The team originally planned to test the servo as a brake directly and the prototype brake to examine the efficiency of each brake. However, the prototype brake was not completed in time for initial testing, so only the servo was tested as a brake.
Figure 1: Prototype brake.
Pictured above is the prototype brake developed by Yuqing. The brake will be attached to the servo motor and tested to determine if it is able to be used as a brake for the AEV.
Figure 2: Laser cut arm
Pictured above is a prototype arm that was designed to hold the servo. The servo will be able to come into contact with the brake so that it may be used as a brake. The servo functioned by using electrical pulses to determine which position to rotate to [1]. For more information on how a servo motor works, check out the video below!
Figure 3 demonstrates the increase in energy necessary to rotate the servo 90 degrees. This accounts for the additional energy, on average, required for the runs where the servo is applied as a brake (Figures 4 and 5).
Figure 3: Power Input with and without the Servo Brake
Figure 4: Energy Cost without Servo
Figure 5: Energy Cost with Servo
While the servo requires additional energy, Figure 6 demonstrates the servo’s ability to stop quickly and accurately, even when travelling at high speeds. As a result, the servo serves as a brake and method of stopping accurately. Therefore, the servo increases the AEV’s safety.
Figure 6: Speed and Stopping Distance after brake is applied with the Servo
References:
[1] Jameco.com. (2019). How Servo Motors Work | Servo Motor Controllers. [online] Available at: https://www.jameco.com/jameco/workshop/howitworks/how-servo-motors-work.html [Accessed 21 Mar. 2019].