Wearable Joint Resistance Control Using Generator-Mode Motor Braking
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Solution Overview
Problem
Existing wearable devices for assisting users with reduced muscular strength or joint problems do not effectively provide resistance without energy consumption, which can lead to inefficiency and potential malfunctions.
Innovation Solution
A wearable device that measures joint angles and adjusts resistance levels using a motor driver circuit with a closed-loop and open-loop connection ratio, allowing the motor to generate resistance as a generator, thereby conserving battery power and providing adjustable resistance forces.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Force
If the motor is controlled to provide resistance force to the user, then the exercise effectiveness is improved, but the battery power is consumed
Solution Approach 1:
Instead of using the motor to generate force that consumes battery power, the invention inverts the approach by using the motor as a generator that converts the user's movement into electrical energy. This allows the system to provide resistance force while simultaneously charging the battery, transforming the energy flow direction from battery-to-motor to motor-to-battery.
Solution Approach 2:
The system enables self-service by allowing the user's own movement to generate the electrical energy needed to power the motor controller and other system components. The motor acts as a generator during exercise, capturing kinetic energy from the user's motion and converting it to electrical energy, thereby making the system partially self-powered.
2Ease of operation
If the motor operates continuously to provide assistance, then the user support is improved, but the device usage time is reduced
Solution Approach 1:
The system employs periodic action by alternating between open-loop and closed-loop motor control states. During exercise mode, the motor operates in closed-loop to provide resistance, then transitions to open-loop to conserve energy. This periodic switching allows the system to provide support when needed while extending overall device usage time through energy recovery during resistance phases.
Solution Approach 2:
The system recovers energy that would otherwise be wasted during exercise. When the motor provides resistance force, the user's movement generates electrical energy through the generator function, which is then stored in the battery. This energy recovery mechanism extends device usage time by converting what would be energy loss into usable power.
3Force
If the resistance level is increased for better exercise effect, then the exercise intensity is improved, but the energy consumption increases
Solution Approach 1:
The system converts the energy that would be lost as heat and waste during high-intensity resistance exercise into useful electrical energy. The motor's generator function captures the kinetic energy from the user's movement against resistance, converting it to electrical energy that charges the battery. This transforms energy waste into energy recovery, allowing high resistance levels without proportional increases in net energy consumption.
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 efficiently provides adjustable resistance without battery power, enhancing user safety and extending device usage time by utilizing the motor as a generator to charge the battery and adjust resistance levels based on user input and joint angles.
Implementation Method 1
when the motor operates as the generator, the method may further include charging a battery of the wearable device based on energy generated by the generator
Data Source
Figure 1A~1B
Figure 1C
Figure 1D
AI summary
A method and device for providing a resistance force to a user is disclosed. To provide a resistance force, the method includes controlling a first switch and a second switch of a motor driver circuit so that a battery does not form a closed loop through the motor driver circuit in response to an exercise mode being set in the wearable device; determining a resistance level to apply to a first joint of a user; determining a connection ratio between a connected time for which terminals of a motor are to be electrically connected in a closed loop and a disconnected time for which the terminals of the motor are to be electrically disconnected, based on the resistance level; and controlling a third switch of the motor driver circuit electrically connected to the motor based on the connection ratio.