AEV Project Updates
Coasting vs. Power Braking
Coasting and Power braking are two of the methods of braking for AEV.
Coasting refers to switching off the motor so that the AEV gradually comes to rest; while power braking refers to reversing the direction of the motors so that the AEV comes to rest due to the opposing force of the motors. There are two factors that will be taken into account when testing the two methods:
- Energy consumption – the greater amount of energy that power braking consumes relative to coasting
- Distance in which the AEV comes to rest
The test needs to determine whether the extra control over the AEV’s motion afforded by power braking is validated by its energy consumption. The coding used for this test could be found at https://u.osu.edu/pcscottworldwide1/home/advance-energy-vehicle/codes/
Graph 1. Power (Watts) vs Time (seconds)
We have tested the AEV for both braking methods until results become consistent. The graph of Power (Watts) vs. Time (seconds) was plotted along with the data collected.
The area under the curve represents the work done in Joules by the motor. From the graph, we can see that the Energy (J) required during power braking is significantly greater than the energy needed during coasting. It can be concluded that power braking is less efficient than coasting.
We can conclude that
- Power braking is more energy efficient over coasting due to the fact that it affords greater control over the AEV.
- Even though energy consumption is greater in the case of power braking, the control that it provides over the AEV’s motion is imperative in reducing the time taken for the final run especially when the weight of the carriage is taken into consideration.
- Furthermore, alternate means of propulsion are being investigated that only require one motor thereby reducing the energy cost and compensating for the extra energy lost during power braking.
Energy Analysis
Potential errors of data were collected when the AEV do not run smoothly on the track. To avoid the data being affected by the error in testing the AEV, we reposition the AEV and test run it from the start again.
Coding used for energy analysis:https://u.osu.edu/pcscottworldwide1/home/advance-energy-vehicle/codes/
Sensor Test
2/10/2018
It was essential these sensors were tested to make sure they were working properly. A task was given where our group had to write a program and run the AEV. Line 1 of this task stated to “Run all motors at a constant speed of 25% power for 2 seconds,” which was programmed by the command The commands in this lab may limit the perfection of the AEV, but not necessarily the success of the AEV. The brake command may be a misnomer, as it does not brake the AEV. It cuts off power to the propulsion, whereby the supply of additional force to its impulse ceases. To “brake” the AEV, equal and opposite force must be applied to the AEV to reduce its momentum to zero. The main opposing forces would be friction and air resistance. Depending on the friction and resistance of the track, commands may need to be issued to pulse the motors in the opposite direction, to stop the forward motion of the AEV