Source Code for Script script-demo_velocityProfile_py

 1  #stella's velocity demo code! 
 2   
 3  if __name__!="__main__": 
 4    import sys 
 5    sys.exit() 
 6   
 7  import ckbot.logical #need to make sure modules can populate and the pcan can recognise the node ID 
 8  import joy  #used to call the feedbackrate function 
 9  import time #used for all of the time related functions 
10  import numpy 
11  #from pylab import plot, show, xlim, xlabel, ylabel, title, grid, savefig 
12  import pylab    
13  c = ckbot.logical.Cluster() #program recognises how many and which modules are attached 
14     
15  c.populate() # node IDs of modules are stored 
16     
17  c.at.Nx05.get_od() #getting object dictionary 
18     
19  c.at.Nx05.od.set_feedbackrate(100) #will get feedback from modules at a rate of 100 Hz 
20     
21  c.at.Nx05.reset() # stores feedback rate in eeprom memory. only have to do once then can delete from code. 
22   
23  time.sleep(5) #has code wait for 5 seconds. for more information type 'help()' then time in the ipython console. 
24   
25  c.at.Nx05.set_pos(-5000)  
26   
27  time.sleep(3) 
28   
29  T0 = time.time() # sets a variable to be equal to the actual time since the start of the epoch. 
30       
31  c.at.Nx05.set_pos(5000) 
32   
33  period = 3 
34   
35  pos = [] #creates an empty position list 
36  t = [] 
37  start_time = time.time() #sets a new variable to a later time  
38   
39  while(T0 - start_time < period):     
40      val = str(c.at.Nx05.get_pos()/100) 
41      pos.append(val)    #first appends the position value, then right after it the corresponding time. 
42      t.append(time.time() - start_time) #akes the  
43      T0 = time.time() #re defines T0 as a later time, which eventually will end the while loop when T0-start_time becomes >= 3 seconds (the period) 
44   
45  #print time_list, list 
46   
47  pylab.plot(t[:31], pos[:31]) 
48   
49  pylab.xlabel('time (s)') 
50  pylab.ylabel('position (deg)') 
51  pylab.title('Position Plot') 
52  pylab.grid(True) 
53   
54  pylab.savefig('position_plot') 
55   
56  pylab.show() #so we can graph the position and time values 
57   
58   
59  vel = [] 
60   
61  for i in range(len(pos)-1): 
62      vel.append((pos[i+1]-pos[i])/(t[i+1]-t[i])) 
63    
64  pylab.plot(t[:31], vel[:31]) 
65   
66  pylab.xlabel('time (s)') 
67  pylab.ylabel('velocity (deg/s)') 
68  pylab.title('Velocity Plot') 
69  pylab.grid(True) 
70   
71  pylab.savefig('velocity_plot') 
72   
73  pylab.show() #so we can graph the position and time values 
74