Princeton University Prospect Eleven Nov. 17, 2005 Vehicle Interface Already substantial electronic information available from the vehicle itself: Engine status –temp, RPM, diagnostic codes,... Transmission – what gear are we in? 4 WD on/off Car traction control –are wheels slipping, are we really moving? Wheel speed/odometry – how far have we moved? how fast? All of this can be utilized with little additional effort. Throttle also already electronic

Princeton University Prospect Eleven Nov. 17, 2005 These inputs come in a variety of forms— Digital : Straight pulses, e.g. from wheel encoders –As wheel turns, a digital line pulses to indicate revolution –Tens to thousands of ticks/rev → Read with a counter circuit Serial data: car’s onboard computer, OBD-II → Read with a dedicated decoder interface A bit-code: transmission position –e.g. “0110” for park, “0111” for drive → Read the digital signal directly

Princeton University Prospect Eleven Nov. 17, 2005 The tension reported by a sensor on the brake line –Resistive load cell produces a voltage proportional to force → Use an Analog-to-Digital converter to read value directly The voltage sent to throttle the car → Use a Digital-to-Analog converter to create the desired voltage Analog: a voltage level of significance

Princeton University Prospect Eleven Nov. 17, 2005

Princeton University Prospect Eleven Nov. 17, 2005 Other thoughts