Design of a simulator for elevator supevisory group controller using ordinal structure fuzzy reasoning with context adaptation

An elevator group supervisory controller is a control system that manages systematically two or more elevators in order to serve passengers as required. The elevator cars are assigned accordingly in response to hall calls, so as to optimize waiting time, riding time, power consumption, passengers’ comfort, etc. In order to design a controller that can solve multiple objectives, fuzzy logic would be a good option. However, since in this particular problem, more than three fuzzy inputs have to be considered, complications might arise in forming rule base and fuzzy rule extraction from experts. To overcome this problem, ordinal structured fuzzy logic is to be used where the rules are described in one dimensional space regardless of the number of inputs. In this project, the simplicity of ordinal structured fuzzy logic in making crucial supervisory control decisions is demonstrated. In addition, in order to further improve the performance, a new approach of ordinal structured fuzzy logic with context adaptation is introduced to implement an elevator group supervisory controller for a building with 15 floors and 4 elevator cars. Simulations comparing ordinal structured fuzzy logic algorithm with and without context adaptation, show that the former performs better. An additional improvement is made possible by applying genetic algorithms to tune the weights attached to each of the fuzzy rule

A Comparative Study of LQR and Integral Sliding Mode Control Strategies for Position Tracking Control of Robotic Manipulators

This paper provides a systematic comparative study of position tracking control of nonlinear robotic manipulators. The main contribution of this study is a comprehensive numerical simulation assessing position tracking performances and energy consumption of integral sliding mode control (ISMC), a linear-quadratic regulator with integral action (LQRT), and optimal integral sliding mode control (OISMC) under three conditions; namely, Case I) without the coupling effect, Case II) with the coupling effect on Link 1 only, and Case III) with the coupling effect on Link 2 only. The viability of the concept is evaluated based on three performance criteria, i.e., the step-response characteristics, position tracking error, and energy consumption of the aforementioned controllers. Based upon the simulation study, it has been found that OISMC offers performances almost similar to ISMC with more than 90% improvement of tracking performance under several cases compared to LQRT; however, energy consumption is successfully reduced by 3.6% in comparison to ISMC. Energy consumption of OISMC can be further reduced by applying optimization algorithms in tuning the weighting matrices. This paper can be considered significant as a robotic system with high tracking accuracy and low energy consumption is highly demanded to be implemented in smart factories, especially for autonomous systems

Stabilization and trajectory tracking control for underactuated quadrotor helicopter subject to wind-gust disturbance

The control of quadrotor helicopter has been a great challenge for control engineers and researchers since quadrotor is an underactuated and a highly unstable nonlinear system. In this paper, the dynamic model of quadrotor has been derived and a so-called robust optimal backstepping control (ROBC) is designed to address its stabilization and trajectory tracking problem in the existence of external disturbances. The robust controller is achieved by incorporating a prior designed optimal backstepping control (OBC) with a switching function. The control law design utilizes the switching function in order to attenuate the effects caused by external disturbances. In order to eliminate the chattering phenomenon, the sign function is replaced by the saturation function. A new heuristic algorithm namely Gravitational Search Algorithm (GSA) has been employed in designing the OBC. The proposed method is evaluated on a quadrotor simulation environment to demonstrate the effectiveness and merits of the theoretical development. Simulation results show that the proposed ROBC scheme can achieve favorable control performances compared to the OBC for autonomous quadrotor helicopter in the presence of external disturbances

DESIGN AND OPTIMIZATION OF BACKSTEPPING CONTROLLER FOR AN UNDERACTUATED AUTONOMOUS QUADROTOR UNMANNED AERIAL VEHICLE

The development of a high performance controller for a quadrotor unmanned aerial vehicle (UAV) is a challenging issue since a quadrotor is an underactuated and a highly unstable nonlinear system. In this paper, the contribution is focused on the design and optimization of a controller for an autonomous quadrotor UAV. Firstly, the dynamic model of the aerial vehicle is mathematically formulated. Then, an optimal backstepping controller (OBC) is proposed. Conventionally, control parameters of a backstepping controller (BC) are often chosen arbitrarily. To this end, it is necessary to invoke a well-established optimization algorithm in order to find the best parameters. Here, the particle swarm optimization (PSO) is utilized as a new key idea to determine the optimal values of the BC parameters. In the algorithm, the control parameters are computed by minimizing the fitness function defined by using the integral absolute error (IAE) performance index. Since the control law is derived based on the Lyapunov theorem, the asymptotical stability of the system can be guaranteed. Finally, the efficiency of the proposed OBC is illustrated by implementing several simulation experiments

A Robust Stabilization using State Feedback with Feedforward

Abstract-In a general nonlinear control system a stabilizing control strategy is often possible if complete information on external inputs affecting the system is available. Assuming that measurements of persistent disturbances are available it is shown that the existence of a smooth uniform control Lyapunov function implies the existence of a stabilizing state feedback with feedforward control which is robust with respect to measurement errors and external disturbances. Conversely, using differential inclusions parameterized as nonlinear systems with state and disturbance measurement errors, it is shown that there exists a smooth uniform control Lyapunov function if there is a robustly stabilizing state feedback with feedforward. This paper demonstrates that if there exists a smooth control Lyapunov function for a general nonlinear system with persistent disturbances for which one has previously designed a feedback controller, a feedforward always exists to be augmented for stability

Automatic human guided shopping trolley with smart shopping system

A shopping trolley is a necessary tool for shopping in supermarkets or grocery stores. However, there are shopping trolleys abandoned everywhere in supermarkets after being used. In addition, there are also shopping trolley safety issues such as sliding down from an escalator. It is known to be an inconvenience and time wasting for customers who are in rush to search for desired products in a supermarket. Therefore, an automatic human and line following shopping trolley with a smart shopping system is developed to solve these problems. A line following portable robot is installed under the trolley to lead the users to the items’ location that they plan to purchase in the supermarket. This paper presents the hardware and software design of the portable robot. The result of the testing on the used sensors like ultrasonic and line sensors are presented. Lastly, the graphical user interface of Android application during the shopping trolley in operation is explained