Collision Detection Objects interfering with the path of the station should be detected at least five feet away. Upon detection, the station should be able to reroute its path around the object to continue tracking the user within a minute of encountering the interfering object. Collision detection should interrupt current tracking process to reroute vehicle. Collision detection should not be employed while the user is controlling the vehicle with the remote control feature. Software The autonomous framework of the system should be dictated by a single microcontroller. The microcontroller shall be programmable using the high level C programming language. The system shall respond to user commands via Android Smartphone application. The user’s Android application shall include a handheld remote control feature to manually guide the station as a fail-safe to autonomous tracking. The Android application shall be available on the Android market for any user to download. The Android smartphone should communicate with the vehicle via Bluetooth. The range of communication between mobile phone and vehicle should be at least 20 feet. Budget The entire unit and parts for all subsystems shall not exceed $2500 in total costs. Pre-purchased or pre-owned parts should be incorporated to the design to reduce costs. Parts shall be both cost-effective and affordable, without sacrificing reliability and performance. Durability The system should be weather resistant and still operable in the presence of mild rain. Parts shall be easily replaceable if broken or damaged. The system should be operable at temperatures as high as 90 degrees and as low as 50 degrees. The vehicle shall be operable on grassy and concrete terrain without imposing any damage to the unit.
Supply Voltage: 3.2-3.4 V Integrated antenna Output Power: 1dBm Size: 26 x 14 x 2 mm Bluetooth Receiver Selection The RN-42 and Bluegiga WT12i are very similar in most aspects and they both would work for ultimate tailgate station. They both are class 2 receivers and have the same interfaces. The current draw is also comparable. The RN-42 is nearly half the price of the WT12i and that is the main reason that we are going with the RN-42 for the vehicle. Bluetooth Receiver Integration The ultimate tailgate station will use the Bluetooth receiver at all times. The station will need to use an android phone for GPS tracking and remote control. The android phone sends signals to the Bluetooth receiver, and then the receiver will send those signals to the master microcontroller. The Bluetooth receiver will be connected to the master microcontroller using a serial connection. Since there is only one serial port on the master microcontroller, a certain baud rate for the connection will need to be set. Otherwise, the master microcontroller may have the Bluetooth receiver and the motor controller set on the same baud rate. The Bluetooth receiver will be connected to the master microcontroller directly. It will use the UART port to connect to the master microcontroller. User Tracking One of the most important subsystems of the project is the user tracking subsystem. It requires that the vehicle calculate its distance and direction from the user in order project its appropriate path. To do this, different location based sensors or methods must be considered. A decision must be made based on which sensor best adheres to the requirements listed in the introduction of this paper. Particularly it is desired that the sensor detect the user from at least 20 feet away and follow with an accuracy of five feet. Keeping these specifications in mind, the following methods for user tracking are considered.