JP2017103989A - Control device using serially connected motors - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a control device having a simple configuration, which can freely set a torque ratio of two serially connected motors sharing a power supply and a motor driver.SOLUTION: A control device using serially connected motors is provided that comprises: a power supply; a motor driver connected to the power supply; two motors connected in series to the motor driver; a shunt circuit connected in parallel to at least one of the motors; shunting means provided in the shunt circuit for adjusting a shunt ratio between a current flowing through the motor and a current flowing through the shunt circuit; and a controller for controlling the operation of the motor driver and the split ratio in the shunting means. By controlling the split ratio in the shunting means by means of the controller, the amount of current flowing through the two motors is made different. Since the torque of the motor is proportional to the current flowing through the motor, it is possible to control the torque of the motor by the split flow ratio.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a control device capable of controlling the outputs of two motors connected in series differently with one power source and a motor driver.

Patent Document 1 describes a control device that controls the operation of a prosthetic hand using two DC motors. This control device includes a drive unit attached to a movable part of a user's body, such as an elbow and a leg, a master motor (drive side DC motor) to which the movement of the movable part is input by the drive unit, and a grasping part of an artificial hand. A slave motor (driven DC motor) to be operated and a connection circuit for electrically connecting the master motor and the slave motor are provided, and the user drives the master motor via the drive unit by moving the movable part. The movement of the master motor drives the slave motor via the connection circuit to operate the artificial hand.
The control device for the prosthetic hand of Patent Document 1 operates the slave motor by the electric energy generated by the master motor, and the master motor and the slave motor are components of the same connection circuit. The current flowing through the motor is common. Since the motor torque is proportional to the current, when two motors with the same characteristics are used, the torque of the slave motor corresponding to the gripping force when the gripper grips or manipulates the object is the same as the torque of the master motor. In addition, the torque that moves the movable part is a reaction force directly felt by the drive side. For this reason, even if a special sensor is not provided, the user can perceive the reaction force when the grasping portion of the prosthetic hand grips or manipulates the object as the torque applied to the movable part. Therefore, a control device having a sense of force can be constructed without using a special power source or sensor, the device can be made light and simple, and maintenance is easy.

  Patent Document 2 discloses a method of presenting an applied force at a slave to a master by detecting the force of the slave using a sensor. This device is equipped with a sensor that detects the force in the slave, calculates the signal from the sensor, and converts it into the current necessary for the force that the master side motor should generate, so that the force at the slave can be sensed by the master. It is configured to be able to.

JP2015-37498A JP 2011-517419 A

  In the control device described in Patent Document 1, since two motors are connected in series to a power source and a motor driver, currents flowing through the individual motors are common. For this reason, if two motors having the same electrical characteristics and mechanical characteristics are used, the flowing current is constant, and the torques of the two are the same. Therefore, if mechanical loss and inertial force are ignored, the master motor A system in which the drive torque of the slave motor and the load torque of the slave motor match can be realized with a relatively simple configuration.

  By the way, when you want to make the output different between the master motor and the slave motor, for example, to increase the output torque of the slave motor compared to the drive torque of the master motor, the slave motor is rated at a higher output than the master motor. It is conceivable to select a motor with a large torque. However, in general, a motor having a larger output tends to have a smaller torque constant. Therefore, if the current is common, the torque ratio matches the ratio of the torque constant. Therefore, the slave motor having a larger rated torque has a higher torque. It causes a contradiction that it becomes smaller. Thus, even if two motors having different outputs are used, there is a problem that it is difficult to obtain a torque output as planned because the ratio of the rated torque and the ratio of the torque constant are actually different.

As shown in FIG. 5, it is also conceivable that the two motors Mm and Ms are provided with individual power supplies Pm and Ps and motor drivers Dm and Ds, respectively, and the two motors Mm and Ms are controlled independently. However, in this case, there are problems that the number of necessary components increases, the apparatus becomes complicated, and the size increases.
Furthermore, it is conceivable to connect a speed reducer to one or both motors to change the output between the two motors. However, the speed reducer has mechanical loss such as friction, and the configuration of the apparatus is complicated. There is a problem.

