Series Elastic Actuator Eliminates Inertia in Exercise Machines
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Solution Overview
Problem
Existing exercise machines generate momentum due to inertia, leading to less efficient workouts and increased injury potential, as they fail to provide resistance that is independent of velocity and position, limiting the ability to perform various exercise modes effectively.
Innovation Solution
A novel exercise apparatus incorporating a series elastic actuator with a torque sensor, comprising a motor, gear reducer, and a planar torsion spring, which measures deflection using position sensors to control force independently of position and velocity, allowing for inertia-free motion and multiple exercise modes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If traditional weights are used for exercise, then the exercise machine structure is simple, but momentum is generated due to inertia which reduces workout efficiency and increases injury risk
Solution Approach 1:
The patent replaces the traditional mechanical weight-based resistance system with an electric motor-driven system. The motor controls the load transfer mechanism to eliminate inertial effects while maintaining resistance forces, thereby improving workout efficiency and reducing injury risk associated with momentum generation.
Solution Approach 2:
The system dynamically adjusts resistance parameters (force, velocity, position) through motor control to eliminate inertial effects. By controlling the load transfer mechanism's velocity and position independently of the user's motion, the system maintains constant resistance without generating momentum, thus resolving the contradiction between simple structure and workout safety/efficiency.
2Speed
If constant speed movement is used in isokinetic exercise, then velocity control is precise, but the force changes while the load transfer mechanism velocity remains constant, requiring complex force control
Solution Approach 1:
The system employs feedback from sensors that detect the user's applied force and the load transfer mechanism's position. This feedback is used by the motor controller to adjust the motor output in real-time, maintaining constant velocity while compensating for varying user force, thus achieving precise velocity control without excessive complexity.
Solution Approach 2:
The motorized load transfer mechanism serves multiple functions: it provides resistance force, controls velocity, and enables different exercise modes (isokinetic, isotonic, isometric) through software configuration. This multi-functionality reduces the need for separate mechanical mechanisms for each exercise type, simplifying the overall device while maintaining precise velocity control.
3Adaptability or versatility
If position-dependent force control is implemented, then the apparatus can vary resistance through the individual's range of motion, but the control system becomes more complex
Solution Approach 1:
The system uses dynamic control where the motor adjusts the load transfer mechanism's position and velocity in real-time based on the user's range of motion and desired force profile. This dynamic adjustment allows variable resistance throughout the exercise range without requiring complex mechanical linkages, achieving adaptability through software-based control.
Solution Approach 2:
Position-dependent force control is achieved by replacing complex mechanical variable resistance mechanisms with an electric motor system. The motor controller receives position feedback and adjusts the applied force accordingly, enabling versatile resistance profiles through software rather than mechanical complexity.
4Productivity
If inertia-free motion is achieved through motorized control, then workout efficiency improves, but the device complexity increases compared to traditional weight systems
Solution Approach 1:
The patent replaces the simple but inefficient mechanical weight system with a motorized actuator system that eliminates inertial effects. Although the motorized system is more complex than weights, it provides superior workout efficiency by maintaining constant resistance without momentum, and the complexity is justified by the performance benefits and ability to provide programmable resistance profiles.
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 apparatus provides a more efficient workout by maintaining constant force regardless of position, reducing injury risk and enabling isokinetic, isotonic, and isometric exercises with variable force profiles, while being cost-effective and reliable compared to traditional systems.
Implementation Method 1
a planar torsion spring, which measures deflection using position sensors
Implementation Method 2
measures deflection using position sensors
Data Source
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AI summary
The disclosure teaches a novel exercise apparatus. This apparatus does not generate load momentum. The apparatus is based around a series elastic torque sensor and contains an intelligent servo drive with reduction gear to control a variable speed rotating motor shaft. The combination of the motor, gear reducer, spring, angle measurement sensors (position sensors), and intelligent motor controller is a series elastic actuator which is the basis for the exercise device. The exercise device also contains a load transfer mechanism adopted to provide an interface between an individual and the torque sensor. The apparatus allows for isokinetic, isometric, isotonic, and variable force modes of exercise without hardware configuration.