Welcome to the wiki page of Team 7! Our autonomous project consists of 4 parts which are indoor autonomous driving, outdoor autonomous driving, parallel parking and stop sign recognition. In this wiki page we are going to walk you through our autonomous vehicle designing process.
(Jerry) Yihui Yang
OE - Output enable. Can be used to quickly disable all outputs. When this pin is low all pins are enabled. When the pin is high the outputs are disabled. Pulled low by default. The 12.4V Lipo battery supplies power to the Electrical Speed Controller (ESC), The relay and the Raspbberry Pi.To power a raspberry Pi, a 12V to 5V step down is needed and the output will be from a USB port so that it can power the Raspberry Pi directly. The battery power goes to a switch and then goes to the RF controlled relay, which serves as an emergency stop switch of the entire system. The COM pin of the relay is connected to the 3.3V pin on the Raspberry Pi which provides the “high logic”. The NO pin stands for the “normally open” which controls logic level for the red LED. The NC pin stands for “normally closed” which controls logic level for the blue LED and it is connected to the output enable “OE” pin on the Pulse Width Modulation (PWM) module which disables the PWM pins on logic high. With this circuit built, we are able to shut down the steering and throttle control using a remote control. OE - Output enable. Disables all output pins on logic high Battery powers RPi thru a “step-down” converter Battery powers ESC, which controls DC motor Battery powers RF relay, which is a part of the emergency stop button Red LED is on when PWM is disabled, blue LED is on when PWM enabled PWM module controls servo motor Problem encountered: Broken RF Relay :( Partial power failure :(
Calibration Values After assembling the vehicle, the circuit and installed Donkey. We were able to calibrate the steering and throttle with PWM values as follow:
Steering: Neutral 330 Left 240 Right 420
Throttle: Neutral 360 Forward Min 370 Forward max 450 Backward min 290