1,720,975 research outputs found
Motion-decoupled internal force control in grasping with visco-elastic contacts
No full textRobotic grasps exhibiting visco-elastic contact interactions with the manipulated object are considered. Control of internal forces is investigated. The presence of nonnegligible compliance at contacts, implies that the object dynamics cannot be neglected when attempting to control internal forces without affecting the object position. A dynamic internal force control is proposed. It is decoupled with respect to the rigid-body object motions
Comparison Between UKF and EKF in Sensorless Synchronous Reluctance Motor Drives
Full text linkThe reduction of the human environmental footprint can be achieved through the use of more efficient motors, such as synchronous reluctance motors (SynRMs). Known for their affordability, SynRMs are increasingly employed in sensorless AC drives. This paper presents a critical comparison of sensorless algorithms based on two nonlinear Kalman Filters (Unscented and Extended). The objective is to highlight the theoretical and practical advantages and drawbacks of each method when applied to the speed control of a SynRM, culminating in a definitive decision on the best choice. The magnetic model of the SynRM is much more nonlinear than that of induction motors, which are predominantly addressed in existing literature. This study aims to fill the gap by answering the question: “Is the extended Kalman filter still the best choice even in the case of nonlinear electric motors?” The answer comes through a large batch of experiments, including speed and load torque tests, zero-speed standstill starts, parameter sensitivity, and evaluation of computational burdens for both Kalman filter algorithms
Some results on output algebraic feedback with applications to mechanical systems
No full textConstructive necessary and sufficient conditions for disturbance decoupling with algebraic output feedback are presented. Necessary and sufficient conditions are also derived for the decoupling problem with internal stability. The same conditions are re-stated in terms of invariant zeros. The groundwork throughout is the dual-lattice structures of invariants introduced by Basile and Marro (1992). Finally, an application to mechanical systems is presented
Automatic Tuning of Extended Kalman Filter in Sensorless Synchronous Reluctance Motor Drives
Full text linkA substantial reduction in the human environmental footprint can be achieved through the use of more efficient motors, such as synchronous reluctance motors (SynRM). As low-cost motors, SynRMs are commonly employed in sensorless AC drives. Sensorless algorithms based on the Extended Kalman Filter (EKF) offer several advantages, but they require a time-consuming trial-and-error tuning procedure. This paper proposes the automatic tuning of the EKF through a second Kalman Filter (KF) in a primary–secondary (PS) configuration. The two KFs work concurrently: the first estimates the required quantities for machine control, and the second updates the process noise statistics of the first KF. The second KF is much easier to tune, requiring only one non-critical parameter. Experimental results confirm the validity of this approach
A trajectory generation algorithm for optimal consumption in electromagnetic actuators
No full textCamless internal combustion engines offer improvements over traditional engines in terms of torque performance, reduction of emissions, reduction of pumping losses and fuel economy. Theoretically, electromagnetic valve actuators offer the highest potentials for improving efficiency due to their control flexibility. For real applications, however, the valve actuators developed so far suffer from high power consumption and other control problems. One key point is the design of the reference trajectory to be tracked by the closed loop controller. In this brief, a design technique aimed at minimizing power consumption is proposed. A constrained optimization problem is formulated and its solution is approximated by exploiting local flatness and physical properties of the system. The performance of the designed trajectory is validated via an industrial simulator of the valve actuator
Dynamic control of internal force for visco-elastic contact grasps
No full textThis paper deals with robotic grasps exhibiting viscoelastic contact interactions with the manipulated object. Such interactions are frequent in advanced robotic applications since in many cases, i.e. when a great precision is needed, elasticity cannot be neglected. This is particularly true in medical applications, as in telesurgery or in laparoscopy, where precision is obviously basic. The control of internal forces for viscoelastic grasps is explored in this work. This is an important issue in teleoperated robotics (telesurgery and so forth). The presence of nonnegligible compliance at the contacts, implies that the object dynamics cannot be neglected when attempting to control internal forces without affecting the object position. A geometric approach to derive a control law dynamically decoupling the internal force control action from the object dynamics is proposed
Perfect anti-windup in output tracking scheme with preaction
No full textThis paper proposes a dynamic anti-windup compensation scheme for linear control systems with saturating actuators. Perfect tracking is achieved using pre-actuation and a dynamic compensator controlling the reset windup phenomenon. Two performance indices are considered and an example is included to illustrate the effectiveness of the proposed method
Robust Decoupling Control of Contact Forces in Robotic Manipulation
No full textThis paper deals with the problem of controlling contact forces in robotic manipulators with general kinematics. The main focus is on control of grasping contact forces exerted on the manipulated object. A visco-elastic model for contacts is adopted. Robustness of the decoupling controller with respect to the uncertainties affecting system parameters is investigated. Sufficient conditions for the invariance of decoupling action under perturbations on the contact stiffness and damping parameters are provided. These conditions are meaningful for several classes of manipulation systems with general kinematics
Noninteracting force/motion control of defective manipulation systems
No full textThis paper deals with the problem of noninteracting force/motion control for manipulation systems with possible kinematic defectivity. A geometric approach is adopted in the paper. The main result of the paper shows that a suitable choice of the outputs exists, for which a structural noninteraction property holds, and such that most practical manipulation tasks can be naturally specified
Geometric Disturbance Decoupling Control of Vehicles with Active Suspensions
No full textIn this paper the problem of localizing disturbances of a vehicle with active suspensions is investigated. We focus on the regulation of the chassis posture in spite of inaccessible disturbances. The regulated variables, i.e. the roll and pitch angles and the chassis heights, can be disturbance decoupled by state feedback. The decoupling problem is analyzed from a geometric control point of view. The geometric aspects of the vehicle dynamics are emphasized and it is shown that disturbance localization is a structural property of vehicles with active suspensions. On the implementation side, we show that, if suspensions heights along with their derivatives are available as measured outputs, disturbance localization can be gained by a static output feedback
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