Performance Test 2

Performance Test 2

 

Situation

The team completed performance test 2 in the previous weeks. Since the team found out that the propellers used in previous design cannot offer enough energy to the AEV to drag the model AEV up to the inclined track even under 90 or 95 percent of power, the team changed the propellers on the AEV and therefore went through a major change on the percent of power used in the Audrino code. This change can be seen in the Appendix A : Audrino Code. The change on the percent of power output is the adjustment to the new propeller and is not related to the core change made on the code to improve the performance of the AEV.

In performance test 1, the group used basic Audrino code to control the AEV. There was no codes relates to immediate brake. The Code Series 1 follows the method used in performance test 1 and from Code Series 1 in  , it can be seen that the code simply have brake(4) after goFor(x). The group suggested that according to the code, the AEV is supposed to stop right after finish climbing the inclined track and reach the flat track, and use inertance to finish the rest of the distance before the sensor and stop. The group than set the motor speed output to 1, which is too low to start the motor and can make the AEV “stop” and wait for 7 seconds in front of the gate with the following line goFor(7). The AEV then should travel a certain amount of distance and brake, and use inertance again to travel the rest of the distance and attach to the model AEV in the loading zone.

Since from the observation, the group found out that the distance the AEV travel with   inertance is  not easy to control and therefore the distance AEV travel with Code Series 1 is not consistency and varies a lot in different run, the group decided to develop a new code that can help the AEV to brake immediately, and reduce the influence the AEV’s inertance has on the total distance the AEV travel. The group added reverse to realize this function, since reverse will give AEV a force on the opposite direction from its original speed and therefore the AEV will have a negative accelerate speed, when the negative accelerate speed is large enough, the AEV’s speed can decrease to zero quickly, and if the motor can be broke down exactly at the time when the speed is zero, the AEV can stop immediately. The team also tested the AEV for several times to adjust the speed, the distance and the time used for each line to get a code that can let the AEV perform comparatively consistent. The code can be found in Code Series 2 in Appendix A : Audrino Code.

To compare the performance of AEV with different code, the group did multiple adjustments on Code Series 1 and Code Series 2 to reach comparatively consistent performance and then ran the AEV for 6 times for each code, and recorded the distance between the mark line and the position they stopped.

The group tested the voltage of the battery during the experiments. The change of the voltage is about 0.2V, whose influence on the AEV’s performance can be ignored according to the Battery Testing lab’s result.

 

Result & Analysis

Figure.1 : Distance AEV travels without Reverse()

Figure.2 : Distance AEV travels with Reverse()

It can be seen from the Figure.1 : Distance AEV travels using code without reverse  that the distance AEV travels with Code Series 1 is quite random and don’t have a certain increasing or decreasing pattern. From the distance AEV slide in the loading zone, it can be seen that AEV hit to the model AEV on the track and travel with the model AEV for the most of the runs completed with the code without reverse. Since the AEV need to run down a slide after passing the gate, and the resistance force is small enough to be ignored on the steel track, it can be suggested that the AEV accelerate while sliding down even the motors stop and therefore can’t stop by itself quickly after run on the flat track again and has a high possibility to hit the model AEV in the loading zone. Which is contrary to the team’s goal to ensure the safety of the AEV.

Compared to the Figure.2 : Distance AEV travels using code with reverse, it can be seen that the AEV stop in the range of 3.8cm on the part before the gate and a range of 4.0cm after the gate, which is small compared to the range of 15.2cm and 13.1 cm for the Code Series 1, the code without reverse. The performance of the AEV is consistent and pass the test successfully at a rate of 83.3%. This result proves that reverse is useful for immediate brake and should be used for forward experiment.

Although from the Figure.3 : Energy consumed for both code, it can be seen that code without reverse use less energy than code with reverse, the team still choose to use code with reverse for the safety.

Figure.3 : Energy consumed for both code

Takeaways

From the experiment, the team got the conclusion that to ensure the distance the AEV travel and the consistency of the AEV’s performance, the Code Series 2, the code with reverse to ensure the immediate brake of the AEV.

There are things need to be improved in the code. First, the AEV’s performance is still not consistent enough with the reverse, and stopped before attaching to the model AEV in one of the run, which can lead to serious safety issue since the AEV will travel with a high speed without the model AEV and will crash to the gate on its way back. More codes should be added to ensure this kind of situation will not happen.

The team faced a difficult situation to meet in previous weeks since teammates were all busy for the final month and the team was trying to contact each other through text more frequently and figure out how to distribute assignments through text or before the lectures to make the teammates’ time more efficiency. This is proved to be useful as teammates were used of the job from previous assignments and can help the team to keep going in the final weeks.