Balance-Assistive Linkage With Lockable Joints for Fall Prevention
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Solution Overview
Problem
The degeneration of the human balance control system, often due to aging or pathologies, increases the risk of falls, which are a significant concern during rehabilitation therapy and daily living, with existing technologies failing to provide effective fall prevention.
Innovation Solution
A balance-assistive device with a support interface, sensors, and a linkage structure featuring independently actuatable lockable lower-pair joints that can rapidly transition between compliant and rigid states to provide support when abnormal forces are detected, using a controller to lock the joints and immobilize the system.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a rigid support structure is used to prevent falls, then fall prevention capability is improved, but user freedom of movement and comfort deteriorate
Solution Approach 1:
The support structure employs dynamically adjustable stiffness through lockable lower-pair joints that can transition between locked (rigid) and unlocked (compliant) states. During normal activity, the joints remain unlocked allowing natural movement. When abnormal forces indicating a fall are detected by sensors, the controller locks the joints to provide rigid support, thus adapting the structure's stiffness to operational requirements.
Solution Approach 2:
The system changes the mechanical parameter of joint stiffness by actuating braking mechanisms at selected lower-pair joints. The controller receives sensor data about forces exerted on the support interface and actuates the braking mechanisms to lock joints, transforming the support structure from a compliant state during normal use to a rigid state during fall prevention, thereby optimizing the balance between comfort and safety.
2Ease of operation
If a flexible support structure is used to allow movement, then user comfort and freedom of movement are improved, but fall prevention capability deteriorates
Solution Approach 1:
The support structure dynamically adjusts its mechanical properties through lockable lower-pair joints. During normal activity, the joints remain unlocked providing flexible support for comfortable movement. When sensors detect abnormal forces indicating a fall, the controller rapidly locks the joints to provide rigid support, thus adapting the structure's stiffness to operational requirements and ensuring fall prevention capability is available when needed.
Solution Approach 2:
The system changes the mechanical parameter of joint stiffness by actuating braking mechanisms at selected lower-pair joints. The controller receives sensor data about forces exerted on the support interface and actuates the braking mechanisms to lock joints, transforming the support structure from a compliant state during normal use to a rigid state during fall prevention, thereby optimizing the balance between comfort and safety.
3Reliability
If a complex locking mechanism is used to provide rigid support, then fall prevention capability is improved, but device complexity increases
Solution Approach 1:
The locking mechanism is segmented into multiple independent lower-pair joints, each equipped with its own braking mechanism. This segmentation allows the system to lock only the necessary joints to prevent falls while maintaining simplicity in each individual joint's design. The controller can selectively lock specific joints based on the detected fall direction and severity, reducing the overall complexity compared to a fully rigid locking system.
Solution Approach 2:
Different lower-pair joints are equipped with different properties (lockable vs. non-lockable) based on their specific functional requirements. The braking mechanisms are integrated locally at each lockable joint, allowing independent actuation and simplifying the control system. This local quality approach enables the system to provide rigid support where needed while maintaining simplicity in the overall mechanism design.
Data Source
AI summary
A device having a support interface and one or more sensors disposed to sense forces exerted on the support interface. The device includes a linkage structure having a plurality of lower-pair joints and a plurality of linkages. The support interface is coupled to one of the plurality of linkages. Each of the plurality of lower-pair joints couples two of the plurality of linkages such that the linkage structure defines a closed kinematic chain. A selected plurality of the lower-pair joints is a plurality of lockable lower-pair joints. Each of the plurality of lockable lower-pair joints has a locally actuatable braking mechanism that is actuatable independently of any other of the plurality of lower-pair joints.