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Purpose Retinal vein cannulation is an experimental procedure during which a clot-dissolving drug is injected into an obstructed retinal vein. However, due to the fragility and minute size of retinal veins, such procedure is considered too risky to perform manually. With the aid of surgical robots, key limiting factors such as: unwanted eye rotations, hand tremor and instrument immobilization can...
This paper presents the latest results in the development of the low-level controller of the robotic hand UBH-IV (University of Bologna Hand, version IV). In particular, the friction effects acting at joint level have been rendered by means of a LuGre-like model and a procedure for the identification of the friction model parameters is described. With the aim of providing an online estimation of the...
This paper reports the modeling activities related to the development of an innovative tendon-driven robotic finger, designed as the fundamental element of a new biologically-inspired artificial hand. The finger is realized in plastic material by means of 3D-printing, a production process that allows a remarkable simplification of the mechanical design. Through 3D-printing, we were able to easily...
In this paper, the characterization of the force distribution along a tendon sliding on a curved pathway, subject to friction and visco-elastic effects, is investigated. In order to have a better understanding of the system behavior, a specific setup able to measure tension forces in different points along the tendon's path has been built. Experimental data collected by measuring the tendon tension...
Tendon-based transmission systems present many positive aspects and greatly simplify the mechanical design of small robotic devices, such as robotic fingers. On the other hand, they introduce several nonlinear effects that must be properly considered by the control algorithms to achieve a suitable performance level in the regulation of the finger joint torques. In this paper, the model of the tendons-based...
Among the methods to grant the stability of a telemanipulation system, the bilateral time domain passivity framework has the appealing characteristic to consider both, force and velocity signals exchanged between master and slave systems, and the power introduced or dissipated by the elements that compose the telemanipulation system. In previous works, it has been shown how the bilateral passivity...
The time domain passivity framework is attracting interest as a method for granting stability in both telerobotics and haptic contexts; this paper employs this approach in order to introduce a novel concept, the Bilateral Energy Transfer for haptic telepresence. Loosely speaking, the Bilateral Energy Transfer is the straightforward transfer of energy between the two opposite sides of a teleoperation...
In this paper, two problems related to the simulation of virtual environments for haptic systems are considered. The first problem is how to simulate, in discrete time and with low computational effort, dynamic systems in order to preserve their passivity properties. As a matter of fact, simulation of complex systems in real time may lead to undesired effects, like unstable behaviours of the haptic...
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