Adjustable Exoskeleton Hip Pivot for Torque Compensation
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Solution Overview
Problem
Exoskeletons with tool-holding arms generate forward torque at the hip joint, causing users to lean back and increase body load, which is difficult to counteract without heavy batteries or complex mechanisms, and when used for backpacks, backward torque is similarly problematic, affecting user mobility and comfort.
Innovation Solution
The exoskeleton's hip pivot is misaligned in the sagittal plane relative to the user's hip pivot, either forward or rearward, to reduce torque requirements, allowing for adjustable positioning to compensate for different loads and movements, thereby minimizing counterweight mass and increasing mobility.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Force
If a spring is used to create counteracting torque at the hip joint, then the forward torque is reduced, but the torque in the swing phase becomes too great
Solution Approach 1:
The patent applies dynamics by making the hip joint actuated and adjustable, allowing the moment arm length to be dynamically changed based on operational phase. The actuator can modify the moment arm length to be shorter during swing phase (reducing excessive torque) and longer during stance phase (increasing counteracting torque effectiveness), thus resolving the contradiction between providing sufficient counteracting torque and avoiding excessive swing phase torque
Solution Approach 2:
The patent changes the parameter of moment arm length to resolve the torque contradiction. By adjusting the moment arm length of the counterweight, the system can optimize torque characteristics for different phases of operation, transforming the fixed-parameter spring system into a variable-parameter actuated system that adapts to operational requirements
2Force
If an actuated hip joint is used to reduce forward torque, then torque control is improved, but power consumption increases and heavy batteries are required
Solution Approach 1:
The patent uses a counterweight mechanism to generate passive gravitational torque that counteracts the forward torque from the tool. This passive counterweight system reduces the need for active actuation, thereby lowering power consumption while maintaining effective torque control. The actuator only needs to make minor adjustments rather than continuously fighting gravity
Solution Approach 2:
The counterweight system provides self-service by automatically generating counteracting torque through gravity without requiring continuous power input. The system uses the user's own body weight and the counterweight's gravitational force to balance the tool's forward torque, reducing dependence on powered actuation
3Force
If heavier counter weights are installed to provide necessary torque, then torque balance is improved, but the exoskeleton becomes heavier and harder to move
Solution Approach 1:
The patent changes the moment arm length parameter to reduce the required counterweight mass. By increasing the moment arm length, the system achieves the necessary counter torque with less mass, directly resolving the contradiction between providing sufficient counter torque and minimizing exoskeleton weight
Solution Approach 2:
The patent introduces asymmetry in the hip joint positioning, placing it forward of the user's hip joint to create an asymmetric moment arm configuration. This asymmetric placement optimizes the torque balance by leveraging the user's body mechanics and reduces the counterweight mass needed, thereby reducing overall system weight
4Force
If longer moment arms are used with lighter weights, then counter torque is achieved, but maneuverability in confined spaces is reduced
Solution Approach 1:
The patent applies dynamics by making the moment arm length adjustable rather than fixed. The system can dynamically change the moment arm length to be longer when counter torque is needed and shorter when maneuverability is required, resolving the contradiction between achieving sufficient counter torque and maintaining maneuverability in confined work environments
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
This design reduces counter torque needed to hold tools or backpacks, decreases user fatigue, and enhances mobility by reducing the mass and protrusion of counterweights, while also lowering power consumption in actuated systems.
Implementation Method 1
This produces a forward falling torque about the exoskeleton hip joint that must be resisted by the user
Implementation Method 2
A counter torque can be produced with a range of weights and moment arms
Data Source
Figure 1a~1b
Figure 2a~2b
Figure 2c~2d
AI summary
An exoskeleton device (103; 113; 302; 402) provides for selectively adjusting an exoskeleton hip pivot/pivot position (109; 119; 306; 407; 408; 410) in the sagittal plane relative to the position of the hip pivot (133) of a wearer (101; 111; 301; 401) of the exoskeleton (103; 113; 302; 402). The exoskeleton hip pivots/pivot positions (109; 119; 306; 407; 408; 410) can be shifted forward or rearward relative to the hip pivots (133) of the wearer (101; 111; 301; 401) and can either be automatically actuated by an exoskeleton control system or manually adjusted by the exoskeleton wearer (101; 111; 301; 401). The invention particularly allows for differential hip placement in order to compensate for changing load or actuation conditions.