JP2010236603A - Backlash removing control device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To prevent generation of backlash and lost motion when working and feed a movable member at a high speed when feeding. <P>SOLUTION: In working, one of two motors 11, 21 generates torque for moving the movable member GL and both the motors 11, 21 generate offset torque in a reverse rotation direction, so that generation of backlash and lost motion is prevented. In feeding, both the motors 11, 21 generate torque for moving the movable member GL in the same direction so that the movable member GL is operated for high-speed moving. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a backlash removal control device, which can reliably prevent backlash and lost motion during processing, and can move a movable member at a high speed or a high torque depending on the situation. It is what I did.

In a machine tool, the rotational force (driving force) of a motor is transmitted to a table and a main shaft, which are movable members, via a power transmission mechanism, and the movable member (table and main shaft) is moved.
When the movable member is heavy, such as a table, the movable member is driven via a speed reducer between the motor and the movable member. In the case of a feed mechanism, it is driven via a mechanism such as a ball screw or a rack and pinion.

Since a gear is incorporated in such a power transmission mechanism, backlash becomes a problem when performing accurate position control, and hence accurate machining.
That is, if backlash exists, it becomes difficult to drive the movable member stably with high positional accuracy, which adversely affects machining accuracy.

Furthermore, if backlash is present, when the acceleration of the movable member reverses, the meshing between the gear teeth on the input side (motor side) and the gear teeth on the output side (movable member side) changes, so the lost motion That is, a state occurs in which the input side gear teeth and the output side gear teeth are not engaged with each other during the period from when the engagement is released until the engagement is performed again.
While the lost motion is occurring, the torque of the motor is not transmitted to the movable member, so that an uncontrolled state occurs temporarily and the positioning accuracy deteriorates.

Here, the lost motion generated between the gear connected to the motor side and the gear connected to the movable member side (for example, a ball screw shaft coupled to the table) is described with reference to FIGS. explain. 6A to 6D show only a part of the teeth provided on the gear.
The gear connected to the motor side will be described as “motor side gear G _M ”, and the gear connected to the movable member side will be described as “movable member side gear G _L ”.

Lost motion by backlash, which in the moving direction of the movable member (acceleration) is inverted, occurs because the float with the teeth of the movable member side gear G _L, apart engagement with the teeth of the motor side gear G _M It is.

Figure 6A is in contact tooth surfaces of the motor side gear G _M and the tooth surface of the movable member side gear G _L is, by the motor side gear G _M is rotated in the clockwise direction, the movable member side gear G _L are anti A state of rotating clockwise is shown.

When the motor is decelerated, the movable member (e.g., a table) continues to move due to its own inertia, as shown in FIG. 6B, the engagement of the teeth of the movable member side gear G _L of the motor side gear G _M starts away.

Thereafter, as shown in FIG. 6C, although the motor side gear G _M in the rotating direction of the motor is inverted starts to rotate in the counterclockwise direction, the movable member side gear G _L movable member (e.g., a table) is stopped to stationary, the teeth of the motor side gear G _M and the teeth of the movable member side gear G _L becomes completely separated state, lost motion will occur.

It lost motion, as shown in FIG. 6D, until the teeth of the motor side gear G _M and the teeth of the movable member side gear G _L meshes again.

  In this way, lost motion occurs, which is the main cause of positioning error.

  In order to transmit power from the motor side gear to the movable member side gear while preventing the occurrence of backlash and lost motion as described above, conventionally, a configuration in which the movable member is driven by two motors has been adopted. However, a method for optimally controlling the driving of both motors has been developed.

Here, an example of such a prior art will be described with reference to FIG.
As shown in FIG. 7, in this example, the first motor side gear G _M1 and the second motor side gear G _M2 are engaged with the movable member side gear _GL connected to the movable member.

The first motor side gear G _M1 is connected to the first motor 11, and the motor side gear G _M1 rotates when the motor 11 rotates. The second motor side gear G _M2 is connected to the second motor 21, and the motor side gear G _M2 rotates when the motor 21 rotates.

Explaining the control system, the drive torque command unit 30 outputs a drive torque command τ _d , and the offset torque command unit 31 outputs an offset torque command τ _o .

The value (absolute value) of the drive torque command τ _d is a torque value necessary for moving the movable member via the movable gear _GL , and is set according to the machining program or the like. The polarity of the drive torque command τ _d may be positive or negative depending on the machining situation or the like.
The value of the offset torque command tau _o (absolute value) is set in consideration of the weight and friction of the movable member, the value of the offset torque command tau _o (absolute value), the driving torque command tau value of _d ( It is smaller than the absolute value. The polarity of this offset torque command τ _o is always positive.

When the drive torque command τ _d is input, the zero torque limiter 12 outputs the drive torque command τ _d only when the polarity is positive. When the driving torque command τ _d is input, the zero torque limiter 22 outputs the driving torque command τ _d only when the polarity is negative.

The adder 13 adds the offset torque command τ _o to the drive torque command τ _d output from the zero torque limiter 12 to obtain a total torque command τ _t1, and sends the total torque command τ _t1 to the servo amplifier 14.
The subtracting unit 23 subtracts the offset torque command τ _o from the drive torque command τ _d output from the zero torque limiter 22 to obtain a total torque command τ _{t 2,} and sends the total torque command τ _{t 2} to the servo amplifier 24.

The servo amplifier (current control unit) 14 supplies a current corresponding to the total torque command τ _t1 to the motor 11, and the motor 11 outputs a torque corresponding to the total torque command τ _t1 to rotate the motor side gear _GM1 . To drive.

The servo amplifier (current control unit) 24 supplies a current corresponding to the total torque command τ _t2 to the motor 21, and the motor 21 outputs a torque corresponding to the total torque command τ _t2 to rotate the motor side gear _GM2 . To drive.

The operation of the prior art having such a configuration will be described.
For example, the value of the driving torque command tau _d output from the driving torque command section 30 (absolute value) is a polar positive 10 (i.e. command value is +10 in the drive torque command tau _d), from the offset torque command section 31 The case where the value (absolute value) of the output offset torque command τ _o is 1 and the polarity is positive (that is, the command value of the offset torque command τ _o is +1) will be described.

In this example, the drive torque command τ _d output from the drive torque command unit 30 passes through the zero torque limiter 12 and is output from the zero torque limiter 12, but is blocked by the zero torque limiter 22 and zeroed. It is not output from the torque limiter 22.

Addition unit 13, a drive torque command tau _d command value is +10, command value by adding the offset torque command tau _o +1, command value to output the total torque command tau _t1 of +11.
The servo amplifier (current control unit) 14 supplies a current corresponding to the total torque command τ _t1 to the motor 11, and the motor 11 rotates in the positive rotation direction (clockwise) according to the total torque command τ _t1 whose command value is +11. Direction) to output a torque corresponding to “11”, rotationally drive the motor side gear _GM1 in the forward rotation direction (clockwise direction), and move the movable side gear _GL in the negative rotation direction (counterclockwise direction). Rotating drive.

The subtracting unit 23 subtracts the offset torque command τ _o having a command value of +1 from the drive torque command τ _d having a command value of 0, and outputs a total torque command τ _t2 having a command value of −1.
The servo amplifier (current control unit) 24 supplies a current corresponding to the total torque command τ _t2 to the motor 21, and the motor 21 responds to the total torque command τ _t2 whose command value is −1 in the negative rotation direction (reverse direction). The torque corresponding to “1” is output in the clockwise direction), the torque in the negative rotation direction (counterclockwise direction) is applied to the motor side gear _GM2, and the positive rotation direction (clockwise rotation) is applied to the movable side gear _GL. Direction) torque. This torque becomes the preload torque (offset torque).

As a result, a torque corresponding to “11” acts on the movable member side gear _GL in the negative rotation direction (counterclockwise direction), and a torque corresponding to “1” in the positive rotation direction (clockwise direction). Works. For this reason, the movable member side gear _GL rotates with a torque corresponding to “10” along the negative rotation direction (counterclockwise direction).

