I want to make a circle using parametric equation of a circle

ehte

using x^2+y^2=r^2 where x=r*costheta and y=r*sintheta.
Please help me with this thing.

matthewd92

@George1969 the simple answer is yes, if you can create a parametric formula for a trajectory path it is possible to make the robot follow it.

What I wrote above is the code for making a parametric circle work on a UR3, you would need to understand the UR scripting language to be able to make this work on your robot.  You can find more information on UR Script here

@ehte to make the base the center of the circle, you just need to find the current position of the robot and rotate the Rz portion by 6.28 radians and then go to that point, that should be the easiest way to make the robot the center of a circle

matthewd92

You would need to also base that off of some known point, the center preferably.  Have you tried something like this:

def getNextPositionOnArc(center, theta, radius):
  local x = radius*cos(theta) #Theta in Radians, radius in meters
  local y = radius*sin(theta) #Theta in Radians, radius in meters
  return pose_trans(center, p[x,y,0,0,0,0])
end

Center would need to be the center you want of the circle as a pose, you could define a waypoint and then save that to a variable and pass into the function

global center = Waypoint_Center
global theta = 0
global radius = 0.025
while (theta < 6.29):
  global nextPosition = getNextPositionOnArc(center,theta, radius)
  movej(nextPosition)
  theta = theta + 0.01
end 

Something like that might work

ehte

I want to make a circle where base of the robot act as a centre. Can you please suggest some ideas

George1969

Hello,
I have a question at this post. Firstly, I'm beginner in robots programming and I'm sorry if I say nonsense. I did not manage to go through the script posted by Matthew (if you want to posted step by step how to write the code in UR3 robot). My question is it possible to use this procedure to make the robot to move along a anything curve if I write his parametric equation? (Not a circle like in this example).

Thanks in advanced. 

George1969

Hello Matthew, 
Thanks for your response. I succeeded to write the program for ur to move along a circle. The script's manual is very useful, but I'm not anymore young and I learn more easy from examples.