Roboclaw Solo 30A Problems with Feedback and Range

Questions about using encoders with the Roboclaw product line
Post Reply
bearbait
Posts: 13
Joined: Thu Oct 19, 2017 11:41 pm
Roboclaw Solo 30A Problems with Feedback and Range

Post by bearbait »

I am using a roboclaw solo 30A device (software 4.1.23) to control a Gimson GLA 750 linear actuator with a built in 10k potentiometer for feedback. The control also uses a 10k linear pot.
Power is from a 12v 10Ah SLA battery.

Problem 1:
Encoder connection 1A (pin 9) reports no input from feedback pot. In order to get any reading from this pot I have to connect to encoder connection 1B (pin10). I then have to swap the encoder inputs in IonStudio (V 1.0.0.55). This is not mentioned in the data sheet or user manual. Is this normal? If it is, it should be documented properly.

Using this method I can then gain control, calibrate the feedback pot and get a speed reading of approximately 500 to use for QPPS using the slider in PWM settings. The feedback pot range is from 90 (retracted) to 1750 (extended), adequate for my purpose.

Problem 2:
I have tried to autotune the position controls without success. I then tried to set it manually and ended up with the following parameters:
Velocity PID 0, 0, 0
QPPS 400
Position PID 4000, 10, 1000
Max I 0
Dead zone 10
Min Pos 100
Max Pos 1700

Using Packet Serial and position settings I can fully control the actuator using the motor 1 slider.
If I change to analogue control I cannot get the actuator to fully retract. It stops at approximately 945 units even though the control pot input is definitely 0v (I have checked). The feedback reported range is then 1750 down to 945.
Why is this?
Regards
Bearbait
Kind regards
Bearbait
User avatar
Basicmicro Support
Posts: 1594
Joined: Thu Feb 26, 2015 9:45 pm
Re: Roboclaw Solo 30A Problems with Feedback and Range

Post by Basicmicro Support »

1. I will look into this and see what is going on. The Solo is basically the same processor as the Dual units but some I/Os are disabled. It sounds like we have the 1A/1B labels swapped and the Enc1/Enc2 labels swapped(internaly). Sirry about the trouble on that and glad you found the problem.

2. Autotune does not usually work well with linear actuators. You will usually need to manually tune linear actuators. However in most cases the loading and friction in a linear actuator is such that all you need to set is the approx QPPS and a reasonable P value for position control. I do NOT recommend using a cascaded PID(PIV) for linear actuators. If you have any trouble manually tuning it call in and I'll help you tune it. Should not take long as long as you are all setup for testing.

3. When you set the input mode to Analog the Roboclaw sets the zero point on power up(eg the current position on the analog input will be 0). You can disable the autocalibration by checking the MCU checkbox in General Settings. This will disable the 0 point and range autocalibration which may be what is causing your last problem.
bearbait
Posts: 13
Joined: Thu Oct 19, 2017 11:41 pm
Re: Roboclaw Solo 30A Problems with Feedback and Range

Post by bearbait »

Thanks for your timely response. Is this a new product?
:)
I have now managed to calibrate and tune the unit sufficiently well. It will have to be repeated when under load in the final design.
I have also ticked the "MCU" box which seems to have cured the anomalous position behavior.
Kind regards
Bearbait
User avatar
Basicmicro Support
Posts: 1594
Joined: Thu Feb 26, 2015 9:45 pm
Re: Roboclaw Solo 30A Problems with Feedback and Range

Post by Basicmicro Support »

Yes. The Solo models are pretty much brand new.

Post Reply