Forward Kinematics

Dependencies:   MODSERIAL Matrix mbed

main.cpp

Committer:
MAHCSnijders
Date:
2018-10-31
Revision:
6:fe8712b56eb9
Parent:
5:65a609067e14

File content as of revision 6:fe8712b56eb9:

#include "mbed.h"
#include "math.h"
#include "Matrix.h"

// Stuff die waarschijnlijk weg kan??
const float L0 = 0.15;                      // Length between two motors [meter]
const float L1 = 0.10;                      // Length first beam from right motor2 [meter]
const float L2 = 0.30;                      // Length second beam from right motor2 [meter]
const float L3 = 0.15;                      // Length beam between L2 and L4 [meter]
const float L4 = 0.30;                      // Length first beam from left motor1 [meter]
const float L5 = 0.35;                      // Length from L3 to end-effector [meter]
const double PI = 3.14159265359;

// DEZE MOET ER NOG WEL IN!!!
const float L6 = 1.0;                       // Length beam between frame 0 and motor 1 [meter]
volatile static float Pe_x_cur;             // Current x-coordinate of end-effector from frame 0 [meter]
volatile static float Pe_y_cur;             // Current y-coordinate of end-effector from frame 0 [meter]
volatile double motor_angle1;               // Current angle of motor 1 (left) based on kinematics [rad]
volatile double motor_angle2;               // Current angle of motor 2 (right) based on kinematics [rad]

DigitalOut safetyLED(LED_GREEN);            // Safety check LED


// Useful stuff
Ticker ForwardKinematics_ticker;

void ForwardKinematics()
{
    // Calculation of position joint 1 expressed in frame 0
    float J1x_0 = L6 + L0 + L1*cos(motor_angle2);
    float J1y_0 = L1*sin(motor_angle2);
    
    // Calculation of position joint 3 expressed in frame 0
    float J3x_0 = L6 + L4*cos(motor_angle1); 
    float J3y_0 = L4*sin(motor_angle1);

    // Calculation of Joint 2 expressed in frame 2
    float m_y = J3y_0 - J1y_0;
    float m_x = J1x_0 - J3x_0;
    float m = sqrt(pow(m_y,2) + pow(m_x,2));                                // Radius between Joint 1 and 3
    float delta = acos(- ( pow(m,2) - pow(L2,2) - pow(L3,2))/(2*L2*L3) );
    float mu = acos( (pow(L2,2) - pow(L3,2) + pow(m,2))/(2*m*L2) );         // Angle between L2 and m

    float t_y = J3y_0;
    float t_x = (L0 + L6) - J3x_0;
    float t = sqrt(pow(t_y,2) + pow(t_x,2));                                // Radius between frame 1 and Joint 3
    float phi = acos( (pow(L1,2) - pow(t,2) + pow(m,2))/(2*m*L1) );         // Angle between L1 and m

    float q2 = PI - mu - phi;                                               // Angle that L2 makes in frame 2
    float J2x_2 = L2*cos(q2);
    float J2y_2 = L2*sin(q2);

    // Calculation of Joint 2 expressed in frame 0
    float J1x_1 = L1*cos(motor_angle2);                                     // Joint 1 expressed in frame 1
    float J1y_1 = L1*sin(motor_angle2); 
    float J2x_0 = J2x_2*cos(motor_angle2) - J2y_2 * sin(motor_angle2) + J1x_1 + L0 + L6;    // Joint 2 expressed in frame 0
    float J2y_0 = J2x_2*sin(motor_angle2) + J2y_2 * cos(motor_angle2) + J1y_1;
 
    // Calculation of End-effector
    float f_x = J2x_0 - L6;     // I CHANGED THIS!!!!
    float f_y = J2y_0;
    float f = sqrt(pow(f_x,2) + pow(f_y,2));                                // Radius between motor 1 and Joint 2
    float xhi = acos( -(pow(f,2) - pow(L3,2) - pow(L4,2))/(2*L3*L4) );      // Angle between L3 and L4
    float omega = PI - xhi;                                                 // Angle between L4 and L5
    float n = sqrt(pow(L4,2) + pow(L5,2) - 2*L4*L5*cos(omega));             // Radius between end effector and motor 1

    float theta = acos( (pow(L4,2) - pow(L5,2) + pow(n,2))/(2*n*L4) );      // Angle between n and L4
    float rho = PI - theta - motor_angle1;                                  // Angle between n and L4

    float Pe_x = L6 - n*cos(rho);                                           // y-coordinate end-effector
    float Pe_y = n*sin(rho);                                                // x-coordinate end-effector


    // Implementing stops for safety
    // 45 < Motor_angle1 < 70 graden
    if (motor_angle1 < 0.785398)                                            // If motor_angle is smaller than 45 degrees
    {
        motor_angle1 = 0.785398;
        safetyLED = 0;
    }
    else if (motor_angle1 > 1.22173)                                        // If motor_angle is larger than 70 degrees
    {
        motor_angle1 = 1.22173;
        safetyLED = 0;
    }
    
    // -42 < Motor_angle2 < 85 graden
    if (motor_angle2 < -0.733038)                                           // If motor_angle is smaller than -42 degrees
    {
        motor_angle2 = -0.733038;
        safetyLED = 0;
    }
    else if (motor_angle2 > 1.48353)                                        // If motor_angle is larger than 85 degrees
    {
        motor_angle2 = 1.48353;
        safetyLED = 0;
    }
    
    
    // Delta < 170 graden
    if (delta > 2.96706)                                                    // If delta is larger than 180 degrees
    {
        delta = 2.96706;
        safetyLED = 0;
    }

    // NEEDS TO RETURN END-EFFECTOR COORDINATES
//    return Pe_x;
//    return Pe_y;    
}


int main()
{
    safetyLED = 1;
    while (true) {
    ForwardKinematics_ticker.attach(ForwardKinematics,0.5);
    }
}