Driving apparatus, driving method and apparatus

The present invention relates to a drive device with a speed reducer, a drive method, and a device.

In the drive device, torque is secured by decelerating the rotation of the motor with a reducer. In such a drive device, an encoder that detects the rotation position is provided only on the input shaft of the reducer, and in the case of an AC servomotor, current vector control and servo loop speed control / position control are combined. Is commonly done. In recent years, there is a drive device in which an encoder is also provided on the output shaft of the reducer due to an increasing demand for higher positioning accuracy and a reduction in the cost of the encoder. In the drive device having such a configuration, there is a drive device to which a function of performing torque feedback control is added in consideration of backlash in the speed reducer (see, for example, Patent Document 1).

<p><patcit num="1"><text>Japanese Unexamined Patent Publication No. 2006-50710</text></patcit></p>

<p> However, for example, by performing torque feedback control as in Patent Document 1, the configuration becomes complicated. Therefore, in order to configure the torque feedback control in order to improve the positioning accuracy, it is not possible to easily add the torque feedback control function with the control device having the general configuration detected by the input shaft encoder. It is necessary to adapt to the addition of various control loops. Therefore, the existing control device that does not perform torque feedback control cannot be diverted, and it is necessary to reconstruct the control system that can form a new control loop. That is, in the control device applied to the conventional drive device, there is a problem that the control device cannot be applied by a simple change such as changing the control method, and the performance cannot be easily improved. As described above, in order to improve the performance, a control device having an advanced control function is required, which makes the system expensive.</p><p> The present invention has been made to solve the above problems, and an object of the present invention is to provide a drive device, a drive method, and a device capable of improving positioning accuracy while having a simple configuration.</p>

<p> In order to solve the above problem, one aspect of the present invention is a drive unit that is rotationally driven and a first position detector that detects the rotational angle position of the drive output shaft of the drive unit and generates first position information. A speed reducer connected to the drive output shaft of the drive unit, a second position detector that detects the rotation angle position of the speed reduction output shaft of the speed reducer and generates a second position information, and the first position detector. The drive device is characterized by comprising a control unit that controls the drive unit by selectively using the position information of the above and the second position information.</p><p> Further, another aspect of the present invention includes a drive unit that is rotationally driven, a first position detector that detects the rotational angle position of the drive output shaft of the drive unit and generates first position information, and the drive unit. A drive device including a speed reducer connected to the drive output shaft and a second position detector that detects the rotation angle position of the speed reduction output shaft of the speed reducer and generates a second position information. The driving method is characterized in that it has a control process for controlling the driving unit by selectively using the first position information and the second position information.</p><p> Further, another aspect of the present invention is a first position detector that detects the rotation angle position of the drive output shaft in the drive unit that is rotationally driven and generates the first position information, and a deceleration connected to the drive output shaft. A second position detector that detects the rotation angle position of the deceleration output shaft in the machine and generates a second position information, and at least a semi-closed loop control that controls the drive unit based on the first position information and at least. The drive device is characterized by including a control unit that selectively performs full closed loop control that controls the drive unit based on the second position information.</p><p> Another aspect of the present invention is a device including a drive device for driving the arm portion, wherein the drive device is the drive device according to the embodiment of the present invention.</p>

<p> According to the present invention, the positioning accuracy can be improved even though the configuration is simple.</p>

<figref num="1">It is a block diagram which shows the structure of the drive device by one Embodiment of this invention.</figref><figref num="2">It is a figure which shows the result of the position control of the drive device by one Embodiment of this invention.</figref><figref num="3">It is a block diagram which shows the structure of the drive device by one Embodiment of this invention.</figref><figref num="4">It is a block diagram which shows the structure of the drive device by one Embodiment of this invention.</figref><figref num="5">It is a figure which shows the result of the position control of the drive device by one Embodiment of this invention.</figref><figref num="6">It is a block diagram which shows the structure of the drive device by one Embodiment of this invention.</figref><figref num="7">It is a block diagram which shows the structure of the drive device by one Embodiment of this invention.</figref><figref num="8">It is a block diagram of the apparatus by one Embodiment of this invention.</figref>

