Objective: To determine if power braking is enough of an improvement over coasting to justify the cost in energy.
Coasting Code:
celerate(4,0,30,2)
goFor(3)
brake(4)
Power Braking Code:
celerate(4,0,30,2);
goFor(3);
reverse(4);
celerate(4,0,30,2);
brake(4);
Coasting Data:
Forward distance after motors shut down:
| Round # | Distance traveled (Marks) |
| Round 1 | 287 – 193 = 192.8 |
| Round 2 | 287 – 192 = 194.9 |
| Round 3 | 287 – 193 = 192.8 |
| Round 4 | 287 – 201 = 176.4 |
| Round 5 | 287 – 185 = 209.2 |
Total distance traveled: 966.2 marks
Figure 1: DAT Plot of Power vs. Time (Coasting)
Power Braking Data:
Forward distance after motors begin reversing:
| Total distance (IN) | Forward distance (IN) | Breaking distance | |
| Round 1 | 340 – 141 = 199 | 287 – 141 = 129 | 199 – 129 = 70 = 143.6 marks |
| Round 2 | 335 – 143 = 192 | 285 – 143 = 142 | 192 – 142 = 50 = 102.6 marks |
| Round 3 | 335 – 142.5 = 192.5 | 285 – 142.5 = 142.5 | 192.5 – 142.5 = 50 = 102.6 marks |
| Round 4 | 320 – 143 = 177 | 278-143=135 | 177 – 135 = 42 = 86.1 marks |
| Round 5 | 305 – 135 = 170 | 270 – 135 = 135 | 170 – 135 = 35 = 71.8 marks |
Figure 2: DAT Plot of Power vs. Time (Power Braking)
Analysis:
Pros and cons of power braking and coasting:
While both methods of breaking have a high degree of precision when the battery is fully charged, power braking appears to be more reliable in later trials. The main benefit of coasting is that it requires no energy to bring the AEV to as stop. It should be noted that due to outside factors, later trials began and ended at different points on the track. Because the track appears to sag between supports, it has slopes that vary slightly over a given distance which may have made the change in starting points significant.
Chosen method:
The team will be moving forward with power braking. The long term increase in precision was determined to outweigh the relatively small cost in energy.