See image for reference:

enter image description here

Essentially I have a robotic arm with two linear actuators. Lets say, for example, I wanted the endpoint on the arm (where you see the stepper motors) to move purely in the x direction (extending outwards). Both linear actuators would have to move in tandem with each other at the correct velocities to ensure that they cancel out each others y movements and sum up their x movements.

I have equations that relate the required angular velocity of each segment (and therefore velocities of each linear actuator) to get from point A to point B. I am just confused how to implement this now.

My electronics consist of an arduino and H-bridge. Feedback are potentiometers at the joints.

I'm just looking for general guidance on the procedure, as I am just not sure what steps I need to take here. I have taken a number of classes in control systems, but don't quite understand how to relate all the theory to practice.

  • $\begingroup$ This topic as already a few years but I am confronted to the same problem you had. Do you have any solution available as well as an inverse kinematic model for this arm ? I tried the DH method but I'm quite struggling with linear actuators that converts to an angle rotation. Thank you, $\endgroup$
    – Demipo
    Commented Oct 20, 2022 at 20:05

1 Answer 1


At a high level, you would need to do something like this:

  1. Create a kinematic chain the helps you map from the 2D configuration space (the position of the linear actuators) to the 3D task space (the position of the end of the robotic arm).
  2. Use inverse kinematics (IK) to figure out how the actuators needs to be positioned for a desired task space position. If you use a library like KDL to represent your kinematics, it is easy to use one of their inverse kinematic solvers.
  3. Write a controller that uses this IK solver to move the arm as needed... This part depends on how you are able to control your linear actuators. If your interface to these actuators is a position, identify a sequence of positions in configuration space that you need to traverse will end in the desired task space position.

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