Legged Robot Slip Detection Through Foot Distance Monitoring
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Solution Overview
Problem
Existing robotic systems face challenges in efficiently navigating rough or uneven terrain, particularly in maintaining balance and preventing slips of their feet, which can disrupt their gait and operation.
Innovation Solution
The implementation involves a legged robot using sensors to detect ground reaction forces, monitor foot distances, and adjust actuation and position to control these forces within a threshold friction cone, thereby preventing slips and correcting gait disturbances.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the robot uses sensors to detect ground reaction forces and monitor foot distances to maintain balance on rough terrain, then the robot's stability and ability to prevent slips is improved, but the device complexity increases due to additional sensors and control mechanisms
Solution Approach 1:
The robot employs sensors to continuously monitor ground reaction forces and foot distances, creating a feedback loop that allows the control system to detect slips and adjust actuation in real-time. This feedback mechanism enables the robot to maintain stability on rough terrain by comparing expected versus actual sensor data and making corrective adjustments to foot positioning and body posture.
Solution Approach 2:
The patent replaces purely mechanical balance-maintenance systems with a sensor-based detection and control system. Instead of relying solely on mechanical design features for stability, the system uses electronic sensors to detect ground reaction forces and foot positions, then uses control algorithms to adjust actuation, substituting mechanical passivity with active electronic control.
2Reliability
If the robot adjusts actuation and position to control ground reaction forces within a threshold friction cone, then the robot's ability to prevent slips is improved, but the ease of operation decreases due to complex real-time adjustments
Solution Approach 1:
The system dynamically changes operational parameters including actuation commands, foot position, and body posture based on real-time sensor feedback. The control system adjusts these parameters to keep ground reaction forces within the friction cone, preventing slips. This involves continuous modification of multiple parameters coordinated through the control system.
Solution Approach 2:
The robot performs preliminary adjustments to foot position and actuation before slips occur by continuously monitoring sensor data and predicting potential loss of traction. The system proactively modifies gait patterns and foot placement to prevent slip conditions rather than reacting after slips occur.
3Measurement precision
If the robot monitors foot distances and compares differences to threshold values to detect slips, then the measurement precision of slip detection is improved, but the loss of time increases due to continuous monitoring and comparison operations
Solution Approach 1:
The system uses threshold-based comparison to quickly identify slip conditions without performing complex analysis on every sensor reading. When sensor data exceeds predefined thresholds indicating potential slips, the system immediately triggers corrective action, skipping detailed analysis for normal conditions and focusing computational resources only on anomaly detection.
Data Source
AI summary
An example method may include i) determining a first distance between a pair of feet of a robot at a first time, where the pair of feet is in contact with a ground surface; ii) determining a second distance between the pair of feet of the robot at a second time, where the pair of feet remains in contact with the ground surface from the first time to the second time; iii) comparing a difference between the determined first and second distances to a threshold difference; iv) determining that the difference between determined first and second distances exceeds the threshold difference; and v) based on the determination that the difference between the determined first and second distances exceeds the threshold difference, causing the robot to react.