Robots for rehabilitation tasks require a high degree of safety for the interaction with both the patients and for the operators. In particular, high safety is a stable and intuitive control of the moving elements of the system combined with an external system of sensors able to monitor the position of every aspect of the rehabilitation system (operator, robot, and patient) and overcome in a certain measure all the events that may occur during the robotic rehabilitation procedure. This paper presents the development of an internal torque monitoring system for ASPIRE. This is a parallel robot designed for shoulder rehabilitation, which enables the use of strategies towards developing a HRI (human–robot interaction) system for the therapy. A complete analysis regarding the components of the robotic system is carried out with the purpose of determining the dynamic behavior of the system. Next, the proposed torque monitoring system is developed with respect to the previously obtained data. Several experimental tests are performed using healthy subjects being equipped with a series of biomedical sensors with the purpose of validating the proposed torque monitoring strategy and, at the same time, to satisfy the degree of safety that is requested by the medical procedure.

Abstract. This work addresses the design and numerical characterization of a new exoskeleton solution for human leg motion assistance and rehabilitation. The exoskeleton solution is anthropomorphic, simple, low cost and easy to adapt on the human subject. The design aspect concerns the exoskeleton mechatronic structure, achieved in SolidWorks virtual environment. Numerical simulation is performed in MSC.ADAMS simulation environment. Obtained results for the exoskeleton computed motion are compared with those obtained from experimental walking of healthy subject. The prototype feasibility is studied both for design and operation aspect.

Abstract. In this paper it is presented a numerical simulation and an experimental study of total friction torque from radial ball bearings. For this purpose it is conceived a virtual CAD model of the experimental test bench for bearing friction torque measurement. The virtual model it is used for numerical simulation in Adams software, that allows dynamic study of multi-body systems and in particularly with facility Adams Machinery of dynamic behavior of machine parts. It is manufactured an experimental prototype of the test bench for radial ball bearings friction torque measurement. In order to measure the friction torque of the tested bearings it is used an equal resistance elastic beam element, with strain gauge transducer to measure bending deformations. The actuation electric motor of the bench has the shaft mounted on two bearings and the motor housing is fixed to the free side of the elastic beam, which is bended by a force proportional with the total friction torque. The beam elastic element with strain gauge transducer is calibrated in order to measure the force occurred. Experimental determination of the friction torque is made for several progressive radial loads. It is established the correlation from the friction torque and bearing radial load. The bench allows testing of several types and dimensions of radial bearings, in order to establish the bearing durability and of total friction torque. IntroductionIn the literature are presented a large number of studies concerning the friction, lubrication and wear of materials. Test procedures for experimental measuring for the friction torque in rolling bearings are presented in [1]. For this purpose it is used a modified four ball machine, in order to test rolling bearings. It is monitored the friction torque and operating temperature. Other research [2] examines the frictional power loss of a needle roller bearing lubricated with grease. Obtained results reveal that the test bearing has higher friction compared with bearings lubricated with conventional lubrication. Low cost systems for the force and torque measurement, for wheel bearings are presented in [3]. Also, a study for the friction of a ball screw is presented in [4]. It is presented a theoretical model for the friction between balls of the screw. The study is useful because provides a theory support for reasonably reducing the screw ball friction. Studies based on the lubrication theory are presented in [5]. It is studied the wear behavior, using a four ball wear tester. Tests are made with a low viscosity additivated mineral oil. Two types of balls are used, steel and ceramic and obtained results shows greater resistance of the ceramic balls. The effects of roughness upon friction of the plastics, intended for bearing applications are studied in [6]. Obtained results shows that not exists an optimal roughness for minimum friction for polymers and the friction depends on the bulk properties of the polymer.

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