Redundant Emergency Brake Circuit for Industrial Robots
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Solution Overview
Problem
Industrial robots lack reliable emergency braking mechanisms to safely stop their electric motors in emergency situations, such as when a person enters the protective device surrounding the robot.
Innovation Solution
The industrial robot employs two independent electrical current paths for emergency braking, utilizing a three-phase motor with a three-phase inverter and intermediate circuit capacitor, where semiconductor switches control half-bridges to short-circuit the motor, and a braking resistor is connected in parallel with the capacitor to ensure reliable braking, even if one path fails.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a single electrical current path is used for emergency braking, then the device complexity is reduced, but the reliability of emergency braking is insufficient
Solution Approach 1:
The braking circuit is segmented into two independent electrical current paths (first and second current paths) that can operate separately or together. Each path has its own switching mechanism and circuit components, allowing one path to function as a backup for the other, thereby improving emergency braking reliability without requiring a completely redundant dual-system architecture.
Solution Approach 2:
The control device is configured to detect potential failures in the first current path before they occur and preliminarily activate the second current path as a backup. This preliminary action ensures that when the first path fails, the second path is already prepared and can immediately take over, maintaining emergency braking reliability without adding complex real-time switching mechanisms.
2Reliability
If redundant braking mechanisms are implemented, then the safety and reliability are improved, but the device complexity increases
Solution Approach 1:
The second current path is designed with multi-functionality, serving both as a normal braking path during operation and as a backup path when the first current path fails. This universal design allows the same circuit components to perform multiple functions, reducing the need for entirely separate redundant systems and thereby limiting the increase in device complexity while maintaining improved reliability.
Solution Approach 2:
The control device acts as an intermediary that monitors the status of both current paths and automatically switches between them based on detected failures. This intermediary component manages the complexity of coordinating multiple braking mechanisms by centralizing the control logic, thereby improving motor control reliability through automated failover without requiring complex manual intervention systems.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This solution ensures the electric motor is safely and reliably braked during emergency situations, providing a redundant braking mechanism that maintains motor control and torque calculation for safety and reliability.
Implementation Method 1
a first Braking resistor and a first switch and the industrial robot is set up in such a way to close the first switch during emergency braking to switch the braking resistor in parallel with the intermediate circuit capacitor
Implementation Method 2
the three-phase inverter having a first half-bridge and a second half-bridge, each of which includes semiconductor switches and has an intermediate circuit connected upstream of the three-phase inverter with an intermediate circuit capacitor
Data Source
Figure 1
Figure 2
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AI summary
The invention relates to an industrial robot having a robotic arm. The robotic arm has several axes (A1-A6) and at least one electric drive, which comprises an electric motor (7-12) and power electronics (16) actuating the electric motor (7-12) and is equipped to move the relevant axis (A1- A6). The industrial robot (1) is equipped to short-circuit the electric motor (7-12) in the event of emergency braking simultaneously by means of two independent electric current paths.