Mini Rover Redux

We’re using Scientific Toys’ EZTEC-branded 1:17 scale Chevy Silverado R/C car as a camera platform. This toy is cheap, hacker-friendly, and works astoundingly well for the price.

First, detach the truck body shell from the chassis by removing 3 screws: 2 on top, in the truck bed, and 1 from below, between the front wheels.

Now, open the electronics compartment by removing 4 screws, as shown, and lifting the plastic cover gently up and off. The floppy wire antenna, which is threaded through a hole in the cover, should slip out the bottom as you do this.

Position the video camera mounting base on the car’s electronics compartment cover, as shown. Use the base as a template to drill 3 matching 5/32″-diameter holes in the electronics compartment cover.

TIP: You may find it easier to operate the drill through the baseplate if you remove the camera mount ball joint at the top of the stem first. Simply turn the wingscrew all the way out and the whole assembly will come off.

Turn the electronics compartment cover over, and attach three 10cm standoffs on the top side of the compartment cover using the screws that come with the standoffs.

Route the antenna back through the port in the electronics compartment cover, then reattach the cover to the car chassis using the original screws.

Thread the floppy antenna through the plastic guide tube bundled with the car. Slot the tube into the antenna port to keep the antenna aerial in upright.

If you want to make cosmetic modifications to the chassis, now is a good time. I didn’t like the bare plastic color of the antenna aerial tube, so I covered it in black heat-shrink tubing. I also painted the wheel hubs flat black to cover up the shiny chrome.

Install batteries in the car and the controller. Though they’re more expensive, I like to use NiMH rechargables for R/C applications because they usually have greater capacity than alkaline cells, and are more environmentally friendly.

Turn on the car, grab the controller, and try it out! Note that the controller uses no power when it isn’t transmitting, so it has no on/off switch.

Secure the camera mounting base to the 3 standoffs on the car chassis using the standoffs’ bundled screws. These are nice because they have built-in lock washers to keep things from loosening up due to vibration.

Mount the camera to the base, as specified in the camera directions. Turn on the camera and turn on the base unit. If the camera and base unit are charged, you should see the video feed right away.

If you don’t see the video straightaway, plug the camera and/or the base unit into mains power, using their bundled adapters, and try again. If you still can’t see the feed, follow the manual directions for “pairing” the camera and the receiver.

To mount a second camera, we need to widen the chassis a bit. We’ll use a simple black plastic project enclosure, which will allow us to mount everything neatly and provides a handy “payload” space for other equipment.

Demount the camera from the ROV, and then remove the mounting base. Use the mounting baseplate as a template, as before, to drill a triangle of 5/32″-diameter holes in the center of the enclosure lid, as shown.

Mount the lid, lip up, to the chassis hardpoints, using the screws bundled with the standoffs.

Now, arrange the 2 camera bases as far apart as you can on top of the enclosure box, as shown, and use them again as templates to drill six 5/32″ holes in the plastic. Set the mounts aside, and step-drill these holes up to 5/16″.

Fit a rubber grommet into each of the 6 holes in the top of the project box. These will reduce strain on the mounting platform when the ROV is bouncing around in motion, and prevent the mounting nuts and washers from vibrating loose.

Align the camera mounting bases over the grommet-protected holes and pass a 6-32 x 3/4″ machine screw through each. Secure each screw inside the box with a flat washer and a hex nut, and tighten down securely. Don’t be afraid to crank down on the grommets a bit — that’s why they’re there!

Fit the project box top, with mounted camera bases, over its lid, which you secured to the R/C car chassis in the previous step. Use the screws bundled with the project box, and tighten them down with a Phillip’s head screwdriver.

Install the cameras on their mounting bases, power them up, and pair them with the receiver per their instruction manuals. There are several interesting ways to use a pair of cameras, and which you choose will affect both how the cameras are aligned on the car frame, and which camera is assigned to which radio channel. See below for details.

Wide-angle binocular vision. Angle right and left cameras out to each side by about 30°. The left camera should be assigned Channel 1, and the right camera Channel 2. View them side-by-side by setting the receiver to “Quad” mode. Together, the 2 cameras provide a much more natural 120° field of view.

Back-up camera. Point the left-side camera forward and the right-side camera to the rear. Alternate between them, as necessary (e.g. when reversing the car), by cycling between the 2 channels on the receiver. It doesn’t really matter which camera goes on which channel in this mode.

Stereoscopic 3D. Set both cameras facing forward at the same angle and elevation. If you know how to view stereograms, you can set the receiver to “Quad” mode and view the video feeds either as parallel or cross-eye stereo video, for a full 3D roving experience!