Controlling Gripper Closure

[SEATIGER]

I've been trying to design a manipulator for my project, but cannot figure out how to control closing the gripper. I originally planned to use a standard DC motor and some worm gears.

What would happen if I inadvertently tried to over-rotate the gripper mechanism once it was fully open or closed? If the gears were strong enough to sustain the force would the motor burn up applying a constant load without the shaft spinning?

I will have kids using the ROV consistently and am worried that the gripper could be damaged. I looked into servos, but do not want to use a computer for control. Is there anyway to control servos without a computer? Ideally I'd want to use a joystick for arm movement and buttons for open and closed.

[fluffy111]

You can measure current that flows throu DC motor. If it grab object to much, current rise. So you can use two buttons to close and to open gripper. I think that without any logic, you can not control underwater gripper. If the gripper is on shore, you can use end-switches and some relays.

With Arduino that will be simpl project. You must measure voltage drop on resistor (shunt, I think that every resistor from 10E to 15E will do as long it has 10W or more), and uC can calculate the current with ohm law.

Regards,
fluffy