JPS59115195A - Method and device for holding attitude of stoppage of robot - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for maintaining a constant stopping posture of a robot, and more particularly to improvements in a method and device for maintaining a constant standby posture of a robot after work is completed.

Conventionally, in order to maintain a constant stopping posture of a robot, a so-called servo lock method has been adopted in which each drive shaft (joint) is fixed by driving a servo motor. However, in general, the time during which robots perform accurate operations under advanced control is 30 to 50 hours of the actual line operating time, and the remaining time is spent waiting and not performing any work. There is.

In order to maintain this standby state using the pre-g pi servo lock method, it is of course necessary to use a motor with a capacity higher than that required for actual operation, and in reality, the energy consumption of the motor is required to maintain this standby state. The current situation is that it accounts for the majority.

In addition, for example, a robot's wrist is not dangerous even if it moves a little while it is on standby, so it is problematic from an energy saving perspective to use the normal servo lock method to maintain the posture of the robot's wrist. It becomes.

Furthermore, by requiring such a high-capacity motor, the mechanical structure must be larger and more expensive, and there are also safety issues due to the servo lock system. It is a place where there are many.

In view of the above-mentioned problems of the prior art, the present invention provides a method for holding a stopped posture of a robot, which makes it possible to reduce the weight and cost of the mechanical structure through miniaturization of the motor, as well as improve energy saving and safety. The purpose is to provide equipment.

For this reason, drive shafts (joints) that have brakes and joints that do not have to be installed, and when the robot needs to maintain the same posture for a long time, a standby command is issued and the joints that have brakes activate the brakes. The present invention has realized a method and device for maintaining a stopped posture in which the brake is fixed by stopping power supply to the rear motor and activating a low-torque servo lock for joints where the brake does not make noise.

Embodiments of the present invention will be described below with reference to the accompanying drawings.

The attached drawing is a block diagram showing an example of a system configuration for carrying out the method for maintaining a stopped posture of a robot according to the present invention. In the figure, 1 corresponds to a system control computer, and 2 corresponds to one of the joints having a brake. 3 is a single axis control unit that has the same performance as the first single axis control unit 2 and increases or decreases depending on the number of joints to be supported; 4 is a joint that does not have a brake; 5 is a single-axis control unit that has the same function as the second single-axis unit 4 and increases or decreases depending on the number of required joints; 6 is a motor drive unit; It is a power source.

The first single-axis control unit 2 includes a first position control computer 7, an analog servo 8, a motor drive unit 9, and a first motor unit 10 that includes a position detection sensor and a rotation stop brake. and a position detection processing circuit 11 are provided so as to form a closed loop, and a motor drive power supply opening/closing unit (12) connected to the motor drive unit 9 and also connected to the system control computer 1 and the motor drive power supply 6. A brake control unit 13 is also provided which is connected to the motor unit 10 (VC) and to the system control computer 1.

On the other hand, the second single-axis control unit 4 includes a second position control computer 14, an analog servo 8, a motor drive unit 9, and a second position detection sensor.
The motor unit 15 and the 1-position detection processing circuit 11 are provided to form a closed loop in the same manner as described above, and
A motor current detector 16 and a motor current limiter 1 are connected between the second motor unit 15 and the output side of the analog servo 8.
7 is interposed. Further, the motor drive unit 9 is connected to the motor drive power source 6, and the motor current limiter 17 is connected to the second position control computer 14.

Note that this second single-axis control unit 4 is mainly used for joints such as the wrist that do not require relatively high accuracy in posture maintenance.

Depending on the configuration, in order to temporarily stop the robot during normal work, the system control computer 1 sends command values necessary to maintain the robot's posture to the first and second single-axis control units. 2 and 4, and in the first single-axis control unit 2, the first position control computer 7 controls the analog servo 8, the motor drive unit 9, and the first motor, including itself, so that the first position control computer 7 can maintain the commands. Unit 10 and
A closed loop with the position detection processing circuit 11 is established, and a second
In the single-axis control unit 4, the second position control computer 14 creates a closed loop including itself, the analog servo 8, the motor drive unit 9, the second motor unit 15, and the position detection control circuit 11.

As a result, the first and second motor units 13 and 15 are finely adjusted at all times, and a so-called servo lock is activated to maintain the corresponding joints in a constant posture.

The other single-axis control units 3 and 5 are also controlled in the same manner as described above, so that the stopped posture of the entire robot is maintained.

Next, when the work is completed and the system enters a standby state, the system control computer 1 instructs the first and second single-axis control units 2 and 4 to ``start standby''. In the first single-axis control unit 2, first the brake control unit 13 operates!7 and then the first motor unit l.

