Remote Operated Survalence Vehicle
Project - ROVER
This project was completed awhile ago now but I never got round to posting it.
I set myself the target of building a radio control vehicle that was small, silent and could carry a small wireless camera. (I know what your thinking, I didn't design it to spy on people or pretty women in the changing rooms! Although that is an INTERESTING thought). Back to the design; it also had to be able to be flipped over and still be operable. As for night time use, a row of White Led lights would be used to illuminate objects for the camera. I suppose I could have used IR leds as the camera is able to see that, but they aren't very powerful illumination and consume alot of power (measured 1 IR Led: 3v @ 400mA!, where as a white Led is about 3v @ 90-100mA).
The parts used:
- 1x Rear drive section and differential from a Tamiya Fighter Buggy
- 1x Tamiya 540 Sport tuned motor
- 1x Ripmax Volcano ESC controller (fwd,rev,brk)
- 1x Wireless 2.4Ghz camera and reciever
- 1x 9v PP3 for camera power
- 6x 2200mAh 1.2v sub C cells for main battery (7.2v)
- 4x chrome proline 2.2" rims mounted with dirt hawg/spike tyres
- 1x Acoms BEC 27mhz reciever and transmitter
- 8x 17000mcd high brightness white LEDs
- 2x switches for leds and camera
- 1x Futaba standard servo
- 2x front axles/carriers from traxxas nitro buggy
- 2m Steel 8mm rod, small sheet of perspex and some aluminium sheet 1mm thick
So that was the shopping list, I had most of the bits from my RC hobbies, the camera from ebay, the LEDs from ebay and the steel rod from a hardware shop.
I manufactured the chassis frame from steel rod by bending it to my desired shape and welding support braces joining the two sides. This was fairly easy and this was only my second Arc welding project! Not bad hey! The length of the chassis is 22cm and has an indented bump on either side to allow the car to get over high objects on both sides. The chassis was then sprayed with silver paint to stop it rusting.
Next up was the front steering rack and uprights. This was tricky in that you I had to work out the angles for the wheels to turn sharply and not get caught. The uprights/axles are from another car which made it easier. The servo for steering sits behind the steering rods and is connected with ball joints.
The rear gearbox casing was easy to do as it was already made! (easier than trying to make one I can assure you!) This just sits between the to sides of the chassis and is bolted at the top and bottom.
I covered the chassis in aluminium sheet which was hand formed and drilled/bolted to the chassis frame. The top is held with 3 posts and 3 "shell clips", bent paper clips! I gave the top a nice piece of speaker grill that is stuck on the inside and cut out eclipses on the top.
For the front I used perspex so the camera could see and was protected from head on collisions.
As for the electronics side of the construction, the electronic speed controller is mounted in the center of the car (orange and blue) and is very easy to use, just plug in, setup and it's ready. I have electronic brakes (uses the motor back emf) and have full proportional forward/reverse. The reciever is just any standard 2ch reciever, although make sure the antenna goes straight out of the chassis and up the antenna tube as the chassis conducts interference from the esc and motor (it's happened to me!).
The camera was a little more difficult as when it was all mounted first time I ran the entire car from the 7.2v pack. I switched it on for a trial run, driving around the garden and watching the tv picture, I noticed it was all screwed up when the motor was running! How annoying! I brought it back in, made a small pi filter network, but still no good. Back in again and this time the motor got some filter capacitors to the metal can. Still no luck! The solution was to run the camera from a seperate 9v supply. (the camera should work from 6v-12v, but obviously the drain from the motor knocked it out).
The battery is mounted at the rear (green) and the reciever is mounted under the 9v (black).
The battery was custom made for the size of the chassis by me. 6x 2200mAh Sub C batteries were purchased and were soldered together to make a 7.2v hump pack battery.
For the LED spotlights, I used an automatic switch on circuit. It uses a 741 op-amp and an LDR to switch on the LEDs when it goes into a dark corner. Cool hey! My LED switch has 3 positions, off/on/auto. Can't remember the exact circuit but it's simple enough (search google or radiolocman.com). This also controls the rear red LEDs, so you can tell way the car is round at night!
Speed: roughly 20mph (faster than I had hoped for something this size, very fun though!)
Dimensions: 29cm long, 28cm wide with tires; 12cm wide, 23cm long chassis
Weight: about 1kg
Charging: I use a 7.2v peak fast charger, it takes about 1 hour to fully charge and lasts about 30mins at full.
This is was a fantasic project and I still use it today. Ever since I built the mini micro (rc section) I've wanted to build a faster car and have an onboard camera. Ok it's not smaller than my mini micro truck, it's about twice the size, but to be able to flip over I had to design it to fit within the wheel dimensions (less than 2.2" thick) and that meant all the electronics would be spread out.
As for survalence, I can sit in my room (or at uni!) and drive around outside the building and be watching the TV picture. The look on people's faces when they see this thing and no driver is golden!
If you would like any more detailed information on this project, email me and I'll be glad to help.
The finished Pics: (click to enlarge)
If you build one of these, I would love to hear from you to know how you got on!
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© Oliver Hunt 2006-2011