|M.Sc Student||Keren Roee|
|Subject||Theoretical Investigation of the Dynamics of Spring- Clutch|
Mechanisms for Reducing Energy Expenditure in
|Department||Department of Mechanical Engineering||Supervisor||Professor Yizhar Or|
|Full Thesis text - in Hebrew|
In this work we analyze the energy performance of adding a mechanism of spring and clutches into two simple theoretical models of a walking human, aiming to reduce the energy consumption while walking.
In the first part of this work, we utilize an existing model that represents a walking human with an elastically suspended backpack as a two-mass system. The model, suggested by Ackerman and Seipel , considers only the vertical motion of the body and the backpack, while the legs and the elastic suspension are each represented by linear springs and dampers. We extend this model by adding a clutch mechanism with a trigger that allows the relative distance between the body and backpack to be locked. We analyzed the system with the spring-clutch mechanism, its stability, preferred suspension parameters and optimal lock-release timing of the clutch that allows minimal energy expenditure while walking. We find that using the mechanism and correctly timing the clutch often reduces the energy expenditure of walking with a backpack.
In the second part of this research we analyze a model comprised of five links representing a human walking in the sagittal plane with bulk torso and point feet. We add to this model a spring-clutch mechanism that connects fixed points in the shin and thigh links. This mechanism represents wearable external elastic device with the added property that the spring can be locked during walking. locking the spring holds the spring under load and released later in the walking cycle to use the store potential energy. We try different spring parameters and clutch switching timings to reduce the energy expenditure of the walking human.
From analysis of these models we conclude that a spring-clutch mechanism with proper timing can be used to improve energy efficiency of human walking.