The apparatus of Patent Document 2 requires a large number of sensors, and a circuit, software, and the like for processing sensor signals are necessary, so that the apparatus becomes complicated. Further, since the sensor is used, there is a problem that the calibration of the sensor is required at regular intervals, for example, and whether the maintenance is performed or not greatly affects the performance of the apparatus during actual use.

  An object of the present invention is to provide a control device with a simple configuration that can freely set the torque ratio of two series-connected motors that share a power source and a motor driver.

In order to achieve the above object, a control device using a series motor according to claim 1 adopted by the present invention,
Power supply,
A motor driver connected to the power supply;
Two motors connected in series to the motor driver;
A shunt circuit connected in parallel to at least one of the motors;
A shunting means provided in the shunt circuit for adjusting a shunt ratio between a current flowing through the motor and a current flowing through the shunt circuit;
A controller for controlling the operation of the motor driver and a diversion ratio in the diversion means is provided.

In a control device using a series motor according to claim 2 of the present invention, the shunting means includes a variable resistor for changing the resistance value of the shunt circuit, and the controller controls the resistance value of the variable resistor. Features.

In the control device using the series motor according to claim 3 of the present invention, the shunting means includes switch means for switching the shunt circuit between a short-circuited state and a disconnected state, and the controller controls the switching operation of the switch means. The time for the shunt circuit to be short-circuited is adjusted.

In the control device using the series motor according to claim 4 of the present invention, two motors are set, one being a master motor and the other being a slave motor.
A shunt circuit including a shunt means is connected in parallel to the master motor,
The master motor includes a first encoder that outputs a master rotation signal according to the rotation operation of the rotation shaft of the master motor,
The slave motor includes a second encoder that outputs a slave rotation signal according to the rotation operation of the rotation shaft of the slave motor,
The controller controls the current dividing means to adjust the current flowing through the master motor, and based on the master rotation signal output from the first encoder and the slave rotation signal output from the second encoder, the slave motor It is characterized by controlling the rotational movement of.

  According to the first aspect of the present invention, a shunt circuit is connected in parallel to at least one of two motors connected in series to a common power source and a motor driver, and the current flowing through the motor is connected to the shunt circuit. Since the shunting means for adjusting the shunt ratio between the current flowing through the shunt circuit and the shunt circuit is provided, the amount of current flowing through the two motors can be made different by controlling the shunt ratio in the shunting means by the controller. Since the torque of the motor is proportional to the current flowing through the motor, the torque of the motor can be controlled by the diversion ratio.

According to the second aspect of the present invention, since the variable resistor for changing the resistance value of the shunt circuit is adopted as the shunting means, the current shunt ratio is adjusted by changing the resistance value of the variable resistor. Thus, the torque of the motor can be controlled. Since a variable resistor is used for the diversion unit, the diversion unit can be configured simply.

According to the third aspect of the present invention, since the switch means for switching the shunt circuit between the short-circuited state and the cut-off state is adopted as the shunting means, the current shunting is achieved by changing the short-circuit time of the shunt circuit by the switch means. The motor torque can be controlled by adjusting the ratio. Since the switch means is used as the shunting means, the current shunt ratio between the motor and the shunt circuit can be made 1 if the shunt circuit is cut off.

  According to the fourth aspect of the present invention, a master motor and a slave motor each having an encoder are connected, and a shunt circuit including a shunt unit is connected in parallel to the master motor, and the controller controls the shunt unit to the master motor. While adjusting the flowing current, the rotation operation of the slave motor is controlled based on the master rotation signal output from the first encoder and the slave rotation signal output from the second encoder. Therefore, using two motors connected in series, the slave motor can be driven based on the input to the master motor, and the bilateral can adjust the torque ratio between the master motor and the slave motor. The control device can be constructed with a simple configuration.

