Robot Joint Sensor Cross-Checks for Safe Fault Detection
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Solution Overview
Problem
High-performance robotic systems, such as exoskeletons and unmanned robots, pose safety risks due to component failures or malfunctions, which can lead to unintended operations and potential harm to operators and others in the vicinity, necessitating safe control even after errors occur.
Innovation Solution
A sensor suite discrepancy detection system that utilizes joint position sensors, actuators, and load cells to detect discrepancies in sensor output data, recruiting complementary sensors for safe operation, and executing remedial measures like actuating or shutting down joints to ensure safety.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If high-performance actuators with amplified output torque are used to enhance human capabilities, then productivity and operational capability are improved, but safety risk increases due to potential operator injury or death from unintended operations
Solution Approach 1:
The system performs preliminary safety checks by continuously monitoring sensor data from multiple sources (joint position sensors, actuator sensors, load cells) and comparing transformed sensor output data before executing actuator commands. This preliminary detection of discrepancies prevents unsafe operations from occurring in the first place
Solution Approach 2:
The system implements continuous feedback loops where sensor data is constantly monitored, transformed, and compared against expected values. When discrepancies are detected, the system provides feedback to execute remedial measures such as shutting down actuators or limiting operational capabilities, thereby maintaining safety while allowing high-performance operation under normal conditions
2Measurement precision
If multiple sensors are used to monitor joint position and actuator position, then measurement precision is improved, but device complexity increases due to the need to process and reconcile multiple sensor inputs
Solution Approach 1:
The system employs a universal transformation approach where multiple different sensor types (joint position sensors, actuator position sensors, load cells) are all transformed into a common reference frame using the transmission ratio. This allows diverse sensors to be processed through a unified methodology, reducing complexity while maintaining the precision benefits of multiple measurement sources
Solution Approach 2:
The transmission ratio serves as an intermediary parameter that mediates between different sensor measurements. By transforming all sensor outputs through this common intermediary, the system reconciles measurements from multiple sensors without requiring complex direct comparison logic, thereby simplifying the processing architecture
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
Ensures continued safe operation of robotic systems by detecting and addressing faulty sensor data, allowing for safe mode operation and preventing potential injuries or accidents.
Implementation Method 1
the transmission having a compliance that elastically deforms in proportion to an applied load
Data Source
AI summary
A robot or robotic system comprising a plurality of support structures, and a plurality of joint mechanisms each joint mechanism rotatably coupling at least two of the plurality of support structures. A sensor discrepancy detection system can be operable to interrogate a suite of sensors within the robotic system, and can comprise a plurality of sensor groups, each associated with a respective joint mechanism, and each comprising a plurality of sensors from the suite of sensors. A controller can execute a remedial measure associated with a safety/remedial mode of the robotic system based on an identified discrepancy between the sensor output data of the load cell compared to transformed sensor output data from the joint position sensor and the actuator position sensor, accounting for the transmission ratio, related to a difference in position and representing a transmission deflection, and correlated to a corresponding force associated with the difference in position.