Hereinafter, an embodiment of the present invention will be described with reference to the drawings. (First Embodiment) FIG. 1 is a block diagram showing a configuration of a drive device according to the present embodiment. The drive device 1a shown in FIG. 1 includes a motor 10, a reducer 20, an input axis encoder 31, an output axis encoder 32, a weighting calculation unit 40a, a subtractor 51, 71, a position controller 52, a differentiator 60, and a speed control. It is equipped with a device 72 and a current controller 80. Further, the weighting calculation unit 40a, the subtractors 51 and 71, the position controller 52, the differentiator 60, the speed controller 72, and the current controller 80 form a control unit 100a for controlling the motor 10.

The motor 10 is supplied with a control current, generates an output torque corresponding to the value, and rotates an armature having an output shaft (drive output shaft). The control current is controlled by a general driving method such as PWM (Pulse Width Modulation). The speed reducer 20 is connected to the output shaft of the motor 10 and includes an input shaft that rotates together with the output shaft. The speed reducer 20 decelerates the rotation applied to the input shaft at a desired deceleration rate to rotate the output shaft (deceleration output shaft). Let me. A load is connected to the output shaft of the reducer 20 to supply the converted torque. The input shaft encoder 31 is provided on the input side of the speed reducer 20, detects the rotation angle position of the input shaft of the speed reducer 20, that is, the output shaft (drive output shaft) of the motor 10 (drive unit), and detects the rotation angle. Generate position information (first position information). The output shaft encoder 32 is provided on the output side of the speed reducer 20, detects the rotation angle position of the output shaft (deceleration output shaft) of the speed reducer 20, and generates the detected rotation angle position information (second position information). To do.

The weighting calculation unit 40a selects rotation angle position information of the output shaft of the motor 10 (input shaft of the speed reducer 20) and the output shaft of the speed reducer 20, that is, the first position information and the second position information. In order to control the motor 10 by using the above, the detection position information indicating the detection position is generated. Therefore, the weighting calculation unit 40a sets the selection condition set by the determination unit 41a from the three "first position information", "second position information", and "first and second position information". Selectively use the information to be referred to accordingly. The weighting calculation unit 40a performs a weighting calculation on the "first position information" and the "second position information" according to the weighting coefficient set as the selection condition, and generates the detection position information indicating the detection position.

Further, the weighting calculation unit 40a includes a determination unit 41a that generates a weighting coefficient for the weighting calculation. The determination unit 41a determines the value of the rotation position error generated by the subtractor 51, and changes the weighting coefficient of the weighting operation performed by the weighting operation unit 40a according to the determination result. This rotation position error is generated from the difference between the target rotation position command value of the motor 10 and the detection position information from the weighting calculation unit 40a. For example, the determination unit 41a determines the value of the rotation position error based on the reference value determined according to the target rotation position command value of the motor 10, and sets the reference value determined according to the target rotation position command value of the motor 10 to the reference value. When the position information of 1 is reached, the weighting coefficient is changed so that the second position information is selectively used or the ratio of the second position information is higher than that of the first position information. The reference value determined according to the target rotation position command value of the motor 10 is generated by multiplying the target rotation position command value of the motor 10 by a predetermined ratio. In this way, the weighting coefficient of the weighting calculation unit 40a is changed according to the control state. The weighting calculation unit 40a is proportional to the first position information and the second position information according to the deceleration rate in the speed reducer 20 and the detection gains in the input shaft encoder 31 and the output shaft encoder 32. The conversion will be performed.

