Manuel Arias-Montiel

Finite element modeling and unbalance compensation for a two disks asymmetrical rotor system

In this work a LQR scheme for vibration control in a rotor system is presented. The rotor system has two disks in an asymmetrical configuration along the shaft and its model is obtained by applying finite element techniques. A reduced order model of seven degrees of freedom is experimentally validated for the synthesis of active LQR control laws, using both an output feedback (one disk displacement) and an estimated state feedback controller. The controller is tuned to reduce the vibrations caused by the rotor imbalance in the two disks using only an actuator (active magnetic bearing). Some simulation and experimental results are included to show the transient and steady-state behavior of the overall closed loop system.

Active Vibration Control in a Rotor System by an Active Suspension with Linear Actuators

In this paper the problem of modeling, analysis and unbalance response control of a rotor system with two disks in anasymmetrical configuration is treated. The Finite Element Method (FEM) is used to get the system model including thegyroscopic effects and then, the obtained model is experimentally validated. Rotordynamic analysis is carried outusing the finite element model obtaining the Campbell diagram, the natural frequencies and the critical speeds of therotor system. An asymptotic observer is designed to estimate the full state vector which is used to synthesize a LinearQuadratic Regulator (LQR) to reduce the vibration amplitudes when the system passes through the first critical speed.Some numerical simulations are carried out to verify the closed-loop system behavior. The active vibration controlscheme is experimentally validated using an active suspension with electromechanical linear actuators, obtainingsignificant reductions in the resonant peak.

Active unbalance control in a two disks rotor system using lateral force actuators

This work deals with the problem of modelling and analysis in rotordynamics as well as the active control of vibrations caused by unbalance in a rotor system. The system model was obtained by Finite Element Method taking into account the gyroscopic effects. The finite element model is used to get the Campbell diagram, the critical speeds, the modal shapes and to design the control scheme to attenuate the vibrations amplitude by an active suspension which uses linear electromechanical actuators. Due to the great number of states involved in the model, a state observer is necessary in order to apply a Linear Quadratic Regulator with full state feedback. The controller is applied considering the dynamics of actuators in the active suspension. Some numerical simulations to verify the controller-observer performance and experimental results on a novel test rig to prove the closed loop behavior are presented.

Active unbalance control in an asymmetrical rotor system using a suspension with linear actuators

This work deals with the problem of the active unbalance control in an asymmetrical rotor-bearing system with two disks supported by an active suspension based on two lateral linear actuators. For the analysis and control synthesis a mathematical model is developed using Finite Element Methods (FEM). A linear quadratic regulator (LQR) is applied in order to minimize the displacements of the two disks by means of the application of an active bearing with control forces provided by an arrangement of two linear actuators. The control scheme is designed to attenuate the overall system response in the natural frequencies (resonances), taking into account the unbalance response associated to both disks and shaft and, hence, controlling the system performance during the first modes. To do this, a Luenberger type observer is used to estimate those not measurable states from the displacements in only one shaft point and, therefore, making possible the synthesis of an optimal LQR control based on the estimated state feedback. The control forces obtained from LQR control are introduced to the mathematical model of actuators and taking into account their dynamics, we get the voltage inputs necessary to provide the unbalance compensation forces. The proposed control scheme is proved by numerical results and then, validated experimentally on a test rig which was designed and constructed. Numerical and experimental results show significant reductions in the unbalance response of the overall system.

Design and control of a two disks asymmetrical rotor system supported by a suspension with linear electromechanical actuators

This paper describes the problem of design of an experimental setup for rotordynamic analysis and unbalance control. The rotor system has two disks in an asymmetrical configuration along a steel shaft which is connected to a three phase AC motor by a flexible coupling. A suspension with two linear electromechanical actuators is used to control actively the vibrations caused by unbalance in disks. A LQR scheme with estimated state feedback is developed based on a reduced order finite element model of rotor system. The controller is applied taking into account the actuators dynamics. Some advances in the construction of the prototype and open loop experimental results are presented. The dynamic behavior of the closed loop system are shown by numerical simulations.

A Robust Control Scheme Against Some Parametric Uncertainties for the NXT Ballbot

In this work a Linear Matrix Inequalities (LMIs) approach to provide robustness to an optimal control scheme for the NXT ballbot is proposed. The mathematical model of the system is obtained taking into account the actuators dynamics and in this overall model uncertain parameters appear. These uncertainties can affect (in a negative form) the control algorithm performance, so we define a polytopic model considering some parameters vary within some bounded sets. This polytopic model is used to synthesize a robust control scheme against parameters variation using LMIs. Numerical results show a significant improvement in the closed loop system in comparison with a classic Linear Quadratic Regulator (LQR) control. Finally, some experimental results are presented to show the viability of implementing the control strategy proposed.

Design and Dynamic Modeling of a Novel Single-Wheel Pendulum Robot

Single-wheel mobile robots have emerged as an alternative to multi-wheel robots due to their compact size and motion flexibility. These characteristics could potentially enable single-wheel robots to be used for search and rescue, exploration and carrying loads in reduced spaces. In this work, the design and dynamic coupled model of a novel single-wheel pendulum robot are presented. Both issues are validated by numerical simulations and the obtained results show the viability for the practical implementation of the proposed design and for the development of control algorithms for robot motion.

Design and construction of a passive mechanism for emulation of load forces in an electric power steering system

This article presents the design and construction of a mechanism for emulating load forces caused by the road conditions and friction over an electric power assisted steering (EPAS). This mechanism uses extension springs and a rack-and-pinion mechanism to emulate these load forces. The purpose of devising this mechanism is to build an EPAS system test bench, that allows observing and testing the operation steering system in load conditions.

A numerical approach for the inverse and forward kinematic analysis of 5R parallel manipulator

In this paper a numerical approach for the position, velocity and acceleration analysis for a 5R parallel manipulator is presented. 5R parallel manipulator is a two degrees of freedom planar mechanism which has been extensively studied by analytical methods. In this work, the use of computational tools such as Matlab and ADAMS is proposed in order to solve the inverse and forward kinematic problem of a particular type of 5R symmetric parallel manipulator. The obtained numerical results are validated by comparing them with analytical methods reported in the literature. This numerical approach allows for the co-simulation with other computational tools for the creation of virtual prototypes and it can save time and resources in the development of 5R parallel manipulator applications.

ADAMS-MATLAB co-simulation for kinematics, dynamics, and control of the Stewart–Gough platform:

The mechanical structure known as Stewart–Gough platform is the most representative parallel robot with a wide variety of applications in many areas. Despite the intensive study on the kinematics, dynamics, and control of the Stewart–Gough platform, many details about these topics are still a challenging problem. In this work, the use of automatic dynamic analysis of multibody systems software for the kinematic and dynamic analysis of the Stewart–Gough platform is proposed. Moreover, a co-simulation automatic dynamic analysis of multibody systems (ADAMS)-MATLAB is developed for motion control of the Stewart–Gough platform end-effector. This computational approach allows the numerical solution for the kinematics, dynamics, and motion control of the Stewart–Gough platform and a considerable reduction on the analytical and programming effort. The obtained results in the three topics (kinematics, dynamics, and control) are validated by comparing them with analytical results reported in the literature. This kind of computational approach allows for the creation of virtual prototypes and saves time and resources in the development of Stewart–Gough platform-based robots applications.