Split-Crank Pedaling Device with Independent Motor Torque Control

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Solution Overview

Problem

Conventional pedaling devices with mechanical connections between limbs do not effectively rehabilitate motor output and coordination in stroke patients, as they rely on the non-paretic limb to assist the paretic limb, hindering motor recovery and coordination practice.

Innovation Solution

A split-crank pedaling device with independent motor-controlled crank assemblies and sensors that provide supplemental torque to assist and resist pedal movement, allowing patients to practice strength and coordination between paretic and non-paretic limbs through closed-loop control and gravitational assist modules.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If the crank shaft is split to eliminate mechanical connection between limbs, then motor output and coordination practice are improved, but the difficulty of completing pedaling motions increases making the task too challenging for stroke patients

Engineering Contradiction:

Improvemotor output and coordination practiceVSAvoiddifficulty of completing pedaling motions

Core Design Contradiction:

ReliabilityVSEase of operation

Solution Approach 1:

The patent replaces the purely mechanical split-crank system with a motor-controlled system that uses sensors and feedback control to substitute mechanical connection with intelligent control. Motors are integrated into the crank assemblies and controlled by a controller that receives sensor data and provides supplemental torque to assist patients in maintaining proper pedaling form and coordination.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The patent implements feedback control by using sensors to detect crank position and pedaling form, then using this information to provide real-time supplemental torque through motors. The controller continuously monitors patient performance and adjusts assistance levels to maintain proper coordination while supporting patients who cannot complete the full pedaling motion independently.

Inventive Principle:

Principle #23Feedback

2Adaptability or versatility

If motor-controlled assistance is added to split-crank pedaling device, then patient capability is extended and proper form is maintained, but device complexity increases

Engineering Contradiction:

Improvepatient capability extensionVSAvoidsystem complexity with motors and controls

Core Design Contradiction:

Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The patent applies multi-functionality by integrating motors that can operate in multiple modes: providing supplemental torque to assist pedaling motions, generating resistance to challenge stronger patients, and maintaining crank position. The same motor hardware serves multiple therapeutic functions, reducing the need for separate mechanical systems for each function.

Inventive Principle:

Principle #6Universality (Multi-functionality)

Solution Approach 2:

The patent merges the motor, sensor, and control functions into an integrated system where the motor assembly includes both the actuator and sensing capabilities. This consolidation reduces the number of separate components and simplifies the overall system architecture while maintaining the ability to provide complex assisted and resistant forces.

Inventive Principle:

Principle #5Merging (Combining)

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 patients to generate force and coordinate movements independently, improving motor output and inter-limb coordination, while adapting assistance to individual needs and physiological responses.

Implementation Method 1

A motor is operably connected to the crank assembly and is configured to provide a supplemental torque to the crank assembly

Methodology Applied

Scientific EffectElectromagnetic force: Lorentz Force

Implementation Method 2

A shaft sensor is arranged relative to the crank assembly or the motor. The shaft sensor produces an indication of a position of the shaft

Methodology Applied

Scientific EffectPosition sensing:

Implementation Method 3

A gravitational assist module is executed by the controller to provide supplemental torque output from the motors based upon the rotational positions of the crank assemblies

Methodology Applied

Scientific EffectGravitation: Gravitation

Data Source

PatentUS11154750B2Motor assisted split-crank pedaling device

Publication Date: 2021.10.26 MARQUETTE UNIVERSITY

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.