Variable Stiffness Actuator for Safe and Accurate Robotic Limbs
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing robotic limbs struggle to assist users with impaired limbs by ensuring safe interaction during task execution without compromising accuracy or prolonging task completion time, particularly in post-stroke patients.
Innovation Solution
The use of Variable Stiffness Actuators (VSAs) in supernumerary robotic limbs (SRLs) that can switch between low and high stiffness states, enabling safe interaction and accurate task performance by adjusting stiffness through a compliance curve, allowing for infinite rotation and stiffness adjustment without energy input.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If robotic limbs use fixed stiffness actuators, then structural stability is maintained, but safety during human interaction deteriorates
Solution Approach 1:
The patent applies variable stiffness actuators that dynamically adjust their stiffness parameter in real-time based on operational requirements. The actuator transitions between high stiffness state for structural stability and low stiffness state for safe human interaction, resolving the contradiction between maintaining structural integrity and ensuring safety during contact with users.
2Object-affected harmful factors
If robotic limbs use soft actuators, then safety during interaction is improved, but task execution accuracy deteriorates
Solution Approach 1:
The variable stiffness actuator switches between low stiffness state for safe interaction and high stiffness state for accurate task execution. This dynamic adjustment allows the system to achieve both safety and precision by adapting its mechanical properties to the current operational context.
Solution Approach 2:
The actuator changes its stiffness parameter between two distinct states (high and low) to optimize performance for different tasks. This parameter switching enables the system to meet conflicting requirements of safety and accuracy by adjusting the physical property of the actuator itself.
3Measurement precision
If robotic limbs use rigid actuators, then task execution accuracy is improved, but safety during human interaction deteriorates
Solution Approach 1:
The system uses variable stiffness actuators that can transition from rigid (high stiffness) to compliant (low stiffness) states. During task execution requiring accuracy, the actuator maintains high stiffness. During human interaction, it switches to low stiffness to ensure safety, thus resolving the contradiction between accuracy and safety.
4Adaptability or versatility
If variable stiffness actuators switch between high and low stiffness states, then adaptability is improved, but device complexity increases
Solution Approach 1:
The variable stiffness actuator incorporates an internal mechanism that automatically adjusts stiffness based on operational feedback and control signals. The actuator serves itself by integrating the stiffness adjustment functionality within its own structure, reducing the need for external complex control systems while maintaining high adaptability.
Data Source
AI summary
A supernumerary robotic limb (SRL) system can include a plurality of rigid links, a joint that connects one rigid link to another rigid link in the plurality of rigid arms, and two variable stiffness actuators (VSAs) configured to drive the plurality of rigid links in order to complete at least one task. The VSAs can exhibit infinite rotation and infinite stiffness. The VSAs can include an output link. Additionally, the VSAs can include a set of elastic elements mounted on the output link. The VSAs can include an input link configured to provide kinetic energy for the output link. The VSAs can include a dynamic chassis configured to connect with the input link. Additionally, the VSAs can include a stiffness adjustor included in the dynamic chassis and configured to adjust an elastic transmission between at least one elastic element of the set of elastic elements and the output link.