TWI604915B - Electric gripper system and its control method - Google Patents

Description

Electric jaw system and control method thereof

The invention relates to an electric clamping jaw system and a control method thereof, which are applied to an electric clamping jaw to improve the positioning precision of the clamping jaw mechanism.

Electric grippers are widely used in the automation industry to grip workpieces for assembly. However, each time the electric gripper moves, it will produce an error in the moving position, and it is impossible to accurately reach the originally predetermined target position. According to this, each time the displacement of the electric gripper will continuously accumulate the position error, the gap between the actual moving position and the target moving position will gradually become larger after the electric gripper is operated for a long time, and the eccentricity is generated when the workpiece is clamped. The problem is that the workpiece being clamped constantly collides with the workpiece to be assembled.

See U.S. Patent No. 7,786,851, which provides a positional error that compensates for the movement of the electric jaws as they move. The prior art has a first axis that produces a control command to drive the stepper motor and a second shaft to generate the correct position. Wherein, the second axis generates a speed curve compensation value according to the position of the feedback motor, and then the speed curve compensation value and the control command generated by the original first axis are operated to generate a combined stepping motor command value, thereby compensating the stepping motor. Position error.

Therefore, the prior art can update the current position of the stepping motor each time to improve the accuracy of the single movement of the stepping motor, but if the stepping motor still has a slight difference in each movement In the case of positional errors, the prior art can only compensate for the relative accumulated error by the speed curve compensation value generated by the feedback motor position.

In view of this, the present invention relates to an electric jaw system and a control method thereof, the main purpose of which is to prevent the electric jaw from accumulating positional errors when performing relative displacement, so as to improve the accuracy of the displacement of the electric jaw to the target position. degree.

In order to achieve the foregoing object, an electric gripper system provided by the present invention is for controlling a jaw mechanism to hold a workpiece, the electric jaw system comprising: a motor, a sensor and a control processing unit . The motor is used to drive the jaw mechanism to clamp the workpiece, and the sensor is assembled to the motor, and the sensor generates a current position according to the position of the jaw mechanism.

The control processing unit includes a control block, a transfer block, an access block and a drive block; the transfer block generates a relative position command value, so that the jaw mechanism moves in a relative position and is accessed The block stores an absolute progressive position; the control block receives the relative position command value of the transfer block, and the absolute progressive position of the access block, and the control block generates a target position based on the relative position command value and the absolute progressive position; The control block generates a drive data based on the difference between the current position and the target position, and the rotational speed of the motor. The drive block reads the drive data to drive the motor to drive the jaw mechanism to act. Thereby, the driving block drives the motor at a suitable speed according to the driving data to drive the jaw mechanism to shift to the target position with respect to the position command value, thereby eliminating the position error generated by the clamping mechanism during the movement.

There is another method of controlling an electric gripper system, the method comprising the steps of: a) receiving, by the control block, a relative position command value transmitted by the transfer block, and obtaining an absolute progressive position from the access unit, the control The block generates the mesh based on the relative position command value and the absolute progressive position a position of the target; b) the control block receives the current position generated by the sensor, and calculates a distance between the current position and the target position, the control block is generated based on the distance between the current position and the target position and the rotational speed of the motor Driving data; c) driving block receives driving data, and the driving block drives the motor to drive the jaw mechanism to move to the target position according to the driving data; d) the control block determines whether the jaw mechanism enters a positioning range, when judging the folder The claw mechanism has entered the positioning range, that is, the positioning of the jaw mechanism is completed; otherwise, returning to step b); accordingly, through the calculation of the relative position command value, the progressive position and the current position, the motor is driven at an appropriate speed according to the driving data. The jaw mechanism is controlled to move to the target position to compensate for the position error generated by the jaw mechanism, thereby improving the accuracy of the positioning of the jaw mechanism.

The details and features of the electric jaw system and the control method thereof provided by the present invention will be described in the detailed description of the subsequent embodiments. However, it should be understood by those of ordinary skill in the art that the present invention is not limited to the scope of the invention.

100‧‧‧claw mechanism

200‧‧‧Workpiece

10‧‧‧ motor

20‧‧‧ sensor

30‧‧‧Control Processing Unit

32‧‧‧Transfer block

34‧‧‧Access block

36‧‧‧Control block

38‧‧‧Drive block

S10~S18, S20, S32~S36‧‧‧ steps

1 is a block diagram of an electric jaw system according to a preferred embodiment of the present invention; and FIG. 2 is a perspective view of a sensor of the electric jaw system provided by the preferred embodiment of the present invention coupled to a motor; 3 is a flow chart of a method for controlling an electric gripper system according to the preferred embodiment of the present invention; FIG. 4 is a flow chart showing a procedure for updating an absolute progressive position in FIG. 3; An electric jaw system provided by a preferred embodiment that drives the jaw device A schematic diagram of the movement in an absolute position mode; and FIG. 6 is a schematic view of the electric jaw system provided by the preferred embodiment of the present invention, the jaw mechanism of which is driven to clamp the workpiece.

