Add simple DCM and ZMP regulation simulation script on linear inverted...

Add simple DCM and ZMP regulation simulation script on linear inverted pendulum dynamic to investigate gain behavior.

python/sot_talos_balance/test/simulate-ZMP-DCM-regulation-of-LIP.py

+import matplotlib.pyplot as plt
+w=3.
+A=8.
+N=100000
+a=1
+Kp=8.
+w2=w*w
+dt=0.0001
+#initial conditions
+c=1.
+dc=0.
+ddc=010
+log_c=[]
+z = c - 1/w2 * ddc
+z_m = z
+for i in range(N):
+   #measure and filter
+   z = c - 1/w2 * ddc
+   z_m = z*a + (1-a)*z_m
+   #control
+   xi = c+dc/w
+   ddc = A*(z_m) - A*(1+Kp/w)*xi
+   #integrate
+   dc += dt*ddc
+   c+=dt*dc
+   log_c.append(c)
+   #print c
+
+plt.plot(log_c)
+plt.show()