Production Machine Manual Motion Control With Contact Force Limiting
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Solution Overview
Problem
Existing production machines face challenges in avoiding damage during manual operation due to collisions, as conventional methods like historical path retracing or collision analysis are inadequate, especially when elements have already warped or are difficult to see, leading to high risks of operator error.
Innovation Solution
A control method that monitors drive following errors and limits contact force by using position and force controllers to ensure compliance with predefined limits, including haptic and visual feedback to the operator, allowing for safe manual operation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If the operator manually maneuvers the production machine, then the machine can be positioned and operated flexibly, but the risk of collision and damage increases due to operator error or difficult visibility
Solution Approach 1:
The control unit continuously monitors the contact force between machine elements and provides real-time feedback by limiting the control commands to keep contact force below a specified threshold. This automatic feedback mechanism protects against collisions while maintaining manual operation flexibility.
Solution Approach 2:
The control unit acts as an intermediary between the operator's manual commands and the drive system. It processes the operator's position commands and introduces force limitation as an intermediate control layer, preventing excessive contact forces while preserving the operator's intent.
2Reliability
If collision analysis using a virtual machine model is performed, then collision detection capability is improved, but the device complexity and computing power requirements increase
Solution Approach 1:
The invention extracts the essential collision protection function from complex virtual modeling and implements it directly in the control unit through force limitation of control commands. This simplifies the system by removing the need for separate virtual machine models while maintaining collision detection capability.
Solution Approach 2:
The invention replaces complex computational collision analysis with a simpler force-based control approach. Instead of using virtual models to predict collisions, the system directly limits contact forces through modified control commands, substituting computational complexity with direct force control.
3Reliability
If historical path retracing is used for collision recovery, then the machine can return to the starting point, but this approach fails when elements have already warped or bent
Solution Approach 1:
The system performs preliminary protection by limiting contact forces before damage occurs. By continuously monitoring and limiting control commands to maintain contact force below the threshold, the invention prevents element warping or bending in the first place, making recovery unnecessary.
Solution Approach 2:
The force limitation acts as a cushioning mechanism that prevents excessive contact forces from damaging elements. By maintaining contact force below the specified threshold, the system provides beforehand protection against the types of damage that would make historical path retracing ineffective.
Data Source
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AI summary
The invention relates to a control device (3) of a production machine which receives a present path (B) and a movement command (C1) from an operator (6) via an input device (7) during manual operation of the production machine. At least one element (2) of the production machine should be moved along the present path (B) in a movement direction by means of position-controlled axes (1). The control device (3) determines a series of position setpoint values (x*) for the axes (1) on the basis of the movement command (C1). The position setpoint values (x*) advance with a setpoint velocity (v*) in the movement direction along the present path (B). The control device (3) determines, on the basis of the position setpoint values (x*) and corresponding position actual values (x), control commands (C2) for the drives (12) driving the axes (1) and controls the drives (12) accordingly. The control device (3) determines the control commands (C2) in such a way that a contact force (F), with which the at least one element (2) acts on its environment, is limited to a force limit value (F0) specified to the control device (3). The control device (3) monitors a following error (δx) of the drives (12) for adherence to a predefined maximum value (MAX) and suppresses further movement of the at least one element (2) of the production machine if the maximum value (MAX) is reached.