Legged Robot Posture Control via Friction Cone Constraint
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Legged robots experience slippage issues when interacting with contact surfaces, affecting their normal movement and stability during posture control, particularly when trying to maintain complex terrains and perform specific tasks like terrain observation.
Innovation Solution
A posture control method that acquires target posture data and determines plantar force information using a friction cone constraint, optimizing the robot's posture adjustment by calculating plantar force and force variation to ensure stable movement, incorporating dynamic modeling and quadratic optimization to minimize force and adjust joint torque effectively.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If conventional posture control methods are used for legged robots, then the robot can adjust its posture to adapt to complex terrains and perform specific tasks, but slippage occurs between the robot and the contact surface, affecting normal movement
Solution Approach 1:
The patent changes the control parameters from simple position control to impedance control with adjustable stiffness and damping coefficients. By dynamically adjusting these parameters based on task requirements and contact conditions, the system achieves both accurate posture adjustment and slippage resistance. The impedance controller modifies the relationship between force and position, allowing the robot to maintain stable contact while adapting posture.
Solution Approach 2:
The patent implements feedback control by continuously monitoring contact forces, joint positions, and slippage indicators. The controller uses this feedback to adjust the impedance parameters in real-time, ensuring that the robot maintains optimal grip on the contact surface while achieving the desired posture. The feedback loop detects slippage tendencies and adjusts control forces to prevent slippage occurrence.
2Loss of information
If the legged robot coordinates degrees of freedom of the legs to control torso posture for comprehensive observation, then the sensor can observe more comprehensive information, but the complexity of control increases
Solution Approach 1:
The patent implements a unified impedance control framework that simultaneously handles multiple tasks: posture adjustment, balance maintenance, and contact force regulation. This multi-functional controller eliminates the need for separate control systems for each degree of freedom, reducing overall control complexity while achieving comprehensive observation capabilities through coordinated leg and torso movements.
Solution Approach 2:
The patent merges the control of multiple degrees of freedom into a single impedance control architecture. Instead of independently controlling each joint and torso position, the system combines all these controls into a unified force-position relationship management, simplifying the control structure while maintaining the ability to coordinate complex movements for comprehensive terrain observation.
3Speed
If the legged robot adjusts posture quickly to respond to terrain changes, then the robot can adapt to complex terrains, but slippage is more likely to occur during rapid movements
Solution Approach 1:
The patent employs dynamic impedance control where the stiffness and damping parameters are adjusted in real-time based on the robot's motion state and contact conditions. During rapid posture adjustments, the controller dynamically modifies impedance parameters to maintain optimal contact forces, enabling fast adaptation while preventing slippage through adaptive force regulation that responds to changing dynamic conditions.
Data Source
Figure 1~2
Figure 3~4a
Figure 4b~4c
AI summary
In a posture control method for a legged robot, target posture data of the legged robot is acquired, where the target posture data is posture data corresponding to a target posture to which the legged robot needs to be adjusted; plantar force information of the legged robot is determined according to the target posture data, with a friction cone formed between the legged robot and a contact surface in contact with a foot of the legged robot as a constraint condition; and the constraint condition of the friction cone is introduced, the slippage of the legged robot is reduced, and the legged robot is stably controlled to be adjusted from a current posture to the target posture according to the plantar force information.