Suspension adjustment of an "off-road" robot

Hi,

I'm working on a project named ALR2 (autonomous long range rover), based on
a 1/10 scale off-road RC car (traxxas e-maxx) and I would like your opinion
on how to ajust its suspension in order to carry robotic payload. I've came
up with my own way of doing it, but I'm still open to other solutions that
may be easier or more efficient.

The goal is to have the rover carry the required payload at reasonable
speeds (about 10 mph) over rough terrain with a good suspension dampening
These [electric] cars have individual suspension for each wheel (actually
two shocks per wheel), but the problem is that they come adjusted for
racing, not for carrying payload. In order to carry my stuff around (cpu,
batteries, sensors, microcontrollers, etc - estimated worst case of 8Kg) I
need to adjust the suspension by replacing the springs and shock oil. I
already have a set of springs and oil of different thickness.

I came up with an idea on how to test which setup is more appropriate
without having to devise complicated mathematical models for each one of the
shocks.

Here's what I'm doing: I've installed 3 LEDs on my rover of different
colors. All three leds are pointed to one side of the rover. LED 1 is
positioned in the front, LED 2 in the rear and LED3 on the camera platform
(that is 6 inches higher than the rest of the rover).
In my garage, I've put a few obstacles of different sizes in the rover's
path, and then at night I use a 35mm camera to take a picture of the rover
going through the obstacles. I open the shutter before the rover starts
going through the obstacles and close it after the rover went through the
bumps. (I was a professional photographer, so photo technical details are
under my domain).

The result is a picture with 3 line on it. Well, if the surface is flat and
acceleration/braking isn't too heavy (causing the nose to go up under accel
or the front to dive on braking), then the two LEDs positioned on the rover
base will overlap.

I guess it works (I've already took a series of pictures with the rover
without load), the goal is to find one suspension setting that under desired
load, produces a picture where LED lines are more or less straight.

The drawback of this method is that I'm comparing suspension settings on a
very limited scenario (artificial bumps on a 15ft route), do you think this
would be enough? Any other ideas?

I'll post some pictures somewhere after I finish my testing.

Padu
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