Walking Robot Torque Control for Uneven Terrain Stability
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Solution Overview
Problem
Existing walking robot control methods, such as ZMP and torque-based dynamic walking, face challenges in achieving stable walking on uneven terrain, with ZMP requiring high energy and stiffness and torque-based methods being complex and limited to robots with fewer degrees of freedom, while FSM control methods struggle with balance maintenance.
Innovation Solution
A walking robot equipped with a ground angle calculator, compensation value calculator, target trajectory generator, and servo controller, which calculates and adjusts joint torques based on ground angles and sensor feedback to maintain balance and stability on uneven surfaces, allowing for natural, energy-efficient walking.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If ZMP control method is used to achieve precise position control, then position control precision is improved, but energy consumption increases and joint stiffness becomes high
Solution Approach 1:
The patent replaces the traditional ZMP position-based control mechanism with a torque-based control mechanism. Instead of precisely controlling joint positions through high-servo-gain position control, the system calculates target torques for each joint based on the robot's dynamic model and operating state, then directly applies these torques. This substitution of mechanical position control with torque control reduces energy consumption while maintaining walking stability.
2Measurement precision
If ZMP control method is used to achieve precise position control, then position control precision is improved, but joint stiffness becomes high
Solution Approach 1:
The patent replaces the ZMP position control system with a torque-based control system that directly manipulates joint torques according to the robot's dynamic model. By substituting position control with torque control, the system achieves walking stability without requiring high joint stiffness, thereby reducing the mechanical complexity and improving adaptability to environmental variations.
3Stability of the object's composition
If torque-based dynamic walking control method is used to achieve stable walking, then walking stability is improved, but control complexity increases and applicability is limited to robots with four degrees of freedom or below
Solution Approach 1:
The patent segments the control problem into discrete operating states (e.g., stance phase, swing phase, single-leg support, double-leg support) and defines specific torque control strategies for each state. By dividing the continuous walking cycle into distinct phases with predetermined torque commands, the system simplifies the control complexity while maintaining walking stability, making it applicable to robots with six degrees of freedom.
4Use of energy by moving object
If FSM control method is used to control walking, then energy efficiency is improved and joint stiffness is reduced, but balance maintenance becomes difficult
Solution Approach 1:
The patent incorporates feedback mechanisms by continuously monitoring the robot's operating state (e.g., which legs are in stance or swing phase, ground reaction forces) and adjusting the torque commands accordingly. This feedback allows the FSM control method to maintain balance on uneven terrain while preserving the energy efficiency and low joint stiffness characteristics of the original approach.
Data Source
AI summary
A walking robot capable of implementing a balancing action to ensure a stable walking on uneven ground based on an FSM-based walking control method, and a control method thereof, is capable of implementing stable walking by controlling torques of the hip joint, the knee joint and the ankle joint by use of FSM without calculating complicated Dynamics Equations. The walking robot ensures stable walking on uneven ground through a simple calculation by use of the angle formed by the ground and the both feet The walking robot is made to be applied to a robot provided with joints having six degrees of freedom through a simple calculation of compensation angles.