# Advice Needed - Device to Move the User Up and Down 0-2"

Hi All,

I'm a programmer, but have limited experience in electronics. I want to create a device that you can place on top of a chair that the user can sit on (hopefully low profile) that will move the user up and down at varying heights of 0-2" at varying speeds.

I'm not sure if this is best done with a motor and a mechanism to translate the rotation into up/down movement attached to a seat and a base, an actuator attached to a seat and a base, or an inflatable cushion which will pump and and release at the desired heights and intervals. I would say the speed needs to range from between 1 and 5 times a second. User weight should be up to about 200lbs.

Any advice would be great, thank you.

You might want to do some floor loading calculations as moving that much weight at 5Hz is going to require a significant amount of reaction force. In addition high amplitude vibrations from 1-5 Hz will probably cause walls, windows and the ceiling to resonate, possibly destructively.

For a non-precision application truck air bags might work. If precision is required you'll need hydraulics (expensive) or mechanical heavy engineering such as a rotating cam.

Moving 200 pounds up and down 2". Moving up requires 400 inch-pounds-force. That converts to 45.19 Newton Meters.

5 times a second. That's 200 milliseconds per cycle. Let's say 150 up and 50 down since it should be easier to drop than to lift. 45.19 Newton Meters over 0.15 seconds is about 300 Newton Meters per Second, a.k.a. 300 Watts.

That's about 0.4 horsepower so look for a 1/2hp AC motor.

Assuming I have my conversions right.

I appreciate the replies, thank you. I think I read somewhere that the mobility scooter motors are about 1/2 hp, so maybe that would be an inexpensive route to prototype. Truck air bags is also an interesting idea, but how would you inflate/deflate quickly enough? Thanks so much!

I seriously want to know the purpose of this proposal!

Paul__B:
I seriously want to know the purpose of this proposal!

Rule 34

Paul__B:
I seriously want to know the purpose of this proposal!

Haha, I agree it sounds a little suspect but it's not XXX related. Basically I want to prototype a device to see if moving the user up and down a small amount during locomotion in VR reduces motion sickness.

vinceherman:
Rule 34

Well!

Thatâ€™s certainly new to me!