The difference between the torque in the negative rotation direction (counterclockwise direction) and the torque in the positive rotation direction (clockwise direction) is an internal force having a value of “1”. This internal force “1” meshes the teeth of the motor side gear _{GM1 and} the teeth of the movable member side gear _GL , and also meshes the teeth of the motor side gear _{GM2 and} the teeth of the movable member side gear _GL. It demonstrates the function of preventing the occurrence of backlash and lost motion.

Further, for example, the value (absolute value) of the drive torque command τ _d output from the drive torque command unit 30 is 10 and the polarity is negative (that is, the command value of the drive torque command τ _d is −10), and the offset torque command When the value (absolute value) of the offset torque command τ _o output from the unit 31 is 1 and the polarity is positive (that is, the command value of the offset torque command τ _o is +1), the adding unit 13 determines that the command value is The +1 total torque command τ _t1 is output, and the subtracting unit 23 outputs the total torque command τ _t2 having a command value of -11.

Therefore, the motor 11 outputs a torque corresponding to “1” in the forward rotation direction (clockwise direction) in response to the total torque command τ _t1 having a command value of +1, and the motor 21 has a command value of −11. depending on the overall torque command tau _t2, and outputs the torque corresponding to "11" in the negative direction of rotation (counterclockwise direction).

As a result, the torque corresponding to “1” acts on the movable member side gear _GL in the negative rotation direction (counterclockwise direction) and the torque corresponding to “11” in the positive rotation direction (clockwise direction). Acting, the movable member side gear _GL rotates with a torque corresponding to “10” along the forward rotation direction (clockwise direction).

The difference between the torque in the negative rotation direction (counterclockwise direction) and the torque in the positive rotation direction (clockwise direction) is an internal force having a value of “1”. This internal force “1” meshes the teeth of the motor side gear _{GM1 and} the teeth of the movable member side gear _GL , and also meshes the teeth of the motor side gear _{GM2 and} the teeth of the movable member side gear _GL. It demonstrates the function of preventing the occurrence of backlash and lost motion.

JP-A-4-109890

Incidentally, the prior art as shown in FIG. 7 has the following problems.
That is, in the prior art, although there are two motors 11 and 12, the movable member is moved only by the driving force of one motor, and the driving force of the other motor prevents the occurrence of backlash and lost motion. It is only used to stretch the gear teeth.
That is, only the driving force of one motor contributes to move the movable member, and the other motor is used only to generate an internal force.

Since there are two motors, if the driving force of both motors can be combined and used to move the movable member, the movable member can be moved at high speed during the feeding operation, or the movable member can be moved at high torque during the machining operation. However, in the prior art, such an operation could not be performed.
After all, in the conventional technology, since the device configuration includes two motors, the cost is high, but there is a problem that the cost performance is poor.

  In view of the above prior art, the present invention can reliably prevent the occurrence of backlash and lost motion in a state where it is necessary to prevent the occurrence of backlash and lost motion, and can move the movable member at high speed. An object of the present invention is to provide a backlash removal control device that can move a movable member by combining the torques of two motors in a state that requires high torque movement.

The configuration of the present invention for solving the above problems is as follows.
A movable member side gear connected to the movable member;
A first motor side gear that meshes with the movable member side gear and is driven to rotate by a first motor;
A second motor side gear that meshes with the movable member side gear and is rotationally driven by a second motor;
When a backlash removal control command is input, a zero-torque limit function is provided that allows a drive torque command with a positive polarity to pass but blocks a drive torque command with a negative polarity to pass. A first zero torque limiter that passes the drive torque command as it is regardless of the polarity when the command is not input;
When a backlash removal control command is input, a zero-torque limit function that allows the drive torque command with a negative polarity to pass but cuts off the drive torque command with a positive polarity is demonstrated. A second zero torque limiter that passes the drive torque command as it is regardless of the polarity when the command is not input;
An offset torque command unit that outputs an offset torque command when a backlash removal control command is input, and stops outputting an offset torque command when the backlash removal control command is not input;
Torque is generated according to the value of the total torque command obtained by adding the offset torque command to the drive torque command that has passed through the first zero torque limiter, and the rotation direction is in accordance with the polarity of the total torque command. A first current controller for supplying a current to the first motor,
Torque is generated according to the value of the total torque command obtained by subtracting the offset torque command from the drive torque command that has passed through the second zero torque limiter, and the rotational direction is in accordance with the polarity of the total torque command. A second current controller for supplying a current to the second motor,
When precise positioning of the movable member is required, it is necessary to input a backlash removal control command to the first zero torque limiter, the second zero torque limiter, and the offset torque command unit to move the movable member at high speed. In some cases, a first zero torque limiter, a second zero torque limiter, and a backlash removal control command issuing unit for stopping input of a backlash removal control command to the offset torque command unit are provided.

The configuration of the present invention is as follows.
A movable member side gear connected to the movable member;
A first motor side gear that meshes with the movable member side gear and is driven to rotate by a first motor;
A second motor side gear that meshes with the movable member side gear and is rotationally driven by a second motor;
A first threshold variable torque limiter in which the positive threshold is fixedly set, the negative threshold is variably set, and when a drive torque command is input, the value is limited and output by the positive threshold and the negative threshold. When,
A second threshold variable torque limiter in which the negative threshold is fixedly set, the positive threshold is variably set, and when a drive torque command is input, the value is limited and output by the negative threshold and the positive threshold. When,
An offset torque command section for outputting an offset torque command;
A torque corresponding to the value of the total torque command obtained by adding the offset torque command to the drive torque command that has passed through the first threshold variable torque limiter, and a rotation direction corresponding to the polarity of the total torque command; A first current controller for supplying a current to the first motor,
A torque corresponding to the value of the total torque command obtained by subtracting the offset torque command from the drive torque command passing through the second threshold variable torque limiter, and a rotation direction corresponding to the polarity of the total torque command; A second current control unit for supplying current to the second motor,
When the polarity of the drive torque command input to the first and second threshold variable torque limiters is positive, the absolute value of the drive torque command input to the first and second threshold variable torque limiters and the first A difference value from the absolute value of the positive threshold value of the second threshold variable torque limiter is set as an absolute value of the positive threshold value of the second threshold variable torque limiter, and is input to the first and second threshold variable torque limiters. When the polarity of the drive torque command is negative, the absolute value of the drive torque command input to the first and second threshold variable torque limiters and the absolute value of the negative threshold of the second threshold variable torque limiter are And a threshold value changing unit that sets the difference value as an absolute value of the negative side threshold value of the first threshold value variable torque limiter.

The configuration of the present invention is as follows.
A movable member side gear connected to the movable member;
A first motor side gear that meshes with the movable member side gear and is driven to rotate by a first motor;
A second motor side gear that meshes with the movable member side gear and is rotationally driven by a second motor;
An offset torque command section for outputting an offset torque command;
A first threshold variable torque limiter in which the positive threshold is fixedly set, the negative threshold is variably set, and when a drive torque command is input, the value is limited and output by the positive threshold and the negative threshold. When,
A second threshold variable torque limiter in which the negative threshold is fixedly set, the positive threshold is variably set, and when a drive torque command is input, the value is limited and output by the negative threshold and the positive threshold. When,
A torque corresponding to the value of the first total torque command obtained by adding the drive torque command that has passed through the first threshold variable torque limiter and the offset torque command is generated, and the polarity of the first total torque command is set. A first current control unit for supplying current to the first motor so as to have a corresponding rotation direction;
Torque is generated according to the value of the second total torque command obtained by subtracting the offset torque finger from the drive torque command that has passed through the second threshold variable torque limiter, and the polarity of the second total torque command is set. A second current control unit for supplying a current to the second motor so as to have a corresponding rotation direction;
A threshold value / offset torque value changing unit,
The threshold value / offset torque value changing unit is:
When the polarity of the drive torque command input to the first and second threshold variable torque limiters is positive, the positive threshold of the first threshold variable torque limiter is smaller than the first total torque command, and If the driving torque command is larger than the driving torque command, the absolute value of the value obtained by subtracting the driving torque command from the positive threshold value of the first threshold variable torque limiter is set as the command value of the offset torque command.
When the polarity of the drive torque command input to the first and second threshold variable torque limiters is positive and the positive threshold of the first threshold variable torque limiter is smaller than the drive torque command, the offset torque A value obtained by subtracting the positive threshold value of the first threshold variable torque limiter from the drive torque command is set as the positive threshold value of the second threshold variable torque limiter, with the command value of the command set to 0.
When the polarity of the drive torque command input to the first and second threshold variable torque limiters is negative, the negative threshold of the second threshold variable torque limiter is greater than the second total torque command, and When the driving torque command is smaller than the driving torque command, the absolute value of the value obtained by subtracting the negative threshold value of the second threshold variable torque limiter from the driving torque command is set as the command value of the offset torque command.
When the polarity of the drive torque command input to the first and second threshold variable torque limiters is negative and the negative threshold of the second threshold variable torque limiter is greater than the drive torque command, the offset torque And a value obtained by subtracting the negative threshold value of the second threshold variable torque limiter from the drive torque command is set as the negative threshold value of the first threshold variable torque limiter.

