Modelling and control of a post-stroke robot activated by pneumatic artificial muscles for upper-limb rehabilitation

Nowadays, many people suffer from strokes. This disease, which mainly affects older people, causes a reduction in motor skills. It is important to recover these functions in order to return to a life as normal as possible. Rehabilitation takes place through precise and regular movements performed by the patient. This is where robotics comes in. Integrating robots into the world of rehabilitation allows us to optimise treatments and obtain better final results. A robotic arm activated by artificial pneumatic muscles, developed by Louvain Bionics and INSA Toulouse, has been designed for upper limb rehabilitation. The main objective of this thesis is to model and control the robot. The aim of the project is to find out whether this type of actuator, which is gentler than an electric motor, has sufficient advantages to enter the medical field. An experimental process has been carried out throughout the project. Firstly, experiments were carried out to create a model corresponding to the Festo muscles, the artificial pneumatic muscles used for the robot. Then, several tests validated the performance of the implemented controller. Finally, a hybrid stiffness control, taking full advantage of the physical stiffness of the system, was implemented and evaluated. A robot activated by pneumatic artificial muscles has major advantages, such as its flexibility which gives it a behaviour similar to human muscles. It also has some disadvantages that are not negligible for its future use. Some of the disadvantages are lower accuracy of position control and loud noise due to air supply to the muscles. In addition, the results concerning the hybrid control in stiffness, which may be a main advantage of pneumatic actuators compared to electric ones, are not significantly impressive. However, further research in this area would surely improve the performances, which would make this robot really interesting for the medical robotics market.