Robotic Footstep Timing Using Capture Point Thresholds
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Solution Overview
Problem
Existing robotic systems lack efficient mechanisms for determining the timing of footsteps, leading to inefficient operation and instability, especially in the presence of disturbances.
Innovation Solution
Robotic systems determine mechanically-timed footsteps by calculating a capture point based on the center of mass and velocity, adjusting the timing of foot contact using a threshold position to maintain balance and correct for disturbances.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional timing mechanisms are used for footsteps, then the control system is simpler, but the robot exhibits instability and inefficiency in operation
Solution Approach 1:
The patent implements feedback by continuously monitoring the robot's center of mass position and velocity, then using this information to dynamically adjust footstep timing. The capture point calculation provides real-time feedback about the robot's dynamic state, allowing the control system to adapt footsteps to maintain stability during operation.
Solution Approach 2:
The robot determines its own footstep timing autonomously based on its current dynamic state. The system uses self-generated data from sensors about center of mass position and velocity to automatically adjust the capture point and subsequent footstep timing without external intervention, enabling the robot to self-correct for disturbances.
2Adaptability or versatility
If fixed footstep timing is used, then the control algorithm is simpler, but the robot cannot adapt to environmental disturbances
Solution Approach 1:
The patent transitions from static, pre-programmed footstep timing to dynamic timing that adapts in real-time. The capture point is continuously recalculated based on the robot's current center of mass position and velocity, allowing the footstep timing to dynamically adjust to environmental disturbances and changing operational conditions.
Solution Approach 2:
The system changes the timing parameters of footsteps based on real-time measurements of center of mass position and velocity. By modifying the capture point coordinates dynamically, the system adjusts footstep timing parameters to maintain stability under varying conditions, transforming fixed parameters into adaptive variables.
3Productivity
If mechanically-timed footsteps based on center of mass are implemented, then operational efficiency improves, but the measurement and calculation requirements increase
Solution Approach 1:
The patent replaces traditional mechanical timing mechanisms with a computational approach. Instead of using mechanical clocks or timers to determine footstep timing, the system uses mathematical calculations based on center of mass position and velocity to determine the capture point, substituting mechanical timing with intelligent computation.
Data Source
AI summary
An example implementation for determining mechanically-timed footsteps may involve a robot having a first foot in contact with a ground surface and a second foot not in contact with the ground surface. The robot may determine a position of its center of mass and center of mass velocity, and based on these, determine a capture point for the robot. The robot may also determine a threshold position for the capture point, where the threshold position is based on a target trajectory for the capture point after the second foot contacts the ground surface. The robot may determine that the capture point has reached this threshold position and based on this determination, and cause the second foot to contact the ground surface.