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Week 9 (Oct. 24, 2018): Presentation #2 (Primary & Alternative Design Concepts) Reflection & Eliminating GPS as a Possibility

Earlier this week, to prepare for our presentation on October 24, I looked into different GPS modules. Unfortunately, I concluded that it was not possible to implement one. Recently, I learned in my ME 190 class (Mechatronics System Design) that GPS is not very accurate, as it does not have a fine resolution. Within a 10-meter radius, the satellite cannot distinguish whether the object is at the 1-meter mark or if it’s at the 9-meter mark; in other words, the object that the GPS is attached to will just be a big dot on the map. To illustrate my point, a map is shown below. The top image depicts the position of the GPS user represented by a large dot. That dot covers 10-meters, as the bottom image shows smallest measurement that that can be achieved by zooming in is 10-meters. After travelling nine-meters in one direction, the GPS has not updated the location of the dot. Additionally, the object would have to be travelling faster than 1 m/s; we aimed to have the podcar travel at around 1 m/s, so there is chance that the moving object will still not register on the GPS. Thus, while implementing the GPS would have solved both the collision-avoidance and the location tracking issue, it would not be a viable option for the small-scale model, as the entire track is about two-meters end-to-end.

 

Instead, we will be resorting to using one of the three options: (1) adding a second ultrasonic sensor to the front corner of the podcar, in addition to the sensor that is already on the front of the pod car; (2) installing an IR sensor array; (3) or using a time-of-flight sensor mounted on top of a servomotor to act as a makeshift lidar. Another thing to note is that, currently, the podcars act separately, with each podcar having their own Arduino to control it. If we were to install a centralized master control system that would control all the podcars, this could possibly solve both issues of collision-avoidance and location tracking. The centralized control system would be placed on a tower in the center of the track. A lidar, or if we’re resorting to the time-of-flight sensor mounted on top of a continuous rotation servomotor, would be connected to this central tower to continuously rotate 360 degrees and keep track of all the podcars’ locations. This is something to discuss about with the Small-Scale Track Team, and, should we decide it to be a good idea, possibly ask Dr. Furman about. 

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