stevez said:You might try something where the bed leg meets the floor. This isn't perfect or foolproof but it's simple and could be implemented without modifying the bed. If the bed has 4 legs the weight of the bed is distributed over all 4 legs. The weight on each leg depends on where the patient is - but a given leg would carry some increased load at all times. You might fashion something with a fairly stiff spring and microswitch.
Another approach - some of the structural members in a bed deflect sufficiently to displace a microswitch.
Yet another approach - stick on strain gages on a structural member. With this you should be able to see the presence of a patient. You might also easily see fluctuations if the patient were to have a seizure.