Capstone Project

• This repository records my implementation for the Capstone Project related with the book "Modern Robotics" along with its packaged course videos .
• The project requires us to write a software to plan a trajectory for the end-effector of youBot (a 5R robot arm articulated on a four mecanum wheels mobile base) to move a cube from one to another specific location and implement a control system forcing the whole body to follow that trajectory.
• In this project, you could design the relative configuration of the end-effector and the cube when grasping, planning the end-effectors' trajectory as you like, and adjust the controller parameter to get better performance. The project uses velocity control so no robot dynamics is involved.
• Details of the project (basic operations on VREP, Initial configurations, size of the mobile base, screw axis......) could be found on the project web page

Results

Implement on

To get a balance between faster error twist convergence speed and less oscillation and smaller steady state error, adjusting the Kp,Ki of the feedback controller and obtain a relatively good performance of the robot(Error twist versus time shown below). Besides, you could find the simulation video in \results

Instructions

1. The folder \mr includes the Modern Robotics code library of the corresponding book, you could always download that here. Remember to download and include that in your Matlab searching path.

   % Below is an example for including the source code 
   root = fileparts(pwd);
   project_name = "Final Project";
   sourceCode_name = "mr";
   addpath(genpath(fullfile(root,project_name,sourceCode_name)));

2. Run runscript.m to generate:

   • A file contains the calculated trajectory for the end-effector : Traj.csv

   • A file used to simulate the robot motion in CoppeliaSim : Animation.csv

   • A plot showing the change of error twist versus time and the data file : Xerr.mat

     program running log file shown as follows:

     >> runscript
     Initialization completed
     Initialization completed
     Youbot object created!
     Trajectory generated
     Feedback Control applied, Animation file generated
     Successfully plot Xerror vesus time

3. The code is Object-Oriented, by constructing the youBot object Mybot which is the subclass of the four mecanum wheels mobile base class mobileRobot. With the Inherited feature of OOP and some essential properties and useful methods included in the class file, the code seems very fluent and well wrapped.

   % Manual choose the initial parameter of the controller and the robot
   % configuration
   Mybot.q = [0,0,0];
   Mybot.theta = [0,0,0.2,-1.67,0]';
   Mybot.wheelAngle = [pi/2,pi/2,pi/2,pi/2];% Do not affect the simulation
   Mybot.kp = 1.5 * eye(6);
   Mybot.ki = 0 * eye(6);
   maxspeed = 12.3*ones(1,9);% take uniform max speed.
   jointLimits = [[pi,-pi]',[pi,-pi]',...
       [pi,-pi]',[pi,-pi]'...
       ,[pi,-pi]'];% Designed values to avoid collision : [max;min]
   
   [Td,grasp] = traj2mat(Traj);% Td is a 3D matrix
   
   % Apply Fb control to the Youbot object.
   % All other parameter needed is included in the obj's property.
   [Animation,Xerr] = Mybot.FeedbackControl(dt,Td,maxspeed,grasp,jointLimits);
   

4. Every single file of this code is well commented, if you still have problem understanding some part of that, feel free to contact me via yul131@eng.ucsd.edu.

Acknowledgements

The code is written for the final project for the grad course MAE 204 "Robotics" in University of California San Diego, instructed by Professor Mike Tolley. Use this code only for study and help understand the exponential coordinate representation of robot motion if you are interested.