Assist Device Posture Estimation and Torque Control
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Solution Overview
Problem
Existing assist devices do not effectively prevent excessive force on the lower back when lifting heavy objects, leading to potential lumbago issues due to unreasonable postures.
Innovation Solution
An assist device with a body mounting fixture, actuator, and operation state detector that estimates the wearer's posture and alerts them to avoid excessive force on the lower back by providing warnings and correction guidance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the assist device provides assist torque to the lower back portion, then the burden on the lower back is reduced, but excessive force may still be applied to the lower back when the wearer works in an unreasonable posture
Solution Approach 1:
The controller acquires estimated posture information from operation detection information and uses this feedback to determine whether the posture is reasonable before providing assist torque. When the posture is determined to be unreasonable, the controller restricts generation of assist torque, thereby preventing excessive force on the lower back while maintaining assistance for reasonable postures.
Solution Approach 2:
The controller performs preliminary determination of posture reasonableness before the actuator generates assist torque. By evaluating the estimated posture in advance and restricting torque generation when the posture is unreasonable, the system prevents harmful effects before they occur.
2Ease of operation
If the assist device provides continuous assist torque, then operation assistance is maintained, but the wearer may develop dependence and fail to maintain proper posture
Solution Approach 1:
The system provides feedback by restricting assist torque when unreasonable posture is detected, creating a corrective mechanism that encourages the wearer to maintain proper posture rather than developing dependence on continuous assistance.
Solution Approach 2:
The assist torque generation is made dynamic and conditional based on real-time posture assessment. The controller adjusts the level of assistance by enabling or restricting torque generation according to whether the estimated posture is reasonable, creating an adaptive support system.
3Reliability
If the device adds posture detection and control functions, then lumbago prevention is improved, but device complexity increases
Solution Approach 1:
The controller performs multiple functions using the existing operation detection information: it controls actuator drive, acquires estimated posture information, determines posture reasonableness, and restricts assist torque generation when necessary. This multi-functionality reduces the need for separate dedicated components.
Solution Approach 2:
The system uses its own operation detection information to estimate posture and determine reasonableness, making the posture assessment function self-contained within the existing control architecture rather than requiring entirely separate detection systems.
Data Source
AI summary
An assist device includes a body mounting fixture, an actuator, an operation state detector, and a controller. The controller is configured to control drive of the actuator. The controller is configured to acquire an estimated posture of the wearer, which is estimated based on operation detection information detected by the operation state detector, when the actuator generates the assist torque. The controller is configured to determine whether or not the estimated posture is an unreasonable posture in which an excessive force is applied to a lower back portion.