Hopkins wrote:
> There is a system called dead reckoning in witch you start your robot
> of at a know location and us a gyro to sense every movement along with
> a distance recorder

Actually that's called "inertial navigation".

> The Gyro will give you an output that can be translated into degree's.
> I have seen cheap gyros sold for robot systems.
> I do not know how accurate they are but could be a starting point.
>
> This is a simple system and with an accurate gyro & distance recorder
> you will have accurate results.

This is downright silly for an affordable lawnmower system.

Note that position is the double integral of accelleration.  Any
accelleration measurment error will therefore result in a position error
proportional to the square of the elapsed time.  Not good.

As an exercise, think about navigating a lawn mower to a flower bed just
10 meters away.  To simplify things, just consider movement along a
straight line, meaning the problem is only about a single accelleration
sensor.  Make resonable assumptions about the lawn mower's speed and
accelleration/deceleration capability.  A) Report the accuracy required of
the accellerometer to achieve 500mm position accuracy at the flower bed.
B) Report on the cost and availability of such an accellerometer.

For extra credit: For $100 or less in sensors, how many seconds will the
lawnmower run before its inertial navigation system becomes useless?


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