Dual-loop Torque Sensing for Robotic Arm Safety
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Solution Overview
Problem
Conventional robotic arm torque sensing systems rely on single torque sensors, which cannot detect abnormal operation independently, leading to safety issues and production interruptions, with complex calibration and high costs, and fail to determine which sensor is faulty when an abnormality is detected.
Innovation Solution
A dual-loop torque sensing system using four position sensors coupled to a motor and reduction drive, allowing for the detection of rotational position differences to measure output torque, simplifying installation and enabling continued operation even if one sensing loop fails, with a control device to identify and replace faulty sensors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single torque sensor is used to detect torque in robotic arms, then the structure is simple, but the system cannot detect abnormal operation independently and compromises safety
Solution Approach 1:
The patent divides the torque sensing system into two independent sensing loops: the first loop uses a torque sensor in the motor to detect motor output torque, while the second loop uses a torque sensor in the reduction drive to detect reduction drive output torque. This segmentation allows independent detection and comparison, improving safety without significantly increasing overall system complexity.
Solution Approach 2:
The control device continuously compares torque values from both sensing loops and provides feedback when abnormalities are detected. When the torque values do not match or when a sensor fails, the system generates abnormal operation detection signals, enabling real-time safety monitoring and independent abnormal operation detection.
2Measurement precision
If torque sensors are installed in both motor and reduction drive with strict assembly requirements, then torque detection accuracy is improved, but installation complexity and cost increase
Solution Approach 1:
The patent segments the torque detection function across two different locations (motor and reduction drive), allowing each torque sensor to be installed in its respective optimal position with appropriate calibration procedures for that specific location, thereby maintaining detection accuracy while distributing installation complexity.
Solution Approach 2:
The control device serves multiple functions: it processes torque data from both sensing loops, compares torque values, detects sensor failures, identifies which sensor is faulty, and generates abnormal operation detection signals. This multi-functionality consolidates complex processing tasks into a single device, reducing overall system complexity.
3Reliability
If the robotic arm stops functioning when torque values do not match, then safety is ensured, but production efficiency decreases
Solution Approach 1:
The control device provides continuous feedback by comparing torque values from both sensing loops and generating abnormal operation detection signals only when necessary. This allows the system to maintain operation during normal conditions while ensuring safety through real-time monitoring, balancing safety and production efficiency.
Solution Approach 2:
The dual-loop sensing system performs self-diagnosis by comparing torque values and automatically identifying which sensor is faulty when an abnormality is detected. This self-service capability reduces the need for manual intervention and system shutdowns, maintaining production efficiency while ensuring safety.
4Loss of information
If the robotic arm stops and examines each torque sensor one by one when abnormal torque is sensed, then faulty sensor identification is achieved, but time is lost and production efficiency decreases
Solution Approach 1:
The control device continuously compares torque values from both sensing loops and provides immediate feedback when an abnormality is detected. By analyzing the pattern of torque discrepancies, the system can identify which sensor is faulty in real-time, eliminating the need for manual examination and reducing downtime.
Solution Approach 2:
The system performs preliminary comparison and analysis of torque values from both sensing loops continuously during operation. When an abnormality occurs, the fault identification is already prepared, allowing immediate response without requiring sequential examination of each sensor, thus minimizing downtime.
Data Source
AI summary
A dual-loop torque sensing system includes four position sensors disposed in the motor and the reduction drive to form a dual-loop for detection to calculate the output torques. The detection of the position sensors is for confirming abnormality of the dual-loop or the position sensors. A failure alarm is issued to enhance the safety of the working environment.