  According to the present invention, during processing, the two motors generate torques in the reverse rotation direction, thereby preventing backlash and lost motion. During feeding, the two motors move the movable member in the same direction. By generating the torque to be generated, the movable member can be moved at a high speed.

  Further, according to the present invention, when the torque necessary for feeding the movable member can be generated only by the torque of one motor during machining, the torque for the feeding operation is generated only by one motor. However, when the drive torque command becomes large and the torque necessary for feeding the movable member with only the torque of one motor cannot be generated, the torque for the feeding operation is generated by the two motors. The movable member can be moved with high torque.

  Further, according to the present invention, the backlash removal state can be maintained as long as possible, and a sudden change in generated torque can be prevented.

The block diagram which shows the backlash removal control apparatus which concerns on Example 1 of this invention. The block diagram which shows the backlash removal control apparatus which concerns on Example 2 of this invention. FIG. 9 is a characteristic diagram illustrating characteristics of a first threshold variable torque limiter used in the second embodiment. FIG. 9 is a characteristic diagram illustrating characteristics of a first threshold variable torque limiter used in the second embodiment. FIG. 6 is a characteristic diagram illustrating characteristics of a second threshold variable torque limiter used in the second embodiment. FIG. 6 is a characteristic diagram illustrating characteristics of a second threshold variable torque limiter used in the second embodiment. The block diagram which shows the backlash removal control apparatus which concerns on Example 3 of this invention. Explanatory drawing which shows the generation | occurrence | production state of a lost motion. Explanatory drawing which shows the generation | occurrence | production state of a lost motion. Explanatory drawing which shows the generation | occurrence | production state of a lost motion. Explanatory drawing which shows the generation | occurrence | production state of a lost motion. The block diagram which shows the conventional backlash removal control apparatus.

  Hereinafter, the form for implementing this invention is demonstrated in detail based on an Example.

  A backlash removal control apparatus according to a first embodiment of the present invention will be described with reference to FIG. Note that portions having the same functions as those of the prior art shown in FIG.

<Ingenuity>
The backlash removal control device according to the first embodiment is devised so as to reliably prevent the occurrence of backlash and lost motion during machining and to move the movable member at high speed during feeding operation. It is.

<Configuration>
The movable member side gear _GL is connected to a movable member (for example, a ball screw shaft coupled to a table). The first motor side gear G _M1 and the second motor side gear G _M2 are meshed with the movable member side gear G _L.

In FIG. 1, the meshing state of the gears is shown in a simplified manner. However, when the first motor side gear G _M1 rotates in the positive rotation direction (clockwise direction), the movable member side gear G _L rotates in the negative rotation direction ( When the first motor side gear G _M1 is rotated in the counterclockwise direction) and the first motor side gear G _M1 is rotated in the negative rotation direction (counterclockwise direction), the movable member side gear G _L is rotated in the positive rotation direction (clockwise direction). In addition, the meshing state of the gears is set.

Similarly, when the second motor side gear G _M2 rotates in the positive rotation direction (clockwise direction), the movable member side gear G _L rotates in the negative rotation direction (counterclockwise direction), and the second motor side gear When G _M2 is rotated in the negative rotation direction (counterclockwise direction), the movable member side gear G _L is to rotate in the normal rotation direction (clockwise direction), and sets the state meshing gears.

The first motor side gear G _M1 is connected to the first motor 11, and the motor side gear G _M1 rotates when the motor 11 rotates. The second motor side gear G _M2 is connected to the second motor 21, and the motor side gear G _M2 rotates when the motor 21 rotates.

  The control system will be described in addition to the zero torque limiters 12a and 22a, the addition unit 13, the subtraction unit 23, the servo amplifiers (current control units) 14 and 24, the drive torque command unit 30, and the offset torque command unit 31. The backlash removal control command issuing unit 40 is provided.

When the backlash removal control command issuing unit 40 determines that the precise positioning of the movable member is necessary, the backlash removal control command issuing unit 40 outputs the backlash removal control command BR so that the precise positioning of the movable member is not necessary. If it is determined that the backlash is not, the output of the backlash removal control command BR is stopped.
The backlash removal control command BR is sent to the zero torque limiters 12a and 22a and the offset torque command unit 31.

The backlash removal control command issuing unit 40 determines whether or not a precise positioning of the movable member is necessary, and various methods such as the following can be adopted as the determination method. .
(1) Referring to the machining program, etc., determine whether cutting or feeding is in progress. If cutting is in progress, determine that precise positioning is necessary. It is judged that the precise positioning is unnecessary.
(2) It is detected whether the cutting drill is rotating or stopped, and if it is detected that the cutting drill is rotating, it is determined that a precise positioning is necessary because it is being processed. If it is detected that the position is stopped, it is determined that the precise positioning is not necessary because it is not being processed such as during a feeding operation.
(3) The backlash removal control command issuing unit 40 is in a situation where precise positioning is required by inputting a status signal indicating whether or not precise positioning is required manually by the operator from the outside. Determine whether or not.

The drive torque command unit 30 outputs a drive torque command τ _d .
The value (absolute value) of the drive torque command τ _d is a torque value necessary for moving the movable member via the movable gear _GL , and is set according to the machining program or the like. The polarity of the drive torque command τ _d may be positive or negative depending on the machining situation or the like.

Offset torque command unit 31, when the backlash elimination control command BR is input, and outputs the offset torque command tau _o, when the backlash elimination control command BR is not input, the output of the offset torque command tau _o Stop.

The value of the offset torque command tau _o (absolute value) is set in consideration of the weight and friction of the movable member, the value of the offset torque command tau _o (absolute value), the driving torque command tau value of _d ( It is smaller than the absolute value. The polarity of this offset torque command τ _o is always positive.

Zero torque limiter 12a, when the backlash elimination control command BR is input, the drive torque command tau _d is input, and outputs only passes the command drive torque tau _d when its polarity is positive When the polarity is negative, the output of the drive torque command τ _d is cut off.
Further, the zero torque limiter 12a has no zero torque limit function when the backlash removal control command BR is not input, and when the drive torque command τ _d is input, the polarity is positive or negative. Regardless, the drive torque command τ _d is passed and output as it is.

Zero torque limiter 22a, when the backlash elimination control command BR is input, the drive torque command tau _d is input, and outputs only passes the command drive torque tau _d when the polarity is negative When the polarity is positive, the output of the drive torque command τ _d is cut off.
Further, the zero torque limiter 22a has no zero torque limit function when the backlash removal control command BR is not input, and the polarity is positive or negative when the drive torque command τ _d is input. Regardless, the drive torque command τ _d is passed and output as it is.

The adding unit 13 adds an offset torque command τ _o to the drive torque command τ _d output from the zero torque limiter 12 a to obtain a total torque command τ _{t 1,} and sends the total torque command τ _{t 1} to the servo amplifier 14.
The subtracting unit 23 subtracts the offset torque command τ _o from the drive torque command τ _d output from the zero torque limiter 22 a to obtain a total torque command τ _{t 2,} and sends this total torque command τ _{t 2} to the servo amplifier 24.

The servo amplifier (current control unit) 14 supplies a current corresponding to the total torque command τ _t1 to the motor 11, and the motor 11 outputs a torque corresponding to the total torque command τ _t1 to rotate the motor side gear _GM1 . To drive.

The servo amplifier (current control unit) 24 supplies a current corresponding to the total torque command τ _t2 to the motor 21, and the motor 21 outputs a torque corresponding to the total torque command τ _t2 to rotate the motor side gear _GM2 . To drive.

