Minimal Control Input Research Articles

Control of a building system with sudden nonlinearity using the sliding mode technique

In civil engineering application such as the seismic resistant structural design, a building system often enters into its nonlinear range to minimize the force transfer to the superstructure. An ideal control design should enhance the usefulness of the nonlinear behavior by diminishing its adverse effects at a minimal control input. This study developed a unified feedback mechanism based on the sliding mode control approach that fostered the multiple selected modal control of a structural system undergoing linear and nonlinear stages of hysteretic deformations. The ideal sliding surface for controlling a specific mode was designed based on the interaction characteristics between two modes at two different stages of deformation. An ′ S′ type functional form of the control force was developed on either side of the sliding surface based on the velocity feedback of the system by ensuring reachability to the ideal sliding surface. To demonstrate the effectiveness of the adopted control, a five-story shear building with uniform mass and initial stiffness distribution with concentrated nonlinearity at the base column was considered under 10 earthquake excitations. The system was studied under the proposed control along with the uncontrolled system. In addition to the adopted control, a popular and existing LQG control technique was also implemented based on the equivalent linearized structural system for comparison. The adopted control provided the desired performance of the structural system while keeping the effectiveness of the system’s nonlinearity under earthquake excitations. Considering the system’s responses and the input control force, the efficiency of the adopted mechanism outperformed the LQG control, which was found to amplify the unfavorable effects of the system’s nonlinearity.

Position control of a pneumatic surgical robot using PSO based 2-DOF H∞ loop shaping structured controller

This research proposed novel development of a 2-DOF H∞ loop shaping structured controller based on Particle Swarm Optimization (PSO) that considers the closed-loop dynamic response, robustness, stability, and minimal control input in design criteria to control position of 3-DOF pneumatic surgical robot. Unlike other conventional H∞ controllers, the proposed controller offers robustness, high performance, but cost-effective simple structure, which has recently received attention from several researchers and preferred in industrial applications. The proposed technique is simulated and experimented on a nonlinear system of a pneumatic 3-DOF surgical robot for a Minimally Invasive Surgery (MIS). Mechanical design, dynamics modeling, and system identification of the surgical robot are conducted. The simulation results verify that the proposed controller can gain a better H∞ sub-optimal solution than the conventional 2-DOF H∞ loop shaping controller. Also, the experiments confirm that the proposed controller is capable to tolerate the perturbed conditions and can be alternative to the conventional controllers in pneumatic controlled system

H-Infinity Controller Based on LMI Region for Flexible Robot Manipulator

This study presents investigations into the development of H-infinity controller with LMI region schemes for trajectory tracking and vibration control of a Flexible Robot Manipulator System. A constrained planar single-link flexible manipulator is considered and the dynamic model of the system is derived using the assume mode method. H-infinity synthesis with pole clustering schemes is used to control the hub angle with very minimal vibration at the end-point of the manipulator. The performance of the flexible robot manipulator system is examined in terms of time response specifications of hub angle, minimal vibration at the end-point of the manipulator and minimal control input torque. To examine the effectiveness of the proposed controller, it is compared with hybrid input shaping with collocated PD controller schemes. The implementation results show that H-infinity controller with confined closed-loop poles based on LMI region produce a fast tracking capability with very minimal end-point vibration and smooth control input torque.

H-Infinity Controller with LMI Region Schemes for a Lab-Scale Rotary Pendulum Crane System

This study presents an H-infinity controller with LMI region schemes for a lab-scale rotary pendulum crane system. H-infinity synthesis with pole clustering schemes is used to control the hub angle of the arm of rotary pendulum crane system with very minimal sway angle. The performance of the lab-scale rotary pendulum crane system is examined in terms of time response specifications of hub angle of the arm, minimal sway angle of pendulum and minimal control input. To examine the effectiveness of the proposed controller, it is compared with LQR controller schemes. The implementation results show that H-infinity controller with confined closed-loop poles based on LMI region produce a fast tracking capability with very minimal sway and control input.

Discussion on: “Continuous Fuzzy Controller Design Subject to Minimizing Control Input Energy with Output Variance Constraints”

Discussion on: “Continuous Fuzzy Controller Design Subject to Minimizing Control Input Energy with Output Variance Constraints”

Continuous Fuzzy Controller Design Subject to Minimizing Control Input Energy with Output Variance Constraints

This paper presents the stability synthesis subject to minimum control input energy and output variance constraints for a class of nonlinear systems, which is modeled by the Takagi–Sugeno (T–S) fuzzy model. For this T–S type fuzzy model, the proposed fuzzy controller design approach not only ensures the stability of the closed-loop system, but also minimizes the control input energy with output variance constraints. The proposed method uses linear matrix inequality technique to find the common positive definite covariance matrix and feedback gains for each rule of the T–S fuzzy models. Finally, the proposed model-based fuzzy control method is used to deal with the control problem of the translational oscillation with a rotational proof mass actuator (TORA) system.