# What is the Name of the part I'm describing

I'm looking for a part that will do a particular function. It has to be able to move along one axis and tell me the force that is being exerted on it.

Kind of how like a piston moves inside an engine (one axis of movement) except that something will be pushing at the top of the piston and I need to know how hard its pushing. Another difference is that the piston won't be constantly moving back in forth, but needs to be able to receive commands like. move x centimeters forward and then remain stationary at its new position.

I know to make this it would involved a sensor and something that can exert force but what is the name of the described machine?

Edit #1 - Response to Matthew Gordon

The piston would have to move between 0-6 centimeters. The form factor would be small, ideally smaller than the palm of your hand. (Smaller=better) The forces it would have to deal with are comparable to the forces exerted on a bicycle by its chain. I'm a math/cs person not engineering so I don't know technical terms for these kinds of things off the top of my head. It would have to be real time sensor reading, but the volume of data could be processed by a phone. Would have to working in conjunction with wireless communication, probably Bluetooth, but I'd have to look into the latency requirements to be sure.

• Do you have any specific information? The force measurement would be most accurate using a load cell or by strain gauging a mounting point, although you could infer it from hydraulic/air pressure if using an piston or electrical current if using a motor. Possible mechanisms for linear movement are, hydraulic/compressed air cylinders, lead screws, linear motors. Which solution you go for requires more information about loads, control resolution, cost, space requirements etc – Matthew Gordon Apr 8 '14 at 17:04
• Linear Actuator (with position feedback?), and maybe a load cell? – Andrew Apr 10 '14 at 8:01

## 2 Answers

It sounds like you're describing a linear actuator with a pressure sensor (or strain gauge) attached to the end.

To bridge that system across bluetooth, you may want to check out one of several microcontrollers -- look for bluetooth modules, a motor (or servo) controller, and analog inputs (to read the strain gauge).

• Yes, that is what I'm describing. Thanks! – Carlos Bribiescas Apr 8 '14 at 19:09

Linear servo actuator, combined with a load-cell, inline, to measure the load that is transferred between the actuator and the load that it is connected to.

The main advantage of a load cell is that it gives analog output (voltage) that can be sensed. They don't require bridges to convert weak signals to senseable signals as do the strain gauges.

This combination is used for advanced robots, that have to be rapid for better control and also especially for back-driving the robot's manipulators.