Robot Walking Control via Torque Compensation for Energy Efficiency
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Solution Overview
Problem
Current walking control methods for robots with multiple legs face challenges in maintaining stable and energy-efficient walking, often resulting in unnatural gait patterns and difficulty with tasks like ascending stairs or avoiding obstacles, due to high servo gain and joint rigidity in position-based control, and complexity in dynamic equation solving for torque-based control.
Innovation Solution
A walking control apparatus and method that includes joint portions, a state database, an inclination sensing unit, a torque calculator, and a servo controller, which calculates compensation angles based on the robot's upper body inclination to adjust desired positions and torques, allowing for low servo gain and energy-efficient walking with reduced joint rigidity, enabling the robot to walk naturally and perform complex tasks.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If position-based ZMP control method is used, then accurate position control is achieved, but high servo gain is necessary resulting in high energy consumption and high joint rigidity
Solution Approach 1:
The patent replaces the traditional position-based control mechanism with a torque-based control mechanism. Instead of controlling joint positions directly with high servo gain, the system calculates desired torques for each joint based on dynamic equations and applies them directly. This substitution of control approach eliminates the need for high servo gain while maintaining control accuracy, thereby reducing energy consumption and joint rigidity.
2Manufacturing precision
If position-based ZMP control method is used, then accurate position control is achieved, but high joint rigidity applies considerable shock to walking surfaces
Solution Approach 1:
The patent replaces the position-based control system with a torque-based control system that directly commands joint torques. This substitution allows for softer, more compliant motion control that reduces impact shocks transmitted to the walking surface while maintaining accurate trajectory following through dynamic modeling and torque optimization.
3Use of energy by moving object
If torque-based dynamic walking control method is used, then energy efficiency is improved, but complex dynamic equation solving is required
Solution Approach 1:
The patent applies preliminary action by pre-calculating and storing dynamic equations, inertial parameters, and gravitational force models for the robot system. These pre-computed models enable real-time torque calculation without requiring complex runtime solving, thus maintaining energy efficiency while reducing computational complexity during actual walking control.
4Use of energy by moving object
If FSM control method is used, then energy efficiency is improved with low joint rigidity, but accurate whole-body motion control is difficult
Solution Approach 1:
The patent implements dynamics by using real-time dynamic modeling and torque-based control that adapts to the robot's current state and environmental conditions. This dynamic approach allows for accurate whole-body motion control while maintaining low joint rigidity and energy efficiency, overcoming the limitations of static FSM control methods.
Data Source
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AI summary
A walking control apparatus of a robot includes joint portions provided in each of a plurality of legs of the robot, a state database to store state data of each of the legs and state data of the joint portions corresponding to the state of each of the legs, when the robot walks, a position instruction unit to store desired positions corresponding to the state data of the joint portions, an inclination sensing unit to sense an inclination of an upper body of the robot, a torque calculator to calculate torques using the inclination of the upper body and the desired positions, and a servo controller to output the torques to the joint portions to control the walking of the robot. Since the robot walks by Finite State Machine (FSM) control and torque servo control, the rotation angles of the joint portions do not need to be accurately controlled. Thus, the robot walks with low servo gain and energy consumption is decreased. Since the robot walks with low servo gain, each of the joints has low rigidity and thus shock generated by collision with surroundings is decreased.