How the human brain controls hand movements to carry out different tasks is still debated. The concept of synergy has been proposed indicate functional modules that may simplify control postures by simultaneously recruiting sets muscles and joints. However, whether what extent synergic are encoded as such at a cortical level remains unknown. Here, we combined kinematic, electromyography, activity measures obtained magnetic resonance imaging while subjects performed variety towards virtual...

This paper presents an updated and comprehensive description of offset-free MPC algorithms for nonlinear (and linear) discrete-time systems, with the intended objectives clarifying main concepts, showing new results, highlighting subtleties by means challenging applications. First, tracking problem systems is presented, putting a strong accent on role disturbance model observer, then novel stronger estimation results are presented. Next, recent advances in linear described, which show...

Systematic optimization of the tooth contact pattern under load is an open problem in design spiral bevel and hypoid gears. In order to enhance its shape position, gear engineers have been assisted by numerical tools based on trial-and-error approaches, and/or they relying expertise skilled operators. The present paper proposes a fully automatic procedure optimize loaded pattern, with advantage eventually reducing time cost. main was split into two identification subproblems: first, identify...

This paper presents a new systematic method for identifying the values of machine-tool settings required to obtain flank form modifications in hypoid gears. The problem is given nonlinear least-squares formulation, and it solved by Levenberg–Marquardt with trust-region strategy. To test method, same ease-off topography was obtained means very different sets settings, including set only kinematic parameters highly redundant 17 parameters. In all cases, goal achieved few iterations, residual...

To adapt to many different objects and tasks, hands are very complex systems with degrees of freedom (DoFs), sensors, actuators. In robotics, such complexity comes at the cost size weight hardware devices, but it strongly affects also ease their programming. A possible approach simplification consists in coupling some DOFs, thus affording a reduction number effective inputs, eventually leading more efficient, simpler, reliable designs. Such can be software level, achieve faster, intuitive...

Microgeometry optimization has become an important phase of gear design that can remarkably enhance performance. For spiral bevel and hypoid gears, microgeometry is typically represented by ease-off topography. The optimal shape be defined as the outcome a process where generally conflicting objective functions are simultaneously minimized (or maximized), in presence constraints. This matter naturally lends itself to framed multi-objective problem. paper proposes general algorithmic...

Feedback control of robotic systems interacting with the environment through contacts is a central topic in legged robotics. One main challenges posed by this problem choice model sufficiently complex to capture discontinuous nature dynamics but simple enough allow online computations. Linear models have proved be most effective and reliable for smooth systems; we believe that piecewise affine (PWA) represent their natural extension when contact phenomena occur. Discrete-time PWA been deeply...

Haptic shared control enables a human operator and an autonomous controller to share the of robotic system using haptic active constraints. It has been used in teleoperation for different purposes, such as navigating along paths minimizing torques requested manipulator or avoiding possibly dangerous areas workspace. However, few works have focused on these ideas account user's comfort. In this article, we present innovative haptic-enabled approach aimed at workload during teleoperated...

This paper presents an automatic procedure to optimize the loaded tooth contact pattern of face-milled hypoid gears with misalignments varying within prescribed ranges. A two-step approach is proposed solve problem: in first step, pinion microtopography automatically modified bring perturbed patterns (as assembly errors are varied tolerance limits) match a target area while keeping them off edges; second subset machine-tool settings identified obtain required topography modifications. Both...

Despite some prematurely optimistic claims, the ability of robots to grasp general objects in unstructured environments still remains far behind that humans. This is not solely caused by differences mechanics hands: indeed, we show human use a simple robot hand (the Pisa/IIT SoftHand) can afford capabilities are comparable natural grasping. It through observation such human-directed operations realized how fundamental everyday grasping and manipulation role compliance, which used adapt shape...

This work proposes a solution to the grasp synthesis problem, which consist of finding best hand configuration given object for specific manipulation task while satisfying all necessary constraints. problem had been divided into sequential sub-problems, including contact region determination, inverse kinematics and force distribution, with particular constraints each step tackled independently. may lead unnecessary effort, such as when one problems has no output previous input. To overcome...

This paper presents a methodology to accurately record human finger postures during grasping. The main contribution consists of kinematic model the hand reconstructed via magnetic resonance imaging one subject that (i) is fully parameterized and can be adapted different subjects, (ii) amenable in-vivo joint angle recordings optical tracking markers attached skin. principal novelty here introduction soft-tissue artifact compensation mechanism optimally calibrated in systematic way....

In this paper, we present a method to reconstruct the configurations of kinematic trees rigid bodies not using measurements relative angles (such as, e.g. rotary encoders at joints) but absolute posture sensors as IMUs) along with suitable filter algorithms. We argue that relatively larger inaccuracies shown by can be compensated processing, such passive complementary filters exploiting Mahony-Hamel formulation. The proposed is applicable systems where feasible or convenient, joint...

Recent work on the analysis of natural and robotic hands has introduced notion postural synergies as a principled organization their complexity, based physical characteristics hand itself.Such include mechanical arrangements joints fingers, couplings, low-level control reflexes, that determine specific way concept "hand" is embodied in human being or robot.While focus done so far with been motion planning for grasp acquisition, this paper we set out to investigate role different embodiments...

Despite being a classical topic in robotics, the research on dexterous robotic hands still stirs lively activity. The current interest is especially attracted by underactuated where high number of degrees freedom (DoFs), and relatively low actuation co-exist. correlation between DoFs obtained through wise distribution actuators aimed at simplifying control with minimal loss dexterity. In this sense, application bio-inspired principles bringing toward more conscious design. This work proposes...

In this paper, we set out to investigate the performances of some algorithms proposed in gear literature for identifying machine-tool settings required obtain predesigned tooth surface topographies, or needed compensate flank form deviations real teeth. For ease comparison, problem is formulated as a nonlinear least squares problem, and most widely employed are derived special cases. The included analysis (i) one-step methods, (ii) iterative (iii) methods with step control. performance index...

In this letter, we propose a two-stage strategy for optimal control problems of robotic mechanical systems that proves to be more robust, and yet efficient, than straightforward solution strategies. Specifically, focus on simplified humanoid model, represented as two-dimensional articulated serial chain rigid bodies, in the tasks getting up (sitting down) from (to) supine prone postures. Interactions with environment are integral parts these motions, <italic...

Humans explore and adapt neuro-motor strategies to cope with limitations of multi-joint impedance regulation mechanism. For instance, predictive control degrees redundancy further regulates the endpoint in addition co-contractions. Inspired by these observations, this paper proposes a novel Tele-Impedance algorithm that replicates human's arm stiffness robot controlling common-mode configuration-dependant stiffness. Design controller its stability is addressed experimentally evaluated...