ScaraArms.h

00001 // SCARA_Arms library
00002 // Code to compute the shoulder angles required to move a Dual-Arm SCARA robot to required x,y position
00003 // More information at http://robdobson.com/scara-arm-calculations
00004 // Copyright (C) Rob Dobson 2013-2015, MIT License
00005 
00006 #ifndef SCARAARMS_H
00007 #define SCARAARMS_H
00008 
00009 // Description of a Dual-Arm SCARA robot
00010 // The two arms of the robot are akin to two human arms with the hands permanently clasped together
00011 // The arms are always in the same plane (generally horizontal) and the hands hold a stick (also in the same plane)
00012 // On the end of the stick is the tool (pen/actuayor/nozzle/laser etc)
00013 
00014 class ScaraArms
00015 {
00016 public:
00017     // Constructor
00018     // The measurements required to describe a Dual-Arm SCARA robot of the kind described above are:
00019     // 1) Distance between shoulders
00020     // 2) Distance from shoulder to elbow
00021     // 3) Distance from elbow to hand
00022     // 4) Distance from hand to tool (length of stick holding the tool)
00023     ScaraArms(double betweenShouldersMM, double shoulderToElbowMM, double elbowToHandMM, double handToToolMM);
00024     
00025     // Compute the angles at the shoulders given the required XY position of the tool in radians
00026     // Note that the way the angles are measured is that theta1 (the left arm angle) is measured counter-clockwise from 3 O'Clock
00027     // theta2 (the right arm angle) is measured clockwise from 9 O'Clock
00028     // To calculate both clockwise from 9 O'Clock use PI-theta2
00029     // To convert the angles to degrees multiply by 180/PI
00030     // The XY position has it's origin (0,0) at the left shoulder
00031     void ConvertXYtoScara(double x, double y, double &theta1, double &theta2);
00032 
00033     // Compute the XY position of the tool given the angles at the shoulders
00034     // See the comments above for the reverse calculation concerning the way the angles are measured and the origin 
00035     // of the XY coordinates
00036     // These calculations use a different mathematical model as the conversion in this direction is simpler and
00037     // it provides a useful cross check
00038     void ConvertScaratoXY(double theta1, double theta2, double &x, double &y);
00039     
00040 private:
00041     double _betweenShouldersMM;
00042     double _shoulderToElbowMM;
00043     double _elbowToHandMM;
00044     double _handToToolMM;
00045 };
00046 
00047 #endif