F. Durante

Control Architecture of a 10 DOF Lower Limbs Exoskeleton for Gait Rehabilitation

This paper describes the control architecture of a 10 DOF (Degrees of Freedom) lower limbs exoskeleton for the gait rehabilitation of patients with gait dysfunction. The system has 4 double-acting rod pneumatic actuators (two for each leg) that control the hip and knee joints. The motion of each cylinders piston is controlled by two proportional pressure valves, connected to both cylinder chambers. The control strategy has been specifically designed in order to ensure a proper trajectory control for guiding patients legs along a fixed reference gait pattern. An adaptive fuzzy controller which is capable of compensating for the influence of the dry friction was successfully designed, implemented and tested on an embedded real-time PC/104. In order to verify the proposed control architecture, laboratory experiments without a patient were carried out and the results are reported here and discussed.

A Novel Quad Harmony Search Algorithm for Grid-based Path Finding

A novel approach to the problem of grid-based path finding has been introduced. The method is a block-based search algorithm, founded on the bases of two algorithms, namely the quad-tree algorithm, which offered a great opportunity for decreasing the time needed to compute the solution, and the harmony search (HS) algorithm, a meta-heuristic algorithm used to obtain the optimal solution. This quad HS algorithm uses the quad-tree decomposition of free space in the grid to mark the free areas and treat them as a single node, which greatly improves the execution. The results of the quad HS algorithm have been compared to other meta-heuristic algorithms, i.e., ant colony, genetic algorithm, particle swarm optimization and simulated annealing, and it was proved to obtain the best results in terms of time and giving the optimal path.

A robot actuated by shape memory alloy wires

The paper presents the design of a 3-DOF parallel robot actuated by SMA wires. The paper explains the kinematic model, the mechanical design and the control system of the robot. The robot control system is a closed loop one with the feedback of the electric resistance of the SMA wires. The actuators are Nitinol wires of a diameter of 0.15 mm. The prototype of the robot is manufactured and the first experimental tests were carried out. The results of a step response test and of some trajectory control are shown and validate the design.

Numerical modelling and experimental validation of a McKibben pneumatic muscle actuator

The McKibben muscle belongs to the type of muscles known as braided muscles. It is made of an inner hyper-elastic tube, surrounded by a braided shell made of inextensible threads; both ends provide mechanical and pneumatic seal. A finite element model of a McKibben pneumatic muscle was built and experimentally validated. The model is based on characteristic parameters of McKibben muscles. It takes into account the non-linearity of the constitutive material of the inner tube. It does not simulate backslashes between the tube and the shell at rest condition, but it models threads and rubber that are always connected. However, it does not consider friction among threads. In order to build and to validate the proposed numerical model, an experimental prototype of the muscle was designed and built. Both isotonic and isometric tests were carried out. Same tests were simulated in the finite element environment. The model validation was performed by comparison between experimental and numerical results.

Development and testing of a grasper for NOTES powered by variable stiffness pneumatic actuation

In natural orifice transluminal endoscopic surgery (NOTES) the peritoneal cavity is reached through natural orifices (mouth, rectus and transvaginal duct), by means of little cuttings in the walls of hollow organs. Due to narrow spaces, NOTES needs robotic systems to assure operation/movement precision and patient safety. Variable stiffness actuation (VSA) assures both requirements.

Gait Training using Pneumatically Actuated Robot System

Powered exoskeleton device for gait rehabilitation has been designed and realized, together with proper control architecture. Its DOFs allow free leg motion, while the patient walks on a treadmill with its weight, completely or partially supported by the suspension system. The use of pneumatic actuators for actuation of this rehabilitation system is reasonable, because they offer high force output, good backdrivability, and good position and force control, at a relatively low cost. The effectiveness of the developed rehabilitation system and proposed control architecture was experimentally tested. During the experiments, the movement was natural and smooth while the limb moves along the target trajectory.

Control architecture for a lower limbs rehabilitation robot system

This paper describes the control architecture for lower limbs rehabilitation robot system and its implementation. The system has exoskeleton structure with 10 DOF (Degrees Of Freedom) and is pneumatically actuated.

Powered Lower Limb Orthosis for Assisting Standing Up and Sitting Down Movements

For older and some classes of disabled people there is often the need for assistance in sitting down and standing up, although they may be able to walk. This is due to limited power in the muscles of the legs.

Characterization and modeling of a 3D scanner for mobile robot navigation

In this paper an accurate physics-based simulation model of the 3D laser scanner, based on 2D range sensor (SICK LD-OEM1000) is presented. The model of the 2D sensor derives from the characteristics of the physical one and includes the uncertainty of the measurement, the dependency of the beam incidence angle and the target surface properties. Some experiments aimed to characterize the effects of the operation time, time autocorrection, different object surface properties and orrientations are also presented in this paper. 3D scanner virtual model, developed in rigid body dynamics environment, was verified experimentally and the resultss are reported.

Mechanical design of a 3-dof parallel robot actuated by smart wires

In this paper the design of the kinematics, the device elements and the drivers of a 3-dof (degrees of freedom) robot driven by smart wires is presented. The wires are made by a shape memory alloy (SMA) and have a diameter of 0.15 mm. This robot has a parallel structure including a fixed plate and a moving plate. The plates are linked together by 3 SMA wires and a mechanical spring is located in the central part. Possible applications are the control devices to orient a mirror, a sample under a microscope or to orient the head of a micro snake like robot.