Roboclaw Encoder question

Hi there.

I am using a Roboclaw 2x7A Motor Controller to control a Sito motor linear actuator with encoder (https://sito-motor.en.alibaba.com/).

I am hoping to these cylinders to respond like servos to PWM values in a large Hexapod. When using the PC software to control the actuator for some reason the values for the encoder only count down, regardless of direction. The sito motor company provides sparse information on what type of encoder this actually is but I am completely stumped as to how to determine its positon with this infinitely declining number?

Any advice would be much appreciated.
Thanks,

Hello.

It is difficult to tell what kind of feedback output that linear actuator provides from the link you provided. It is possible that the company that makes those has different configurations that have different types of outputs. How many pins does your motor have for feedback output? You could probe the feedback pins with an oscilloscope or (if you move the motor slowly) a multimeter to see how they behave. If the outputs are quadrature encoder outputs you should see two square waves on two different pins (which you can read more about in the Incremental rotary encoder section of this wikipedia page). If the feedback is an analog encoder or potentiometer, you should see a voltage on one pin that is high at one end of the range of the motion and low at the other end. The RoboClaw can work with either of those two feedback types.

-Nathan

HI Again.
So after some experimentation with an oscilloscope I ended up getting the Roboclaw to read the encoder Perfectly using an RC filter. Now im onto my second problem. I need the actuator to respond to PWM from a servo controller, which is achievable, but due to the unfortunate fact that it can’t remember its encoder positions during shutdowns I have moved toward the use of a homing switch. This works fine while homing the actuator while its plugged into a PC but it doesn’t work well at all when auto homing without a PC. I understand its running at %25 Duty cycle or something but it moves so slow it times out whenever it tries to home. This simply won’t do, and since I’ve ordered 14 of these roboclaws for my desired application it sucks even more. Is there a way it could home itself at a higher duty cycle? And perhaps with a longer timeout? I absolutely love the roboclaw and how capable it is, its just frustrating there are a few things (like homing duty and timeouts) that exist in the firmware and can’t be changed.
Please help resolve this problem

Hello.

I recommend contacting Ion Motion Control (the RoboClaw’s manufacturer) directly to see if there are any settings changes they can recommend for your application.

-Nathan