Robot Boundary Control With Haptic Feedback for Safety Limit Testing

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Solution Overview

Problem

Existing robot control methods are difficult and non-intuitive, especially when dealing with complex boundaries defined by curved hypersurfaces, making it challenging to test safety actions effectively, such as stopping the robot when it approaches workspace limits or exceeds speed limits.

Innovation Solution

A method that allows the robot to operate in two modes: the first mode triggers safety reactions when limits are met, while the second mode applies a motor-driven actuating force to return the robot to a safe position, providing haptic feedback and allowing intuitive testing of safety limits without triggering safety reactions.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If safety actions are triggered automatically when limits are met, then robot safety is improved, but the ability to test safety limits intuitively deteriorates

Engineering Contradiction:
Improverobot safetyVSAvoidtesting safety limits
Core Design Contradiction:
ReliabilityVSEase of operation

Solution Approach 1:

The system dynamically switches between two operating modes: a first mode where safety actions are automatically triggered when limits are met, and a second mode where the robot can be manually guided beyond limits for testing purposes. This dynamic switching resolves the contradiction by allowing the system to adapt its safety behavior based on the operational context.

Inventive Principle:
Principle #15Dynamics

Solution Approach 2:

The system changes the parameter of safety reaction triggering based on the selected operating mode. In the first operating mode, safety reactions are triggered automatically when distance conditions are met. In the second operating mode, the triggering parameter is modified to allow manual guidance beyond limits, enabling intuitive testing while maintaining safety monitoring.

Inventive Principle:
Principle #35Parameter changes

2Ease of operation

If manual guidance to test safety limits is implemented, then testing intuitiveness is improved, but safety monitoring reliability deteriorates

Engineering Contradiction:
Improvetesting safety limitsVSAvoidsafety monitoring
Core Design Contradiction:
Ease of operationVSReliability

Solution Approach 1:

The system dynamically adjusts its safety monitoring behavior based on the operating mode. In the second mode designed for testing, the system allows manual guidance beyond limits while still monitoring the distance to boundaries, ensuring that safety data is collected without compromising actual operational safety.

Inventive Principle:
Principle #15Dynamics

Solution Approach 2:

The operating mode selection acts as an intermediary that mediates between safety monitoring and manual testing. When the second mode is selected, it temporarily modifies the safety reaction triggering to allow testing, but the underlying safety monitoring system remains active and can restore automatic triggering when the mode is changed back.

Inventive Principle:
Principle #24Intermediary (Mediator)

3Measurement precision

If complex curved hypersurface boundaries are used, then workspace definition precision is improved, but testing difficulty increases

Engineering Contradiction:
Improveworkspace boundary definitionVSAvoidtesting safety actions
Core Design Contradiction:
Measurement precisionVSDifficulty of detecting and measuring

Solution Approach 1:

The system uses the distance calculation means to automatically calculate the distance from the robot's state variable to the complex curved hypersurface boundaries. This self-service approach eliminates the need for manual testing of complex boundaries, as the system autonomously monitors and detects when limits are met, resolving the testing difficulty while maintaining high precision.

Inventive Principle:
Principle #25Self-service

Applied Scientific Principles

This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.

Function Achieved in This Case

Enables intuitive and reliable safety monitoring and testing of robot limits, allowing operators to experience tactile resistance when approaching boundaries, improving the control and safety of robot operations in complex environments.

Implementation Method 1

a distance-dependent actuating force is applied to the robot by a motor in order to reduce the distance when the robot is unobstructed

Methodology Applied
Scientific EffectHaptic feedback: Mechanical Force

Data Source

PatentEP3974125B1Method and device for controlling a robot
Publication Date: 2024.07.17 KUKA DEUT GMBH
  • EP3974125B1 patent drawingFigure 1~3
  • EP3974125B1 patent drawingFigure 2
  • EP3974125B1 patent drawing

AI summary

According to a method according to the invention, to move a robot by manually applying a guiding force to the robot in an operating mode (M2), a distance (d) of a state variable (x1) of the robot from at least two different predetermined references (yn, yn+1, B) in a state space ({Xi, Xj}) of the robot is determined (S200); the smallest (dmin) of the distances is determined (S210-S270); and a positioning force (f) is applied to the robot by motor (S280) in order to minimize the smallest of the distances when the robot is unobstructed.Additionally or alternatively, to control the robot in at least one pose, optionally in a first operating mode (M1) or a different second operating mode (M2), in the first operating mode a distance (d) of a state variable (x2) of the robot from a first limit (G1, G2) is determined (S40); and a safety reaction (STOP 1) is triggered (S60) if the distance meets a first condition (d > 0); and in the second operating mode in which the robot can be moved by manually applying a guiding force to the robot; the distance of the state variable of the robot from the first limit is determined (S70); the safety reaction is not triggered because the distance meets the first condition; and a positioning force (F) is applied to the robot by a motor as a function of the distance (S110) in order to reduce the distance if the distance meets the first condition when the robot is unobstructed.