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Setting Minimum distance from object

#1
I have been trying to figure out a way to set a minimum distance from my tool to a part as it moves through a program. As the parts that are used are complex and varying diffrent sizes of objects are used I want to automate this process.

I assumed that RoboDK would have some sort of constraint built in for this but it seems not, so I have decided to try creating a py script. my code it below

Code:
from robolink import *
from robodk import *


# Connect to RoboDK
RDK = Robolink()


# Get the robot and tool and object
robot = RDK.Item('KUKA KR 6 R900-2')
tool = RDK.Item('Kinect')
object = RDK.Item('Piston deform')

# Set the minimum distance constraint
min_distance = 5000  # Set the desired minimum distance in millimeters


while True:
   # Get the pose of the robot, tool, and object
   robot_pose = robot.Pose()
   tool_pose = tool.PoseTool()
   object_pose = object.Pose()

   # Calculate the position of the tool in the global reference frame
   tool_pose_global = robot_pose*tool_pose

   # Calculate the distance between the tool and object
   dist = distance(tool_pose_global.Pos(), object_pose.Pos())

   # If the distance is less than the minimum distance, move the robot away from the object
   if dist < min_distance:
       displacement = min_distance - dist
       direction = (tool_pose_global.Pos() - object_pose.Pos()) / distance
       new_pos = robot_pose * transl(displacement * direction)
       robot.MoveJ(new_pos)


I seem to be having problems with the third last line of my code that starts direction as  I get an error as such:

direction = (tool_pose_global.Pos() - object_pose.Pos()) / distance
TypeError: unsupported operand type(s) for -: 'list' and 'list' 


my simulation is trying to scan an object on a turntable with a camera from a  set distance from the surface of the complex object as it moves from a front facing orientation with respect to the object to an almost top down view with respect to the object as seen in the attached picture.

I am not very good with programming in general and this is my first attempt in RoboDK. I am not sure if my code will even work if this error is fixed so I was wondering if anyone could help, or if there might be an easier way to do this.   


Attached Files Thumbnail(s)
   
#2
You are using add/subract/multiply operators on a 3-dimensional list of values (3D vectors). You should use the required functions to perform these operations on 3D vectors.

Example:
Code:
delta_vector = subs3(tool_pose_global.Pos(), object_pose.Pos())
direction = mult3(delta_vector, 1.0/distance)
More information here:
https://robodk.com/doc/en/PythonAPI/robo...math.subs3
#3
I have changed my code slightly to incorpirate the new information you gave me as below


Code:
from robolink import *
from robodk import *


# Connect to RoboDK
RDK = Robolink()


# Get the robot and tool and object
robot = RDK.Item('KUKA KR 6 R900-2')
tool = RDK.Item('Kinect')
object = RDK.Item('Piston deform')

# Set the minimum distance constraint
min_distance = 5000  # Set the desired minimum distance in millimeters


while True:
   # Get the pose of the robot, tool, and object
   robot_pose = robot.Pose()
   tool_pose = tool.PoseTool()
   object_pose = object.Pose()

   # Calculate the position of the tool in the global reference frame
   tool_pose_global = robot_pose*tool_pose

   # Calculate the distance between the tool and object
   dist = subs3(tool_pose_global.Pos(), object_pose.Pos())
   newdist = mult3(dist,1.0)

   # If the distance is less than the minimum distance, move the robot away from the object
   if newdist < min_distance:
       displacement = min_distance - newdist
       direction = mult3(dist, 1.0/dist)
       new_pos = robot_pose * transl(displacement * direction)
       robot.MoveJ(new_pos)





But now I am getting the error: Minimumdistance1.py", line 32, in
                          if newdist TypeError: '


I am assuming this means it cant compare the dist < min_distance as they are stored as different types, but I am unsure how as I believe they are both scalar types from the code snippets below 

Code:
newdist = mult3(dist,1.0)
min_distance = 5000

I think I am getting closer to a final script but the last few lines are causing me some problems. any advice would be great
#4
You are using a vector as if it was the norm. You can calculate the norm of a vector by using the norm function:

Code:
distance = norm(vector)

In your example:

Code:
dist_norm = norm(dist)
#5
I have further modified my code and now there are no errors when doing the quick program check. However when I set the minimum distance to larger than 760 I get a weird response as seen in the video attached. I am sure this has to do with the fact that my TVP is offset from the flange by 760mm, and the targets for the movement are based around the TCP changing angles around the parts reference frame which will change if the minimum distance is larger than the initial offset of 760mm. 

I am unsure of if this is a problem with my code or I am going to have to use another way other than targets to define my path as it will change depending on the minimum distance I set and the scanning program I have made. My code is below if there are any obvious problems with it but I cant seem to see any.


Code:
from robolink import *
from robodk import *


# Connect to RoboDK
RDK = Robolink()


# Get the robot and tool and object
robot = RDK.Item('KUKA KR 6 R900-2')
tool = RDK.Item('Kinect')
object = RDK.Item('Piston deform')

# Set the minimum distance constraint
min_distance = 800  # Set the desired minimum distance in millimeters


while True:
   # Get the pose of the robot, tool, and object
   robot_pose = robot.Pose()
   tool_pose = tool.PoseTool()
   object_pose = object.Pose()

   # Calculate the position of the tool in the global reference frame
   tool_pose_global = robot_pose*tool_pose

   # Calculate the distance between the tool and object
   dist = subs3(tool_pose_global.Pos(), object_pose.Pos())
   newdist = norm(dist)

   # If the distance is less than the minimum distance, move the robot away from the object
   if newdist < min_distance:
       displacement = min_distance - newdist
       displacement = int(displacement)
       direction = mult3(dist, 1.0/newdist)
       new_pos = robot_pose * transl(displacement * direction)
       robot.MoveJ(new_pos)


Attached Files
.mp4   RoboDK - 3d scanning - Free (Trial) - 23 days left 2023-02-22 16-09-43.mp4 (Size: 10.5 MB / Downloads: 173)
  




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