The objective of spatially-aware access control models is to regulate the access to protected objects based on position information. In that last years, increasing attention has been paid to spatiallyaware access control models for mobile and pervasive applications. Following the experience of design of the GEO-RBAC model, in this paper we want to look at those models with a critical eye and po...

Contour error reduction for modern machining processes is an important concern in multi-axis contour tracking applications in order to ensure the quality of final products. Many control methods were developed in time domain to deal with contour tracking problems, and a proportional–derivative (PD) position domain control (PDC) was also proposed by the authors. It is well known that proportional...

A new conceptually simple approach to controlling compliant motions of a robot manipulator is presented. The "hybrid" technique described combines force and torque information with positional data to satisfy simultaneous position and force trajectory constraints specified in a convenient task related coordinate system. Analysis, simulation, and experiments are used to evaluate the controller's ...

This work is part of a collaboration with the cancer institute L eon B erard (Lyon, France) and concerns conformal radiotherapy. The current medical process begins by acquiring a reference computed tomog-raphy volume of a patient, and by computing an irradiation procedure. During several weeks, the patient comes every day for an irradiation session. In order to have a safe and eecient irradiati...

A variety of sensors and positioning methods have been developed over the years. Most methods rely on active sensors (such as sonars or lasers) which have range and power restrictions, or rely on computationally complex (and often slow) methods such as recovering position from stereo or optical flow. This paper describes a system that can determine a robot’s position and orientation, in all six...

RC-servos are widely used to build robots with many degrees of freedom, because they are small, inexpensive, and easy to interface. Their main advantage, though, is their good weight-to-torque ratio. Many robots in the RoboCup Humanoid League, for example, almost entirely consist of servos. RC-servos come in two flavors: analog and digital. In analog servos, the internal controller is synchroni...

Conventionally, tendon-driven manipulators implement some force control scheme based on tension feedback. This feedback allows the system to ensure that the tendons are maintained taut with proper levels of tensioning at all times. Occasionally, whether it is due to the lack of tension feedback or the inability to implement sufficiently high stiffnesses, a position control scheme is needed. Thi...

Modelling of the motion of a helicopter with a suspended load is described. The mathematical model takes into account stochastic disturbances acting on the load suspension point. The proposed approach allows solution of the problem of optimal control with minimization of oscillation and control power expenditure. The evolution of the system solution with time is investigated for various disturb...

The application of parallel force/position control to teleoperation systems is considered in this paper. Higher priority is given to position control at the master side and to force control at the slave side of the teleoperation system. The stability and performance of the proposed controller is investigated by analyzing the three decoupled systems obtained from projecting the closed-loop syste...