For participants only. Not for public distribution.

Note #15
Front, rear, and top subassemblies

John Nagle
Last revised February 3, 2003.

We can make this project much easier to build by constructing three subassemblies: the front bumper unit, the rear bumper unit, and the top unit. Each unit starts from an off-the-shelf bolt-on truck accessory, to which we add sensors. The subassemblies can be built separately from the work on the truck and bolted on later. So we can spread the work out. Here's the basic concept, which needs to be firmed up.

Front bumper unit

Start with a heavy-duty brush guard. Add sensors

Short-range stereo camera 1, at top center
Main VORAD antenna 1, at license plate.
Aux side VORAD units 2, on wings.
Ground microwave rangefinders 1, center, pointed down.
Water sensor 1, center bottom
Ground microwave rangefinders 2, ahead of each wheel.
Emergency stop buttons 2, on wings.

Top unit

Start with a heavy-duty roll bar. Add supports and protection for the laser rangefinder(s), which will be partly over the cab, but supported by the roll bar.

Laser rangefinder 1 or 2, at top center
Camera for road-following 1
Wipers/washers as required

 

Rear bumper unit

Start with a heavy-duty bumper. Add sensors.

Aux side VORAD units 2, on wings.
Aux rear VORAD units 2, pointed backwards
Emergency stop buttons 2, on wings.

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The front bumper unit is the most critical, with the most sensors. It needs to be very rugged. This is where BattleBots expertise will be really useful. We need two, so we'll have a spare in case we break one in testing. If anything gets bashed, it's going to be that unit.

The wiring for each subassembly should come out at a single point, so we can have a wiring harness connection to the vehicle. We'll also need to make up a standalone test rig for each subassembly.

In addition to the sensors, each unit may need its own ruggedized "small computer", to collect most of the sensor wiring into a single Ethernet connection. That may be in the bumper, or elsewhere.

The Eaton VORAD anticollision system illustrated parts list shows their sensors. VORAD has a main antenna which must be placed at the front license plate position, and little microwave rangefinders for protecting The "microwave rangefinders" ahead of each wheel may also be VORAD units, or we may use something else like this back up sensor. (Those units are for creeping forward under difficult conditions.)

The "stereo camera" referred to will probably be the Point Grey "Bumblebee". We'll have to protect it, perhaps by mounting it inside a Lexan cylinder. We may need to provide it with a moveable protective cover to keep it clean; it's only used when creeping forward over a steep rise, where we can't see the other side, and for other slow-speed situations.

The bumper pictures above are for illustration only, they're not parts choices.