For a detailed description of the technical features of the present invention, the following preferred embodiments are described with reference to the following drawings, wherein: FIG. 1 and FIG. 2 are provided as a preferred embodiment of the present invention. An electric jaw system for driving a positional movement of a jaw mechanism 100, the motorized jaw system comprising a motor 10, a sensor 20 and a control processing unit 30 for driving the clip The claw mechanism 100 performs positional movement.

As shown in FIG. 1, the sensor 20 is mounted to the motor 10, and the sensor 20 generates a current position of the jaw mechanism 100 in accordance with the position of the jaw mechanism 100.

The control processing unit 30 includes a transfer block 32, an access block 34, a control block 36, and a drive block 38. The control block 36 is connected to the transfer block 32, the access block 34, Driving block 38 and sensor 20, the transfer block 32 produces a relative position command value. Access block 34 stores an absolute progressive position. The relative position command value causes the motor 10 to drive the jaw mechanism 100 to move in the relative position mode.

The control block 36 reads the relative position command value, the absolute progressive position and the current position, and the control block 36 generates a target position based on the relative position command value and the absolute progressive position, the control block 36 based on calculating the current position and the target position. The distance, as well as the speed of the motor 10 (deceleration or acceleration), produces a drive profile that is the speed profile.

The driving block 38 reads the speed curve and converts the acceleration curve into an electrical signal. (ie, current or voltage), the drive motor 10 drives the jaw mechanism 100 to displace.

Referring to Figures 2 and 3, in accordance with the above description of the electric jaw system provided by the preferred embodiment of the present invention, a method for controlling the system is further described. The method includes the following steps: First, step S10 is executed, the control block 36 receives the relative position command value transmitted by the transfer block 32; then, in step S12, the control block 36 obtains the absolute progressive position from the access block 34; and then performs step S13, the control block 36 will be in the relative position. The command value and the absolute progressive position are added to generate a target position. This absolute progressive position is the current position of the jaw mechanism 100 in an ideal state. The relative position command value is the distance that the jaw mechanism 100 needs to move. The absolute progressive position is the current position in the ideal state of the jaw mechanism 100, and the initial state of the absolute progressive position is a preset value.

Step S20 updates the absolute position and adds the relative position command value to the absolute progressive position previously stored in the access block 34 to overwrite the absolute progressive position previously stored in the access block 34. Thereby, when the motor 10 drives the jaw mechanism 100, the new absolute progressive position is the current position of the ideal state of the jaw mechanism 100, and the current position of the ideal state indicates that the jaw mechanism 100 does not generate a moving distance when displaced. The location of the error. The step of updating the absolute progressive position is performed to eliminate the positional error caused by the jaw mechanism 100 after displacement.

Step S14 is that the control block 36 receives the current position generated by the sensor 20. Following the step S15, the control block 36 calculates the difference between the current position and the target position, and the rotational speed of the motor 10 to generate the driving data; and calculates the difference between the current position and the target position to compensate for the previous displacement of the jaw mechanism 100. The positional error enables the jaw mechanism 100 to accurately reach the target position.

Then, in step S16, the control block 36 transmits the driving data to the driving block. 38. After the driving block 38 receives the driving data, the driving motor 10 drives the jaw mechanism 100 to start shifting to the target position. Then, in step S17, the control block 36 determines whether the motor 10 has entered a positioning range. When the control block 36 determines that the motor 10 has entered the positioning range, the positioning of the motor 10 is completed (ie, step S18). When the control block 36 determines that the motor 10 has not entered the positioning range, the process returns to step S14, causing the control block 36 to reacquire the current position of the motor 10, and continuously repeats the looping steps S14 to S17 until the motor 10 enters the positioning range. . Wherein, the positioning range is a specification tolerance of the workpiece.

During the movement of the jaw mechanism 100, it can be moved to the target position in the absolute position mode or moved to the target position in the clamping mode, and the jaw mechanism 100 switches the movement mode according to the demand (switching the movement mode of the jaw mechanism 100) The prior art is not the scope of the present invention and will not be described here. The movement mode of the jaw mechanism 100 is divided into two types, one is relative position movement and the other is absolute position movement. The relative position movement command commands the jaw mechanism 100 to move to a target position after moving a fixed distance, and the absolute position movement command commands the jaw mechanism 100 to move to the target position; for example, the target position is 3 mm, when the current position of the jaw mechanism 100 is 1mm. If the jaw mechanism 100 is moved in the relative position, the movement command received is moved forward to 2 mm; if the jaw mechanism 100 is moved in the absolute position, the movement command received is moved to a position of 3 mm.

Referring to FIG. 4, which is a flow for updating the absolute progressive position, first step S32 is executed. The control block 36 first determines whether the jaw mechanism 100 is moved in the absolute position mode. If the determination result is yes, step S33 is updated. Absolutely progressive position; otherwise, step S34 is performed. Referring to Fig. 5, which is a state in which the jaw mechanism 100 is moved, the arrow is the direction in which the jaw mechanism 100 moves.