<Backlash removal operation>
The operation of this embodiment having such a configuration will be described.
When the backlash removal control command BR is output from the backlash removal control command issuing unit 40, that is, when precise positioning is necessary because the machining is in progress, the zero torque limiters 12a and 22a exhibit the zero torque limit function. In addition, since the offset torque command τ _o is output from the offset torque command unit 31, an operation similar to that of the prior art shown in FIG. 7 is performed.

For example, the value of the driving torque command tau _d output from the driving torque command section 30 (absolute value) is a polar positive 10 (i.e. command value is +10 in the drive torque command tau _d), from the offset torque command section 31 The case where the value (absolute value) of the output offset torque command τ _o is 1 and the polarity is positive (that is, the command value of the offset torque command τ _o is +1) will be described.

In this example, the drive torque command τ _d output from the drive torque command unit 30 passes through the zero torque limiter 12a and is output from the zero torque limiter 12a, but is blocked by the zero torque limiter 22a to zero. It is not output from the torque limiter 22a.

Addition unit 13, a drive torque command tau _d command value is +10, command value by adding the offset torque command tau _o +1, command value to output the total torque command tau _t1 of +11.
The servo amplifier (current control unit) 14 supplies a current corresponding to the total torque command τ _t1 to the motor 11, and the motor 11 rotates in the positive rotation direction (clockwise) according to the total torque command τ _t1 whose command value is +11. Direction) to output a torque corresponding to “11”, rotationally drive the motor side gear _GM1 in the forward rotation direction (clockwise direction), and move the movable member side gear _GL in the negative rotation direction (counterclockwise direction). To rotate.

The subtracting unit 23 subtracts the offset torque command τ _o having a command value of +1 from the drive torque command τ _d having a command value of 0, and outputs a total torque command τ _t2 having a command value of −1.
The servo amplifier (current control unit) 24 supplies a current corresponding to the total torque command τ _t2 to the motor 21, and the motor 21 responds to the total torque command τ _t2 whose command value is −1 in the negative rotation direction (reverse direction). The torque corresponding to “1” is output in the clockwise direction), the torque in the negative rotation direction (counterclockwise direction) is applied to the motor side gear _GM2, and the positive rotation direction (clockwise) is applied to the movable member side gear _GL. (Turning direction) torque is applied. This torque becomes the preload torque (offset torque).

As a result, a torque corresponding to “11” acts on the movable member side gear _GL in the negative rotation direction (counterclockwise direction), and a torque corresponding to “1” in the positive rotation direction (clockwise direction). Works. For this reason, the movable member side gear _GL rotates with a torque corresponding to “10” along the negative rotation direction (counterclockwise direction).

The difference between the torque in the negative rotation direction (counterclockwise direction) and the torque in the positive rotation direction (clockwise direction) is an internal force having a value of “1”. This internal force “1” meshes the teeth of the motor side gear _{GM1 and} the teeth of the movable member side gear _GL , and also meshes the teeth of the motor side gear _{GM2 and} the teeth of the movable member side gear _GL. It demonstrates the function of preventing the occurrence of backlash and lost motion.

Further, for example, the value (absolute value) of the drive torque command τ _d output from the drive torque command unit 30 is 10 and the polarity is negative (that is, the command value of the drive torque command τ _d is −10), and the offset torque command When the value (absolute value) of the offset torque command τ _o output from the unit 31 is 1 and the polarity is positive (that is, the command value of the offset torque command τ _o is +1), the adding unit 13 determines that the command value is The +1 total torque command τ _t1 is output, and the subtracting unit 23 outputs the total torque command τ _t2 having a command value of -11.

Therefore, the motor 11 outputs a torque corresponding to “1” in the forward rotation direction (clockwise direction) in response to the total torque command τ _t1 having a command value of +1, and the motor 21 has a command value of −11. depending on the overall torque command tau _t2, and outputs the torque corresponding to "11" in the negative direction of rotation (counterclockwise direction).

As a result, the torque corresponding to “1” acts on the movable member side gear _GL in the negative rotation direction (counterclockwise direction) and the torque corresponding to “11” in the positive rotation direction (clockwise direction). Acting, the movable member side gear _GL rotates with a torque corresponding to “10” along the forward rotation direction (clockwise direction).

The difference between the torque in the negative rotation direction (counterclockwise direction) and the torque in the positive rotation direction (clockwise direction) is an internal force having a value of “1”. This internal force “1” meshes the teeth of the motor side gear _{GM1 and} the teeth of the movable member side gear _GL , and also meshes the teeth of the motor side gear _{GM2 and} the teeth of the movable member side gear _GL. It demonstrates the function of preventing the occurrence of backlash and lost motion.

<High-speed feed operation>
On the other hand, when the backlash removal control command BR is not output from the backlash removal control command issuing unit 40, that is, when precise positioning is not required because it is not being processed (for example, during a feed operation), the zero torque limiter 12a. , 22a does not exhibit the zero torque limit function, and the offset torque command τ _o is not output from the offset torque command unit 31.

In this case, the drive torque command τ _d output from the drive torque command unit 30 passes through the zero torque limiter 12a and the addition unit 13 as they are and is input to the servo amplifier 14, and at the same time, the zero torque limiter 22a and the subtraction are performed. The signal passes through the section 23 as it is and is input to the servo amplifier 24.
That is, the total torque command τ _t1 and the drive torque command τ _d are equal, and the total torque command τ _t2 and the drive torque command τ _d are equal.

Therefore, for example, when the value (absolute value) of the drive torque command τ _d is 10 and the polarity is positive (that is, the command value of the drive torque command τ _d is +10), the following operation is performed.

The servo amplifier (current control unit) 14 supplies a current corresponding to the drive torque command τ _d (= total torque command τ _t1 ) to the motor 11, and the motor 11 responds to the drive torque command τ _d having a command value of +10. Thus, a torque corresponding to “10” is output in the forward rotation direction (clockwise direction), and the motor side gear _GM1 is rotationally driven in the forward rotation direction (clockwise direction).
Thereby, a torque corresponding to “10” acts on the movable member side gear _GL in the negative rotation direction (counterclockwise direction).

At the same time, the servo amplifier (current control unit) 24 supplies a current corresponding to the drive torque command τ _d (= total torque command τ _t2 ) to the motor 21, and the motor 21 has a drive torque command τ _{d with} a command value of +10. Accordingly, a torque corresponding to “10” is output in the forward rotation direction (clockwise direction), and the motor side gear _GM2 is rotationally driven in the forward rotation direction (clockwise direction).
Thereby, a torque corresponding to “10” acts on the movable member side gear _GL in the negative rotation direction (counterclockwise direction).

Eventually, the torque corresponding to “20” acts on the movable member side gear _GL in the negative rotation direction (counterclockwise direction). Since the torque acting on the movable member side gear _GL is doubled as described above, the movable member can be moved in the negative direction at a high speed in a situation where high accuracy is required, such as during a feeding operation, but high accuracy is required. It can be moved.

On the other hand, for example, when the value (absolute value) of the drive torque command τ _d is 10 and the polarity is negative (that is, the command value of the drive torque command τ _d is −10), the movable member side is the same as above. A torque corresponding to “20” is applied to the gear _GL in the forward rotation direction (clockwise direction). Since the torque acting on the movable member side gear _GL is doubled as described above, the movable member can be moved in the positive direction at a high speed in a situation where high accuracy is required, such as during feeding operation, but high accuracy is not required. It can be moved.

  Eventually, during machining, the backlash removal control command BR is output, so that the functions of the zero torque limiters 12a and 22a and the offset torque command unit 31 are exhibited and the preload torque (offset torque) is performed as in the conventional case. As a result, backlash and lost motion can be prevented, precise positioning can be performed, and machining accuracy can be improved.

On the other hand, during the feeding operation, by the backlash elimination control command BR is not output, the zero torque limiter 12a, and functions 22a and offset the torque command section 31 is stopped, according to a command value of the driving torque command tau _d The two motors 11 and 21 rotate in the same direction, and the torque obtained by combining the torques of both the motors 11 and 21 acts on the movable member side gear _GL , so that high-speed feeding of the movable member can be realized.