The subtractor 51 subtracts the value of the detection position information supplied from the weighting calculation unit 40a from the target rotation position command value of the motor 10. That is, the detected position information from the weighting calculation unit 40a is supplied as a negative feedback signal for feedback control in the position control loop, and a rotation position error with respect to the target rotation position command value is generated by subtracting it from the target rotation position command value. .. The position controller 52 is supplied with the rotation position error generated by the subtractor 51, and generates a target rotation angular velocity according to the rotation position error. The position controller 52 generates a target rotational angular velocity with respect to the supplied rotational position error by a predetermined transfer function or arithmetic processing based on a proportional coefficient.

The differentiator 60 differentiates the rotation angle position information (armature position information) of the output shaft of the motor 10 detected by the input shaft encoder 31, and the amount of change in the rotation angle per unit time, that is, the detection angular velocity information (armature). Child velocity) is generated. The subtractor 71 subtracts the value of the detection angular velocity information from the differentiator 60 from the target rotation angular velocity command value of the motor 10. That is, the detection angular velocity information from the differentiator 60 is supplied as a negative feedback signal of feedback control in the speed control loop, and the rotation angular velocity error from the target rotation angular velocity is derived by subtracting from the target rotation angular velocity. The speed controller 72 is supplied with the rotation angular velocity error generated by the subtractor 71, and generates a control amount command value according to the rotation angular velocity error. The speed controller 72 generates a control amount command value for the supplied rotation angular velocity error by a predetermined transfer function or arithmetic processing based on a proportional coefficient. The current controller 80 supplies the control current for driving the motor 10 to the motor 10 according to the generated control amount command value. Further, the current controller 80 performs current vector control based on the control current for driving the motor 10 and the rotation angle position information (armature position information) of the output shaft of the motor 10.

With the configuration shown above, the drive unit is fully closed according to the rotation angle position of the output shaft of the reducer 20 and the rotation angle position of the input shaft of the reduction gear 20, that is, the output shaft of the motor 10. Loop control can be performed. In full closed loop control, the rotation angle position of the output shaft of the reducer 20 is used as a feedback signal for position control. As a result, the accuracy of the stop position can be improved. However, the drive device includes the reducer 20 in the position control loop, and the loop gain is increased due to the decrease in followability due to the elasticity of the reducer 20 and the delay due to the influence of wasted time caused by the backlash of the gear. It may not be possible and the responsiveness may decrease.

Therefore, in the drive device shown in the present embodiment, the positioning accuracy of the stop position by the fully closed loop control is ensured, and the responsiveness when the target rotation position is changed is improved. A drive device having a configuration in which the speed reducer 20 that affects responsiveness is removed from the position control loop can prevent a decrease in responsiveness. Further, when the target rotation position is significantly changed, it is desirable that the drive device can secure responsiveness until it approaches the stop position. Therefore, the drive device in the present embodiment gives priority to ensuring responsiveness rather than ensuring stop position accuracy until the target rotation position is reached. Based on this prioritization, the drive device 1a changes the feedback signal of the position control loop according to the weighting coefficient by the weighting calculation unit 40a. That is, the drive device 1a in the present embodiment is controlled based on the rotation angle position of the input shaft of the speed reducer 20, that is, the output shaft of the motor 10 in a state where the deviation to the stop position is large and the error with respect to the stop position is large ( Perform semi-closed loop control) to ensure responsiveness. Then, when the drive device 1a approaches the stop position and the error with respect to the stop position is small, the stop position accuracy can be ensured by performing full closed loop control.

As described above, the drive device 1a in the present embodiment realizes the above-mentioned characteristic change by changing the information to be fed back while having the configuration of the position control loop without increasing the number of new control loops. Can be done. For example, the relational expression of the information to be fed back is shown as Eq. (1).

θ_s = k × θ1_s + (1-k) × θ2_s, k = 0 ~ 1 (1)

In equation (1), θ_s indicates the detected rotation position, θ1_s indicates the input shaft rotation position detected by the encoder 31, θ2_s indicates the output shaft rotation position detected by the encoder 32, and k is 0 or more and 1 or less. Indicates the weighting factor shown as the value of. Equation (1) is an equation that performs a weighted averaging operation on the first position information and the second position information using the weighting coefficient (k), and by appropriately selecting the value of k, respectively. The ratio of can be changed. Then, by gradually changing the value of k, it is possible to absorb sudden fluctuations in the output (detection position information) at the time of switching.

