https://pvela.gatech.edu/classes/ 2026-04-08T20:06:36+00:00 https://pvela.gatech.edu/classes/ https://pvela.gatech.edu/classes/lib/exe/fetch.php?media=wiki:dokuwiki.svg text/html 2024-08-21T01:38:56+00:00 Anonymous (anonymous@undisclosed.example.com) https://pvela.gatech.edu/classes/doku.php?id=ece4560:piktul:01calib&rev=1724204336&do=diff Piktul: Calibration Activity Every robot needs to be calibrated in some manner or another. This activity is about doing that for the small planar Piktul robot that you'll be working with first. A huge chunk of the information can be found in the manipulation interface documentation page which includes both the Matlab files you'll need to proceed plus the instructions for how to connect and calibrate the text/html 2024-08-21T01:38:56+00:00 Anonymous (anonymous@undisclosed.example.com) https://pvela.gatech.edu/classes/doku.php?id=ece4560:piktul:02fkin&rev=1724204336&do=diff Piktul: Forward Kinematics Compute the forward kinematics of the Piktul manipulator. The home configuration should have the robot arm straight out and up at some height. Doing so defines the zero transformation for the rotational joint variables. The linear joint coordinates should go to whatever value is specified (for these zero as a length should be sensible). Most of the piktul robotic arms can't quite manage a zero gripper height (except for one or two of the super-saggy ones), and it … text/html 2024-08-21T01:38:56+00:00 Anonymous (anonymous@undisclosed.example.com) https://pvela.gatech.edu/classes/doku.php?id=ece4560:piktul:03invkin&rev=1724204336&do=diff Piktul: Inverse Kinematics Using the link lengths for the forward kinematics, work out the inverse kinematics for the piktul end-effector. That is, given $(x_e^*, y_e^*, z_e^*, \theta_e^*)$, figure out a joint configuration $\vec \alpha$ that places the manipulator end-effector there.. The height part is easy, since that is determined by $\alpha_1$$\alpha_2$$\alpha_3$\begin{equation} \theta_e = \alpha_2 + \alpha_3 + \alpha_4 \end{equation}$\alpha_2$$\alpha_3$$\alpha_4$$\theta_e^*$\begin{equ… text/html 2024-08-21T01:38:56+00:00 Anonymous (anonymous@undisclosed.example.com) https://pvela.gatech.edu/classes/doku.php?id=ece4560:piktul:04pnp&rev=1724204336&do=diff Piktul: Pick and Place ---------- The value of a robotic arm is in its ability to perform repetitive movements with high precision. The ability to do so is called repeatability. Part of the high cost of robotic machines lies in their extremely high repeatability combined with the high precision. Some robot arms are accurate down to sub-millimeter and have a reach that spans a couple meters, which means that their accuracy is a fraction of a percentage relative to their overall length (less th… text/html 2024-08-21T01:38:56+00:00 Anonymous (anonymous@undisclosed.example.com) https://pvela.gatech.edu/classes/doku.php?id=ece4560:piktul:05resratepos&rev=1724204336&do=diff Piktul: Resolved Rate Position Movement ---------- This module explores trajectory generation using the Jacobian. The objective here is to create a trajectory for the arm to follow, at only the position level. As the piktul manipulator space has equal dimension to the $R^3$$\alpha$$180/\pi$ text/html 2024-08-21T01:38:56+00:00 Anonymous (anonymous@undisclosed.example.com) https://pvela.gatech.edu/classes/doku.php?id=ece4560:piktul:06resratevec&rev=1724204336&do=diff Piktul: Resolved Rate End-Effector Movement ---------- In the previous adventure module, the position of the end-effector was controlled to follow a trajectory. Naturally, since the final joint variable controlled the orientation of the end-effector only (e.g., was a pure rotation), it did not figure as part of the resolved rate trajectory.$SE(2) \times \mathbb{R}$$SE(2)$$g$$g = (x, y, z, \theta)^T$\begin{equation} \dot g = \left[ \begin{matrix} \dot x \\ \dot y \\ \dot z \\ \dot \theta \en… text/html 2024-08-21T01:38:56+00:00 Anonymous (anonymous@undisclosed.example.com) https://pvela.gatech.edu/classes/doku.php?id=ece4560:piktul:calibrate&rev=1724204336&do=diff Lynx6 Calibration The manipulator setup function is called piktul_calibrate and is what you should invoke to first get acquainted with the manipulator. The idea behind calibration is that the servo commands go from 500 to 2500, but as a user you'd like to be able to enter joint commands in more sensible units (like degrees or inches). Therefore a linear mapping is needed to go between the desired joint configuration (in degrees or inches) and the actual servo commands. The way it is done i… text/html 2024-08-21T01:38:56+00:00 Anonymous (anonymous@undisclosed.example.com) https://pvela.gatech.edu/classes/doku.php?id=ece4560:piktul:interfacing&rev=1724204336&do=diff Manipulator Interface Code: Execution This section further discusses the interface code, beyond the calibration variables. The code described here should not be run until AFTER you have configured and calibrated the manipulator and the piktul m-file. text/html 2024-08-21T01:38:56+00:00 Anonymous (anonymous@undisclosed.example.com) https://pvela.gatech.edu/classes/doku.php?id=ece4560:piktul:issues&rev=1724204336&do=diff Having Issues with Piktul? Introducing a piece of technology into the class can be a big pain. There are a few ways to do things properly, and lots of ways to head into the non-functional realm of things. Here are a few things that can lead to non-functional: text/html 2024-08-21T01:38:56+00:00 Anonymous (anonymous@undisclosed.example.com) https://pvela.gatech.edu/classes/doku.php?id=ece4560:piktul:setup&rev=1724204336&do=diff Piktul Setup This page describes how to get it connected up and ready for use through Matlab. After the calibration step, interfacing the manipulator is done through a piktul class file. If you have Matlab on your laptop and would prefer to use it in the lab rather than the lab computers, then feel free to do so. However, that would most likely mean that you will need a USB-to-Serial converter. I have some in my office and will try to remember to bring them in. To be safe, just e-mail me a…