  A backlash removal control apparatus according to a second embodiment of the present invention will be described with reference to FIG. Parts having the same functions as those in the first embodiment shown in FIG.

<Ingenuity>
In the backlash removal control apparatus according to the second embodiment, the torque for driving the movable member can be obtained only by the torque of one motor while the movable member is being moved in a situation where precise positioning is required such as during machining. In the case of a shortage, the track followability is maintained by cooperating another motor to compensate for the torque.

<Configuration>
The functions and configurations of the motors 11 and 21, the movable member side gear G _L , and the motor side gears G _M1 and G _M2 are the same as those in the first embodiment.

  Explaining the control system, the control system includes threshold variable torque limiters 12b and 22b, addition unit 13, subtraction unit 23, servo amplifiers (current control units) 14 and 24, drive torque command unit 30, and offset torque command unit 31. In addition, a threshold value changing unit 50 is provided.

  A positive threshold value Shp1 and a negative threshold value Shm1 are set in the threshold variable torque limiter 12b. In this case, the positive threshold value Shp1 is a fixed value (for example, +10), and the negative threshold value Shm1 is variably set by the threshold value changing unit 50 as described later (see FIGS. 3A and 3B).

The positive-side threshold value Shp1 that is a fixed value is the total torque command when the command value of the drive torque command τ _d that has passed through the threshold variable torque limiter 12b is +10 (that is, the total torque command that combines the offset torque command τ _o with the drive torque command τ _d This is set in consideration that the motor 11 can output the maximum torque when the command value of τ _t1 is +11).

When the value (absolute value) is 10 or less and the polarity is positive, the drive torque command τ _d output from the drive torque command unit 30 passes through the threshold variable torque limiter 12b as it is. If the absolute value exceeds 10 and the polarity is positive, the polarity remains positive, but the value (absolute value) is limited to 10 by the positive side threshold Shp1 and output from the threshold variable torque limiter 12b. The
Further, when the polarity of the drive torque command τ _d output from the drive torque command unit 30 is negative, the polarity remains negative, but the value (absolute value) is limited by the negative threshold value Shm1. It is output from the threshold variable torque limiter 12b.

  A positive threshold value Shp2 and a negative threshold value Shm2 are set in the threshold variable torque limiter 22b. In this case, the negative threshold value Shm2 is a fixed value (for example, −10), and the positive threshold value Shp2 is variably set by the threshold value changing unit 50 as described later (see FIGS. 4A and 4B).

The negative threshold value Shm2, which is a fixed value, is the total torque obtained by adding the offset torque command τ _o to the drive torque command τ _d when the command value of the drive torque command τ _d that has passed the threshold variable torque limiter 22b is -10. This is set in consideration that the motor 21 can output the maximum torque when the command value of the command τ _t2 is −11).

When the value (absolute value) is 10 or less and the polarity is negative, the drive torque command τ _d output from the drive torque command unit 30 passes through the threshold variable torque limiter 22b as it is. If the absolute value exceeds 10 and the polarity is negative, the polarity remains negative, but the value (absolute value) is limited to 10 by the negative threshold value Shm2, and is output from the threshold variable torque limiter 22b. The
In addition, when the polarity of the drive torque command τ _d output from the drive torque command unit 30 is positive, the polarity remains positive, but the value (absolute value) is limited by the positive threshold value Shp2. It is output from the threshold variable torque limiter 22b.

The threshold value changing unit 50 determines the negative threshold value Shm1 of the threshold variable torque limiter 12b or the threshold variable torque limiter 22b according to the value (absolute value) and polarity of the drive torque command τ _d output from the drive torque command unit 30. The positive threshold value Shp2 is changed.

For example, the polarity of the drive torque command τ _d output from the drive torque command unit 30 is positive, and the value (absolute value) is the threshold value (absolute value) of the positive threshold value Shp1 set in the threshold variable torque limiter 12b. Is larger than the difference (absolute value) between the value (absolute value) of the drive torque command τ _d and the threshold value (absolute value) of the positive threshold value Shp1, the value of the positive threshold value Shp2 of the threshold variable torque limiter 22b. Set as (absolute value).
Therefore, for example, when the command value of the drive torque command τ _d is +12, the positive threshold value Shp1 of the threshold variable torque limiter 12b is +10, so the positive threshold value Shp2 of the threshold variable torque limiter 22b is +2. (See FIG. 4B).

Further, the polarity of the drive torque command τ _d output from the drive torque command unit 30 is negative, and the value (absolute value) is the threshold value (absolute value) of the negative threshold value Shm2 set in the threshold variable torque limiter 22b. Is larger than the difference (absolute value) between the value (absolute value) of the drive torque command τ _d and the threshold value (absolute value) of the negative threshold value Shm2, the value of the negative threshold value Shm1 of the threshold variable torque limiter 12b. Set as (absolute value).
Therefore, for example, when the command value of the drive torque command τ _d is −12, the negative threshold value Shp2 of the threshold variable torque limiter 22b is −10, and therefore the negative threshold value Shm1 of the threshold variable torque limiter 12b is -2 (see FIG. 3B).

The drive torque command unit 30 outputs a drive torque command τ _d .
The value (absolute value) of the drive torque command τ _d is a torque value necessary for moving the movable member via the movable gear _GL , and is set according to the machining program or the like. The polarity of the drive torque command τ _d may be positive or negative depending on the machining situation or the like.

The offset torque command unit 31 outputs an offset torque command τ _o .
The value of the offset torque command tau _o (absolute value) is set in consideration of the weight and friction of the movable member, the value of the offset torque command tau _o (absolute value), the driving torque command tau value of _d ( It is smaller than the absolute value. The polarity of this offset torque command τ _o is always positive.
In this example, the command value of the offset torque command τ _o is set to +1, for example.

<High torque movement>
The operation of this embodiment having such a configuration will be described.
For example, the value (absolute value) of the drive torque command τ _d output from the drive torque command unit 30 is 12 and the polarity is positive (that is, the command value of the drive torque command τ _d is +12). The case where the value (absolute value) of the output offset torque command τ _o is 1 and the polarity is positive (that is, the command value of the offset torque command τ _o is +1) will be described.

In this case, the threshold characteristic of the threshold variable torque limiter 12b remains as shown in FIG. 3A, but the threshold characteristic of the threshold variable torque limiter 22b is changed by the threshold changing unit 50.
That is, since the command value of the drive torque command τ _d is +12, the threshold value changing unit 50 takes into account that the positive side threshold value Shp1 of the threshold value variable torque limiter 12b is +10, and the positive side of the threshold value variable torque limiter 22b. The threshold value Shp2 is changed to +2 (see FIG. 4B).

The drive torque command τ _d having a command value of +12 output from the drive torque command unit 30 is output with the command value being limited to +10 by passing through the threshold variable torque limiter 12b, and passes through the threshold variable torque limiter 22b. As a result, the command value is limited to +2 and output.

Addition unit 13, a drive torque command tau _d command value is +10, command value by adding the offset torque command tau _o +1, command value to output the total torque command tau _t1 of +11.
The servo amplifier (current control unit) 14 supplies a current corresponding to the total torque command τ _t1 to the motor 11, and the motor 11 rotates in the positive rotation direction (clockwise) according to the total torque command τ _t1 whose command value is +11. Direction) to output a torque corresponding to “11”, rotationally drive the motor side gear _GM1 in the forward rotation direction (clockwise direction), and move the movable member side gear _GL in the negative rotation direction (counterclockwise direction). To rotate.

The subtracting unit 23 subtracts an offset torque command τ _o having a command value of +1 from a drive torque command τ _d having a command value of +2, and outputs a total torque command τ _t2 having a command value of +1.
The servo amplifier (current control unit) 24 supplies a current corresponding to the total torque command τ _t2 to the motor 21, and the motor 21 rotates in the positive rotation direction (clockwise) according to the total torque command τ _t2 whose command value is +1. Direction) to output a torque corresponding to “1”, rotationally drive the motor side gear _GM2 in the forward rotation direction (clockwise direction), and move the movable member side gear _GL in the negative rotation direction (counterclockwise direction). To rotate.

As a result, the torque corresponding to “12” acts in the negative rotation direction (counterclockwise direction) on the movable member side gear G _L due to the torque in the same rotation direction generated by the motors 11 and 21, thereby causing the negative rotation. Rotate along direction (counterclockwise).

At this time, the motor 11 and 21 to cooperate, because it drives the movable member side gear G _L in the negative rotation direction (counterclockwise direction) by the inertia force of the movable member, the teeth of the motor side gear G _M1 and engagement with the teeth of the movable member side gear G _L, and engagement with the teeth of the movable member side gear G _L of the motor side gear G _M2 is maintained, backlash occurs and lost motion generation There is no.

Eventually, even if the command value of the drive torque command τ _d is +12 and the command value exceeds the individual maximum output torque of the individual motors 11 and 12, both the motors 11 and 12 are generated in cooperation. Since the torque in the same rotational direction is transmitted to the movable member side gear _GL , the movable member can be moved with a high torque required by the drive torque command τ _d .

Next, for example, the value (absolute value) of the drive torque command τ _d output from the drive torque command unit 30 is 12 and the polarity is negative (that is, the command value of the drive torque command τ _d is −12), and the offset torque A case where the value (absolute value) of the offset torque command τ _o output from the command unit 31 is 1 and the polarity is positive (that is, the command value of the offset torque command τ _o is +1) will be described.

In this case, the threshold characteristic of the threshold variable torque limiter 22b remains as shown in FIG. 4A, but the threshold characteristic of the threshold variable torque limiter 12b is changed by the threshold changing unit 50.
That is, since the command value of the drive torque command τ _d is −12, the threshold value changing unit 50 considers that the negative side threshold value Shm2 of the threshold value variable torque limiter 22b is −10. The negative threshold value Shm1 is changed to −2 (see FIG. 3B).

The drive torque command τ _d having a command value of −12 output from the drive torque command unit 30 is output with the command value being limited to −10 by passing through the threshold variable torque limiter 22b, and the threshold variable torque limiter 12b is output. By passing, the command value is limited to -2 and output.

The subtracting unit 23 subtracts the offset torque command τ _o having a command value of +1 from the drive torque command τ _d having a command value of −10, and outputs a total torque command τ _t2 having a command value of −11.
The servo amplifier (current control unit) 24 supplies a current corresponding to the total torque command τ _t2 to the motor 21, and the motor 21 responds to the total torque command τ _t2 having a command value of -11 in the negative rotation direction (reverse direction). The torque corresponding to “11” is output in the clockwise direction), the motor side gear _GM2 is rotationally driven in the negative rotation direction (counterclockwise direction), and the movable member side gear _GL is rotated in the positive rotation direction (clockwise). Direction).

The adding unit 13 adds the drive torque command τ _d having the command value of −2 and the offset torque command τ _o having the command value of +1, and outputs the total torque command τ _t1 having the command value of −1.
The servo amplifier (current control unit) 14 supplies a current corresponding to the total torque command τ _t1 to the motor 11, and the motor 11 responds to the total torque command τ _t1 having a command value of −1 in the negative rotation direction (counterclockwise). The torque corresponding to “1” is output in the clockwise direction), the motor side gear G _M1 is rotated in the negative rotation direction (counterclockwise direction), and the movable member side gear G _L is rotated in the positive rotation direction (clockwise). Direction).

As a result, the torque corresponding to “12” acts on the movable member side gear _GL in the positive rotation direction (clockwise direction) due to the torque in the same rotation direction generated by the motors 11 and 21, and the rotation direction ( Rotate along (clockwise direction).

At this time, since the motors 11 and 21 work together to drive the movable member side gear _GL in the forward rotation direction (clockwise direction), the inertial force of the movable member and the teeth of the motor side gear _GM1 engagement with the teeth of the movable member side gear G _L, and engagement with the teeth of the movable member side gear G _L of the motor side gear G _M2 is maintained, the generation and development of lost motion backlash No.

Eventually, even if the command value of the drive torque command τ _d is +12 and the command value exceeds the individual maximum output torque of the individual motors 11 and 12, both the motors 11 and 12 are generated in cooperation. Since the torque in the same rotational direction is transmitted to the movable member side gear _GL , the movable member can be moved with a high torque required by the drive torque command τ _d .

<Backlash removal operation>
When the absolute value of the drive torque command τ _d becomes smaller than 10 due to the reversal of the trajectory, the motor 11 is similar to the state when the backlash removal control command BR is output in the first embodiment. , by one of 12, preload (offset) torque generated according to the drive torque and the offset torque command tau _o according to the drive torque command tau _d, by the other motors 11 and 12, corresponding to the offset torque command tau _o By generating the preload (offset) torque, it is possible to move the movable member while preventing the occurrence of backlash and the generation of lost motion.

  A backlash removal control apparatus according to a third embodiment of the present invention will be described with reference to FIG. Note that parts having the same functions as those of the second embodiment shown in FIG.

<Ingenuity>
Backlash removal control apparatus of the third embodiment, and further effectively utilizing the offset torque command tau _o, while maintaining as long as possible backlash elimination condition, by continuously increasing or decreasing the torque value of the offset torque command tau _o Thus, sudden changes in the total torque commands τ _t1 and τ _t2 are prevented.

<Configuration>
A positive threshold value Shp1 and a negative threshold value Shm1 are set in the threshold variable torque limiter 12c. In this case, the positive threshold value Shp1 is a fixed value (for example, +10), and the negative threshold value Shm1 is variably set by the threshold value / offset torque value changing unit 60 as described later.
The value of the negative side threshold Shm1 is set to 0, for example, in a state where it is not variably set by the threshold / offset torque value changing unit 60.

A positive threshold value Shp2 and a negative threshold value Shm2 are set in the threshold variable torque limiter 22c. In this case, the negative threshold value Shm2 is a fixed value (for example, −10), and the positive threshold value Shp2 is variably set by the threshold value / offset torque value changing unit 60 as described later.
The positive side threshold value Shp2 is set to 0, for example, in a state where it is not variably set by the threshold value / offset torque value changing unit 60.

Offset torque command unit 31a is output to offset torque command tau _o, the torque value of the offset torque command tau _o, as will be described later, is variably set by a threshold offset torque value changing section 60.
Note that the torque value of the offset torque command τ _o is, for example, +3 in a state where it is not variably set by the threshold / offset torque value changing unit 60.

The threshold / offset torque value changing unit 60 obtains information on the drive torque command τ _d , the total torque commands τ _t1 , τ _t2 and the threshold variable torque limiters 12c, 22c.
Then, the threshold value / offset torque value changing unit 60, based on such information, as will be described in detail later.
(1) The torque value of the offset torque command τ _o ,
(2) the negative threshold value Shm1 of the threshold variable torque limiter 12c;
(3) the positive threshold value Shp2 of the threshold variable torque limiter 22c;
Is optimally variably set.

  The configuration of other parts is the same as that of the second embodiment shown in FIG.

<Operation>
The operation of the present embodiment having such a configuration will be described by dividing it into first to sixth states.

(1) When the command value of the torque command τ _d is positive and Shp1> τ _t1 .
In this case, the threshold / offset torque value changing unit 60 includes the negative threshold value Shm1 of the threshold variable torque limiter 12c, the positive threshold value Shp2 of the threshold variable torque limiter 22c, and the offset torque command τ output from the offset torque command unit 31a. The torque value of _o is not changed.

Therefore, for example, if the command value of the torque command τ _d is +6, the torque value of the offset torque command τ _o output from the offset torque command unit 31a is +3, and the command value output from the threshold variable torque limiter 12c. Is +6, the command value of the total torque command τ _t1 output from the adder 13 is +9.
Further, since the torque value of the offset torque command τ _o output from the offset torque command unit 31 a is +3 and the command value output from the threshold variable torque limiter 22 c is 0, the total torque output from the subtractor 23. The command value of the command τ _t2 is −3.

Therefore, the motor 11 outputs a torque corresponding to “9” in the positive rotation direction (clockwise direction) in response to the total torque command τ _t1 having the command value +9, and the motor 21 has a total command value of −3. Torque corresponding to “3” is output in the negative rotation direction (counterclockwise direction) according to the torque command τ _t2 , and the movable member side gear GL corresponds to “6” along the negative rotation direction (counterclockwise direction). Rotate with torque
The internal force “3” generated at this time exhibits a function of preventing the occurrence of backlash and the generation of lost motion.

