Robot Footstep Contact Detection Using Joint Dynamics and Odometry
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Solution Overview
Problem
Robots face challenges in accurately detecting footstep contact with the ground surface during movement, leading to potential destabilization and disruption of balance due to late detection of touchdown or unexpected impacts.
Innovation Solution
A method and system for footstep contact detection in robots using joint dynamics and odometry to determine unexpected torques on swing legs, classifying impacts as touchdowns or trips, and generating appropriate responses to maintain stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the robot uses traditional odometry and joint dynamics to detect footstep contact, then the detection accuracy is limited, but the computational complexity and processing time increase
Solution Approach 1:
The patent segments the footstep contact detection process into distinct phases: swing phase and stance phase. During the swing phase, the system monitors for unexpected torques that indicate potential contact. During the stance phase, the system confirms touchdown based on odometry and joint dynamics. This segmentation allows the system to apply different detection strategies for different phases, improving accuracy while managing computational complexity.
Solution Approach 2:
The patent implements preliminary action by predicting the expected torque profile during the swing phase before actual contact occurs. The system calculates anticipated joint dynamics and odometry changes, then compares actual measurements against these predictions. This preliminary modeling enables the system to detect deviations that indicate footstep contact, improving detection accuracy without requiring complex real-time analysis during the actual contact event.
2Loss of time
If the robot detects footstep contact later, then the processing time is reduced, but the robot stability and balance are disrupted
Solution Approach 1:
The patent implements continuous feedback by monitoring joint dynamics and odometry throughout the gait cycle. The system constantly compares actual measurements against predicted values and immediately detects deviations that indicate footstep contact. This real-time feedback mechanism enables the robot to detect contact events without time delay and respond promptly to maintain stability and balance during locomotion.
Solution Approach 2:
The patent employs dynamic detection by continuously updating the expected torque profile and joint dynamics model as the robot moves through its gait cycle. The system adapts its detection thresholds and prediction models based on the current phase of locomotion, allowing it to detect contact events in real-time while accounting for the dynamic nature of robot movement. This dynamic approach ensures timely detection without compromising stability.
3Measurement precision
If the robot uses unexpected torque analysis to detect impacts, then the detection sensitivity increases, but the false positive rate increases
Solution Approach 1:
The patent changes detection parameters dynamically based on the gait phase. During the swing phase, the system uses unexpected torque analysis with specific thresholds calibrated for that phase. During the stance phase, different parameters and thresholds are applied. The system also adjusts detection sensitivity based on the predicted joint dynamics and odometry for the current moment in the gait cycle. These parameter changes allow high sensitivity for detecting actual contacts while reducing false positives by adapting to the expected mechanical behavior at each phase.
Data Source
AI summary
A method of footstep contact detection includes receiving joint dynamics data for a swing phase of a swing leg of the robot, receiving odometry data indicative of a pose of the robot, determining whether an impact on the swing leg is indicative of a touchdown of the swing leg based on the joint dynamics data and an amount of completion of the swing phase, and determining when the impact on the swing leg is not indicative of the touchdown of the swing leg, a cause of the impact based on the joint dynamics data and the odometry data.