Update sim_fiction_compensation.m

In line 15, q(3) (z) should have been q(5) (z_tilde). This drastically improves the friction observer. z is not observable and should not be used in your control law.

Author: jasonnicholson

sim_fiction_compensation.m

@@ -12,7 +12,7 @@
     % here we use similar values as in Table I
     k = 10;
     zdot_tilde = q(2) - ( (q(5)*abs(q(2))*sigma_0) / (Fc+(Fs-Fc)*exp(-(q(2)/vs)^2)) ) -k*e;
-    F_tilde =  sigma_0*q(3) + sigma_1 * zdot_tilde + sigma_2*q(2);
+    F_tilde =  sigma_0*q(5) + sigma_1 * zdot_tilde + sigma_2*q(2);
 
     u = -Kv*q(2)-Kp*e-Ki*q(4) + F_tilde; % the input here is a step function, second derivative of xd is zero
 
@@ -25,4 +25,4 @@
     qdot_4 = e;
     qdot_5 = zdot_tilde;
     xdot = [qdot_1 ; qdot_2; qdot_3; qdot_4; qdot_5];
-end
+end