What can I use instead of a motor?

[JTsyo]

Working on a design right now that has a motor to actuate a mechanism. The mechanism only has 100deg of freedom so I don't think a motor is the optimal driving source. Is there such a thing as a circular piston or such? The design needs about 1Nm (0.738 ft-lbf) of torque.

Providing feedback to the control system is a bonus. That would save from having to design something to measure and provide feed back.

 

[Mark R]

servo-motor?

The working range and torque vary according to model. As they are servos, they include feedback (the input signal is position, the motor will then automatically drive to the programmed position). A simple electronic circuit or microcontroller can be used to generate the input signal.

A typical cheap servo motor ($5-10) from a toy shop would offer about 270 degrees of motion, 10-20 N-cm torque and a rotation speed of about 1000 deg/s, with positioning accuracy of better than 5 degrees.

These are a standard industrial part available in a wide variety of performance/torque/speed/movement range/etc. grades, should you need something better than a toy grade part.

 

[CycloWizard]

By 100 degrees of freedom, you mean that it can only rotate 100 degrees? There are plenty of cheap motors with built-in encoders and controllers that can limit rotation within this range, depending on the functionality you need.

 

[JTsyo]

By 100 degrees of freedom, you mean that it can only rotate 100 degrees? There are plenty of cheap motors with built-in encoders and controllers that can limit rotation within this range, depending on the functionality you need.

yea, the two phrases kind of merged. The only degree of freedom is rotation and that is limited to 100deg.

 

[CycloWizard]

yea, the two phrases kind of merged. The only degree of freedom is rotation and that is limited to 100deg.

Here is a really cheap ($20) simple one that will do 0.75 N-m. There are plenty of others (I just googled "100 degree rotation motor" to find this one), and there are other non-motor possibilities, depending on your application. I think a motor will be your cheapest, simplest, and most reliable option though.