5 Jacobian evaluationSpeed of theEnd EffectorUsing the q it is possible to retrive the pose of the robot and the carthesian coordinate of the End Effector.TimeTrajectoryCompensate the error of the position due to numerical integration
11 Software Main Structure The software is thought in order to pilot a robot.It is a good approach organize the software it in the following way:- First Task -> Move the robot to the HOME position (safe pose);- Second Task -> Move the robot, our simulatoin;- Third Task -> Go back to HOME.This logic can be achieved through a Sequence structure.
13 TrajectoryThe robot must be settled avoiding a singular initial pose.In such way it is possible to achieve and follow a feasible path without problemsA1A2Initial Conditions:Q1 -> -pi/2Q2 -> pi/2Q3 -> 0Geometry of the robot:A1 -> 300mmA2 -> 350mmA3 -> 0mm
14 ROBOT VISUALIZATIONThis Vi helps the user to understand the pose of the robot and monitor the evolution of the motion.We need to have the full structure as output, this will simplify the programming interface a lot.Arm_visualizer.vi
15 Jacobian and Pseudoinversion This Vi must evaluate the Jacobian Matrix.The input are the angles of the joints.The output should be a matrix, and this should be inverted in a second Vi.NB: J is related to the dimension of the joints, so it is usefull to create a Vi that output these informations.
16 DerivatorThis Vi must evaluate the velocity of the End EffectotImportant: during the first loop we cannot evaluate the speed, so we need to pass directly a value.This VI must have 2 additional imput, 2 single value ( double ).These inputs will be used later to introduce a numeric error compensation.
17 IntegratorThis VI is used after the multiplication between the presudoinverse Jacobian and the End Effector Velocity Vector. By integrating the output of that multiplication the qs (angles of the joijts) of the robot can be evaluated.Using the Output of this Vi it is possible to connect the Robot Visualization Vi, and watch the motion of the robot directly during the processing loop.
18 Images: Some HintsA Good methodology in LabView is to start building your Vi referring to an example, copying part of the code and then start adding your own «code».So, how can we open an Image in Labview?Go to:…Program Files (x86)\National Instruments\LabVIEW 2010\examples\Vision\1. Getting Started
19 How Initialize and Load an Image We should works with 2 images at the same time:One is the source imageOne is the destination ImageThis is due to the library related to the image processing.LabView does not allow the user to overwrite an image from the same function.
20 Camera View Simulation Vi that simulates the camera mounted on the End EffectorInput:- Image of the ground- Coordinates of the End EffectorGIVENVi that performs the chek of the image, the task is to identify the center of a dot seen by the camera.Use Vision Assistant!Vi that returns the coordiante of the identified dot in the world coordiante system
21 NB: Camera and Robot Reference Coordinate Systems are different! Camera SimulationThe simulation is based on the identification of a region of 640x480 pixels centered and oriented according to the actual pose of the End Effector.NB: Camera and Robot Reference Coordinate Systems are different!Camera RCSWorld RCS
22 To overcome this issue is possible to shift and rotate the image. Camera SimulationOne of the limits of the graphic library in LabView is that you can not crop region of image using any orientation.To overcome this issue is possible to shift and rotate the image.ROI Centered to the origin 0,0 with dimensions 800x800 pixelsWhy 800x800?In this region i can have all the possible 640X480 sub regions with any generic orientation!Region to Crop
23 We shift the image, not the reference system! Camera SimulationWe shift the image, not the reference system!Region to CropRegion to Crop
24 Camera SimulationNow we can apply the rotation to the image.
25 Camera SimulationWe can now Crop the image to the 640x480 region.This is the resulting image that simulates the view of the camera!
26 Camera SimulationNB: The rotation of the image is done around the center of the image itself.
29 From Camera to World RCS Now we have the estimation of the position of the dot expressed in the camera reference coodinate system, but the robot usually works inside its own space (called also World).We need a Vi that performs the transformation between the camera rcs and the world rcs.Camera Reference SystemDot identified inside the imageField of view of the camera inside the world reference systemCoordinates of the dot expressed in the world system