1 is a circuit diagram showing a first embodiment of a control device using a series motor according to the present invention. FIG. It is a circuit diagram which shows 2nd Embodiment of the control apparatus using the serial type motor which concerns on this invention. It is a time chart which shows the control aspect of the current shunt ratio by the switch means in this case control apparatus shown in FIG. It is a circuit diagram which shows 3rd Embodiment of the diversion means in the control apparatus using the serial type motor which concerns on this invention. It is a circuit diagram which shows an example of the conventional control apparatus. The example which applied this invention to the drive control means of an artificial leg is shown. It is a figure which shows the example which applied this invention to the surgery assistance robot.

[First Embodiment]
FIG. 1 is a circuit diagram showing a schematic configuration of a control device (hereinafter referred to as “the present control device”) using a series motor according to the present invention. In the drawing, the power system wiring is indicated by a solid line, and the control system wiring is indicated by a broken line.

As shown in FIG. 1, the present control device includes a power source P, a motor driver D connected to the power source P, two motors Mm and Ms connected in series to the motor driver D, and at least one motor ( In this example, a shunt circuit bc connected in parallel to the motor Mm) and a shunt means provided in the shunt circuit bc for adjusting the shunt ratio between the current flowing through the motor Mm and the current flowing through the shunt circuit bc are provided. Prepare. The power source P is a DC power source, and the two motors Mm and Ms are DC motors.

In this example, a variable resistor VR for changing the resistance value of the shunt circuit bc is used as the shunting means. The controller C controls the operation of the motor driver D and adjusts the resistance value of the variable resistor VR to control the current splitting ratio of the current that branches and flows between the motor Mm and the shunt circuit bc.

  Further, in this example, one of the two motors is set to the master motor Mm, the other is set to the slave motor Ms, and the shunt circuit bc including the variable resistor VR is connected in parallel to the master motor Mm. The slave motor Ms includes a first encoder ec2 that outputs a slave rotation signal according to the rotation operation of the rotation shaft of the slave motor Ms. The first encoder ec1 outputs a master rotation signal according to the rotation operation of the rotation shaft of the motor Mm. Including. The controller C not only adjusts the current flowing through the master motor Mm by controlling the variable resistor VR, but also the master rotation signal output from the first encoder ec1 and the slave rotation signal output from the second encoder ec2. Based on the above, the rotation amount of the slave motor Ms is controlled. Each of the first encoder ec1 and the second encoder ec2 is a rotary encoder connected to the rotation shaft of the motor.

  In general, a DC motor is connected to a circuit and generates resistance, inductance, and counter electromotive force when a current is passed. However, the inductance and the counter electromotive force can be ignored under a very low speed state where the rotational speed of the motor is very slow. Further, under the slow speed state, the increasing component of the resistance that generates the shaft output depending on the rotation speed can be ignored. Then, under the very low speed condition, the motor shaft output torque is expressed by the product of the torque constant and current that are determined electrically and physically for each motor, so it can be said that it depends on the value of the current flowing through the motor. it can. Therefore, it can be seen that the shaft output torque of the motor can be changed by changing the current value.

The control device of this example changes the current flowing through the master motor Mm by changing the resistance value of the variable resistor VR connected in parallel to the master motor Mm, thereby changing the shaft output torque of the master motor Mm. Is. Assuming that the current flowing through the circuit is i, the current flowing through the motor Mm is i ₁ , the resistance of the motor Mm is Ra, the resistance of the variable resistor VR is Rs, and the shunt ratio is n, from these relationships, can get.
1) i = n · i ₁ = i ₁ + (n−1) i ₁
2) (n-1) i ₁ / i ₁ = Ra / Rs
3) n = 1 + (Ra / Rs)

Since n> 1 from Equation 3 above, by connecting the variable resistor VR in parallel to the master motor Mm, the current i ₁ flowing through the master motor Mm becomes smaller than the circuit current i, and the resistance value Rs of the variable resistor VR It can be seen that the current i ₁ flowing through the master motor Mm can be reduced as the value of is reduced.

The current i ₁ flowing through the master motor Mm is 1 / n of the circuit current i. However, since the circuit current i flows through the slave motor Ms, the shaft output torque generated by the slave motor Ms is the axis of the master motor Mm. N times the output torque.

