Remote controlled vehicles are a particularly onerous design problem. Since they move the RF link is constantly under duress and could be stretched to the limits of its reliability at any moment. There is also the condideration of the following paradox.

If the vehicle is designed to STOP when the RF link goes down in an attempt to make the vehicle safe so that it does not accidently run down the design engineer then it stops in its track right where it stands! The in-path person is thus safe.

On the otherhand if the RF link breaks right as the huge remote controlled vehicle is turing around at the end of the field, using a public roadway as the turn around zone, just as a school bus load of kids is barreling down the road at full speed, the vehicle has STOPPED because the link is down. Is that a correct design assumption?

--------------
Operation of vehicles, motorized rigs, and conveyances is basically unsafe even with sane, fit, sober/drug free human beings at the controls. It is really necessary to take this into consideration when trying to make a remotely piloted vehicle. Contrary to my earlier comment about using a single channel RF link I would suggest that a redundant channel should always be available to be used as a backup should the primary channel fail to perform as expected. It would also be best if the secondary channel used a different technology as well. If example if a 480 mHz FM channel was used for the primary data link then it may be a good idea to use a low frequency AM link for the backup scheme. I would also suggest that at all times the design of such vehicles be "remote comntrolled" via a human being operator that has a visual link with the vehicle at all times as opposed to trying to implement an "auto pilot" type of control.

Michael Karas