Biorobotics 7
/
Inverse_kinematic
Inverse kinematics
main.cpp
- Committer:
- MAHCSnijders
- Date:
- 2018-10-29
- Revision:
- 1:df3d7f71db4b
- Parent:
- 0:4a9c733c3b53
- Child:
- 2:8632e61cafc8
File content as of revision 1:df3d7f71db4b:
#include "mbed.h" #include "math.h" #include "Matrix.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 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] Ticker kinematics_ticker; // Ticker function for inverse kinematics void InverseKinematics() { // Calculation of the position of joint 3 in frame 0 float n = sqrt(pow(Pe_x,2) + pow(Pe_y,2)); // Radius between origin frame 0 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 = atan(L5*sin(q4)/(L4 + L5*cos(q4))); // Angle between n and L4 float lambda = PI - atan(abs(Pe_y/Pe_x)); // Entire angle between x-axis frame 0 and n float des_motor_angle1 = lambda - theta; float J3x_0 = 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 = abs(J3y_0 - Pe_y); // 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; // 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 // Calculation of motor_angle2 float beta = atan(L2*sin(q2)/(L1+L2*cos(q2))); // Angle between r and L1 float gamma = PI - atan(abs(J2y_1/J2x_1)); // Angle between r and x-axis // check if gamma works! des_motor_angle2 = gamma - beta; float J1x_0 = L0 + 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 // Determining angle delta for safety float m = sqrt(pow((abs(J3x_0)+J1x_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 } int main() { kinematics_ticker.attach(InverseKinematics,0.5); }