1,721,040 research outputs found
Kinematic design of a gravity compensated robot for device for ultrasound examination and assessment of endothelial dysfunction
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Design and kinematic optimization of a novel underactuated robotic hand exoskeleton
No full textThis study presents the design and the kinematic optimization of a novel, underactuated, linkage-based robotic hand exoskeleton to assist users performing grasping tasks. The device has been designed to apply only normal forces to the finger phalanges during flexion/extension of the fingers, while providing automatic adaptability for different finger sizes. Thus, the easiness of the attachment to the user’s fingers and better comfort have been ensured. The analyses of the device kinematic pose, statics and stability of grasp have been performed. These analyses have been used to optimize the link lengths of the mechanism, ensuring that a reasonable range of motion is satisfied while maximizing the force transmission on the finger joints. Finally, the usability of a prototype with multiple fingers has been tested during grasping tasks with different objects
A new screw theory method for the estimation of position accuracy in spatial parallel manipulators with revolute joint clearances
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New generation emerging technologies for neurorehabilitation and motor assistance
No full textThis paper illustrates the application of emerging technologies and human-machine interfaces to the neurorehabilitation and motor assistance fields. The contribution focuses on wearable technologies and in particular on robotic exoskeleton as tools for increasing freedom to move and performing Activities of Daily Living (ADLs). This would result in a deep improvement in quality of life, also in terms of improved function of internal organs and general health status. Furthermore, the integration of these robotic systems with advanced bio-signal driven human-machine interface can increase the degree of participation of patient in robotic training allowing to recognize user's intention and assisting the patient in rehabilitation tasks, thus representing a fundamental aspect to elicit motor learning
A 3-RSR Haptic Wearable Device for Rendering Fingertip Contact Forces
No full textA novel wearable haptic device for modulating contact forces at the fingertip is presented. Rendering of forces by skin deformation in 3 degrees of freedom (DoF), with contact - no contact capabilities, was implemented through rigid parallel kinematics. The novel asymmetrical three revolute-spherical-revolute (3-RSR) configuration allowed compact dimensions with minimum encumbrance of the hand workspace. The device was designed to render constant to low frequency deformation of the fingerpad in 3 DoF, combining light weight with relatively high output forces. A differential method for solving the non-trivial inverse kinematics is proposed and implemented in real time for controlling the device. The first experimental activity evaluated discrimination of different fingerpad stretch directions in a group of 5 subjects. The second experiment, enrolling 19 subjects, evaluated cutaneous feedback provided in a virtual pick-and-place manipulation task. Stiffness of the fingerpad plus device was measured and used to calibrate the physics of the virtual environment. The third experiment with 10 subjects evaluated interaction forces in a virtual lift-and-hold task. Although with different performance in the two manipulation experiments, overall results show that participants better controlled interaction forces when the cutaneous feedback was active, with significant differences between the visual and visuo-haptic experimental conditions
Dynamics Modeling of an Encountered Haptic Interface for Ball Catching and Impact Tasks Simulation
No full textThis paper deals with a model-based control strategy implemented on an encountered haptic interface developed for the simulation of ball catching tasks. A dynamical model of a reference device has been developed and validated by experimental results. This model was applied to increase the control performance and to simulate realistic impacts. The control strategy to generate the haptic interface trajectories consistent with the simulation of ballistic motion of virtual objects has been defined. At the impact instant the perceptively correct kinetic energy is transferred from the device end-effector to the user hand adopting a velocity scaling rule. Experimental results confirm control accuracy in fast dynamics trajectory tracking
A new method for the estimation of position accuracy in parallel manipulators with joint clearances
No full textThe contribution of cutaneous and proprioceptive sensory modalities in haptic perception of orientation
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