Linear Actuator with Jrk serial command, speed, power supply


I’m using the Generic Linear Actuator (4" Stroke, 12V, 1.5) with the Jrk 21v3. I want to use the serial command pololu protocol to drive the jrk with an arduino.
Till now everything is working fine (Motor On/Off, set target, …).
Now I have 2 questions to go on:

  • I want to change the speed of the linear acturator during runtime. I haven’t found any command for this. I can change the Max. duty cycle at the Plololu Jrk Configuration Utility from 600% to e.g.300% to reduce the speed. But I would like to do it during runtime with the serial interface (from arduino).
    Is there any possibility?

  • I want to monitor the 12V supply voltage. I am think of using LiPo’s for the power supply. So it would be good to know the actual voltage. It is possible to read internal variables from the jrk over the serial command like the actual position. But I havent found some informations about the power supply. Is there an internal variable I can read?

Thanks in advance
and best regards

Hello, Christian.

There is not a way to change the maximum speed or read the input voltage using serial commands.

One way to change the speed on the fly would be to not use the PID control feature of the jrk and have the feedback mode set to none (speed control mode). With your Arduino, you can then directly read the feedback of the linear actuator, implement a PID control loop, and send serial commands to the jrk to drive the linear actuator accordingly. You might find the Arduino PID Library helpful for implementing a control loop.

Since you are already using an Arduino, you might consider reading your battery directly using a voltage divider and one of the analog inputs on your Arduino.

- Jeremy