Power-Assist Robot Torque Control for Simultaneous Lifting and Walking
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Solution Overview
Problem
Existing power assist robot systems face limitations in providing simultaneous assistance to waist and hip joints during heavy-object lifting and walking, with existing systems either restricting movement or requiring separate driving sources, and often suffer from safety issues and discontinuity in movement patterns.
Innovation Solution
A power assist robot apparatus with rotatably driving portions located near the waist, an upper-body frame, and thigh frames, along with angle detecting and floor-reaction-force detecting components, which calculates and applies drive torque to assist upper body and thigh movements, allowing for simultaneous heavy-object lifting and walking without restricting side-to-side motion or turning.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a passive system (spring-type or rubber-type) is used, then the system is simple in structure, but it can only provide power assistance in one direction
Solution Approach 1:
The patent combines multiple drive sections (waist drive section and hip drive section) into a single integrated power assist suit system. The waist drive section provides assistance in the vertical direction while the hip drive section provides assistance in the forward direction, merging their functions to achieve multi-directional power assistance capability
2Force
If an electric motor-type system with high-reduction-ratio speed reducer is used, then power assistance is strong, but safety problems occur
Solution Approach 1:
The patent employs dynamic control strategies where the drive control section continuously adjusts the output torque based on real-time detection of wearer's movement state, posture, and workload. This dynamic adjustment ensures that power assistance is provided only when needed and within safe limits, preventing sudden or excessive forces that could compromise safety
3Force
If a pneumatically driving-type system is used, then power assistance is strong, but the system becomes heavy due to air compressor
Solution Approach 1:
The patent segments the power assist suit into independent drive sections (waist drive section and hip drive section), each with its own drive source. This segmentation allows for distributed weight placement and enables the use of lighter individual motors compared to a single centralized pneumatic system, reducing overall system weight while maintaining strong power assistance capability
4Ease of operation
If action pattern reproduction-type system is used, then control is simple, but movement discontinuity occurs during pattern switching
Solution Approach 1:
The patent implements feedback control where the drive control section continuously monitors the wearer's actual movement through detection devices (acceleration sensors, angle sensors) and adjusts the drive output in real-time. This feedback mechanism ensures smooth transitions between different movement patterns and maintains movement continuity, eliminating the discontinuities that occur in open-loop pattern reproduction systems
5Adaptability or versatility
If master-slave control-type system is used, then follower movement is achieved, but feedback delay causes wearer to feel resistance
Solution Approach 1:
The patent uses prediction algorithms in the drive control section that anticipate the wearer's intended movement based on detected tendencies (from acceleration patterns, muscle activity, or posture changes). By providing power assistance in advance of the actual movement requirement, the system eliminates feedback delays and creates a natural, resistance-free wearing experience
Data Source
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AI summary
There are provide a power assist robot apparatus capable of assisting heavy-object lifting action and walking movement with fewer driving sources, and a method for controlling the power assist robot apparatus. Two power-assist electric motors that produce drive torque for assisting upper body's movement and thigh's movement are located near opposite lateral sides in a right-left direction of the wearer's waist, respectively. Each lower-limb assist arm has one end fixed to a rotary shaft of the power-assist electric motor and the other end to which a lateral side of the thigh is attached. An upper-body assist arm placed at the wearer's chest and a main frame that holds the two power-assist electric motors at both ends thereof and is placed at the wearer's waist are connected by a driven rotary shaft which is rotatable about a vertical axis and a driven rotary shaft which is rotatable about a right-left axis.