Stationary Exercise Device Torque Balance via Flywheel Rotation
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Solution Overview
Problem
Existing stationary exercise devices face difficulties in determining torque balance between limbs without additional external sensors, making it challenging and costly to measure torque effectively.
Innovation Solution
A detection device measures time intervals and time differences during the rotation of the driving wheel, allowing a control device to calculate torque at the driving wheel without additional sensors, correlating this torque to the position of the cranks and displaying the torque balance between limbs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If additional external sensors (strain gauges, tension sensors) are used to measure torque, then measurement precision is improved, but device complexity and cost increase
Solution Approach 1:
The flywheel serves dual purposes: it provides mechanical energy storage while simultaneously acting as the measurement object. By detecting the flywheel's rotational characteristics (time intervals, velocity variations), the system measures torque without requiring separate sensors on the driving assembly, thus eliminating additional complexity while maintaining measurement capability
Solution Approach 2:
The patent introduces an intermediary measurement approach by using the flywheel's rotational parameters as a mediator to infer torque. Instead of directly measuring torque with sensors on the cranks or axles, the system measures the flywheel's rotational behavior (time intervals between predetermined positions, velocity changes) and calculates torque from these indirect measurements, simplifying the overall system
2Measurement precision
If additional external sensors are installed to measure torque balance, then measurement capability is improved, but manufacturing cost increases
Solution Approach 1:
The flywheel is designed to perform multiple functions simultaneously: energy storage, momentum maintenance, and torque measurement reference. By making the flywheel serve as both a functional component and a measurement reference, the patent eliminates the need for separate measurement devices, thereby reducing manufacturing costs while maintaining measurement capability
Solution Approach 2:
The existing flywheel structure serves its own measurement needs. The flywheel's inherent rotational characteristics are utilized as the measurement basis, eliminating the need for external sensors and their associated costs. The system uses what it already has (the flywheel) to perform the measurement function
3Measurement precision
If torque is measured using strain gauges on cranks or axles, then direct torque measurement is achieved, but device complexity and installation difficulty increase
Solution Approach 1:
The patent uses the flywheel's rotational parameters as an intermediary to indirectly measure torque. Instead of installing sensors directly on the cranks or axles to measure torque, the system measures the flywheel's rotational characteristics (time intervals between predetermined positions, velocity variations) and derives torque information from these measurements, significantly simplifying installation while maintaining measurement accuracy
Solution Approach 2:
The patent replaces direct mechanical torque measurement (strain gauges on cranks/axles) with a rotational dynamics-based measurement system. By using the flywheel's rotational behavior and applying mechanical principles (angular momentum, torque-time relationships), the system achieves torque measurement without direct mechanical sensors on the driving components
Data Source
AI summary
A stationary exercise device with a driving assembly with a driving wheel rotating around a driving axle, a first and a second crank each connected to the driving wheel and two pedals, each connected to one of the cranks, a flywheel connected to the driving assembly by at least one gear mechanism, a brake assembly for applying a braking force to the flywheel, at least one measuring device for measuring the position of the first and second crank is provided. A detection device detects several time intervals, in each of which the flywheel is displaced a predetermined angle, the detection device further detects time differences between at least two of the time intervals. A control device determines, through dependence of the time differences between at least two of the time intervals, a torque at the driving wheel or a value dependent on the torque at the driving wheel.