![](/media/cache/group/default_image.jpg.50x50_q85.jpg)
Inverse kinematics
main.cpp
- Committer:
- MAHCSnijders
- Date:
- 2018-11-01
- Revision:
- 9:2944c792daa2
- Parent:
- 8:01eb609fe0c1
- Child:
- 10:c35d16ad1b6b
File content as of revision 9:2944c792daa2:
#include "mbed.h" #include "math.h" 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 float L6 = 1.00; // Length from frame 0 to motor 1 const double PI = 3.14159265359; volatile float Pe_x; // x-coordinate of end-effector from frame 0 [meter] volatile float Pe_y; // y-coordinate of end-effector from frame 0 [meter] volatile static float des_motor_angle1; // Desired angle of motor 1 (left) based on kinematics [rad] volatile static float des_motor_angle2; // Desired angle of motor 2 (right) based on kinematics [rad] DigitalOut safetyLED(LED_BLUE); // Safety check LED Ticker kinematics_ticker; // Ticker function for inverse kinematics void InverseKinematics() { // Calculation of the position of joint 3 in frame 0 float n = sqrt(pow((L6-Pe_x),2) + pow(Pe_y,2)); // Radius between motor 1 and endeffector [meter] float omega = acos(-(pow(n,2) - pow(L4,2) - pow(L5,2))/(2*L4*L5)); // Angle between L4 and L5 [rad] float q4 = PI - omega; // Angle of joint 3 between L3 and L4 float theta = acos( -(pow(L5,2) - pow(n,2) - pow(L4,2))/(2*n*L4) ); // Angle between n and L4 float lambda_stuff = Pe_y/(L6-Pe_x); float lambda = PI - atan(lambda_stuff); // Entire angle between L0 and n des_motor_angle1 = lambda - theta; float J3x_0 = L6 + L4*cos(des_motor_angle1); // x-coordinate of joint 3 in frame 0 float J3y_0 = L4*sin(des_motor_angle1); // y-coordinate of joint 3 in frame 0 // Calculation of the position of joint 2 in frame 0 float S = J3y_0 - Pe_y; // I CHANGED THIS!!! // Distance between height endeffector and joint 3 float kappa = asin(S/L5); // Angle of L5 float J2x_0 = (L3+L5)*cos(kappa) + Pe_x; // x-coordinate of joint 2 in frame 0 float J2y_0 = (L3+L5)*sin(kappa) + Pe_y; // y-coordinate of joint 2 in frame 0 // Calculation of the position of joint 1 in frame 0 float J2x_1 = J2x_0 - L0 - L6; // x-coordinate of joint 2 in frame 1 float J2y_1 = J2y_0; // y-coordinate of joint 2 in frame 1 float r = sqrt(pow(J2x_1,2) + pow(J2y_1,2)); // Radius between origin frame 1 and J2 float alfa = acos( -(pow(r,2) - pow(L1,2) - pow(L2,2))/(2*L1*L2) ); // Angle opposite of radius r float q2 = PI - alfa; // Angle between L1 and L2 // Delta < 170 graden SAFETY LIMITATION if (r > 2.96706) // If delta is larger than 175 degrees than r is this { r = 0.2399; // I CHANGED THIS safetyLED = 0; } // Calculation of motor_angle2 I CHANGED THIS!!! float beta = acos(- (pow(L2,2) - pow(r,2) - pow(L1,2))/(2*L1*r)); // Angle between r and L1 float zeta = acos(J2x_1/r); // Angle between r and x-axis of frame 1 des_motor_angle2 = zeta - beta; // Determining angle delta for safety float J1x_0 = L0 + L6 + L1*cos(des_motor_angle2); // x-coordinate of joint 1 in frame 0 float J1y_0 = L1*sin(des_motor_angle2); // y-coordinate of joint 1 in frame 0 float m = sqrt(pow((J1x_0 - J3x_0),2) + pow((J3y_0 - J1y_0),2)); // Radius between Joint 1 and Joint 3 float delta = acos(- (pow(m,2) - pow(L2,2) - pow(L3,2))/(2*L2*L3)); // Angle between L2 and L3 // Implementing stops for safety // 45 < Motor_angle1 < 70 graden if (des_motor_angle1 < 0.785398) // If motor_angle is smaller than 45 degrees { des_motor_angle1 = 0.785398; safetyLED = 0; } else if (des_motor_angle1 > 1.22173) // If motor_angle is larger than 70 degrees { des_motor_angle1 = 1.22173; safetyLED = 0; } // -42 < Motor_angle2 < 85 graden if (des_motor_angle2 < -0.733038) // If motor_angle is smaller than -42 degrees { des_motor_angle2 = -0.733038; safetyLED = 0; } else if (des_motor_angle2 > 1.48353) // If motor_angle is larger than 85 degrees { des_motor_angle2 = 1.48353; safetyLED = 0; } } int main() { safetyLED = 1; while (true) { kinematics_ticker.attach(InverseKinematics,0.5); } }