Design 3.2

For the second and final iteration of design 3, we decided on simplifying the project once again, and utilizing a set of four servo motors with the use of a clutch transmission setup, similar to one found manual automobile. In essence, the fixed gears and freely rotating gears would remain the same as before. However a sleeve would be fitted around the fixed hub gear at all times. Given the signal to engage, a servo, connected directly to fixed rack and pinion would push the sleeve to mesh with freely rotating gear. Once in contact, both the fixed hub gear and freely rotating gear would be rotating simultaneously, thereby effectively engaging the appropriate shaft.

This was an effective design, however despite its canny similarities to manual transmission, our design did not take into consideration the use of synchronizer rings. We decided this would likely be unnecessary since our system would be moving at rather low speeds (motor input was 30rpm at most), and because we were constrained by a deadline and could not afford to overcomplicate the system.

 However, there was one issue with this design. We would not be able to have the base and arm shafts rotating at different speeds. In order to accomplish this task, we would need an infinite range of gear ratios. In other words, a continuously variable transmission. Again, we decided on not following this route due to lack of manufacturing time.

Picture below is the initial version of this design using a push pull solenoid in place of a servo powering a rack and pinion. We later realized that a push-pull solenoid would likely face overheating issues so the servo system would be more efficient.