Modern_Robotics/code/MATLAB/ComputedTorque.m

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%*** CHAPTER 11: ROBOT CONTROL ***
function taulist = ComputedTorque(thetalist,dthetalist,eint,g,Mlist, ...
Glist,Slist,thetalistd,dthetalistd, ...
ddthetalistd,Kp,Ki,Kd)
% Takes thetalist: n-vector of joint variables,
% dthetalist: n-vector of joint rates,
% eint: n-vector of the time-integral of joint errors,
% g: Gravity vector g,
% Mlist: List of link frames {i} relative to {i-1} at the home
% position,
% Glist: Spatial inertia matrices Gi of the links,
% Slist: Screw axes Si of the joints in a space frame,
% thetalistd: n-vector of reference joint variables,
% dthetalistd: n-vector of reference joint velocities,
% ddthetalistd: n-vector of reference joint accelerations,
% Kp: The feedback proportional gain (identical for each joint),
% Ki: The feedback integral gain (identical for each joint),
% Kd: The feedback derivative gain (identical for each joint).
% Returns taulist: The vector of joint forces/torques computed by the
% feedback linearizing controller at the current instant.
% Example Input:
%{
clc;clear;
thetalist = [0.1; 0.1; 0.1];
dthetalist = [0.1; 0.2; 0.3];
eint = [0.2; 0.2; 0.2];
g = [0; 0; -9.8];
M01 = [[1, 0, 0, 0]; [0, 1, 0, 0]; [0, 0, 1, 0.089159]; [0, 0, 0, 1]];
M12 = [[0, 0, 1, 0.28]; [0, 1, 0, 0.13585]; [-1, 0 ,0, 0]; [0, 0, 0, 1]];
M23 = [[1, 0, 0, 0]; [0, 1, 0, -0.1197]; [0, 0, 1, 0.395]; [0, 0, 0, 1]];
M34 = [[1, 0, 0, 0]; [0, 1, 0, 0]; [0, 0, 1, 0.14225]; [0, 0, 0, 1]];
G1 = diag([0.010267, 0.010267, 0.00666, 3.7, 3.7, 3.7]);
G2 = diag([0.22689, 0.22689, 0.0151074, 8.393, 8.393, 8.393]);
G3 = diag([0.0494433, 0.0494433, 0.004095, 2.275, 2.275, 2.275]);
Glist = cat(3,G1,G2,G3);
Mlist = cat(4,M01,M12,M23,M34);
Slist = [[1; 0; 1; 0; 1; 0], ...
[0; 1; 0; -0.089; 0; 0], ...
[0; 1; 0; -0.089; 0; 0.425]];
thetalistd = [1; 1; 1];
dthetalistd = [2; 1.2; 2];
ddthetalistd = [0.1; 0.1; 0.1];
Kp = 1.3;
Ki = 1.2;
Kd = 1.1;
taulist ...
= ComputedTorque(thetalist,dthetalist,eint,g,Mlist,Glist,Slist, ...
thetalistd,dthetalistd,ddthetalistd,Kp,Ki,Kd)
%}
% Output:
% taulist =
% 133.0053
% -29.9422
% -3.0328
e = thetalistd - thetalist;
taulist ...
= MassMatrix(thetalist,Mlist,Glist,Slist) ...
* (Kp * e + Ki * (eint + e) + Kd * (dthetalistd - dthetalist)) ...
+ InverseDynamics(thetalist,dthetalist,ddthetalistd,g,zeros(6,1), ...
Mlist,Glist,Slist);
end