Combination of Quadrature and Absolute Encoder
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citrusying
- Posts: 4
- Joined: Wed Jul 18, 2018 10:50 am
Combination of Quadrature and Absolute Encoder
Hi
I am using 2 DC motors with quadrature encoders (Motor 1 and 2) with a RoboClaw 2x30A. Unfortunately Motor 2has a suspected faulty encoder such that the encoder counts do not increase with the motor shaft rotation.
To circumvent the issue, I would like to explore using a standard potentiometer as an absolute encoder for Motor 2 while keeping to the quadrature encoder for Motor 1. In that case, I would use the wiring diagram for quadrature encoder wiring for Motor 1 and absolute encoder wiring for Motor 2. Will this be a problem for RoboClaw to function? For this potentiometer (https://uk.rs-online.com/web/p/potentiometers/1548183/), its max voltage is 5V, is it still necessary to include a resistor? If so, how should I determine the type of resistor to use since I would also be using 1 potentiometer instead of 2?
Thanks.
I am using 2 DC motors with quadrature encoders (Motor 1 and 2) with a RoboClaw 2x30A. Unfortunately Motor 2has a suspected faulty encoder such that the encoder counts do not increase with the motor shaft rotation.
To circumvent the issue, I would like to explore using a standard potentiometer as an absolute encoder for Motor 2 while keeping to the quadrature encoder for Motor 1. In that case, I would use the wiring diagram for quadrature encoder wiring for Motor 1 and absolute encoder wiring for Motor 2. Will this be a problem for RoboClaw to function? For this potentiometer (https://uk.rs-online.com/web/p/potentiometers/1548183/), its max voltage is 5V, is it still necessary to include a resistor? If so, how should I determine the type of resistor to use since I would also be using 1 potentiometer instead of 2?
Thanks.
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Basicmicro Support
- Posts: 1594
- Joined: Thu Feb 26, 2015 9:45 pm
Re: Combination of Quadrature and Absolute Encoder
Potnetiometers have a limited amount of turn. Some as little as 90 degrees. Some are multi turn but still a limited number of turns. If you application only uses that amount of range then there shouldnt be a problem. You can set one encoder to quadrature and the other to absolute(eg analog).
You do still need the resistor. The analog inputs on the Roboclaw have a range of 0 to 2v. The resistor is there so the pot will produce a full range(0 to 2v) approximately. If you dont use it the pot will use 0 to 5v and anything above 2v is simply clipped so you lose alot of range on your pot. In that 2v range roboclaw has 11bits of resolution(2048 descrete positions).
You do still need the resistor. The analog inputs on the Roboclaw have a range of 0 to 2v. The resistor is there so the pot will produce a full range(0 to 2v) approximately. If you dont use it the pot will use 0 to 5v and anything above 2v is simply clipped so you lose alot of range on your pot. In that 2v range roboclaw has 11bits of resolution(2048 descrete positions).