a-remus / bender_project_matlab

MODELLING AND CONTROL OF DEFORMABLE OBJECTS

Matlab Version: 2018b Add-ons to be installed:

• Simscape
• Simscape Multibody 6.0;
• Simscape Multibody from Matlab code;
• Simscape Multibody Multiphysics library;
• Flexible Body Models in Simscape Multibody;
• Robot Arm with conveyor belts (for grippers model);

calibration procedure

Model extraction, by introducing a certain deformation delta on the 4 inputs. The purpose is to provide the next phase with a model to be used to superimpose beam and fixture markers.

alignment bending procedure

By using the previously computed model, it is possible by minimizing the distance between the two set of markers.

home position ros

In charge of computing the initial joint pose for the two robots, with a sign modification to adapt the model in simulation with the one in real world.

calibration stability analysis

This module is specifically designed to compute a NxN grid of sensitivity Jacobians to be used to check the stability interval for a given set of values

stability analysis

It actually performs the computation of the eigenvalues of matrix (pinv(J*) J(u)), with J* model in the final configuration.

Bugs and future work

Deformable object may lead to errors for the very first execution, due to disconnection of beam key-frames.

As a future work it would be good to automatically insert the desired number of key-frames throughout the length of the beam.

bender_project_matlab's Issues

Automtic insertion of the desired number of key-frames throughout the length of the beam.

So far we exploited a built-in implementation of the deformable beam, in which it is possible to choose the number of elements composing the beam. Nevertheless we need to put frames on the beam to identify key-points from which we can apply our control law.

In the work done so far, such frames have to be placed manually inside the deformable beam Simulink block and even doing so, after a clean start of MATLAB frames get disconnected from the object, throwing an exception and requiring to manually reconnect them.

For this reason it is necessary to investigate how to integrate such key-frames in an automatic manner, this task requires to modify the code of the Simulink block.

For more insights let's visit:

• https://it.mathworks.com/matlabcentral/fileexchange/47051-flexible-body-models-in-simscape-multibody
• https://it.mathworks.com/matlabcentral/fileexchange/45410-simscape-multibody-model-from-matlab-code

Adopt the model of KUKA LWR 4+ instead of KUKA IIWA

Many examples over the Internet deal with KUKA family robots in simscape multibody, however for this project we exploited KUKA IIWA instead of LWR 4+ which is the one in the ECN shopfloor.

The two are almost identical apart from the fact that angles 2, 4 and 6 exploits an opposite angle convention so that if we want to see the trajectory simulated in Simscape Multibody on the real robot so far importrobot('iiwa7.urdf') is used counting on the fact that the robot model is already loaded in the MATLAB environment.

It is necessary to find a way to integrate the kuka_lwr4p.urdf model so that inverse-kinematics simulink block can exploit this one and be coherent with the real robot.