The weighting coefficient for the first position information and the second position information may be complementary to "0" and "1" set according to the selection condition. When the weighting coefficient selectively outputs "0" and "1" to selectively output the first position information and the second position information, the weighting calculation unit 40a functions as a selection unit. To do. At that time, when "0" and "1" are specified as the weighting coefficients for the first position information and the second position information, respectively, the feedback signal of the position control loop is second by the weighting calculation unit 40a. It is a configuration of full closed loop control with the position information of. That is, in the equation (1), k = 0 is set.

Further, the weighting calculation unit 40a may perform a low-pass filter processing for removing high frequency components on the output signal. As a result, it is possible to absorb sudden fluctuations in the output (detection position information) that may occur when the weighting coefficient is switched instantaneously.

Next, with reference to the figure, the simulation result when the weighting coefficient of the weighting calculation unit 40a is set to either 0 or 1 is shown. FIG. 2 is a diagram showing the result of position control of the drive device in this embodiment. In FIG. 2 (a), the vertical axis represents the rotation position (milliradiant) and the horizontal axis represents the time (seconds). The step response when a change of 1 (milliradiant) is given as the target rotation position command value at time 0 seconds is shown. In this figure, the graph shown in the waveform S101 shows the result in the present embodiment, and the graph shown in the waveform S102 is controlled based on the rotation angle position of the input shaft of the speed reducer 20, that is, the output shaft of the motor 10 (semi-closed loop control). ) Is shown in the rotation angle position of the output shaft of the speed reducer 20. In the graph shown in waveform S101, it has converged to the target rotation position command value (1 (milliradiant)) by 0.5 seconds, but in the graph shown in waveform S102, it is affected by the load and is about 0.2 (milliradiant). There is an error in. In addition, when the step response applied at time 0 seconds is stable at time 5 seconds, the load is increased and the influence of disturbance is evaluated. In the graph shown in waveform S101, the target rotation position command value (1 (milliradiant)) has converged by the time 5.5 seconds, but in the graph shown in waveform S102, it is about 0.4 (millimeter) due to the influence of the increased load. Radiant) and the error increases.

FIG. 2 (b) shows the change in position error (err) on the same time axis as in FIG. 2 (a). The value of the position error increases instantaneously at time 0 seconds and time 5 seconds, and decreases like the primary response characteristic as it approaches the target rotation position. Here, a reference value corresponding to the target rotation position command value is determined, and it is determined whether or not the value of the position error exceeds the reference value. FIG. 2C is a graph showing the result of the above determination. A positive pulse indicates when the position error value exceeds the specified reference value. During the period of the pulse, the drive device 1a interrupts the fully closed loop control and switches to the control that prioritizes the responsiveness (semi-closed loop control).

(Second Embodiment) The driving device of this embodiment is shown with reference to FIG. FIG. 3 is a block diagram showing a configuration of a drive device according to the present embodiment. The drive device 1b shown in FIG. 3 includes a motor 10, a reducer 20, an input axis encoder 31, an output axis encoder 32, a weighting calculation unit 40b, a subtractor 51, 71, a position controller 52, a differentiator 60, and a speed controller. It is equipped with 72 and a current controller 80. Further, the weighting calculation unit 40b, the subtractors 51 and 71, the position controller 52, the differentiator 60, the speed controller 72, and the current controller 80 form a control unit 100b that controls the motor 10. The same components as in FIG. 1 are designated by the same reference numerals. Further, the present embodiment is an embodiment in which the weighting calculation unit 40a in the first embodiment is replaced with the weighting calculation unit 40b. However, the determination unit 41b included in the weighting calculation unit 40b is different from the determination unit 41a in the weighting calculation unit 40a.

