Safety Device Asymmetric Signal Processing for Rotating Machinery
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Solution Overview
Problem
Existing safety devices for machines with rotating parts often rely on redundant signal processing branches that are identical, leading to potential errors and increased complexity, compromising safety and assembly efficiency.
Innovation Solution
A safety device utilizing two independent signal processing branches, one hardware-based and one software-based, to evaluate a rotary encoder's signals, providing increased redundancy without the need for two separate transmitters, and incorporating a phase shift evaluation for fault detection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If two identical signal processing branches are used for redundancy, then safety is improved, but device complexity and susceptibility to identical errors increase
Solution Approach 1:
The patent applies asymmetry by using two different signal processing principles (hardware-based and software-based) instead of identical branches. This asymmetric approach ensures that errors affecting one branch type are less likely to affect the other, providing genuine redundancy while avoiding the complexity of perfectly matching two identical systems.
Solution Approach 2:
The patent substitutes hardware-based signal processing with software-based signal processing in one branch, and vice versa. This replacement strategy allows the system to maintain redundancy while reducing mechanical/physical complexity, as software can be more easily modified and tested than hardware circuits.
2Reliability
If two separate rotary encoders are used for redundancy, then safety is improved, but assembly and adjustment effort increase
Solution Approach 1:
The patent merges the function of two separate rotary encoders into a single encoder by using two different evaluation methods (hardware and software processing) on the signals from one encoder. This consolidation maintains safety redundancy while significantly reducing assembly complexity, as only one encoder needs to be physically installed and adjusted.
Solution Approach 2:
The single rotary encoder is made multi-functional by having its signals processed through two different pathways (hardware-based and software-based signal processing). This universal approach allows one encoder to serve the dual purpose of providing redundant safety signals without requiring two separate encoder installations.
3Speed
If hardware-based signal processing is used, then response speed is improved, but susceptibility to hardware faults increases
Solution Approach 1:
The patent changes the parameter of signal processing methodology by using both hardware-based and software-based processing. This parameter diversification ensures that the advantages of hardware (speed) are complemented by the advantages of software (flexibility and fault tolerance), creating a balanced system that mitigates the weaknesses of each approach.
Data Source
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AI summary
The safety device (1) has a safety circuit (2) that uncovers a guard control (5) for opening a cover of the machine as soon as the rotating speed of a rotating part of the machine stands or fall below a threshold rotating speed. The safety circuit has a hardware-based signal processing branch (31) and a software-based signal processing branch (32) for evaluating a rotary encoder (36). The safety circuit uncovers the guard control when both signal processing branches register a still stand or falling below of the threshold rotation speed. An independent claim is included for a cutting machine with a cutter for cutting strand-like foods.