Group F
ENGR 1182
Dr. Busick
1 March 2018
Lab Report
Contributers: Ryan Stuckey, Jack Wagner
Motivation:
The Advanced Energy Vehicle (AEV) is a light weight vehicle that runs on a monorail and is move along in either direction by dual electric propellers. While these propellers provide an efficient method of propulsion, they do not provide a way to brake. This is what the power braking research and development aimed to fix. By using the servo motor, a brake could be created that would “squeeze” the monorail between a brake “arm” and the pulleys on top of the AEV.
Research:
Before creating a brake arm, it had to be decided how it would work, where it would be placed, and what the most efficient, reliable way of producing the brake arm was. The first question was fairly simple to answer; the brake arm would be most effective when it pushed on the opposite direction of the pulleys (See Figure 1).
After deciding where to place the brake arm, the placement had to be chosen. Because of the nature of the servo motor, a position had to be chosen where the arm could swing up and into position. The placement of the brake arm was also affected by the places in which the servo motor could be mounted, as it was not extremely easy to mount due to only having two mounting holes, both of which were in inconvenient positions. After much thought, it was initially decided that the servo motor would be placed to the left of the L-support arm. However, mounting the servo arm here would require the addition of parts, which would add more weight, and the use of tape, which was unconventional and decreased the aesthetics of the advanced energy vehicle. Finally, after some brainstorming, the idea of laser cutting a slot in the L-support arm was brought up. This slot would allow the servo to be vertically inserted and secured with the included screw holes (See Figure 2).
Finally, a method of producing both the brake arm and the new L-support arm had to be chosen. 3D printing the brake arm would provide a reliable way to produce the brake arm while also keeping costs down. And the new L-support arm, because it was modified from the old one, could be laser cut to match the specifications seen below. The below image of the new support arm was produced and refined in SolidWorks.
The last part of the initial design phase was to decide how the brake arm would be designed. After some thought, a design was chosen that would fit around the monorail. However, because it would be 3D printed with polylactic acid, a common type of 3D printing plastic, the brake arm would have a low coefficient of kinetic friction. To fix this, the brake arm would then be fitted with a material with a higher coefficient of kinetic friction. After the initial brake arm is produced, the team will test various materials to determine which material is best at stopping the AEV. Three different versions of the brake arm were made, with each one improving on the functionality and overall aesthetics of the AEV (See Figure 3, 4, and 5). Each version of the brake arm was designed and implemented into the AEV using SolidWorks (See Figure 6).
The brake arm would have two principal positions- on and off. The angle between these positions would be about 15.2° (See Figure 7). When applied, the brake arm would make contact with the monorail, in theory stopping the AEV in a short amount of time. After the brake arm is printed and implemented, tests will be made to observe how the brake arm changes the stopping time of the AEV.
Evaluation:
While the propellers provide an excellent way of propelling the AEV, they are unable to stop it efficiently because of their design. Using the servo motor allows a brake arm to be implemented, improving the safety and efficiency of the vehicle by providing a method of braking. Using SolidWorks, the team was able to produce a brake arm that will be 3D printed in the future. The brake arm will then go through testing in order to improve its efficiency and functionality.
Tables and Figures
Figure 1: The brake arm will provide a force opposite to that of gravity, thus “squeezing” the monorail and stopping the AEV.
Figure 2: The L-support arm is seen above, with the original shown first and the new arm shown second below.
Figure 3: The initial design of the brake arm; as seen it is rather “clunky” and visually unappealing.
Figure 4: The second iteration of the brake arm; from version 1, the method of attachment to the servo motor was changed and a section was cut out to make room for the servo motor.
Figure 5: The final design of the brake arm. The edges were filleted to give it a more round and appealing look. Also, between versions 2 and 3, the hole was cut in the support arm, changing the design of the brake arm.
Figure 6: The final design of the brake arm attached to the AEV. Notice the placement of the servo motor within the L-support arm.
Figure 7: The brake arm has a range of about 15.2°, as seen above away from the rail and below flush with the rail, at its two main positions.
