Robot Gait Control via Imaginary Spring-Damper Model
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Solution Overview
Problem
Conventional methods for controlling the gait of wearable robots struggle to maintain balance, especially when subjected to external forces, and fail to effectively manage the transition between double-leg and single-leg support states during walking.
Innovation Solution
The method involves forming imaginary suspension systems using spring-damper models between the robot's body and imaginary walls, calculating reaction forces, and converting them into drive torques using a Jacobian transposed matrix to maintain balance and stability, particularly through the use of ankle, knee, hip, pitching, and rolling joints.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If conventional control methods are used to control the robot to walk along a preset path, then the robot can follow the path, but the robot cannot maintain balance when wobbled by external forces
Solution Approach 1:
The patent introduces an imaginary suspension system as an intermediary between the robot body and the external environment. This virtual suspension model (comprising imaginary springs and dampers) acts as a mediator that generates counteracting forces to stabilize the robot when subjected to external disturbances, without requiring physical modification to the robot structure.
Solution Approach 2:
The patent replaces physical mechanical suspension systems with a virtual/imaginary suspension model implemented through control algorithms. By using computational models (imaginary springs and dampers) instead of physical mechanical components, the system achieves balance stabilization while reducing mechanical complexity and weight.
2Stability of the object's composition
If the robot uses a rigid support structure to maintain balance, then stability is improved, but energy consumption increases and movement flexibility is reduced
Solution Approach 1:
The patent employs a dynamic control approach where the imaginary suspension parameters (spring stiffness and damper coefficients) are adjusted in real-time based on the robot's state and external disturbances. This dynamic adaptation allows the system to maintain stability with minimal energy expenditure, rather than relying on continuous rigid support that would consume more energy.
Solution Approach 2:
The patent changes the parameters of the imaginary suspension system (spring constants, damping coefficients) according to the robot's operating conditions. By dynamically adjusting these parameters, the system optimizes the balance between stability and energy consumption, using stiffer virtual springs when stability is needed and softer springs when energy conservation is prioritized.
3Reliability
If the robot uses complex sensor systems to detect external forces, then balance control is improved, but device complexity and cost increase
Solution Approach 1:
The patent replaces complex physical sensor systems with a virtual sensing approach. Instead of using multiple force sensors, accelerometers, and gyroscopes to detect external forces, the system uses the imaginary suspension model to infer and respond to disturbances through control algorithms, significantly reducing hardware complexity.
Solution Approach 2:
The patent creates a virtual copy of the physical suspension system in the form of an imaginary suspension model. This computational model replicates the behavior of physical springs and dampers, allowing the system to sense and respond to external forces through software rather than requiring equivalent physical sensing hardware.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach enhances the robot's ability to maintain balance and stability by absorbing shocks and reducing energy consumption, effectively managing the transition between support states and minimizing movement errors, thereby improving the reliability of the robot's gait control.
Implementation Method 1
applying the variation in the distance and the variation in the speed to an imaginary spring-damper model formed between the body of the robot and the imaginary wall, and calculating an imaginary reaction force required by the body of the robot
Data Source
AI summary
A method includes: forming an imaginary wall at a position spaced apart and outward from feet of the robot when the robot is in a double-leg-support state; kinetically calculating a variation in a distance between a body of the robot and the imaginary wall and a variation in a speed of the body of the robot relative to the imaginary wall using an angle of a joint and lengths of links of the robot; applying the variation in the distance and the variation in the speed to an imaginary spring-damper model formed between the body of the robot and the imaginary wall, and calculating an imaginary reaction force required by the body of the robot; and converting the calculated reaction force into a drive torque required by the body of the robot using a Jacobian transposed matrix.