Limitations on space and power mean that limb joints for robots and prosthetics must be highly optimised for mechanical performance in areas such as stiffness, strength, friction , mechanical advantage, backlash and endurance. Biological joints me remarkably compact and long lasting and therefore it is desirable to produce bio-inspired of joints. This thesis presents a bio-inspired joint for robotics and prosthetics which is based on the human knee joint. The novel condylar joint has the same desirable features as the human knee joint including compactness is, high mechanical advantage: high stiffness and locking in the upright position. The condylar hinge joint has a mechanical advantage that is greater than that for a pin-jointed hinge by up to 35% which means that the actuator force can be reduced by up to 35% for squatting type movements. A design process has been developed for designing a condylar hinge joint for different applications. This is non-trivial because for each four-bar mechanism geometry and femur profile theme is a unique profile of tibia that has to be determined. ,ln addition, if there are constraints on the size of the tibia then it is necessary to have an iterative design process. A |Matlab code has been developed to generate the tibia profile from an animation of the four-bar motion. Parametric performance maps have been developed for two particular femur profiles. These maps show how performance varies for different four-bar mechanism geometrics. Four measures of performance are modelled which are peak mechanical advantage, RMS mechanical advantage, slicing ratio and angular range. Over 12,000 design cases have been modelled and these arc presented on a total of 44 design maps. A full size prototype has been built and tested for stiffness, friction and endurance. Additional rapid prototyping tests have been conducted in order to assess the feasibility of rapid joint construction for prosthetics.
| Identifer | oai:union.ndltd.org:bl.uk/oai:ethos.bl.uk:619141 |
| Date | January 2013 |
| Creators | Etoundi, Appolinaire C. |
| Publisher | University of Bristol |
| Source Sets | Ethos UK |
| Detected Language | English |
| Type | Electronic Thesis or Dissertation |
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