  A case where the present control device configured as described above is applied to bilateral control will be described. In FIG. 1, the master motor Mm and the slave motor Ms are substantially the same motors having the same rated torque and torque constant. Further, the input to the master motor Mm is performed at a very low speed.

When an external force is applied to the rotation shaft of the master motor Mm to rotate it, an induced current flows through the internal circuit due to the induced electromotive force generated thereby. Based on this induced current, the motor driver D drives the slave motor Ms. At this time, the user can have a sense of force because the rotating shaft receives a reaction force upon input to the master motor Mm.

  Further, based on the master rotation signal output from the first encoder ec1 that detects the rotation amount of the master motor Mm and the slave rotation signal output from the second encoder ec2 that detects the rotation amount of the slave motor Ms, The controller C can control the motor driver D to accurately adjust the rotation amount of the slave motor Ms. The ratio of the shaft rotation amount with the slave motor Ms to the shaft rotation amount of the master motor Mm may be 1: 1, but the above ratio may be changed according to the situation of implementation.

  The amount of current flowing through the master motor Mm is adjusted by the resistance value of the variable resistor VR provided in the shunt circuit bc. When the shunt ratio of the current flowing through the master motor Mm is set to n, the circuit current i flows through the slave motor Ms, whereas the master motor Mm flows a current 1 / n of the circuit current i. Since the shaft output torque of the motor depends on the current, an output that is n times larger than the input to the master motor Mm can be obtained from the slave motor Ms.

  In short, when the rotational shaft of the master motor Mm is rotationally driven, the present control device can obtain a rotational output corresponding to the amount of rotation and the shunt ratio of the shunt circuit from the slave motor Ms, and at the time of input power It has a sense of consciousness. Therefore, it is considered that the present control device is preferably applied to, for example, a rehabilitation walking training device or a walking assist device.

[Second Embodiment]
Since the present control apparatus shown in FIG. 1 uses a variable resistor VR as a shunting means, in order to set the shunt ratio to 1, the resistance value of the variable resistor VR must be infinite. It is difficult to set the diversion ratio to 1. Further, if the variable resistor VR having a large resistance value is used, the shunt ratio can be made close to 1. However, for this purpose, there is a restriction that the variable resistor VR having a large rated power must be used.

Therefore, as shown in FIG. 2, it can be considered that the diversion means connected in parallel to the master motor Mm is constituted by the switch means SC. The switch means SC has a function of continuously switching the shunt circuit bc between a short circuit state and a cut state. Specifically, it is preferable to use a semiconductor switching device using a transistor or FET. The semiconductor switching device has an advantage that the circuit can be ON / OFF controlled at a high speed, and there are few problems of switch contact wear and noise generation.

In the case control apparatus shown in FIG. 2, the shunt circuit bc is continuously switched at high speed between the short circuit state and the cut state by the switch means SC. For example, the ON / OFF operation is performed at time intervals as shown in FIG. As shown in FIG. 3, when the switch means SC is turned on to short-circuit the shunt circuit bc, almost all of the current flows to the shunt circuit bc and does not substantially flow to the master motor Mm. If the value is i, the instantaneous current value (switch current) flowing through the shunt circuit bc is i, and the motor current is zero. On the other hand, when the switch circuit SC is turned off and the shunt circuit bc is disconnected, the circuit current flows only to the master motor Mm, so the motor current is i and the switch current is 0.

The current value im flowing through the master motor Mm can be expressed as an average value of the current flowing intermittently. That is, since the current im flows through the master motor Mm when the switch means SC is in the OFF state, im can be expressed by the following equation 4 where the circuit current is i.
4) im = i × OFF time / (ON time + OFF time)

  From the above equation 4), it can be seen that the average current value flowing through the master motor Mm can be changed by changing the ratio of the ON-OFF time of the switch means SC. Then, by changing the average current value, the torque output of the master motor Mm also changes in proportion. On the other hand, a circuit current i flows through the slave motor Ms. Therefore, the output torque ratio of the master motor Mm to the slave motor Ms can be controlled by adjusting the ratio of the ON time and the OFF time of the switch means SC.