In step S34, the control block 36 determines whether the jaw mechanism 100 is in the clamp mode. When the determination result is YES, step S35 is performed to update the absolute progressive position; otherwise, step S33 is performed. Referring to FIG. 6, the jaw mechanism 100 is moved in a clamping mode, and the jaw mechanism 100 is The state of the workpiece 200 is clamped.

In step S35, when the control block 36 determines that the jaw mechanism 100 is in an abnormal state, step S33 is performed to update the absolute progressive position; otherwise, step S36 is performed to end the update of the absolute progressive position flow. This abnormal condition is a condition that the jaw mechanism 100 is in the process of displacement due to the occurrence of foreign matter or the inability to continue moving during the movement.

The foregoing step S33 updates the absolute progressive position, and stores the current position of the jaw mechanism 100 generated by the sensor 20 to the access block 34, which overwrites the absolute value originally stored in the access block 34. The progressive position, ie the updated absolute progressive position, is the current position of the jaw mechanism 100.

According to this, the absolute progressive position is updated through the above steps, and the absolute progressive position can be continuously updated during the movement of the jaw mechanism 100 without affecting its actuation, and the displacement of the jaw mechanism 100 is improved by continuously updating the absolute progressive position. Accuracy to the target location.

Finally, it is to be noted that the constituent elements disclosed in the foregoing embodiments are merely illustrative and are not intended to limit the scope of the present invention, and alternative or variations of other equivalent elements should also be the scope of the patent application of the present application. Covered.

100‧‧‧claw mechanism

10‧‧‧ motor

20‧‧‧ sensor

30‧‧‧Control Processing Unit

32‧‧‧Transfer block

34‧‧‧Access block

36‧‧‧Control block

38‧‧‧Drive block

Claims (8)

An electric jaw system for controlling a jaw mechanism to hold a workpiece, the motorized jaw system comprising: a motor for driving the jaw mechanism; a sensor disposed on the workpiece a motor, the sensor generates a current position according to the position of the jaw mechanism; and a control processing unit includes a control block, a transfer block, an access block and a drive block; the control The block connects the transfer block, the access block, the drive block and the sensor, the transfer block generates a relative position command value, and the access block stores an absolute progressive position; the control The block reads the relative position command value, the absolute progressive position and the current position, and the control block generates a target position based on the relative position command value and the absolute progressive position, the control block is based on the difference between the current position and the target position, and the rotation speed of the motor A driving data is generated; the driving block reads the driving data to drive the motor to drive the jaw mechanism to act. A control method for an electric gripper system according to claim 1, wherein the method comprises the steps of: a) receiving, by the control block, a relative position command value transmitted by the transfer block, and accessing the slave Obtaining an absolute progressive position in the unit, the control block generates a target position based on the relative position command value and the absolute progressive position; b) the control block receives the current position generated by the sensor, and calculates the distance between the current position and the target position The control block generates driving data based on the distance between the current position and the target position and the rotation speed of the motor; c) the driving block receives the driving data, and the driving block drives the motor to drive the clip according to the driving data. The claw mechanism moves to the target position; d) the control block determines whether the jaw mechanism enters a positioning range, and when it is determined that the jaw mechanism has entered the positioning range, the positioning of the jaw mechanism is completed; otherwise, the process returns to step b). According to the control method of the electric gripper system of claim 2, in the step d), when the control block determines that the jaw mechanism has not entered the positioning range, an update of the absolute position progressive process is performed, and the update is performed. In the absolute position progression process, when it is determined that the jaw mechanism is moved in an absolute position mode, moved in a clamping mode, an abnormality occurs, or any of the foregoing, the current position of the jaw mechanism is stored to the access unit to the current The position overwrites the absolute progressive position originally stored in the access unit, thus updating the absolute progressive position to the current position of the jaw mechanism. The control method of the electric gripper system according to claim 3, wherein, when the updating of the absolute position progressive flow is performed, first determining whether the clamping mechanism moves in an absolute position mode; when the determination result is negative, the subsequent determination Whether the clamping mechanism is moved in the clamping mode; when the determination result is no, it is determined whether the clamping mechanism is abnormal; when the determination result is negative, the updating absolute position progressive process is ended. According to the control method of the electric gripper system of claim 2, wherein, in step a), when the control block obtains the relative position command value and the absolute progressive position, the control block will have a relative position command value and The sum of the absolute cumulative positions overwrites the absolute progressive position of the access block to update the absolute progressive position as the sum of the relative position command value and the absolute cumulative position. The control method of the electric gripper system according to claim 2, wherein the positioning range is a specification tolerance of the workpiece. The electric jaw system according to claim 1, wherein the driving data is an acceleration curve of the motor. The control method of the electric gripper system according to claim 2, wherein the driving data is an acceleration curve of the motor.