The internal brake is activated and the joint is fixed. Subsequently, the motor rotation source opening/closing unit 12 operates to cut off the current supply to the motor drive unit 9 and release the servo lock. Similar motion control is possible with other single-axis control unit 3.
The joints with brakes are mechanically held in a constant position during a series of motion controls.
The position detection of the position control computer 7, the second motor unit 10, and the position detection processing circuit 11 maintains the same function as in the normal operating state. Since the position of each joint in this state is slightly different from the value commanded by the system control computer 1, the position when the brake of the first motor unit 10 is activated is determined by the first position control computer 7. The information is fed back to the system control computer 1 via the system control computer 1, and the overall position information is corrected.

On the other hand, in the second control unit 4 which has received the "standby start" command, the second position control computer 14 issues a control command to the motor current limiter 17, and at the same time sets the servo deviation tolerance value. Rewrite it and make it bigger. This is because the second position control computer 14 is preset with a servo deviation tolerance value that regulates the movement of the joints, and during normal work, the position is calculated based on the information from the position detection processing circuit 11. ! When the error exceeds the @1” distribution setting value, it is judged as abnormal.
This is done in order to avoid this. The motor current limiter 17 regulates the current to a low level so that the current exceeding a certain value does not pass through the second motor unit 15, so information from the motor 14Lff and the detector 16 is constantly input to this. . However, when the MIJ current limit is activated, the position loop cane is made small so that it responds slowly even if the posture of the vehicle changes due to an external force.

, the same operation control as above is performed for the other single axis control circuits 5, and through a series of 1ilJIl, the joints that are not braked are held in a constant posture by a low torque servo lock. becomes.

The function of the motor current limiter 17 is, for example, to sample the required torque when the motor is in a stopped position and to prevent it from exceeding this value, or to reduce the torque to zero when the motor is stopped, and then restore the balance after a certain period of time. The torque may be set to a constant value so that the posture is maintained.

Next, when receiving a "wait cancellation" command and returning to normal operation, the first step is to return to normal operation. Both the second single-axis control units 2 and 4 perform operations in reverse to the above. In other words, 1. The first single-axis control unit 2 operates to supply current to the system drive unit 9, and then the brake control unit 13 operates in response to a command from the system control computer 1 to On the other hand, in the second single-axis control unit 4, the motor current limiter 17 stops its operation based on a command from the second position control computer 14, and then “Start waiting”
An action is performed to return the joint to the position it was in when the command was received.

Through this series of motion controls, each joint returns to its normal state, and thereafter motions related to normal work are controlled based on commands from the system control combiator 1.

As described above in detail, the method for maintaining a stopped posture of a robot according to the present invention combines joints with and without brakes, and allows these two types of joints to simultaneously perform different movements such as θ[ The joints with brakes are mechanically fixed, allowing the robot to maintain a fixed stopping position.
In addition, joints that do not have brakes are fixed with low torque (low current) servo locks, which reduces the load on the motor, making it possible to use smaller motors. Therefore, the adoption of such a small motor not only significantly contributes to energy saving, but also has the effect of making the mechanical structure as small and inexpensive as possible, and the stopped state due to the brake and low torque servo lock is
This has made it possible to prevent abnormal movements of the robot, making a significant contribution to safety.

[Brief explanation of the drawing]

The drawing is a block diagram showing an example of a system configuration for carrying out the method for maintaining a stopped posture of a robot according to the present invention. 1......System III Ill computer 2...First single-axis control unit 4...Second single-axis control unit 9・・・
...Motor drive unit 10...
- First motor unit 12...Motor drive power supply opening/closing unit 13...Brake control unit 14...Position control computer 15...
...Second motor unit 17...Motor current limiter (1 other person)

Claims (2)

[Claims] (1) Sends a standby start command, activates the brake and fixes the drive shaft that will damage the brake, activates a low torque servo lock to fix the drive shaft that does not have a brake, and applies the rear brake. A method for maintaining a stopped posture of a robot, characterized by cutting off the supply of current to a drive source of a drive shaft. (2) A system control computer, which operates based on instructions from the system control computer, and
Brake f that operates the brake in the motor unit of
A first single-axis control unit comprising a BLJ control unit and a motor drive power supply opening/closing unit that operates based on instructions from the system control computer and turns on and off current supply to the motor drive unit, and a position control computer that operates based on instructions from the system control computer; and a position control computer that operates based on instructions from the position control computer and regulates the second motor unit so that a vL flow exceeding a certain value does not flow to the second motor unit. 1. A stop posture holding device for a robot, characterized in that a second single-axis control unit is provided with a motor current limiter for controlling fbII.