The weighting calculation unit 40b includes a determination unit 41b that generates a weighting coefficient for the weighting calculation. The determination unit 41b determines the value of the target rotational angular velocity of the motor 10 generated by the position controller 52, and changes the weighting coefficient of the weighting operation according to the determination result. For example, the determination unit 41b determines the value of the target rotational angular velocity of the motor 10 based on a predetermined reference value. The determination unit 41b selectively uses the second position information when the target rotation angular velocity of the motor 10 drops to a predetermined reference value, or the second position information from the first position information. Change the weighting factor to increase the ratio of.

(Third Embodiment) The driving device of this embodiment is shown with reference to FIG. FIG. 4 is a block diagram showing a configuration of a drive device according to the present embodiment. The drive device 1c shown in FIG. 4 includes a motor 10, a reducer 20, an input axis encoder 31, an output axis encoder 32, a weighting calculation unit 40c, a subtractor 51, 71, a position controller 52, a differentiator 60, and a speed controller. It is equipped with 72 and a current controller 80. Further, the weighting calculation unit 40c, the subtractors 51 and 71, the position controller 52, the differentiator 60, the speed controller 72, and the current controller 80 form a control unit 100c that controls the motor 10. The same components as in FIG. 1 are designated by the same reference numerals. Further, the present embodiment is an embodiment in which the weighting calculation unit 40a in the first embodiment is replaced with the weighting calculation unit 40c. However, the determination unit 41c included in the weighting calculation unit 40c is different from the determination unit 41a in the weighting calculation unit 40a.

The weighting calculation unit 40c includes a determination unit 41c that generates a weighting coefficient for the weighting calculation. The determination unit 41c determines the value of the detected rotational angular velocity generated from the differentiating operation by the differentiator 60 as the rotational angular velocity of the output shaft of the motor 10, and changes the weighting coefficient of the weighting operation according to the determination result. For example, the determination unit 41c determines the value of the detected rotational angular velocity according to a predetermined reference value. When the detected rotational angular velocity drops to the specified reference value, the determination unit 41c selectively uses the second position information, or increases the ratio of the second position information to the first position information. Change the weighting factor so that it does.

Further, with reference to FIG. 5, the simulation result when the weighting coefficient of the weighting calculation unit 40c is set to either 0 or 1 is shown. FIG. 5 is a diagram showing the result of position control of the drive device in this embodiment. In FIG. 5 (a), the vertical axis represents the rotation position (milliradiant) and the horizontal axis represents the time (seconds). The step response when a change of 1 (milliradiant) is given as the target rotation position command value is shown. In this figure, the graph shown in the waveform S111 shows the result in the present embodiment, and the graph shown in the waveform S112 is controlled based on the rotation angle position of the input shaft of the speed reducer 20, that is, the output shaft of the motor 10 (semi-closed loop control). ) Is shown in the rotation angle position of the output shaft of the speed reducer 20. In the graph shown in waveform S111, it has converged to the target rotation position command value (1 (milliradiant)) by 0.5 seconds, but in the graph shown in waveform S112, it is affected by the load and is about 0.2 (milliradiant). There is an error in. In addition, the load is increased at time 5 seconds when the step response applied at time 0 seconds is stable, and the effect of disturbance is evaluated. In the graph shown in waveform S111, the target rotation position command value (1 (milliradiant)) has converged by the time 5.5 seconds, but in the graph shown in waveform S112, it is about 0.4 (millimeter) due to the influence of the increased load. Radiant) and the error increases.

FIG. 5 (b) shows the change in the detected rotational angular velocity on the same time axis as in FIG. 5 (a). The value of the detected rotational angular velocity increases instantaneously at the time of 0 seconds and the time of 5 seconds, and the value of the detected rotational angular velocity decreases excessively as the target rotation position is approached. Here, the determination unit 41c determines a reference value of a desired value, and determines whether or not the detected rotational angular velocity is lower than the reference value. FIG. 5C is a graph showing the result of the above determination. A positive pulse indicates a case where the value of the ejection angular velocity exceeds the set reference value. During the period of the pulse, the drive device 1c suspends the fully closed loop control and switches to the control that prioritizes the responsiveness (semi-closed loop control).

