Biped Robot Walking Control for Stable Double-Stance Propulsion
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Solution Overview
Problem
Bipedal walking robots face instability due to insufficient driving force during double stance, where both legs are in contact with the ground simultaneously, leading to complex walking control and reduced efficiency.
Innovation Solution
A walking control system and method that adjusts torque in the drive device to virtually move the foot ends of both lower limbs by a predetermined stable distance in the opposite direction to the walking direction, generating driving force during double stance, allowing the link device to be propelled forward, even when both legs are fixed on the ground.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If conventional walking control is used without double stance strategy, then the control is simpler, but the driving force is insufficient during double stance
Solution Approach 1:
The patent applies preliminary action by pre-planning and executing foot placement strategies before the double stance phase occurs. The controller calculates optimal foot placement positions in advance and adjusts torques during the transition to single stance, ensuring that the robot is properly positioned to generate sufficient driving force when both feet are on the ground, rather than reacting insufficiently during the double stance itself.
2Productivity
If torque is adjusted to generate driving force during double stance, then walking efficiency is improved, but the control complexity increases
Solution Approach 1:
The patent implements dynamics by continuously adjusting torque commands based on the robot's current state and predicted future states. The controller dynamically modifies torque profiles during the walking cycle, particularly during the transition to and from double stance, allowing the system to adapt to varying terrain and maintain walking efficiency without requiring a completely rigid control structure.
Solution Approach 2:
The patent employs feedback mechanisms where the controller continuously monitors the robot's actual position, velocity, and joint states, then compares these against the desired trajectory. Based on this feedback, the controller adjusts torque commands in real-time to maintain accurate foot placement and generate appropriate driving force during double stance, reducing the need for overly complex open-loop control strategies.
3Ease of operation
If both legs are moved alternately without double stance control, then the walking pattern is simpler, but the stability is reduced
Solution Approach 1:
The patent applies preliminary action by pre-calculating optimal foot placement positions and timing before the double stance phase. The controller plans the swing leg trajectory and stance leg positioning in advance, ensuring that when both feet contact the ground simultaneously, the robot achieves a stable configuration with proper weight distribution, rather than reacting to instability after it occurs.
4Force
If foot ends are virtually moved in opposite direction during double stance, then driving force is generated, but the mechanical stress on links increases
Solution Approach 1:
The patent applies parameter changes by dynamically adjusting torque magnitudes and distribution across different joints based on the walking phase and terrain conditions. During double stance, the controller modulates torque parameters to generate necessary driving force while avoiding excessive stress concentrations, and adjusts foot placement distance parameters to optimize the trade-off between propulsion and mechanical loading on the link structure.
Data Source
AI summary
A walking control method of a robot is provided. The method includes receiving a walking command of the robot including a link device having a plurality of links that correspond to both lower limbs. In response to receiving the walking command, implementing walking of the robot by providing torque to the link device to move a first lower limb is moved. In a double stance state where foot ends of the both lower limbs are simultaneously in contact with ground while the lower limb to be moved is changed, a driving force is generated in the double stance by adjusted the torque of the drive device to virtually move the foot ends of the both lower limbs by a predetermined stable distance in an opposite direction to a walking direction.