Wednesday, November 30, 2016

New Robotic Arm with Dynamixel servos

During the last year and some months I was getting my Master degree. As part of the embedded systems class, I created a Robotic Arm that could write some letters. Pretty cool, right?

The arm has 3 Degrees of Freedom (DOF) using Dynamixel RX-10 servos. I controlled the robot with a Beaglebone Black board with a cape that has a MAX485 chip. This chip converts UART TTL communications to RS-485 differential protocol (used on the Dynamixel servos). Also. I had to create some drivers for the controller to speak Dynamixel language (specific data frames format) on the communications bus.

For the arm to reach some point in 3D space, I programmed the kinematic equations that translated this desired point to a set of angles for the servos. I used the equations proposed by Núñez et al on the paper “Explicit analytic solution for inverse kinematics of Bioloid humanoid robot” (IEEE paper site).

Also I created two trajectories generators: one for free trajectories (moving from 1 point to another without care of the described trajectory) and one for linear  trajectories (moving between 2 points describing a straight line).

Finally I programmed the a routine on the robot using these trajectories functions, so it can describe some letters on a vertical plane. Here's a video of the robot:

The code for the project is found here: project link.
Also here is the technical document for the project (in spanish): document link

My github site: