Manual Control Unit Disconnection Safety for Multi-Axis Robots

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Solution Overview

Problem

Existing methods for disconnecting a manual control unit from a multi-axis robot often trigger an emergency stop, failing to meet safety constraints and differentiate between device errors and the presence or absence of the manual control unit.

Innovation Solution

A method that uses redundant signals to detect the presence of the manual control unit with high safety levels, allowing disconnection without triggering an emergency stop, and differentiating between communication errors and the absence of the unit by monitoring specific wiring circuit states.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of operation

If the manual control box is disconnected without a specific device, then the disconnection process is simple, but an emergency stop is automatically triggered

Engineering Contradiction:

Improveease of disconnectionVSAvoidemergency stop activation

Core Design Contradiction:

Ease of operationVSObject-affected harmful factors

Solution Approach 1:

The system performs preliminary actions by detecting the disconnection request before actual disconnection occurs. The control unit identifies when the manual control box is being disconnected and preemptively prevents the emergency stop signal from being triggered, allowing smooth disconnection without harmful effects.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The control unit acts as an intermediary between the manual control box and the emergency stop system. It receives signals from the manual control box and intermediates the disconnection process, distinguishing between intentional disconnection and actual emergency conditions, thereby preventing false emergency stop activation.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Reliability

If the emergency stop button and deadman switch are wired on two independent electrical lines for safety, then safety reliability is improved, but the system cannot differentiate between a plug and the manual control box

Engineering Contradiction:

Improvesafety reliabilityVSAvoidability to differentiate device presence

Core Design Contradiction:

ReliabilityVSLoss of information

Solution Approach 1:

The electrical connection is segmented into multiple distinct signals: at least one first signal for the emergency stop button and at least one second signal for device identification. This segmentation allows the control unit to simultaneously monitor safety circuits and identify whether the connected device is a manual control box or just a plug.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

Different electrical lines are assigned different functions with distinct signal characteristics. The first electrical line carries emergency stop signals while the second electrical line carries identification signals. This local differentiation of signal qualities enables the control unit to distinguish between a plug and the manual control box while maintaining safety reliability.

Inventive Principle:

Principle #3Local quality

3Reliability

If a connection/disconnection switch is added to prevent emergency stop during disconnection, then disconnection safety is improved, but the device complexity increases

Engineering Contradiction:

Improvedisconnection safetyVSAvoidnumber of switches and circuits

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The control unit is designed with multi-functionality, serving both as the central control system and as the disconnection safety mechanism. It integrates the functions of detecting disconnection requests, identifying device presence, and preventing false emergency stop activation, eliminating the need for separate dedicated switches or circuits.

Inventive Principle:

Principle #6Universality (Multi-functionality)

Solution Approach 2:

The control unit performs self-service by automatically detecting when the manual control box is disconnected and autonomously preventing the emergency stop signal from being triggered. The system monitors its own state and adjusts its response accordingly, eliminating the need for external connection/disconnection switches.

Inventive Principle:

Principle #25Self-service

Data Source

PatentEP3023850B1Process for deconnecting a manual control unit of a multiaxis robot and robot for the implementation of such a process

Publication Date: 2018.02.28 STAUBLI FAVERGES SA

Figure 1
Figure 2~3

AI summary

This method relates to disconnecting a manual control box (10) from a multi-axis robot (R), comprising a cable (1) for connecting the box (10) to a controller (C). The cable (1) has an input electrical line and an output electrical line for each of two electrical wiring circuits for an emergency stop button (10A), and an input electrical line and an output electrical line for each of two wiring circuits for a deadman's switch (10B).The method includes successive steps in which: - a) an operator makes a request to disconnect the box (10), - b) for a predetermined time, the safety controller (5) does not trigger an emergency stop based on the control of the electrical wiring circuits, - c) at the end of the predetermined time, the safety controller (5) does not trigger an emergency stop if and only if, on the one hand, only one of the two wiring circuits of the emergency stop button (10A) is open and, on the other hand, only one of the two wiring circuits of the dead man's contactor (10B) is open.