Robotic Arm Inertial Sensor Failure Detection
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Solution Overview
Problem
Existing robotic devices with multijoint structures face challenges in accurately controlling arm movement due to inertial forces, leading to vibration and potential sensor failure detection issues, as previous methods rely on pre-set threshold values that may not account for varying operation states, resulting in inaccurate failure determination.
Innovation Solution
A robotic device configuration that compares sensor detection data in real-time operation to determine inertial sensor failure by calculating and comparing angular velocities and accelerations, using dynamic threshold values based on actual operation data, ensuring reliable failure detection across various operation modes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Force
If the arm weight is reduced to decrease inertial force, then the actuator load is reduced, but the arm rigidity deteriorates and vibration increases
Solution Approach 1:
The patent applies counterweight mechanism by adding a counterweight portion to the robotic arm structure. This counterweight compensates for the inertial force generated during arm movement, allowing the arm to be designed with lighter weight while maintaining dynamic balance. The counterweight is positioned and sized to create opposing gravitational and inertial forces that cancel out the arm's inertial effects during operation.
Solution Approach 2:
The patent changes the physical parameters of the arm structure, specifically the moment of inertia, by incorporating the counterweight. This parameter change allows the arm to achieve optimal dynamic characteristics where the reduced weight decreases inertial force while the counterweight compensation prevents excessive vibration and maintains control stability.
2Device complexity
If a pre-set threshold value is used for sensor failure detection, then the detection method is simple, but accurate failure determination cannot be performed across varying operation states
Solution Approach 1:
The patent transitions from a static threshold value to a dynamic threshold mechanism. The threshold is no longer fixed but is calculated in real-time based on current operation parameters such as arm position, velocity, acceleration, and payload. This dynamic threshold adapts to varying operation states, enabling accurate sensor failure detection across different working conditions while maintaining reasonable system complexity.
Solution Approach 2:
The patent implements feedback-based threshold adjustment where the expected sensor values are continuously calculated based on the robotic arm's actual operation state and fed back to determine the threshold. This feedback mechanism allows the system to distinguish between normal operational variations and actual sensor failures by comparing sensor readings against dynamically updated expected values.
Data Source
AI summary
A robotic device having an arm including an actuator and inertial sensor, a first calculator adapted to calculate an angular velocity and an angular acceleration of the actuator based on a rotational angle data from an angle sensor, a second calculator adapted to calculate one of an angular velocity and an angular acceleration of the arm based on an output detected by the inertial sensor, and a comparator adapted to compare one of the angular velocity and the angular acceleration calculated by the first calculator and one of the angular velocity and the angular acceleration calculated by the second calculator with each other, and it is determined that the inertial sensor is at fault if an absolute value of the difference between the actuator and the arm in one of the angular velocity and the angular acceleration in the comparison section is larger than a threshold value.