  In this example, there is also an advantage that the shunt circuit bc is cut off by the switch means SC, and the shunt ratio of the current flowing through the master motor Mm can be set to 1. Further, since the ratio of the ON / OFF time of the switch means SC can be easily changed, there is an advantage that it is possible to respond immediately when it is necessary to change the torque ratio between the master motor Mm and the slave motor Ms.

  FIG. 2 shows a configuration in which the speed reducers R1 and R2 are connected to the respective rotation shafts of the master motor Mm and the slave motor Ms. However, this speed reducer is unnecessary by using the current dividing means using the switch means SC. Can be. By omitting the speed reducer, there is an advantage that mechanical loss is reduced and some of the factors that reduce the transmission sensitivity of the force sense can be eliminated.

[Third Embodiment]
As shown in FIG. 4, it is conceivable to connect a resistor in series with the switch means SC as the current dividing means provided in the current dividing circuit bc. By connecting the resistor, when the switch means SC is always ON due to a failure of the controller C or the switch means SC and the shunt circuit bc is maintained in a short-circuited state, the master motor Mm has this resistance and the motor resistance. Therefore, there is an advantage that the operation of the master motor Mm can be guaranteed. The resistor may be a fixed resistor, but a variable resistor VR can also be used as shown.

[Other Embodiments]
The shunting means can be connected in parallel to the slave motor Ms instead of the master motor Mm. Further, it is possible to connect the flow dividing means in parallel to both the master motor Mm and the slave motor Ms.

The present invention can be applied to a walking assist device using a part of the user's body as input means. For example, FIG. 6 shows a walking support apparatus in which a master is attached to the left arm, a slave is attached to the right leg prosthesis, and a controller / driver / power source is attached to the waist. In this example, since an output larger than the input is required, walking can be supported by amplifying the input to the master motor Mm and outputting a large torque from the slave motor Ms. On the other hand, in applications where a delicate output such as a prosthetic hand is required, the input of the master motor Mm may be reduced and output from the slave motor Ms. Thus, the torque ratio between the master motor Mm and the slave motor Ms can be set as appropriate according to the application target.

  Further, as shown in FIG. 7, if the present invention is applied to a surgical operation support robot, the number of sensors can be reduced, so that the circuit and software for processing sensor signals can also be reduced. It is possible to obtain the advantage of being easy. Furthermore, since maintenance such as sensor calibration work can be reduced, there is also an advantage that the apparatus performance during actual use is stabilized.

P Power source D Motor driver C Controller Mm Master motor Ms Slave motor VR Variable resistance SC Switch means

Claims (4)

Power supply,
A motor driver connected to the power supply;
Two motors connected in series to the motor driver;
A shunt circuit connected in parallel to at least one of the motors;
A shunting means provided in the shunt circuit for adjusting a shunt ratio between a current flowing through the motor and a current flowing through the shunt circuit;
A controller using a series motor, comprising: a controller for controlling the operation of the motor driver and a diversion ratio in the diversion means.   The control device using a series motor according to claim 1, wherein the shunting means includes a variable resistor for changing a resistance value of the shunt circuit, and the controller controls the resistance value of the variable resistor.   The shunting means includes switch means for switching the shunt circuit between a short circuit state and a disconnected state, and the controller controls the switching operation of the switch means to adjust the time when the shunt circuit is in the short circuit state. A control device using a series motor. One of the two motors is set as the master motor and the other as the slave motor.
A shunt circuit including a shunt means is connected in parallel to the master motor,
The master motor includes a first encoder that outputs a master output signal in accordance with the rotation operation of the rotation shaft of the master motor,
The slave motor includes a second encoder that outputs a slave output signal in accordance with the rotation operation of the rotation shaft of the slave motor,
The controller controls the current dividing means to adjust the current flowing through the master motor, and based on the master rotation signal output from the first encoder and the slave rotation signal output from the second encoder, the slave motor The control apparatus using the serial motor according to any one of claims 1 to 3, which controls the rotation operation of the motor.

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