Fabrício Gonzalez Nogueira

Simplified dead-time compensator for multiple delay SISO systems

This paper presents a dead-time compensation structure able to deal with stable and unstable multiple delay single input single output (SISO) systems. The proposed method aims to simplify the primary controller by replacing it for FIR filters placed at the feedback path. Such modification reduces the total number of parameters to be tuned which facilitates the overall design in comparison with other primary controllers normally considered. Simulation results show a better performance for the proposed control approach compared with other dead-time compensator (DTC) recently proposed in the literature.

Trajectory tracking control of a mobile robot using lidar sensor for position and orientation estimation

In this paper it is investigated the trajectory tracking control of a wheeled mobile robot using a laser rangefinder sensor to estimate the robot position and orientation (posture). This technique is compared with the conventional odometry method where the encoders data are used for posture estimation. The paper also presents the description of the robot as well as its mathematical modeling. Two controllers in cascade were used to implement the tracking control. A kinematics controller generates the references for internal motor speed controllers. Experimental results in an indoor environment are presented for trajectories with no obstacles.

Trajectory tracking control of a nonholonomic mobile robot with differential drive

This paper presents the development and trajectory tracking control of a nonholonomic mobile robot with differential drive. The used control system is composed of two loops cascaded, with internal PID controlling the speed of the two wheels and an external loop controlling the robot position and orientation. The second one is a feedfoward kinematics controller which is tuned according to desired closed-loop characteristics specified by the user. The control strategies were embedded in a digital module based in a 32-bit ARM microcontroller. In order to evaluate the performance of the developed robot, trajectory tracking tests were carried out for different trajectories and initial conditions. Preliminary experimental results are presented for reference trajectories without obstacles.

Anti-windup dead-time compensation based on generalized predictive control

This work proposes an anti-windup dead-time compensator (DTC) based on a generalized predictive controller (GPC). At first, it is analysed the dead-time compensation properties of the GPC by its formulation in a DTC structure. Secondly, a saturation model is added in order to overcome windup problems. The proposed control structure does not use any extra tuning parameter due to the anti-windup characteristic. Simulation results are used to compare the proposed controller with others anti-windup DTCs proposed in literature.

Tuning of a dead-time compensator focusing on industrial processes

This paper proposes tuning rules for the Simplified Dead-Time Compensator (SDTC), which is intended to deal with stable, unstable and integrative dead-time processes. The main contribution is the proposal of new guidelines for the tuning of the robustness filter. The new set of rules allow for the use of lower order filters which are able to simultaneously account for closed-loop robustness and noise attenuation. Through illustrative examples, it is shown that the proposed approach provides enhanced disturbance rejection and noise attenuation in the control of industrial processes when compared with other recently published works. Furthermore, the internal temperature of an in-house thermal chamber is controlled to evaluate the applicability of the strategy on real processes.

Self-tuning adaptive controller applied to the boost converter voltage control

This paper presents the design and simulation tests of fixed and adaptive pole placement control techniques to the Boost converter voltage control. Due to the converter non-minimum phase characteristics, no zeros cancellation was considered in the design procedures. An indirect self-tuning (STR) adaptive controller with online plant estimation and controller design was evaluated. A recursive least-squares method was used to identify the plant model in real time. Simulations results with a nonlinear model are presented and discussed. It can be noticed that for abrupt changes in the plant dynamics or operational condition, the STR adaptive control works better, rejecting disturbances and following the reference signal. In the other hand, the system with the fixed controller, after some specific load resistance change, cannot reject disturbances, leading the system to an oscillatory response.