Mitigation - Improvising and Adapting

With the realization that the locking mechanism was not going to be working as intended, a significant redesign was required.

We turned back to our initial design matrix, to see what other forms of lifting mechanisms could be used.

With deadlines fast approaching, it may be too difficult to work out a complete redesign to incorporate pneumatics, and sourcing cables would also require significant redesign of mounting elements and the actual purchase of the cables themselves. The Lead Screw idea, which was initially ranked last in our matrix, scored very high in the durability, which we now realize is a factor that should have been weighted more heavily. Additionally, with the lead screw mechanism, most of the design can remain relatively the same, with a few changes made to the webs for proper constraining and mounting of the motors.

Additionally, because the motors we had were not able to provide a large amount of torque, we had to also consider suitable motor replacements.

First we considered the 28byj-48 stepper motors.

Pros Cons

- Easily Available From Amazon - Large profile size

- Very high amount of torque (64 reduction gearbox) - Heavy

- Not too expensive (~6$ per motor) - Very slow (1 min/in actuation)

While this motor seemed promising, it was very slow, and speed was an important criteria for our project, thus we chose to keep exploring more options.

We soon found a different stepper motor, KP35FM2-035, a stepper motor made by Japan Servo Co.

Pros Cons

- Easily Available From Sayal Electronics - Very Large profile size

- Moderate amount of Torque - Very Heavy

- Good speed (~5s/in actuation) - Somewhat costly (~8$ per motor

To compare these two motors, a decision matrix was used.

While the KP35FM2-035 was heavier, more expensive, and lower torque, it was still somewhat close to the 28byj-48 in these factors. However, it was so much faster in actuation, and with speed being a very important criteria for our project, the KP35FM2-035 was chosen as the motor for the project.

Here is an evolution of the motors we have considered throughout the project:

The next steps involve carrying out the required redesigns to incorporate the new motors, and the threaded rod mechanism. While the locking platform did not go at all according to plan, we were able to improvise and adapt to the problem, and have come up with a serviceable solution.