Motor-Assisted Split-Crank Pedaling for Paretic Limb Support
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Solution Overview
Problem
Conventional pedaling devices for stroke patients, such as bicycles and stationary bicycles, often require the non-paretic limb to compensate for the paretic limb, hindering motor recovery and inter-limb coordination, and existing split-crank devices are too challenging for many patients to use effectively.
Innovation Solution
A split-crank pedaling device with independent crank assemblies and motors that provide closed-loop motor control, including gravitational assistance and proportional gain correction, to support the paretic limb and enhance inter-limb coordination.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the crank shaft is split to eliminate mechanical connection between paretic and non-paretic limbs, then inter-limb coordination and paretic limb motor output are improved, but the device becomes too difficult for many stroke patients to use effectively
Solution Approach 1:
The system uses shaft sensors to detect the position of each crank assembly and calculates phase error between them. The controller provides real-time feedback by operating motors to generate supplemental torque that corrects coordination errors, allowing patients to learn proper coordination while receiving guidance from the system.
Solution Approach 2:
The controller dynamically adjusts the amount of supplemental torque based on the calculated phase error. By changing the control parameter (torque magnitude) in response to patient performance, the system adapts to patient capabilities while maintaining rehabilitation goals, making the device usable across different patient skill levels.
2Adaptability or versatility
If motor-controlled assistance is added to split-crank pedaling device, then patient capability is extended to perform pedaling tasks, but device complexity increases
Solution Approach 1:
The system divides the control function into separate components: shaft sensors detect position, a controller calculates phase error, and motors provide corrective torque. This segmentation allows each component to be optimized independently while working together to achieve the overall rehabilitation function.
Solution Approach 2:
The controller acts as an intermediary between the sensors and motors, processing sensor data to calculate phase error and generating appropriate motor commands. This intermediary layer manages the complexity by centralizing the control logic and coordinating the interaction between sensing and actuation subsystems.
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 device enables effective rehabilitation by challenging yet tractable pedaling tasks, improving motor output and coordination between the paretic and non-paretic limbs, promoting sustained patient engagement and rehabilitation progress.
Implementation Method 1
A first motor is operably connected to the first crank assembly. The controller operates at least one of the first motor or the second motor to provide a supplemental torque to one of the first crank assembly and the second crank assembly.
Implementation Method 2
A first shaft sensor is arranged relative to the first crank assembly or the first motor. The first shaft sensor produces an indication of a position of the shaft of the first crank assembly.
Implementation Method 3
The controller calculates a phase error between the positions of the first and second shafts and a predetermined phase relationship between the first and second shafts.
Data Source
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AI summary
Split-crank pedaling devices and methods of operation support patient use and rehabilitation, particularly for stroke patients. A split-crank pedaling device includes first and second crank assemblies. First and second motors are operably connected to the first and second crank assemblies. A first shaft sensor produces an indication of a position of the shaft of the first crank assembly. A second shaft sensor produces an indication of a position of the shaft of the second crank assembly. A controller is communicatively connected to the first and second motors and the first and second shaft sensors and calculates a phase error between the positions of the first and second shafts and a predetermined phase relationship between the first and second shafts. The controller operates at least one of the first motor or the second motor to provide a supplemental torque to one of the first crank assembly and the second crank assembly.