(2) When the command value of the torque command τ _d is positive and τ _t1 ≧ Shp1 ≧ τ _d .
In this case, the threshold / offset torque value changing unit 60 does not change the negative side threshold Shm1 of the threshold variable torque limiter 12c and the positive side threshold Shp2 of the threshold variable torque limiter 22c, but outputs from the offset torque command unit 31a. The torque value of the offset torque command τ _o to be executed is changed by calculation as shown in the following equation.
τ _o = | Shp1-τ _d |

Therefore, for example, if the command value of the torque command τ _d is +8, the torque value before the change of the offset torque command τ _o output from the offset torque command unit 31a is +3, and is output from the threshold variable torque limiter 12c. Since the command value is +8, the command value of the total torque command τ _t1 output from the adder 13 is +11. That is, τ _t1 ≧ Shp1 ≧ τ _d .
Therefore, the threshold / offset torque value changing unit 60 calculates τ _o = | Shp1-τ _d | = | 10−8 | = 2, and calculates the offset torque command τ _o output from the offset torque command unit 31a. Change the torque value from +3 to +2.

Then, the command value of the torque command τ _d is +8, the torque value of the offset torque command τ _o output from the offset torque command unit 31a is +2, and the command value output from the threshold variable torque limiter 12c is +8. _Therefore , the command value of the total torque command τ _t1 output from the adder 13 is +10.
Further, since the torque value of the offset torque command τ _o output from the offset torque command unit 31a is +2 and the command value output from the threshold variable torque limiter 22c is 0, the total torque output from the subtractor 23 The command value of the command τ _t2 is −2.

Therefore, the motor 11 outputs a torque corresponding to “10” in the forward rotation direction (clockwise direction) in response to the total torque command τ _t1 having the command value +10, and the motor 21 has a total command value of −2. Torque corresponding to “2” is output in the negative rotation direction (counterclockwise direction) according to the torque command τ _t2 , and the movable member side gear GL corresponds to “8” along the negative rotation direction (counterclockwise direction). Rotate with torque
The internal force “2” generated at this time exhibits a function of preventing the occurrence of backlash and the generation of lost motion.
That is, the backlash removal state is maintained.

(3) When the command value of the torque command τ _d is positive and τ _d > Shp1.
In this case, the threshold / offset torque value changing unit 60 does not change the negative threshold value Shm1 of the threshold variable torque limiter 12c, but the value of the positive threshold value Shp2 of the threshold variable torque limiter 22c and the offset torque command The torque value of the offset torque command τ _o output from the unit 31a is changed by calculation as shown in the following equation.
Shp2 = τ _d -Shp1
τ _o = 0

Therefore, for example, if the command value of the torque command τ _d is +11, since the positive threshold value Shp1 of the threshold variable torque limiter 12c is +10, τ _d > Shp1.
Therefore, the threshold value / offset torque value changing unit 60 calculates Shp2 = τ _d −Shp1 = 11−10 = 1 and changes the value of the positive threshold value Shp2 of the threshold variable torque limiter 22c from 0 to 1.
The threshold / offset torque value changing unit 60 changes the torque value of the offset torque command τ _o output from the offset torque command unit 31a from +3 to 0.

Then, the command value of the torque command τ _d is +11, the torque value of the offset torque command τ _o output from the offset torque command unit 31a is 0, and the command value output from the threshold variable torque limiter 12c is 10. _Therefore , the command value of the total torque command τ _t1 output from the adder 13 is +10.
Further, since the torque value of the offset torque command τ _o output from the offset torque command unit 31a is 0 and the command value output from the threshold variable torque limiter 22c is +1, the total torque output from the subtractor 23 The command value of the command τ _t2 becomes +1.

Therefore, the motor 11 outputs a torque corresponding to “10” in the positive rotation direction (clockwise direction) in response to the total torque command τ _t1 having a command value of +10, and the motor 21 has a total torque having a command value of +1. Torque corresponding to “1” is output in the positive rotation direction (clockwise direction) according to the command τ _t2 , and the movable member side gear GL is torque corresponding to “11” along the negative rotation direction (counterclockwise direction). Rotate with.
That is, the backlash removal state is released, and both the motors 11 and 21 can work together to move the movable member with high torque.

(4) When the command value of the torque command τ _d is negative and Shm2 <τ _t2 .
In this case, the threshold / offset torque value changing unit 60 includes the negative threshold value Shm1 of the threshold variable torque limiter 12c, the positive threshold value Shp2 of the threshold variable torque limiter 22c, and the offset torque command τ output from the offset torque command unit 31a. The torque value of _o is not changed.

Therefore, for example, if the command value of the torque command τ _d is −6, the torque value of the offset torque command τ _o output from the offset torque command unit 31a is +3, and the command output from the threshold variable torque limiter 12c. Since the value is 0, the command value of the total torque command τ _t1 output from the adder 13 is +3.
Further, the torque value of the offset torque command τ _o output from the offset torque command unit 31a is +3, and the command value output from the threshold variable torque limiter 22c is −6. The command value of the torque command τ _t2 is −9.

Therefore, the motor 11 outputs a torque corresponding to “3” in the forward rotation direction (clockwise direction) in response to the total torque command τ _t1 having the command value +3, and the motor 21 has a total command value of −9. Torque corresponding to “9” is output in the negative rotation direction (counterclockwise direction) according to the torque command τ _t2 , and the movable member side gear GL corresponds to “6” along the positive rotation direction (clockwise direction). It rotates with torque.
The internal force “3” generated at this time exhibits a function of preventing the occurrence of backlash and the generation of lost motion.

(5) When the command value of the torque command τ _d is negative and τ _t2 ≦ Shm2 ≦ τ _d .
In this case, the threshold / offset torque value changing unit 60 does not change the negative side threshold Shm1 of the threshold variable torque limiter 12c and the positive side threshold Shp2 of the threshold variable torque limiter 22c, but outputs from the offset torque command unit 31a. The torque value of the offset torque command τ _o to be executed is changed by calculation as shown in the following equation.
τ _o = | τ _d -Shm2 |

Therefore, for example, when the command value of the torque command τ _d is −8, the torque value before the change of the offset torque command τ _o output from the offset torque command unit 31a is +3, and is output from the threshold variable torque limiter 22c. Since the command value to be executed is -8, the command value of the total torque command τ _t2 output from the subtractor 23 is -11. That is, τ _t2 ≦ Shm2 ≦ τ _d .
Therefore, the threshold / offset torque value changing unit 60 calculates τ _o = | τ _d -Shm2 | = | −8 − (− 10) | = 2 and outputs the offset torque output from the offset torque command unit 31a. The torque value of the command τ _o is changed from +3 to +2.

Then, the command value of the torque command τ _d is −8, the torque value of the offset torque command τ _o output from the offset torque command unit 31a is +2, and the command value output from the threshold variable torque limiter 12c is 0. _Therefore , the command value of the total torque command τ _t1 output from the adder 13 is +2.
Further, the torque value of the offset torque command τ _o output from the offset torque command unit 31a is +2, and the command value output from the threshold variable torque limiter 22c is −8. The command value of the torque command τ _t2 is −10.

Therefore, the motor 11 outputs a torque corresponding to “2” in the positive rotation direction (clockwise direction) in response to the total torque command τ _t1 having the command value +2, and the motor 21 has a total command value of −10. Torque corresponding to “10” is output in the negative rotation direction (counterclockwise direction) according to the torque command τ _t2 , and the movable member side gear GL corresponds to “8” along the positive rotation direction (clockwise direction). It rotates with torque.
The internal force “2” generated at this time exhibits a function of preventing the occurrence of backlash and the generation of lost motion.
That is, the backlash removal state is maintained.

