/******************************************************************
*   Inverse Kinematics code to control a (modified) 
*   LynxMotion AL5D robot arm using a PS2 controller.
*
*   Original IK code by Oleg Mazurov:
*       www.circuitsathome.com/mcu/robotic-arm-inverse-kinematics-on-arduino
*
*   Great intro to IK, with illustrations:
*       github.com/EricGoldsmith/AL5D-BotBoarduino-PS2/blob/master/Robot_Arm_IK.pdf
*
*   Revamped to use BotBoarduino microcontroller:
*       www.lynxmotion.com/c-153-botboarduino.aspx
*   Arduino Servo library:
*       arduino.cc/en/Reference/Servo
*   and PS2X controller library:
*       github.com/madsci1016/Arduino-PS2X
*
*   PS2 Controls
*       Right Joystick L/R: Gripper tip X position (side to side)
*       Right Joystick U/D: Gripper tip Y position (distance out from base center)
*       R1/R2 Buttons:      Gripper tip Z position (height from surface)
*       Left Joystick L/R   Wrist rotate (if installed)
*       Left Joystick U/D:  Wrist angle
*       L1/L2 Buttons:      Gripper close/open
*       X Button:           Gripper fully open
*       Digital Pad U/D:    Speed increase/decrease
*
*   Eric Goldsmith
*   www.ericgoldsmith.com
*
*   Current Version:
*       https://github.com/EricGoldsmith/AL5D-BotBoarduino-PS2
*   Version history
*       0.1 Initial port of code to use Arduino Server Library
*       0.2 Added PS2 controls
*       0.3 Added constraint logic & 2D kinematics
*       0.4 Added control to modify speed of movement during program run
*       0.5 Write to servos directly in microseconds to improve resolution
*           Should be accurate to ~1/2 a degree
*
*    To Do
*    - Improve arm parking logic to gently move to park position
*
* This program is free software: you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation, either version 3 of the License, or
* (at your option) any later version.
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
* GNU General Public License for more details.
* <http://www.gnu.org/licenses/>
* 
******************************************************************/

Video Demonstration: https://www.youtube.com/watch?v=unTXPJ-zYNc