Biomechatronic System Design
Knee Exoskeleton Design
Overview
The following project highlights the design of a Hinged Knee Brace Exoskeleton aimed toward the demographic of children suffering from Cerebral Palsy.
The design encompasses a range of specifications to allow for assistance to the child with the motions of sitting, standing and walking and transition between them. Therefore, the overall design will assist and address the issue of motion being prohibited and limited with children that suffer from the condition.
The specifications of this design include the Knee Exoskeleton to be focused on the use for children of various ages and is capable of providing sit-to-stand and walking assistance. Furthermore, the design has the following primary requirements:
• Based on existing hinged knee brace.
• Minimise the amount of development.
• Adaptable to a wide range of children sizes.
• Lightweight and completely portable.
• Simple feedback and control mechanisms.
• Quiet and efficient.
• Powered by readily available energy sources.
• Low maintenance.
• Easy to repair.
• Low cost (manufacturing and market).
Approach
The knee exoskeleton design approach focused on biomechanical analysis and force reduction for children with Cerebral Palsy.
The design began by analyzing gait cycles and anatomical planes to understand knee movement mechanics, followed by calculating the specific forces and torques acting on the knee during various activities (sitting, standing, walking, and transitions).
The design incorporated a liquid spring hinge mechanism that functions like a shock absorber to reduce pressure on the knee joint, absorb body weight, and assist in knee extension movements.
This mechanical foundation was then enhanced with electronic components to create a complete mechatronic system.
The approach prioritized reducing the 400-500N force endured by the tibia during sit-to-stand transitions, addressing the increased energy expenditure (3-5 times higher) required by children with CP compared to those without, and providing adjustable support through the spring hinge system.
The University of Sydney
Vishant Prasad