Legged Robot Foot Trajectory Planning for Impact-Aware Ground Contact
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing legged robot technologies face issues with limited passive flexible buffering, complex hardware structure, and inaccurate control algorithms that lead to premature or delayed ground contact, causing excessive impact forces and accelerated hardware aging.
Innovation Solution
A planning and control method that utilizes a foot-end dynamic model and discrete collision model to optimize swing leg trajectories, ensuring early and delayed collisions are within target constraints, using a foot-end dynamic model and whole-body dynamic model for impact-aware control.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a foot pad with flexibility or buffer device is mounted to provide passive mechanical impedance, then the buffering effect is improved, but the device complexity and weight increase
Solution Approach 1:
The patent replaces passive mechanical buffering systems (foot pads, spring-damper devices, VIA, VSA) with an active control algorithm that plans contact velocity to approach zero. This substitution eliminates the need for complex mechanical impedance adjustment mechanisms while achieving the desired buffering effect through computational control.
Solution Approach 2:
The patent extracts the buffering function from the mechanical hardware level and relocates it to the control algorithm level. By planning the contact velocity to approach zero, the system achieves buffering without requiring physical buffer devices, thereby simplifying the hardware structure.
2Adaptability or versatility
If VIA or VSA is adopted to provide variable passive mechanical impedance, then the buffering effect is adjustable, but the overall structure becomes overly complex with large volume and weight
Solution Approach 1:
The patent replaces variable impedance actuators (VIA/VSA) with a control algorithm that achieves adjustable buffering by planning contact velocity to approach zero. This eliminates the need for heavy mechanical impedance adjustment mechanisms while maintaining adaptability through computational control.
Solution Approach 2:
The patent extracts the variable impedance function from the actuator hardware and relocates it to the trajectory planning algorithm. By controlling the contact velocity to approach zero, the system achieves variable buffering effects without the weight and complexity of VIA/VSA actuators.
3Speed
If the legged robot performs highly dynamic movement with traditional control algorithms, then the movement speed is improved, but the actual trajectory deviates from planned trajectory causing premature or delayed ground contact
Solution Approach 1:
The patent applies preliminary action by planning the contact velocity to approach zero before ground contact occurs. This advance planning ensures that even during highly dynamic movements, the foot sole contacts the ground with minimal velocity, preventing premature or delayed contact and reducing impact forces.
Solution Approach 2:
The patent uses feedback by continuously monitoring the movement state and adjusting the trajectory planning to ensure contact velocity approaches zero. This feedback mechanism maintains trajectory precision during high-speed dynamic movements, preventing deviations that would cause premature or delayed ground contact.
4Object-affected harmful factors
If contact velocity is planned to approach zero in traditional control algorithms, then the impact force is reduced, but the computational load increases and precision remains insufficient
Solution Approach 1:
The patent applies preliminary action by pre-planning the contact velocity to approach zero in the trajectory optimization. This approach reduces impact forces while maintaining computational efficiency, as the zero-contact-velocity constraint is integrated into the trajectory planning stage rather than requiring complex real-time computations.
Data Source
AI summary
Provided are a planning and control method for a legged robot, an apparatus, a robot, and a storage medium. The method includes: determining, based on the movement state and the swing parameter of each leg at the next moment, a foot-end reference state of each leg, and planning, based on a foot-end dynamic model and a discrete collision model, an impact-aware swing leg trajectory for a leg that starts to swing at the next moment; and performing, based on the movement state, the reference state sequence, and the foot-end reference state, whole-body control on the legged robot, and performing, based on a whole-body dynamic model and the discrete collision model, impact-aware whole-body control for a leg that is a supporting leg in planning but does not touch the ground.