This project idea stems from laziness to swing myself. I'd like to build something to keep my hammock swinging. I am fine with getting it going but I'd like to maintain the swing for as long as possible or indefinitely.
I am thinking about having a motor on the ground besides the hammock with a pulley on the drive shaft. Then have a rope attached to hammock and pulley. Wind the pulley and release.
Things I don't know:
torque requirements for the motor (I weigh ~150lbs)
how to time the winding and unwinding with the resonant frequency of the swinging. This would minimize energy consumption and result in a smoother transition in direction.
The motor can change rotation direction or there could be a fishing reel type of mechanism. Not sure yet..
Interesting project.
I think about a construction that moves me from the sketch production place to bed.....
Your project.....
If You have a motor sized like an oil barrel the matter is pretty much the angle of the swing. Just force the sofa up to the desired angle and drop it.
Using a more resonably sized motor You might need to check when maximun torc is reached and drop, if cource also watching the maximum angle.
Starting, running and stopping.. Classical terms for many processes.
A length of elastic rope / bungee code operated by an offset on the pulley ought to
make it tolerant of variations in position and limit the torque requirements. Finding the
natural frequecy of swing will allow much less power to be needed (once the swing has
built up).
A fairly large gear ratio would be needed to reduce the motor speed to the swing rate (which
will be of order of 1Hz)