Assist Device Load Weight Estimation via Acceleration Sensor
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Solution Overview
Problem
Conventional assist devices require a dedicated sensor on the sole or hand to detect load weight, increasing costs and making it difficult for users to wear them, as they need to control assist torque based on load weight.
Innovation Solution
An assist device with a first wearing tool on the waist, an arm turnable with respect to the thigh, a motor, a second wearing tool on the arm, an acceleration sensor, and a rotation detector, where a control device estimates the load weight using the sensor and rotation detector outputs to control the motor torque.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a dedicated sensor is provided on the sole or hand to detect load weight, then assist torque can be controlled in accordance with load weight, but cost increases and ease of wear decreases
Solution Approach 1:
The acceleration sensor, originally designed to detect body movement and posture, is made multi-functional by using it to estimate load weight through the estimation process that combines acceleration data with arm rotation state data from the rotation detector
Solution Approach 2:
The control device introduces an intermediary estimation process that mediates between the acceleration sensor outputs and the required load weight information, converting acceleration data into weight estimates through computational processing rather than direct measurement
2Measurement precision
If a dedicated sensor is provided on the sole or hand to detect load weight, then assist torque can be controlled in accordance with load weight, but the number of wearable components increases
Solution Approach 1:
The acceleration sensor is made multi-functional by using it to estimate load weight through the estimation process that combines acceleration data with arm rotation state data from the rotation detector
Solution Approach 2:
The system uses the acceleration sensor's inherent capability to detect body movement and posture to serve the additional function of load weight estimation, making the sensor self-sufficient without requiring external dedicated sensors
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
Enables control of assist torque based on load weight without a dedicated sensor, reducing costs and enhancing user convenience by eliminating the need for additional wearable sensors.
Implementation Method 1
an acceleration sensor provided on the first wearing tool
Implementation Method 2
a rotation detector that detects a turning state of the arm
Data Source
AI summary
An assist device includes: a first wearing tool mounted to at least a waist portion of a user, an assist arm disposed along a thigh portion of the user and being turnable with respect to the first wearing tool; a motor that generates torque for turning the assist arm; a second wearing tool provided on the assist arm and mounted to the thigh portion; an acceleration sensor provided on the first wearing tool; a rotation detector that detects a turning state of the assist arm; and a control device that controls the motor. The control device includes a processing portion that executes an estimation process of obtaining an estimated weight of a load to be lifted by the user based on an output of the acceleration sensor and an output of the rotation detector, and a control process of controlling the motor based on the estimated weight.