Fahad Mumtaz Malik

Nonlinear stabilizing control of a rotary double inverted pendulum: a modified backstepping approach:

Modified backstepping control is proposed for an under-actuated rotary double inverted pendulum. The system has actuated rotary base joint with which two unactuated links are attached. The proposed control design is a three step process for de-coupled system model. In the first stage, a backstepping controller is designed for each of the active and passive joints. In the second stage, compensation is introduced in the respective control efforts to cater for uncertain terms based on Lyapunov function for each joint. Finally, the controllers obtained in the two stages are combined to form a total control law. The performance of the proposed control scheme is evaluated by convergence analysis and simulations.

Optimal output quadratic regulation

To have an accurate information of system states is always being a challenging task for the control designers irrespective the system is linear or non linear. This information is used for state feedback in tracking of a reference signal. An observer based optimal linear quadratic scheme is presented in this paper. Linear time invariant (LTI) system is used for reference tracking in the presence of external disturbance once only plant input and output is available to us. The proposed closed loop structure is capable of rejecting the disturbance by utilizing the prior information of disturbance. A optimize quadratic cost function effectively utilizing the observed plant states is defined. Its performance in the presence of observer makes it more realistic for practical use. Suggested algorithm performance is discussed with the simulation results with third order linear system.

Control and Stabilization of Unmanned Helicopter with Suspended Payload

Unlike fixed wings aircrafts, helicopters are the one of the most attractive aerial vehicles for carrying suspended load due to their capabilities of hovering and vertical takeoff and landing (VTOL). In spite of their better maneuvering and payload transporting abilities, when carrying slung load they are more prone to vibrations. Load behaves as pendulum causing disturbances in helicopter which adversely affects its control and stabilization. If vibrations are not controlled they may cause fatal accidents. Linear matrix inequality based sliding mode control is developed to stabilize payload in presence of air disturbances. Simulations are performed during hovering operation for helicopter. Due to the rapid response and robustness of SMC payload and helicopter states are achieved with the help of proposed control scheme.

High gain observer based adaptive SMC for longitudinal dynamics of a customized mini UAV

This paper deals with the design of adaptive SMC integrated with a standard high gain observer for tracking the longitudinal dynamics of a customized mini UAV. In the proposed scheme for control law model parameters are assumed to be unknown and are estimated via adaptive laws, while the system states are estimated using high gain observer. Extensive simulations have been carried out to check the robustness of the system to external disturbances and model parametric uncertainties. Simulation results show the effectiveness of ASMC with HGO compared to full state feedback ASMC.

Time-limited Gramians-based model order reduction for second-order form systems:

A new scheme for model order reduction of large-scale second-order systems in time-limited intervals is presented. Time-limited Gramians that are solutions of continuous-time algebraic Lyapunov equations for second-order form systems are introduced. Time-limited second-order balanced truncation procedures with provision of balancing position and velocity Gramians are formulated. Stability conditions for reduced-order models are stated and algorithms that preserve stability in reduced-order models are discussed. Numerical examples are presented to validate the superiority of the proposed scheme compared with the infinite-time Gramians technique for time-limited applications.

Sampled data gyroscope stabilization of two degree of freedom platform

Main focus of this research is on stabilization of two degree of freedom platform. Previously, most of the work done on this specific problem is in continuous domain but here we designed a controller using sampled data control technique. Controller is designed for approximate equivalent system model using sliding mode controller in discrete domain for the stabilization of this platform. System is approximated using Euler method technique. In the next stage this work is extended to hardware implementation of the problem. The hardware is designed such that, platform is stabilized by rotation of motors in Azimuthal direction and Elevation direction. Arduino, inertial measurement unit and motor driver are used with the motors to implement the control designed in discrete domain.