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In various interaction tasks using Underwater Vehicle Manipulator Systems (UVMSs) (e.g. sampling of the sea organisms, underwater welding), important factors such as: i) uncertainties and complexity of UVMS dynamic model ii) external disturbances (e.g. sea currents and waves) iii) imperfection and noises of measuring sensors iv) steady state performance as well as v) inferior overshoot of interaction force error, should be addressed during the force control design. Motivated by the above factors, this paper presents a model-free control protocol for force controlling of an Underwater Vehicle Manipulator System which is in contact with an unknown compliant environment, without incorporating any knowledge of the UVMS’s dynamic model, exogenous disturbances and sensor’s noise model. Moreover, the transient and steady state response as well as reduction of overshooting force error are solely determined by certain designer-specified performance functions and are fully decoupled by the UVMS’s dynamic model, the control gain selection, as well as the initial conditions. Finally, a simulation study clarifies the proposed method and verifies its efficiency.

In this paper, novel event-triggered strategies for the design of model predictive (MPC) controllers are presented. The MPC framework consists in finding the solution to a constraint optimal-control problem at every time-step. The case of triggering the optimization of the MPC only when is needed, is investigated. The centralized case is treated first and the results are then extended to a decentralized formulation. We consider a system composed by a number of interconnected subsystems, each one of them controlled by a robust MPC algorithm. Using the Input-to-State (ISS) property of the decentralized MPC controller we reach to an event-triggering rule, for each of the subsystems.

In this paper we use the centralized multirobot navigation function methodology established by the authors, augmented with an enhanced dipolar navigation field suitable for non-holonomic vehicls. A properly designed discontinuous feedback control law is applied to steer the nonholonomic vehicles. The esulting high frequency switching behavior, known as chattering, which is inherent in discontinuous controllers, is tackled with an appropriately designed discontinuous backstepping controller, which effectively reduces chattering. The vehicles are assumed to have limitations on their maximum achievable velocities. Those issues are taken into account in the control law design. The resulting closed form control scheme provides robust navigation withguaranteed collision avoidance and global convergence properties, as well as fast feedback, rendering the methodology particularly suitable for real time implementation, on systems with limited actuation capabilities. Collision avoidance and global convergence properties are verified through non - trivial computer simulations.

We present the design of a pre-shaping module that feeds an industrial robot controller with a pseudo-reference trajectory and guarantees that the controller output acts as a required nonlinear control scheme. This is to enable the rapid testing and prototyping of control schemes on real robots without having to intervene with the hardware and low level software of their industrial controllers.

In this work we construct a general dynamic model for a system with multiple mobile manipulators which carry a deformable object, It incorporates all dynamics and significant mechanical constraints. In the model we consider the mobile platforms and the onboard manipulators as a single system, we take into account the nonholonomic constraints imposed on the platforms and provide necessary conditions for stability of the mechanism against tipping over. Finally, the properties of the set of admissible reaction forces, defined by the constraint equations, are discussed.