(Fourth Embodiment) The driving device of this embodiment is shown with reference to FIG. FIG. 6 is a block diagram showing a configuration of a drive device according to the present embodiment. The drive device 1d shown in FIG. 6 includes a motor 10, a reducer 20, an input axis encoder 31, an output axis encoder 32, a weighting calculation unit 40d, a subtractor 51, 71, a position controller 52, a differentiator 60, and a speed controller. It is equipped with 72 and a current controller 80. Further, the weighting calculation unit 40d, the subtractors 51 and 71, the position controller 52, the differentiator 60, the speed controller 72, and the current controller 80 form a control unit 100d that controls the motor 10. The same components as in FIG. 1 are designated by the same reference numerals. Further, the present embodiment is an embodiment in which the weighting calculation unit 40a in the first embodiment is replaced with the weighting calculation unit 40d. However, the determination unit 41d included in the weighting calculation unit 40d is different from the determination unit 41a in the weighting calculation unit 40a.

The weighting calculation unit 40d includes a determination unit 41d that generates a weighting coefficient for the weighting calculation. The determination unit 41d makes a determination based on the target rotation position command value of the motor 10 and the rotation angle position information (first position information) detected by the input shaft encoder 31, and the weight of the weighting calculation unit 40d is determined according to the determination result. Change the coefficient. For example, the determination unit 41d determines whether or not the difference between the target rotation position command value of the motor 10 and the detected first position information is smaller than the predetermined reference value. When the difference is smaller than the reference value, the determination unit 41d selectively uses the second position information, or sets the weighting coefficient so that the ratio of the second position information is higher than that of the first position information. To change. According to the present embodiment, the determination unit 41d makes a determination by comparing the target rotation position command value of the motor 10 with the detected first position information, so that continuous determination is possible.

(Fifth Embodiment) The driving device of this embodiment is shown with reference to FIG. 7. FIG. 7 is a block diagram showing a configuration of a drive device according to the present embodiment. The drive device 1e shown in FIG. 7 includes a motor 10, a reducer 20, an input axis encoder 31, an output axis encoder 32, a weighting calculation unit 40e, a subtractor 51, 71, a position controller 52, a differentiator 60, and a speed controller. It is equipped with 72 and a current controller 80. Further, the weighting calculation unit 40e, the subtractors 51 and 71, the position controller 52, the differentiator 60, the speed controller 72, and the current controller 80 form a control unit 100e that controls the motor 10. The same components as in FIG. 1 are designated by the same reference numerals. Further, the present embodiment is an embodiment in which the weighting calculation unit 40a in the first embodiment is replaced with the weighting calculation unit 40e. However, the determination unit 41e included in the weighting calculation unit 40d is different from the determination unit 41a in the weighting calculation unit 40a.

The weighting calculation unit 40e includes a determination unit 41e that generates a weighting coefficient for the weighting calculation. The determination unit 41e makes a determination based on the target rotation position command value of the motor 10 and the rotation angle position information (second position information) detected by the output shaft encoder 32, and determines the weighting coefficient of the weighting operation according to the determination result. change. For example, the determination unit 41e determines whether or not the difference between the target rotation position command value of the motor 10 and the detected second position information is smaller than the predetermined reference value. When the difference is smaller than the reference value, the determination unit 41e selectively uses the second position information, or sets the weighting coefficient so that the ratio of the second position information is higher than that of the first position information. To change. Comparing the fourth embodiment and the fifth embodiment, it is different whether the detected position information is the first position information or the second position information. Since the determination unit 41e in the present embodiment determines by comparing the target rotation position command value of the motor 10 with the detected second position information, continuous determination is possible.

