José Fermi Guerrero-Castellanos

A Robust Nonlinear Observer for Real-Time Attitude Estimation Using Low-Cost MEMS Inertial Sensors

This paper deals with the attitude estimation of a rigid body equipped with angular velocity sensors and reference vector sensors. A quaternion-based nonlinear observer is proposed in order to fuse all information sources and to obtain an accurate estimation of the attitude. It is shown that the observer error dynamics can be separated into two passive subsystems connected in “feedback”. Then, this property is used to show that the error dynamics is input-to-state stable when the measurement disturbance is seen as an input and the error as the state. These results allow one to affirm that the observer is “robustly stable”. The proposed observer is evaluated in real-time with the design and implementation of an Attitude and Heading Reference System (AHRS) based on low-cost MEMS (Micro-Electro-Mechanical Systems) Inertial Measure Unit (IMU) and magnetic sensors and a 16-bit microcontroller. The resulting estimates are compared with a high precision motion system to demonstrate its performance.

A Backstepping Approach to Decentralized Active Disturbance Rejection Control of Interacting Boost Converters

In this paper, the local trajectory tracking control problems ascribed to two interacting plants, considered as agents, are formulated as adaptive control problems, which involve online interaction estimation and interaction elimination. This approach gives rise to a robust decentralized collaborative control with virtually no information on the part of the agents. It is shown that when the interconnection effects are viewed as exogenous unstructured disturbances, such disturbance can be actively estimated and canceled from each individual subsystem model dynamics. The case presented deals with two agents, two interconnected boost dc–dc power converters, powered each one by a nonidentical photovoltaic module that represents a time-varying power supply. Then, a backstepping-based control together with an extended state observer is developed by each agent. The mutual goals of agents are to maintain a desired behavior (time-varying current demand) of the entire system in order to maintain the desired output voltage value and an equitable current sharing in each converter in order to supply a dc motor. The proposed distributed control technique is implemented in two TMS320F28335 digital signal processor (each one per agent) and its performance is experimentally evaluated in real time. It is shown that the proposed scheme is robust with respect to interaction, unmodeled nonlinearities, and unmodeled dynamics.

Event-triggered observer-based output-feedback stabilization of linear system with communication delays in the measurements

In this paper, an original framework is proposed for the stabilization of a linear system with delays in the measurements: i) an observer estimates the full state information of the plant from a partial measurement, ii) an event-based control technique computes and updates the control signal only when a certain condition is satisfied and iii) an event-based corrector updates the model used to calculate the control law when it deviates from the estimated state. It is notably proved that such a proposal renders the closed-loop system stable for larger delays in the measurements than in the classical continuous-time control case. Simulation results are provided.

A CMOS Frequency Doubler from the Analog Cosine Mapping Function

This work presents the design of a new frequency doubler by a simple inductorless active network, without the exigency of additional quadrature signals. The frequency doubling function of the proposed circuit relies on the analog cosine mapping operation. The mapping circuit is possible in voltage mode as the circuit is based on two face-to-face CMOS inverters switched by the same differential input signal. The circuit is designed, with a simple set of functions, according to the nonlinear circuit’s nature. It was designed in a CMOS 0.18-

Self-triggered control for the stabilization of linear systems

upmu

Evaluation of gain scheduled predictive control in a nonlinear MIMO model of a hydropower station

μm process with a doubling frequency up to

Decentralized ADR angular speed control for load sharing in servomechanisms

8~text{ GHz }