Robot Emergency Stop Simulation for Virtual Boundary Calibration

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Solution Overview

Problem

Current simulation tools tend to underestimate the braking distance of robots during emergency stops, particularly when safety equipment is integrated, leading to potential contact with barriers, and existing methods fail to accurately determine the necessary virtual boundary distance to prevent such contact without overly restricting the robot's movement.

Innovation Solution

A method that uses a simulation system to calibrate the virtual boundary distance by comparing simulated and actual emergency stop positions, adjusting the distance iteratively to ensure the robot can safely stop before reaching barriers, utilizing a motion simulator and virtual sensors to mimic the robot's movement and deceleration process.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If the virtual boundary distance is increased to ensure safe stopping, then safety is improved, but the robot's freedom of movement is reduced

Engineering Contradiction:
ImprovesafetyVSAvoidfreedom of movement
Core Design Contradiction:
ReliabilityVSEase of operation

Solution Approach 1:

The virtual boundary distance is made dynamic rather than static. The simulation determines the minimum distance required for safe stopping under different operating conditions (robot configuration, speed, payload), allowing the boundary to adapt to current robot state. This resolves the contradiction by providing safety margins only when and where needed, rather than imposing a uniform restriction on all movements.

Inventive Principle:
Principle #15Dynamics

Solution Approach 2:

The invention changes the parameter of virtual boundary distance from a fixed value to a variable determined by simulation. By calculating the actual stopping distance based on robot mass, velocity, friction coefficients, and configuration, the boundary distance parameter is optimized to be exactly sufficient for safety without excessive margin, thus maintaining freedom of movement while ensuring safety.

Inventive Principle:
Principle #35Parameter changes

2Device complexity

If conventional simulation tools are used to determine stopping distance, then computational simplicity is maintained, but accuracy of stopping distance prediction deteriorates

Engineering Contradiction:
Improvesimulation complexityVSAvoidstopping distance accuracy
Core Design Contradiction:
Device complexityVSMeasurement precision

Solution Approach 1:

The simulation incorporates feedback loops that iteratively adjust the virtual boundary distance based on calculated stopping distances. The system simulates robot deceleration, measures the actual stopping point, and uses this feedback to refine the boundary distance parameter. This feedback mechanism improves accuracy without requiring excessively complex simulation models, as it focuses computational effort on the critical stopping phase.

Inventive Principle:
Principle #23Feedback

Solution Approach 2:

The invention performs preliminary simulation calculations to determine the minimum safe boundary distance before actual robot operation begins. By pre-calculating stopping distances under various conditions and storing these results, the system achieves high accuracy without requiring complex real-time simulations during operation, thus balancing accuracy with computational efficiency.

Inventive Principle:
Principle #10Preliminary action

Data Source

PatentEP3437805B1Robot stopping distance simulating method
Publication Date: 2023.07.19 ABB (SCHWEIZ) AG
  • EP3437805B1 patent drawingFigure 1~4

AI summary

A robot (1) operates in an environment which is divided by a virtual boundary (16) into a roaming region (19) in which the robot is free to move and a braking region (20), and which comprises means (15, 18) for monitoring the virtual boundary (16) and triggering an emergency stop procedure of the robot (1) when the robot (1) passes the boundary from the roaming region (19) to the braking region (20). A method of simulating an emergency stop of the robot (1) comprises the steps of: a) determining (S14) an instant when the robot (1) passes the boundary (16), c) determining (S17) an initial posture and speeds of the robot (1) at the beginning of the emergency stop procedure, d) calculating (S17), based on said initial posture and speeds and an estimated deceleration, a final posture at which the robot (1) comes to a stop, characterized by the step of b) allowing (S16) a predetermined waiting time to pass between steps a) and c).