How do robotic arms/joints know what position they are at?

[Robit1769]

I guess I am interested in the various electronic means of finding out how a robotic joint relays positional information back to it's control unit.

 

[BvU]

Google position sensor

 

[Bystander]

Can you constrain your question? Data formats from sensors? Sensor types?

 

[Robit1769]

Bystander, I should let you know, I'm pretty unfamiliar with robotics. I guess, I am looking to create a small robotic arm, capable of being precisely manipulated. I am looking to familiarize myself with methods that will allow me to do this.

Sensor type: something cheap and obtainable. Something that will fit into a relatively small rig.

 

[Bystander]

https://en.wikipedia.org/wiki/Control_theory Make any sense? This is to give people on the forum an idea of what level of assistance you're seeking.

 

[berkeman]

I guess I am interested in the various electronic means of finding out how a robotic joint relays positional information back to it's control unit.

Welcome to the PF.

Google position sensor

Good advice! When I googled Rotational Position Sensor, the first non-ad hit on the list was this good introductory tutorial:

http://www.electronics-tutorials.ws/io/io_2.html

 

[256bits]

Stepper motors to move the joint could be used. In which case a feedback sensor to the controller could be used to verify position, but can also, and usually is, as operating from input from just the controller without feedback.

 

[donpacino]

typically for robotic joints encoders will be used.

 

[Nidum]

Problem is that a simple jointed arm robot is a bit like a new born donkey when you start it up - legs everywhere .

One of the considerations when designing motion control systems is how to register the position of all moving components at start up . This means either using absolute encoders which always return the true position or simpler encoders which use a homing procedure to initialise position .

Accurately positioning the working end of a jointed arm robot is not straightforward and can be very computer intensive .