(6th Embodiment) Hereinafter, the apparatus of this embodiment will be described with reference to FIG. FIG. 8 is a schematic block diagram showing a configuration of a multi-axis drive type robot arm including the drive devices (1a to 1e) in the present embodiment. In the following description, the multi-axis drive type robot arm will be described as an arm control device (device).

In the description of the present embodiment, as shown in FIG. 8, a case where the arm control device 800 includes the two drive devices 1a according to the present embodiment will be described as an example. Further, as shown in FIG. 8, a case where the arm control device 800 includes two arm portions 801 and 802 (first arm portion and second arm portion) will be described.

In this case, one drive device 1a-1 drives the arm portion 802, and the other drive device 1a-2 is provided on the arm portion 802 to drive the arm portion 801. The drive device 1a-1 is fixed to the pedestal 804 via the support column 803. The pedestal 804 includes, for example, wheels and may be movable in the horizontal direction.

The end of the arm portion 801 on the side not connected to the drive device 1a-2 is provided with, for example, a hand portion (end effector portion) that causes a mechanical action on the work target. The hand part is, for example, a holding part that holds the work object, a welding part that welds the work object, a cutting part that cuts the work object, or an opening / closing part that opens and closes a screw or a bolt that is the work object. is there. The arm portion 801 itself may be such a hand portion itself. The arm control device 800 provided with such a hand portion is, for example, a manipulator.

Further, as shown in FIG. 8, the arm control device includes a main control device 805. The main control device 805 controls the drive devices 1a-1 and 1a-2 based on the rotation angle positions of the drive devices 1a-1 and 1a-2 input via the signal line 808. As a result, the rotation angle positions of the arm portions 801 and 802 are controlled, and the position of the hand portion provided at the end portion of the arm portion 801 is controlled. The main control device 805 controls the drive devices 1a-1 and 1a-2 via the control line 809. Further, the main control device 805 may control the hand portion via the control line 809.

According to the present invention, the drive devices 1a to 1e include a motor 10 that is rotationally driven, an encoder 31 that detects the rotational angle position of the drive output shaft of the motor 10 and generates first position information, and a drive output of the motor 10. The speed reducer 20 connected to the shaft, the encoder 32 that detects the rotation angle position of the speed reduction output shaft of the speed reducer 20 and generates the second position information, and the first position information and the second position information. This can be realized by a configuration including control units 100a to 100e that selectively use and control the drive unit. As a result, the drive devices 1a to 1e can improve the positioning accuracy while having a simple configuration without increasing the number of new control loops. As shown above, the drive devices 1a to 1e perform control (semi-closed loop) using necessary information according to the control state by selectively selecting the first position information and the second position information. Control or full closed loop control) is possible. Further, the drive devices 1a to 1e can also use the information obtained by combining the first position information and the second position information as the detected rotation position information by setting the weighting.

Further, the determination units 41a to 41e detect an abnormal state generated in the controlled object (motor 10, reducer 20, etc.) at an early stage by monitoring the mutual relationship between the first position information and the second position information. It will also be possible to do. For example, each determination unit determines when the relationship between the first position information and the second position information deviates from a certain threshold value or more as an abnormal state, and controls each so as to maintain a stable state as a control system. The operation of the unit may be restricted. The present invention is not limited to each of the above embodiments, and can be modified without departing from the spirit of the present invention. The main control device 805 in the arm control device enables control of a plurality of drive devices 1a to 1e, and any combination of drive device embodiments is possible. Further, in the embodiment of controlling a plurality of drive devices, a signal output from each encoder included in the plurality of drive devices is acquired, and a control command value for each drive device is obtained according to the state of each drive device. May be used as a guide.

1a Imaging device 10 motor 20 reducer 20 31 Input axis encoder 32 output axis encoder 40a Weighting calculation unit 41a Judgment unit 51, 71 subtractor 52 Position controller 60 differentiator 72 speed controller 80 current controller 100a control unit