Series Elastic Holonomic Mobile Platform for Rehabilitation
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Solution Overview
Problem
Current robotic rehabilitation devices for upper limb rehabilitation are either expensive due to mechanical complexity or limited in their ability to provide customized, interactive, and cost-effective home-based therapy, especially for patients with varying levels of impairment.
Innovation Solution
A low-cost, active, omni-directional mobile platform with a 3-DoF series elastic actuator and a compliant parallel mechanism, which transforms the non-backdriveable holonomic platform into a multi-DoF series elastic actuator, eliminating the need for costly force sensors and enabling closed-loop force control with higher controller gains.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If exoskeleton type robots are used for upper limb rehabilitation, then joint specific therapies can be delivered with controlled torques, but the mechanical complexity increases leading to high cost
Solution Approach 1:
The patent introduces a compliant mechanism as an intermediary element between the motor and the patient's limb. This compliant mechanism (containing flexure hinges and elastic elements) serves as a mediator that provides inherent compliance and force sensing capabilities without requiring complex force sensors or backdriveable mechanisms, thus resolving the contradiction between therapy effectiveness and mechanical complexity
Solution Approach 2:
The patent replaces traditional mechanical force sensing mechanisms (such as force sensors, torque sensors, or backdriveable mechanisms) with a compliant mechanism that inherently provides force sensing through its elastic deformation. This substitution eliminates the need for complex mechanical systems while maintaining the ability to deliver controlled joint-specific therapies
2Reliability
If fixed-base end-effector robots are used for rehabilitation, then controlled therapeutic movements can be administered, but portability and home-based utilization are limited
Solution Approach 1:
The patent segments the rehabilitation system into a mobile platform and a compliant mechanism module. This segmentation allows the system to be mounted on mobile platforms (wheels, carts, or wearable structures) rather than being fixed to a base, thereby enabling portability and home-based utilization while maintaining controlled therapeutic movement delivery
3Device complexity
If passive mobile platforms are used for home-based therapy, then cost and portability are improved, but the ability to provide active assistance and force feedback is lost
Solution Approach 1:
The compliant mechanism is designed to be self-sufficient in providing both passive compliance and active force control. The elastic elements and flexure hinges inherently provide compliance and force sensing without requiring external force sensors, enabling the system to deliver active assistance and interactive therapy while maintaining low cost and simplicity
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
The solution provides a cost-effective, portable, and versatile rehabilitation device capable of administering active, passive, and resistive exercises, assisting patients as needed, and ensuring active participation, while maintaining safety and robustness, suitable for home-based therapies with unlimited planar workspace.
Implementation Method 1
a compliant mechanism to measure deflections of the mobile platform
Data Source
AI summary
It is proposed a design and control of series elastic holonomic mobile platform, aimed to administer therapeutic table-top exercises to patients who have suffered injuries that affect the function of their upper extremities. The proposed mobile platform is a low-cost, portable, easy-to-use rehabilitation device for home use. It consists of four actuated Mecanum wheels and a compliant, low-cost, multi degree-of freedom Series Elastic Element as its force sensing unit. Thanks to its series elastic actuation, it is highly backdriveable and can provide assistance/resistance to patients, while performing omni-directional movements on plane. The device helps improving accuracy and effectiveness of repetitive movement therapies completed at home, while also providing quantitative measures of patient progress.