InitRech 2015/2016, sujet 2

Summary

Robots are more and more uses in company and everyday life. One of the main challenge now days is the control in real time of deformable robots.

Unlike the indeformable robot, they having an infinite number of degrees. One of the approach considered is a generic approaches using finite element method and solving interactively an inverse problem through an iterative Gaus-Seidel algorithm.

But this approach is limited to simple robots and despite the advance of computer the control of deformable robot remains a bottleneck. An hight quality of simulation needs a fast high frequency updates up to 1Khz but the simulation of deformable robots has frequency around 10 or 15 Hz.

In first part, we will deal with the formulation of the inverse problem as a Quadratic Programming problem.

In second part we will use a multi-rate simulation in order to provide fast response time to control the robot. And we finish with present a numeric assessment for the validation of the two previous part.

Main contribution

The main contribution of this papers is to model the nonlinear deformation of volumetric soft robot using the FEM, build on the control method of Duriez at high frequency. The high frequency is compatible with real-time constraint of a robotic control system.

They used a non-standard optimization to compute the inverse mode of the robot, the model is obtained by solving a QP optimization. They begins to use the open sources software CGAL to obtain the volumic mesh of the robot.

After this compute, they solved the inverse problem in three step 

-Linearization of the internal forces

- define a constraint space of a reduced size -Optimization of the motion space

The inverse problem can be solved by a varity of method. But the QP method can solve them in high frequency.

Applications

The main application field of deformable robot is the medical field.In fact, deformable robot can be use when a surgeon need to pass some tool into the body of a patient.

A deformable robot can pass by the natural way of a body without the risk to damage the way and the robot can do some surgery.

One of the bigger hope to the future is the possibility to healing without surgery. You take a medication and automatically some robot go inside your body to detect and healing your problem.

Another application of the deformable robot in the medical field is the possibility to replace a part of your body.

The robot can reproduce closer the role of an organs for example. With this technology, problem made by the transplantation of organ can be solved. In fact, if you need a new organs, you no longer need to wait a giver. The risk a rejection will be decrease.

You can also replace a lost arm or hand, and simulate the move of a real hand. If this technology will be properly developed, it will be a rescue for the person who lost a body member.

Deformable robot can be helpful for reeducation too, the utilization of the robot like a connected clothes is a way of this application of that robot.

In another field, deformable robot are used for the agriculture. This type of robots are able to pick up fruit without damaging them, it is can be helpful for farmer. And the consumer can have a product with a better quality.

In a general case, deformable robot can be used in all field where robots are use. We can be see this robot like a evolution of the robot. Christian Duriez said, the robot are like the wheel. The humanity have reinvented the wheel with the evolution of the technology. Why we can’t reinvented robotics?