Freemode with urscript

Technical Questions URScript
1

hello dear community, I am trying to implement by software the free movement with axis restriction, as you are implementing in polyscope and the free mode button of the programming tablet (attached image).

freemode
freemode898×659 41.8 KB

You can help me to find the right way to do it. I have tried the following options:
force_mode() command, restricting axes where force is applied.


def FreeDrive_force(register_flag):
  
	global for_thrd = run force_thread(register_flag)
	global for_thrd = run getForces()
end

##############################################

def end_FreeDrive_force():
	kill for_thrd
	kill for_thrd
end

##############################################

thread force_thread(register_flag):
	limits = [0.1, 0.1, 0.1, 10, 10, 10]
	frame = p[0.0,0.0,0.0,0.0,0.0,0.0]
      #list to select axis move
	selection = [0, 0, 0, 1, 1, 1]
	type=2
	wrench = [0, 0, 0, 0.1, 0.1, 0.1]

	while (not(read_input_boolean_register(register_flag) ==   True  )):	  
	  force_mode(frame,selection , wrench, type, limits)
	  sync()
	end #while
	
	end_FreeDrive_force()
end   #thread define
###############################################

thread getForces():
  zero_ftsensor()
  while True:
    global forces = get_tcp_force()
    sync()
  end  
end

Force sensing with get_tcp_force() and get a proportional value of force to convert it into speed for speedl()



def admitance_mode(register_flag):
 #list to select axis move
  global speed_limits = [0, 0, 0, 0.5, 0.5, 0.5]
  
  global pose_thrd = run getForce()
  global ad_thrd = run admitance_thread(register_flag)
  
end

###############################################################################

def end_admitance_mode():
	kill ad_thrd
	kill pose_thrd
end
###############################################################################

thread admitance_thread(register_flag):




	while (not(read_input_boolean_register(register_flag) ==   True  )):
	
		l = speed_limits
		f =  force
		fn = force_nom
		acc = 0.25
		result = [l[0]*(f[0]/fn), l[1]*(f[1]/fn), l[2]*(f[2]/fn), l[3]*f[3], l[4]*f[4], l[5]*f[5]]
		speedl(result, acc)
		sync()
	end #while
	
	end_admitance_mode()
end   #thread define

thread getForce():
  zero_ftsensor()
  while True:
    global force = get_tcp_force()
	global force_nom = force()
    sync()
  end  
end

thanks for your help

2

Congrats on the first post.

I’ve played with it doing it both ways. I think the best result I had was using force_mode(). Using speedl and a timer was too jerky.

To make it move by hand in the x,y,z my selection was:
[1, 1, 1, 0, 0, 0]

and my limit was:
[0, 0, 0, 0, 0, 0]

If I remember right, it tries to exert 0 force in those vectors and so if you push it, it goes where you want.

I think a better structure would be to go into force mode, and then use your Bool test to decide when to run the end_force_mode() command rather than calling force mode repeatedly.

1 Like
3

Thank you very much, I will try it out and share the code.