Production Machine Axis Control With Force-Limited Manual Movement
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Solution Overview
Problem
In manual operation of production machines, operators often face challenges in preventing collisions and subsequent damage due to unclear movement paths and limited collision detection capabilities, leading to a high risk of operating errors and equipment damage.
Innovation Solution
A control method that monitors drive adherence to a maximum value, limits contact force by determining velocity and force setpoint values, and reverses movement direction when a force limit is reached, allowing for quick response to obstacles and safe retraction of elements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If manual operation is used to allow operator flexibility and setup, then ease of operation is improved, but the risk of collision and equipment damage increases
Solution Approach 1:
The control device determines control commands such that a contact force is limited to a force limit value before actual collision occurs. This preliminary force limitation prevents damage by restricting the maximum contact force that can be exerted during manual operation, allowing operators to move elements freely while maintaining safety margins.
Solution Approach 2:
The system continuously monitors the contact force between machine elements and provides real-time feedback by adjusting control commands to maintain force within specified limits. This closed-loop control allows manual operation with enhanced safety, as the control device automatically responds to force conditions to prevent collisions and damage.
2Reliability
If force limitation is implemented to prevent damage, then equipment safety is improved, but the complexity of the control system increases
Solution Approach 1:
The control device performs multiple functions using existing control infrastructure: it generates position setpoint values, determines control commands for drives, and limits contact force all through the same control device. This multi-functionality approach implements force limitation without requiring separate dedicated safety systems, thereby managing complexity while enhancing equipment safety.
Data Source
AI summary
A control device of a production machine receives a present path and a movement command from an operator during manual operation of the production machine. An element of the production machine should be moved along the present path by means of position-controlled axes. Based on the movement command, a series of position setpoint values having a setpoint velocity is determined for the axes. The control device determines from the position setpoint values and corresponding position actual values control commands for the drives driving the axes and controls the drives accordingly. The determined control commands limit a contact force (F), which the at least one element exerts on its environment, to a force limit value (F0) specified to the control device. The control device monitors a following error of the drives and suppresses further movement of the element when the following error reaches a maximum value.