Industrial Robot Hybrid Position-Force Control for Stable Manual Guidance

Solution Overview

Problem

Existing industrial robot control systems fail to achieve satisfactory rigidity, transparency, and stability when partially guided manually, often resulting in bounces when contacting rigid environmental elements.

Innovation Solution

A control process for industrial robots involving a multi-axis robot arm with electric actuators and sensors, a robot control system with axis controller modules, and a calculation module that calculates composite setpoints, behavior matrices, and articular force setpoints using proportional-integral-derivative controllers to adjust differences between articular positions and internal states.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of operation

If the robot control system uses conventional control methods to achieve rigidity and transparency during manual guidance, then the robot responds well to operator input, but stability deteriorates causing bounces when contacting rigid environmental elements

Engineering Contradiction:

ImprovetransparencyVSAvoidstability

Core Design Contradiction:

Ease of operationVSStability of the object's composition

Solution Approach 1:

The control system dynamically adjusts the damping coefficient based on the robot's operational state and environmental conditions. During manual guidance, the system transitions between different damping levels to maintain both transparency and stability, allowing the robot to be easily moved during normal operation while providing strong damping to prevent bounces when contacting rigid elements.

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The invention changes the damping parameter of the impedance control system adaptively. By modifying the damping coefficient in real-time based on detected contact conditions and operational mode, the system achieves both transparency during manual guidance and stability during contact with environmental elements, resolving the contradiction between these two requirements.

Inventive Principle:

Principle #35Parameter changes

2Stability of the object's composition

If the robot control system increases damping to improve stability, then bounces are reduced when contacting rigid elements, but transparency deteriorates making the robot harder to move during manual guidance

Engineering Contradiction:

ImprovestabilityVSAvoidtransparency

Core Design Contradiction:

Stability of the object's compositionVSEase of operation

Solution Approach 1:

The control system dynamically adjusts the damping coefficient based on the robot's operational state and environmental conditions. During manual guidance, the system transitions between different damping levels to maintain both transparency and stability, allowing the robot to be easily moved during normal operation while providing strong damping to prevent bounces when contacting rigid elements.

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The invention changes the damping parameter of the impedance control system adaptively. By modifying the damping coefficient in real-time based on detected contact conditions and operational mode, the system achieves both transparency during manual guidance and stability during contact with environmental elements, resolving the contradiction between these two requirements.

Inventive Principle:

Principle #35Parameter changes

3Strength

If the robot control system uses high stiffness to maintain rigidity during manual guidance, then the robot remains stable, but transparency deteriorates reducing the ease of manual manipulation

Engineering Contradiction:

ImproverigidityVSAvoidtransparency

Core Design Contradiction:

StrengthVSEase of operation

Solution Approach 1:

The control system dynamically adjusts the damping coefficient based on the robot's operational state and environmental conditions. During manual guidance, the system transitions between different damping levels to maintain both transparency and stability, allowing the robot to be easily moved during normal operation while providing strong damping to prevent bounces when contacting rigid elements.

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The invention changes the damping parameter of the impedance control system adaptively. By modifying the damping coefficient in real-time based on detected contact conditions and operational mode, the system achieves both transparency during manual guidance and stability during contact with environmental elements, resolving the contradiction between these two requirements.

Inventive Principle:

Principle #35Parameter changes

Data Source

PatentUS12409553B2Systems and hybrid position force control processes of an industrial robot

Publication Date: 2025.09.09 STAUBLI FAVERGES SA

AI summary

The present process of controlling an industrial robot includes steps consisting of calculating a time-dependent composite setpoint defining articular forces and/or velocities, according to a target trajectory and to an operating mode; calculating (S106) a behavior matrix which describes a desired behavior of the robot arm, defining directions along which the calculated composite setpoint is to be applied; calculating (S108) an articular force setpoint for controlling the axis controller module and calculating the time derivative of a homogeneous internal state at an articular position. The articular force setpoint for controlling the axis controller module is calculated from a control function which adjusts the difference between the articular position and the internal state determined by integrating said time derivative of the internal state.