GB/T 38559-2020Specification of industrial robots force control (English PDF)

3.1 Passive compliance control

a mechanism that the robot can respond to external forces when it comes into contact with the environment by virtue of the auxiliary compliance mechanism, a method that realizes direct force control through closed loop with explicit force feedback

3.12 Position-based direct force control

a method that a control system is composed of internal position closed loop control and external force closed loop to achieve direct force control

3.13 Torque-based direct force control

a method that a control system is composed of internal torque closed loop control and external force closed loop to achieve direct force control

3.14 Hybrid force control

a force control method that integrates multiple control strategies

3.15 Force/position hybrid control

a composite control strategy after fusion of force control (torque control) and position control (positioning control)

NOTE: It mainly refers to the fusion model of force control and position control.

3.16 Hybrid impedance control

a control method that combines impedance control and force/position hybrid control

3.17 Adaptive force control

an advanced force control method that uses an adaptive control strategy to improve the system's adaptability to unknown environments

3.18 Robust force control

an advanced force control method that adopts a robust control strategy to ensure the robust stability and dynamic performance of the system

3.19 Learning force control

a control method that uses machine learning methods to improve force control parameters and improve force control performance

3.20 Neural-network force control

an advanced force control method that is based on neural network to learn system dynamic characteristics

4.2 Classification by force control strategy

2) impedance control;

3) damping control;

4) admittance control.

b) Direct force control:

1) position-based direct force control;

2) torque-based direct force control.

c) Hybrid force control:

1) force/position hybrid control;

2) hybrid impedance control.

4.2.2 Advanced force control

According to the advanced force control strategy, it is classified into the following categories:

a) adaptive force control;

b) robust force control;

c) learning force control;

d) neural-network force control;

e) fuzzy force control.

4.3 Classification according to sensing method

According to the sensing method, it is classified into the following three categories:

a) end force/torque sensor-based force control;

b) joint torque sensor-based force control;

c) motor current-based force control.

4.4 General technical parameters

4.4.1 Resolution

The minimum control amount of force and moment, in newtons per newton meter [N/(N.m)].

5.2 General performance index

5.2.8 Output time drift

Unless otherwise specified, the output time drift of the sensor in each dimension shall not be greater than the output time drift specified in Table 2.

5.2.9 Output temperature drift

Unless otherwise specified, the output temperature drift of the sensor in each dimension shall not be greater than the output temperature drift specified in Table 2.

5.2.10 Overload capacity

Unless otherwise specified, the overload capacity of the sensor in each dimension shall not be less than the overload capacity specified in Table 2.

5.3 Special performance index

5.3.1 Special performance index of resistance strain type force/torque sensor

According to GB/T 18806-2002, the special performance index of resistance strain type force/torque sensor includes:

a) Output impedance The output impedance of the sensor shall meet the requirements of the product technical conditions (detailed specifications).

The output impedance shall be selected from the following values first:

0.06kohm, 0.12kohm, 0.15kohm, 0.24kohm, 0.35kohm, 0.45kohm, 0.6kohm, 0.8kohm, 1.0kohm, 2.0kohm, 2.4kohm, 3.5kohm, 10kohm.

b) Insulation resistance The insulation resistance between the lead wire of the sensor and the housing shall not be less than 500Mohm.

5.3.2 Special performance index of piezoelectric force/torque sensor

According to the provisions of JB/T 7482-2008, the special performance index of the resistance strain type force/torque sensor shall include:

a) Insulation resistance: the insulation resistance between the lead wire of the sensor and the housing shall not be less than 1013ohm;

6.2 Dynamic force control technology

6.2.1 Definition

Dynamic force control technology is applied force control strategy. Dynamically adjust the force/torque setting value according to the environment and job requirements. Complete robot assembly and other operations.

6.2.2 Application

Dynamic force control technology can be applied to robot assembly, which can be applied but not limited to:

a) pin into the hole;

b) assemble the crank;

c) twist the screw.

6.2.3 Application condition requirements

Dynamic force control technology shall meet the following application condition requirements:

a) emergency stop processing under fault conditions;

b) when collision protection technology is not used, man-machine isolation fences shall be installed;

c) the maximum mass and size of the clamped workpiece shall be set;

d) the maximum operating speed shall be set to prevent the workpiece from detaching or falling due to inertia;

e) the assembly accuracy is better than 1% of force/torque sensor measuring range.

6.3 Constant force control technology

6.3.1 Definition

The end effector of the industrial robot is in the process of operation. Through the use of force control technology, always maintain a constant output force/torque.

6.3.2 Application

6.5 Collision protection technology

6.5.4.2 Application condition requirements in the case of independent robot operation

The application condition requirements for the independent operation of the robot are as follows:

a) it shall have collision detection and emergency braking functions;

b) a smooth contact surface shall be used instead of sharp edges and corners;

c) fences shall be set outside the working range of the robot.

7.1 General rule

The force control application is designed to select the corresponding force control strategy according to the operation requirements of different fields, carry out the analysis and design of the force control application technology, meet its requirements and realize the system function.

7.2 Design principle

The force control application design method shall take safety as the primary design principle. The force control application technology selection and design shall be carried out in a targeted manner.

7.3 Design steps

The design method of force control application is shown in Figure 1. The description shall include the following:

a) Determine the application (field) of industrial robot products;

b) Determine the working conditions of the robot based on whether there is physical contact with person;

c) Determine the necessity of force control application;

d) Choose the right force control application technology. Determine application condition requirements (see Clause 6);

e) Choose the force control strategy to achieve its application (see 4.2), and […]