Blogpost Speed requirement (L2-6)

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Written by: Fabian Suske

Edited and approved by: Carolina Barrera

Table of Contents

Intro:

In order to fulfill the L2-6 subsystem requirement “speed” a test has been carried out. This test followed the Verification and Validation Test Plan. The speed is mainly a requirement that was generated to make an effective system that would allow the user to bring the food elements to the mouth-level and back to the table to roughly complete the mission in the average time to eat a meal.

 

Test Objective:

The test criteria that needs to be tested in this test is the following:

“To successfully verify the L2-6 (Speed) requirement, the Prosthetic Arm shall be operable by the user at a pace of ten “lifts” (ie. movement from resting position on table, to flexion point required to reach mouth) within 8 minutes.” [1]

 

Therefore 10 movements of 120 degrees needs to be completed in under 8 minutes since 60 degrees is our range of motion.

Since the arm utilizes a stepper motor -which gives precise control over the movement (angle, steps), a test algorithm has been set up that moves the arm 10 times up and down in a specific period of time.

Test Method

The test was set up in the following way:

  • C Program to control the movement
  • The prosthetic arm with a mounted forearm
  • Smartphone as stopwatch
  • Camera to document the test

Process

Since the arm is going to be moving from the table to the mouth level to reach the food and feed it to the mouth, there were three demos performed in which the team measures 60,__ and __ degrees going down and up. The idea is that if the team is able to complete the moves under the time stated in the requirement then the requirement will be evaluated as aa pass.

  1. For this test, the forearm and the bicep needed to be assembled together. The initial angle is the angle closest to the bicep.
  2. A code was implemented so the motor run 60 degrees down and back.
  3. For the other two angles, the same procedure of steps 1 and 2 were implemented

 

Test Conclusion:

The arm needed 4:06 minutes [2]to complete the task. Since the allocated time for this requirement was 8 minutes, the prosthetic arm came in slightly over half of the time. Therefore the test is 100%completed.

Resources

[1] https://drive.google.com/drive/folders/0B3qlnfB-grPcVzJOTTZyemZ2R3c

[2] https://www.youtube.com/watch?v=VoRxWJ_K93U&feature=youtu.be