1,721,113 research outputs found
Experimental validation of a special state observer for a class of flexible link mechanisms
No full textThis paper presents an experimental validation of a state observer for flexible-link manipulators (FLM). The design of this observer is based on an accurate dynamic model of the mechanisms, able to take into account the coupled rigid-flexible dynamics of the system. Experimental results on a single-link manipulator affected by gravity force show that the proposed observer achieves a good estimation of the plant dynamics even if the displacement signal is not measured. The evaluation of the performance is done experimentally by comparing the estimated elastic displacement with the measures obtained on the field
Dynamics and control of flexible-links mechanism
No full textIn questa tesi vengono affrontate alcune problematiche legate alla modellizzazione dinamica, alla simulazione Real-Time ed al controllo predittivo di meccanismi a membri deformabil
Actuation Along a Single Linear Axis: The Kinematics of the Single-Rail Tripteron
No full textThe aim of this work is to introduce the kinematics of one possible implementation of the Tripteron robot. The variant discussed here is referred to as the ‘single rail’ Tripteron, given that the three axes of the actuated prismatic joints are coincident. This configuration allows to shape, by design, the Jacobian matrix, allowing to tune along the Cartesian directions the speed and force generation capabilities by setting the three relevant angles to the kinematic design. The possibility of providing the actuation along a single line also allows to provide it by means of a Permanent Magnet Linear Synchronous Motor (PMLSM) with three shuttles. A prototype of the manipulator has been developed to test the feasibility of the design
Intelligent Automated Process: a Multi Agent Robotic Emulator
No full textThe demands of modern industry push towards
new adaptive and configurable production systems where multiagent
techniques and technologies, suitable for modular, decentralized,
complex and time varying environments, can be
exploited. In this work a generic assembly line is evaluated and
the basic features, problems and non-idealities that can occur
during the production are taken into account for evaluating
and developing an intelligent automated emulated process made
of Multi-Agent Robotic Systems. A simplified agentification of
the process is made: the main elements of the production are
modeled as an agent while the operators that work to restock
the local working station stores are considered as autonomous
(robotic) agents
Energy-optimal motion laws for servo-actuated systems considering asymmetric transmission efficiency
No full textThe synthesis of optimal motion trajectories is a well-established and cost-effective approach to improving the energy performance of mechatronic systems. This work introduces a method for the generation of energy-optimal trajectories in servo-actuated systems incorporating transmissions with non-unitary efficiency and with asymmetric (direct/reverse) power transmission behavior.The importance of incorporating the efficiency effect relies on the fact that the actual dynamics shows a not-smooth behavior, making the ideal system prediction erratic and the solution of the minimum-energy problem challenging. The proposed approach takes advantage of the known structure of the optimal solution, allowing the motion planning problem to be reformulated as an iterating quadratic programming problem. Optionally, a set of nonlinear equations has to be solved if acceleration/jerk limits are considered. These are constructed on the basis of continuity conditions that ensure physical and dynamical consistency. The formulation allows for real-time implementation, thus extending the applicability of minimum-energy trajectories in industrial scenarios, as general-purpose solvers do not cope with real-time requirements. Finally, the energy-saving capabilities are shown through comparison with a standard double-S law
Thermo-mechanical analysis of a fire door for naval applications
No full textIn this work, the thermo-mechanical response of fire doors for naval application is considered. In order to evaluate their behaviour, fire doors must undergo a standardized fire test. A realistic simulation of the heating process can be useful during the design phase in order to reduce the number of prototypes to be constructed and tested. In this work, a finite element model is developed with the aim of capturing the qualitative behaviour of the fire door and its supporting frame. Two different types of thermal analysis are considered: (1) transient analysis and (2) steady-state analysis. A non-linear mechanical analysis predicts the displacement field that occurs at the end of the heating phase. The adopted model is validated through a comparison with experimental measurements obtained during standard fire tests, confirming that the proposed approach can be a valid tool for the prediction of the thermo-mechanical performance of a naval fire door. © The Author(s) 2015
Model-based trajectory planning for flexible-link mechanisms with bounded jerk
No full textThis paper deals with the model-based development of optimal jerk-limited point-to-point trajectories for flexible-link robotic manipulators. In the proposed approach, an open-loop optimal control strategy is applied to an accurate dynamic model of flexible multi-body planar mechanisms. The model, which has already been fully validated through experimental tests, is based on finite element discretization and accounts for the main geometric and inertial nolinearities of the linkage. Exploiting an indirect variational solution method, the necessary optimality conditions deriving from the Pontryagin's minimum principle are imposed, and lead to a differential Two-Point Boundary Value Problem (TPBVP); numerical solution of the latter is accomplished by means of collocation techniques. The resulting motion and control profiles can be used as feedforward reference signals for a position and vibration control. Considering a lightweight RR robot, simulation results are provided for rest-to-rest, jerk-limited trajectories with minimum actuator jerks and vibrations. However, the strategy under investigation has general validity and can be applied to other types of machanisms, as well as with different objective functions and boundary conditions. Numerical evidence clearly indicates that the use of a composite cost functional and the imposition of jerk constraints can greatly reduce vibration phenomena during high-speed motion of flexible-link manipulators
Optimal trajectory planning for nonlinear systems: robust and constrained solution
No full textThis paper presents a solution to the problem of generating constrained robust trajectory
planning for nonlinear plants. By using an indirect variational solution method, the necessary
optimality conditions deriving from the Pontryagin’s minimum principle are imposed, and
lead to a differential Two-Point Boundary Value Problem (TPBVP); numerical solution of
the latter is accomplished by means of collocation techniques. The robustness to parametric
mismatches is obtained trough the use of sensitivity functions, while a hard constraint on
actuator effort is obtained using a smoothing technique. Numerical results shows that the
robustness can be greatly improved, and that the inclusion of constraints on actuator effort
does not affect it
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