Drone Truck

I plan on taking a R/C Truck and making it autonomous. Parts I plan on using:

R/C Truck (T.B.D. on which one) Arduino UNO 2x MaxSonar EZ0

Is there anything else you guys think I need or need to know?

BTW This is my first experience with Arduino.

By “R/C Truck” - do you mean a toy R/C truck, or do you mean something like a hobby R/C truck (like a Traxxas or similar)?

If the latter, it will be an expensive option, but fairly easy to control (just use the Servo library, more or less - the rest is programming). If the former, though - then you will have to do one of two things:

  1. Hack the control system on the R/C vehicle - reverse engineer how it controls the motors and/or servos via on-board h-bridges and the like - not easy, but doable!
  2. Remove the control system, leaving bare wires to the motors (or other devices) that control the vehicle - then use purchased or custom-built h-bridge controllers and such to interface the Arduino to the motors (more expensive, but may be easier in the short run)

Note that for the above two options (that only apply to the “cheap toy R/C vehicle”, mind you), you are likely going to need additional components.

For that matter - you -are- going to need additional no matter what you do (you don’t mention wire, breadboards, other parts, solder, soldering iron, multimeter, etc - do you have all that, too?)…

Something to note about the Maxbotix sensors if you are planning on using their serial output (instead of the other options - which you might want to use instead) is that they output true RS-232 level serial voltages - not TTL serial (unless they’ve changed things since the last I looked). So if you are planning on going that route, you might need level shifters/translator ICs and such to interface them to the Arduino (look into the MAX232 line of conversion ICs - note these are not made by Maxbotix).


By R/C Truck I mean something like a $30 toy truck or something you can get from Goodwill. Is there any other sensors for obstacle avoidance that you could recommend?

I do have the solder, soldering iron, etc...

eberk_dankil: By R/C Truck I mean something like a $30 toy truck or something you can get from Goodwill.

Ok - then you are going to face the issues I noted before. If at all possible, you should try to "hack" the controller on the R/C truck. The best way to do this is to open up the vehicle, locate the PCB, and identify the wires from the motors (there will be two wires for the drive motor, and likely two wires for the steering motor - unless there isn't a steering motor; there may be a couple of electromagnets for steering, so there could be 3 or 4 wires from those). Once you've identified those wires, take a picture of everything, and start putting notes on the picture (a digital camera and MSPaint or similar will work OK).

If you can keep the wires attached while you investigate, that can be best - but you might find it easier (once you have noted everything down) to clip the wires from the control board (leave a little bit on the board so you can identify the wires by color - so when you later re-connect things, it will be easier).

You basically want to trace the wires from where they connect to the transistors (or IC) on-board the controller PCB that form the h-bridge that controls the relevant motor. If your steering system uses a motor, it will have the same arrangement (plus possibly a feedback potentiometer, or a couple of end-of-travel feedback switches - note these and their wires as well, if they exist). You will need to be familiar with how an h-bridge is designed (you might also want to familiarize yourself with half-bridge motor controllers as well - some companies use these to cut costs; look into how the old Milton Bradley Big Trak was designed for its motor controllers), so you know how to diagram and spot it. You're going to want to identify the transistors, so you can find the transistor base inputs (there will be four on a regular h-bridge), and where they lead. You want to trace them beyond the base bias resistor, and hook your Arduino's digital outputs to those. If you trace further, you'll likely find yourself in the output section of the radio receiver on the controller PCB; newer (made in the last 5-10 years?) toy R/C cars typically use one of a handful of "standard" R/C controller chipsets (they come in a pair - transmitter and receiver) - the receiver chip outputs a HIGH/LOW bit values to activate the h-bridge or other items on the vehicle (so if you see an on-board IC on the controller PCB - you might want to try to find a PDF of the datasheet online, and use that to forward trace from those outputs to the h-bridge, while you back-trace from the motors to the h-bridge to get a -complete- picture).

Once you know where the control points are, then you can isolate them, and isolate the h-bridge from the on-board controller circuitry, leaving the h-bridge powered and hooked up to the motors, and disconnected from the controller. Hook up your digital I/O pins from the Arduino (or, if you're squeamish - use a buffer IC or your own transistor to switch things) and tie the grounds together, then start coding. Remember that for all of this poking and searching, to use a multimeter to verify voltages and such (if you have the controller with the car - and can hook into the PCB, you can find/verify control points this way). Another handy tool to use is a scanner - scan the traces on the PCB, take a scan or photo of the "top" of the PCB, dim it (alpha transparency), flip and reverse it, and overlay it for an "x-ray" view of the parts and traces; then use the "fill" tool to fill in the traces to see where they go from part to part (you'll need photo-editing software for this; photoshop or the GIMP will work OK).

eberk_dankil: Is there any other sensors for obstacle avoidance that you could recommend?

Well - there's the Sharp IR sensors which can be used; plus there's the myriad of available ultrasonic sensors like the Parallax Ping and various "knockoffs" like the SRF04 ultrasonic sensor.

If you're going to goodwill, though - look around for Polaroid cameras - specifically the Sun 660 and the Spectra series. These cameras have a really nice single-element ultrasonic sensor in them, that has a fairly narrow beam and a good range. They are essentially the equivalent of the SensComp 6500 ultrasonic ranger. The only problem is that they are not friendly to interface to with the Arduino. There are some articles out there that detail it - back in the 1980s, these modules from the Polaroid cameras were used by just about every robotics hobbyist out there - do some searching on "Polaroid Ultrasonic Ranger Seattle Robotics" to find the best articles. One of the authors of the articles actually recently (last year, I think) in Servo (or Nuts and Volts - I forget which) showed how to hook the ranger up to the Arduino, and also gave code on it - so you might also look into those articles as well.