Frequency Detector for Reciprocating Motion in Walking Assist Devices
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Solution Overview
Problem
Existing robotic suits and walking assist devices face challenges in synchronizing the frequency of user motion with assistance, leading to inefficient power consumption and short operation times, and require manual adjustments which are cumbersome.
Innovation Solution
A frequency detector for reciprocating moving bodies that estimates the frequency of motion waveforms and automatically adjusts the rigidity of the joint to synchronize the motion, reducing power consumption and user load by using an oscillation-related information output portion, frequency estimating portion, and adjusting portion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Weight of moving object
If a robotic suit uses a small and light battery to reduce user burden, then the battery weight is reduced, but the continuous operation time becomes short due to high power consumption of the electric actuator
Solution Approach 1:
The patent applies periodic action by using a cam mechanism that converts rotational motion into periodic reciprocating motion. The cam and compression spring generate torque only during specific phases of the rotation cycle, creating periodic assistance rather than continuous actuation. This reduces the duty cycle of the electric motor, allowing it to operate intermittently and consume less energy, thereby extending continuous operation time while using a lighter battery.
Solution Approach 2:
The patent replaces a purely electric actuation system with a hybrid mechanical system consisting of a cam mechanism and compression spring. The cam profile is designed to generate the required torque characteristics mechanically, eliminating the need for a high-power continuous electric motor. This mechanical substitution significantly reduces power consumption while maintaining the required assistance torque.
2Duration of action of moving object
If a one leg-type walking assist device uses a cam and compression spring to generate torque without an electric motor, then continuous operation time is extended, but manual adjustment of the compression spring requires troublesome tool-based operations
Solution Approach 1:
The patent implements self-service by enabling the user to adjust the compression spring preload directly through the operating interface without requiring external tools. The adjustment mechanism is integrated into the device structure, allowing the user to perform maintenance and calibration operations independently. This eliminates the need for tool-based adjustments and makes the device more user-friendly while maintaining the mechanical torque generation system.
3Reliability
If PID control is used to reduce torque deviation between the robotic suit and the user, then torque synchronization is improved, but the frequency of user motion is not directly estimated, making it difficult to enhance synchronism
Solution Approach 1:
The patent employs feedback control by using sensors to detect the user's motion frequency and using this information to adjust the cam profile or actuator control in real-time. The detected frequency feedback allows the system to synchronize the assistance torque with the user's natural walking rhythm, enhancing synchronism beyond what fixed PID parameters can achieve. This adaptive feedback mechanism directly addresses the frequency estimation challenge.
Data Source
AI summary
A frequency detector includes an oscillation related information output portion to which moving body position related information and a correction parameter are input, and which outputs a frequency adjustment parameter and estimated moving body position related information; a frequency estimating portion to which the frequency adjustment parameter is input, and which outputs an estimated frequency; and an adjusting portion to which the moving body position related information, the estimated moving body position related information, and the estimated frequency are input, and which outputs the correction parameter.