Explanation of Symbols]

[0080] 50, 50a, 100, 100a motor control system M Motor P1 First power supply R1, R2, R3 breaker section 110 Drive Circuit 111 Inverter Circuit 112 Inverter drive circuit P2 Second power supply 120, 220 Control Unit 20 Robot Arms 21 Hand 22 Link 1 23 Second Link 24 Wrist joint 25 Elbow joint 26. Shoulder joint 27 Main unit

Claims

1. A motor control system, An inverter circuit including input / output elements, An inverter drive circuit that switches between the on and off states of the switching element, Equipped with, When applying a short brake to the motor, a switching unit switches the power supply that provides power to the inverter drive circuit from a first power supply that supplies power to the inverter circuit to a second power supply that is different from the first power supply, A control unit that applies a short brake to the motor by transmitting a control signal to the inverter drive circuit. Equipped with, The second power supply provides power to the control unit, It includes a first interruption unit that interrupts the power supply from the first power source to the inverter circuit, The switching unit switches whether the power supply wiring of the inverter drive circuit is electrically connected to the terminal on the inverter circuit side of the first break-off unit or to the positive terminal of the second power supply. When the first disconnector is in the connected state, the power supply wiring is electrically connected to the terminal of the first disconnector; when the first disconnector is in the disconnected state, the power supply wiring is electrically connected to the positive terminal of the second power supply. The switching unit comprises a second interruption unit, one end of which is connected to the terminal of the first interruption unit, and a third interruption unit, one end of which is connected to the positive terminal of the second power supply, with the other end of the second interruption unit and the other end of the third interruption unit connected to the power supply wiring of the inverter drive circuit. Motor control system.

2. When applying a short brake to the motor, the power supply from the first power source to the inverter circuit and the inverter drive circuit is interrupted. The motor control system according to claim 1.

3. The system further comprises a machine learning model trained to determine whether the robot arm has come into contact with or approached a human or object, based on images taken of the area surrounding the robot arm operated by the motor, or information from a contact sensor mounted on the robot arm. If the machine learning model determines that the result is positive, the power supply from the first power source to the inverter circuit and the inverter drive circuit is cut off. The motor control system according to claim 2.

4. The control unit controls the braking force by the short brake so that the back electromotive force generated between the terminals of the motor falls below a predetermined value. The motor control system according to claim 1.

5. The control unit applies a short-circuit brake to the motor when lowering an item if the weight of the item being gripped by the robot arm's hand, which is operated by the motor, is large. The motor control system according to claim 1.

6. The motor is included in each of the multiple joints of the robot arm. The control unit makes the braking force due to short braking differ among the multiple motors. The motor control system according to claim 1.

7. The motor is included in the joint of the robot arm. The control unit changes the flexibility of the joint by applying a short brake to the motor. The motor control system according to claim 1.

8. A motor control method for a motor control system comprising: a first power supply for supplying power to an inverter circuit including a switching element; a second power supply different from the first power supply; a control unit that applies a short-circuit brake to a motor by transmitting a control signal to an inverter drive circuit that switches the on and off states of the switching element; a first interruption unit that interrupts the power supply from the first power supply to the inverter circuit; and a switching unit that switches whether the power supply wiring of the inverter drive circuit is electrically connected to the terminal on the inverter circuit side of the first interruption unit or to the positive terminal of the second power supply, wherein The second power supply provides power to the control unit, The switching unit comprises a second interruption unit, one end of which is connected to the terminal of the first interruption unit, and a third interruption unit, one end of which is connected to the positive terminal of the second power supply, the other end of the second interruption unit and the other end of the third interruption unit are connected to the power supply wiring of the inverter drive circuit. When the first disconnector is in the connected state, the power supply wiring is electrically connected to the terminal of the first disconnector; when the first disconnector is in the disconnected state, the power supply wiring is electrically connected to the positive terminal of the second power supply. When applying a short brake to the motor, the switching unit includes the step of switching the power supply that provides power to the inverter drive circuit from the first power supply to the second power supply. Motor control method.

9. A motor control system program comprising: a first power supply for supplying power to an inverter circuit including a switching element; a second power supply different from the first power supply; a control unit that applies a short-circuit brake to a motor by transmitting a control signal to an inverter drive circuit that switches the on and off states of the switching element; a first interruption unit that interrupts the power supply from the first power supply to the inverter circuit; and a switching unit that switches whether the power supply wiring of the inverter drive circuit is electrically connected to the terminal on the inverter circuit side of the first interruption unit or to the positive terminal of the second power supply, wherein The second power supply provides power to the control unit, The switching unit comprises a second interruption unit, one end of which is connected to the terminal of the first interruption unit, and a third interruption unit, one end of which is connected to the positive terminal of the second power supply, the other end of the second interruption unit and the other end of the third interruption unit are connected to the power supply wiring of the inverter drive circuit. When the first disconnector is in the connected state, the power supply wiring is electrically connected to the terminal of the first disconnector; when the first disconnector is in the disconnected state, the power supply wiring is electrically connected to the positive terminal of the second power supply. On the computer, When applying a short brake to the motor, the switching unit controls the power supply that provides power to the inverter drive circuit from the first power supply to the second power supply. A program that executes the command.

Images