(6) When the command value of the torque command τ _d is negative and τ _d <Shm2.
In this case, the threshold / offset torque value changing unit 60 does not change the positive side threshold Shp1 of the threshold variable torque limiter 22c, but the value of the negative side threshold Shm1 of the threshold variable torque limiter 12c and the offset torque command The torque value of the offset torque command τ _o output from the unit 31a is changed by calculation as shown in the following equation.
Shm1 = τ _d -Shm2
τ _o = 0

Therefore, for example, if the command value of the torque command τ _d is −11, the negative threshold value Shpm of the threshold variable torque limiter 22c is −10, and thus τ _d <Shm2.
Therefore, the threshold / offset torque value changing unit 60 calculates Shm1 = τ _d −Shm2 = −11 − (− 10) = − 1, and sets the value of the negative threshold value Shm1 of the threshold variable torque limiter 12c from 0. Change to -1.
The threshold / offset torque value changing unit 60 changes the torque value of the offset torque command τ _o output from the offset torque command unit 31a from +3 to 0.

Then, the command value of the torque command τ _d is −11, the torque value of the offset torque command τ _o output from the offset torque command unit 31a is 0, and the command value output from the threshold variable torque limiter 12c is − Since it is 1, the command value of the total torque command τ _t1 output from the adder 13 is −1.
Further, since the torque value of the offset torque command τ _o output from the offset torque command unit 31a is 0 and the command value output from the threshold variable torque limiter 22c is −10, the total value output from the subtractor 23 is output. The command value of the torque command τ _t2 is −10.

Therefore, the motor 11 outputs a torque corresponding to “1” in the negative rotation direction (counterclockwise direction) according to the total torque command τ _t1 having a command value of −1, and the motor 21 has a command value of −10. Torque corresponding to “10” is output in the negative rotation direction (counterclockwise direction) according to the total torque command τ _t2 , and the movable member side gear GL is set to “11” along the positive rotation direction (clockwise direction). It rotates with the corresponding torque.
That is, the backlash removal state is released, and both the motors 11 and 21 can work together to move the movable member with high torque.

11, 21 Motor 12, 22, 12a, 22a Zero torque limiter 12b, 12c, 22b, 22c Threshold variable torque limiter 13 Adder 23 Subtractor 14, 24 Servo amplifier (current control unit)
DESCRIPTION OF SYMBOLS 30 Drive torque command part 31, 31a Offset torque command part 40 Backlash removal control command issuing part 50 Threshold change part 60 Threshold value / offset torque value change part

Claims (3)

A movable member side gear connected to the movable member;
A first motor side gear that meshes with the movable member side gear and is driven to rotate by a first motor;
A second motor side gear that meshes with the movable member side gear and is rotationally driven by a second motor;
When a backlash removal control command is input, a zero-torque limit function is provided that allows a drive torque command with a positive polarity to pass but blocks a drive torque command with a negative polarity to pass. A first zero torque limiter that passes the drive torque command as it is regardless of the polarity when the command is not input;
When a backlash removal control command is input, a zero-torque limit function that allows the drive torque command with a negative polarity to pass but cuts off the drive torque command with a positive polarity is demonstrated. A second zero torque limiter that passes the drive torque command as it is regardless of the polarity when the command is not input;
An offset torque command unit that outputs an offset torque command when a backlash removal control command is input, and stops outputting an offset torque command when the backlash removal control command is not input;
Torque is generated according to the value of the total torque command obtained by adding the offset torque command to the drive torque command that has passed through the first zero torque limiter, and the rotation direction is in accordance with the polarity of the total torque command. A first current controller for supplying a current to the first motor,
Torque is generated according to the value of the total torque command obtained by subtracting the offset torque command from the drive torque command that has passed through the second zero torque limiter, and the rotational direction is in accordance with the polarity of the total torque command. A second current controller for supplying a current to the second motor,
When precise positioning of the movable member is required, it is necessary to input a backlash removal control command to the first zero torque limiter, the second zero torque limiter, and the offset torque command unit to move the movable member at high speed. Sometimes, the first zero torque limiter, the second zero torque limiter, and the backlash removal control command issuing unit for stopping the input of the backlash removal control command to the offset torque command unit;
A backlash removal control device comprising: A movable member side gear connected to the movable member;
A first motor side gear that meshes with the movable member side gear and is driven to rotate by a first motor;
A second motor side gear that meshes with the movable member side gear and is rotationally driven by a second motor;
A first threshold variable torque limiter in which the positive threshold is fixedly set, the negative threshold is variably set, and when a drive torque command is input, the value is limited and output by the positive threshold and the negative threshold. When,
A second threshold variable torque limiter in which the negative threshold is fixedly set, the positive threshold is variably set, and when a drive torque command is input, the value is limited and output by the negative threshold and the positive threshold. When,
An offset torque command section for outputting an offset torque command;
A torque corresponding to the value of the total torque command obtained by adding the offset torque command to the drive torque command that has passed through the first threshold variable torque limiter, and a rotation direction corresponding to the polarity of the total torque command; A first current controller for supplying a current to the first motor,
A torque corresponding to the value of the total torque command obtained by subtracting the offset torque command from the drive torque command passing through the second threshold variable torque limiter, and a rotation direction corresponding to the polarity of the total torque command; A second current control unit for supplying current to the second motor,
When the polarity of the drive torque command input to the first and second threshold variable torque limiters is positive, the absolute value of the drive torque command input to the first and second threshold variable torque limiters and the first A difference value from the absolute value of the positive threshold value of the second threshold variable torque limiter is set as an absolute value of the positive threshold value of the second threshold variable torque limiter, and is input to the first and second threshold variable torque limiters. When the polarity of the drive torque command is negative, the absolute value of the drive torque command input to the first and second threshold variable torque limiters and the absolute value of the negative threshold of the second threshold variable torque limiter are A threshold value changing unit that sets the difference value of the absolute value of the negative threshold value of the first threshold variable torque limiter;
A backlash removal control device comprising: A movable member side gear connected to the movable member;
A first motor side gear that meshes with the movable member side gear and is driven to rotate by a first motor;
A second motor side gear that meshes with the movable member side gear and is rotationally driven by a second motor;
An offset torque command section for outputting an offset torque command;
A first threshold variable torque limiter in which the positive threshold is fixedly set, the negative threshold is variably set, and when a drive torque command is input, the value is limited and output by the positive threshold and the negative threshold. When,
A second threshold variable torque limiter in which the negative threshold is fixedly set, the positive threshold is variably set, and when a drive torque command is input, the value is limited and output by the negative threshold and the positive threshold. When,
A torque corresponding to the value of the first total torque command obtained by adding the drive torque command that has passed through the first threshold variable torque limiter and the offset torque command is generated, and the polarity of the first total torque command is set. A first current control unit for supplying current to the first motor so as to have a corresponding rotation direction;
Torque is generated according to the value of the second total torque command obtained by subtracting the offset torque finger from the drive torque command that has passed through the second threshold variable torque limiter, and the polarity of the second total torque command is set. A second current control unit for supplying a current to the second motor so as to have a corresponding rotation direction;
A threshold value / offset torque value changing unit,
The threshold value / offset torque value changing unit is:
When the polarity of the drive torque command input to the first and second threshold variable torque limiters is positive, the positive threshold of the first threshold variable torque limiter is smaller than the first total torque command, and If the driving torque command is larger than the driving torque command, the absolute value of the value obtained by subtracting the driving torque command from the positive threshold value of the first threshold variable torque limiter is set as the command value of the offset torque command.
When the polarity of the drive torque command input to the first and second threshold variable torque limiters is positive and the positive threshold of the first threshold variable torque limiter is smaller than the drive torque command, the offset torque A value obtained by subtracting the positive threshold value of the first threshold variable torque limiter from the drive torque command is set as the positive threshold value of the second threshold variable torque limiter, with the command value of the command set to 0.
When the polarity of the drive torque command input to the first and second threshold variable torque limiters is negative, the negative threshold of the second threshold variable torque limiter is greater than the second total torque command, and When the driving torque command is smaller than the driving torque command, the absolute value of the value obtained by subtracting the negative threshold value of the second threshold variable torque limiter from the driving torque command is set as the command value of the offset torque command.
When the polarity of the drive torque command input to the first and second threshold variable torque limiters is negative and the negative threshold of the second threshold variable torque limiter is greater than the drive torque command, the offset torque And a value obtained by subtracting the negative threshold value of the second threshold variable torque limiter from the drive torque command is set as the negative threshold value of the first threshold variable torque limiter.
A backlash removal control device characterized by that.

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