Views
« Back to the SERA Actuator home page
This design was the first design proposed and was based on talks between Professor Pratt and Gui Cavalcanti regarding the limitations Gui found in building a biped with James Whong, another Olin student. Gui completed this design independently from the rest of the team, and therefore it had limited electrical design, anticipating it would be connected to a standard motor controller.
Contents |
Mechanical Design
The design consists of a motor connected to a spur gear train to reduce speed. The gear train feeds into a hexagonal shaft which is mounted on thrust bearings. A worm sits on the shaft and is able to move axially but is between Belleville washers which provide the compliance of the actuator. The worm gear is connected directly the output shaft. The worm was free to move between the springs on the shaft.
Problems Faced
The design suffered from large amounts of stiction due to the design of the spur gears. Furthermore, the tolerances on the frame were too large for the design to function well. The sensing of the linear position of the worm gear went undesigned and therefore there was no way to the measure the torque at the output shaft. Finally, the hex shaft would have worn out rather quickly due to the transmission of torque through its edges.
Design iteration considered: Magnetic coupling
Gui considered putting a ring magnet between the worm and Belleville washers to change the axial constraint on the worm, but this was not used in future designs.
Copyright Notice
The contents of this page are Copyright © 2007 Matthew Aasted, Guilherme Cavalcanti, Jeffrey DeCew, Christopher Dellin, Gill Pratt, Kevin Sihlanick, and Jon Tse.