Biped Robot Foot Posture Control for Stable Monoped Balance
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Solution Overview
Problem
Biped robots face instability when switching from biped to monoped support, making it difficult to maintain balance and preventing overturning due to the need for high force control accuracy.
Innovation Solution
The process of switching is divided into two steps: moving the robot's body near the expected support leg while continuously detecting the zero moment point (ZMP), and then lifting the expected suspending leg once the ZMP is stable within the support area, using a new flywheel model to control the posture of the support leg's foot, equivalent to a massless link, to maintain balance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If biped robot uses conventional balance control algorithms during biped supporting period, then balance can be maintained, but during monoped supporting period the robot becomes unstable and prone to overturning
Solution Approach 1:
The patent divides the support period into distinct phases (biped supporting period and monoped supporting period) and applies different control strategies to each phase. During biped support, conventional ZMP control is used, while during monoped support, a foot posture control strategy based on flywheel model is implemented to maintain stability when only one leg contacts the ground.
Solution Approach 2:
The patent changes the control parameters and control object during the transition from biped to monoped support. Instead of controlling ZMP directly, the system controls the posture parameters of the support leg foot (rotation matrix elements) to maintain stability during monoped supporting period, adapting to the changed support conditions.
2Reliability
If high force control accuracy is used to maintain balance during monoped support, then stability can be maintained, but the device complexity and control difficulty increase
Solution Approach 1:
The patent replaces complex force control with a simplified mechanical model-based control approach. By using the flywheel model to describe the robot's dynamics during monoped support and controlling foot posture parameters directly, the system avoids the need for high-precision force control while maintaining stability.
Solution Approach 2:
The patent introduces foot posture parameters (rotation matrix elements) as an intermediary control variable between the control system and the robot's balance. This intermediary allows indirect control of balance through foot orientation rather than direct force control, simplifying the control requirements.
Data Source
AI summary
A robot balance control method as well as a robot using the same and a computer readable storage medium are provided. In the method, a brand new flywheel model different from the existing flywheel model is created. In this flywheel model, the foot of the support leg of the robot is equivalent to the massless link of the flywheel model, while rest parts of the robot are equivalent to the flywheel of the flywheel model. Compared with the various models in the prior art, this flywheel model is more in line with the actual situation of the robot during the monoped supporting period. By controlling the posture of the foot of the support leg based on this flywheel model, a better balance effect can be achieved, which avoids the overturning of the robot.