Mahyar Naraghi

Bio: Mahyar Naraghi is an academic researcher from Amirkabir University of Technology. The author has contributed to research in topics: Control theory & Model predictive control. The author has an hindex of 12, co-authored 64 publications receiving 492 citations.

A neural network self tuner based on input shapers behavior for anti sway system of gantry cranes

Abstract: The rapid and sway-less conveyance of crane loads has been an essential task and a field of research; considering the broad application of transportation of goods and materials by these systems. In this paper, a neural network self tuner (NNST) controller, which aims to move the load precisely as well as to eliminate its sway, is presented. This controller is capable of being trained flexibly for either increasing the speed of load transportation or decreasing its sway. The developed training algorithm, in this paper, is inspired by a sway elimination method of input shapers. The proposed training method provides the controller with the capability to remove the majority of load sway, at the outset of transportation, and transport it with a slight sway. The results show that the neural network controller with the proposed training method, in the same time, is capable of removing the sway of the load in a better way and be more appropriate for longer distances compared to a proportional-integral-derivative ...

Vehicle stability enhancement — an adaptive optimal approach to the distribution of tyre forces:

Abstract: In this paper, vehicle stability enhancement, based on the integrated vehicle control notion, is presented. A new method for adaptive optimal distribution of braking and lateral tyre forces is employed. The control inputs considered are the individual wheel steering and braking for each wheel. Since a unique set of tyre forces satisfying control objectives cannot be easily determined, an adaptive optimization problem subjected to two equality and four inequality constraints has been solved to achieve an optimal solution. A proper adaptation mechanism is suggested to minimize the negative effects of direct yaw moment control, such as the undesirable decrease in the total speed of the vehicle. The effectiveness of the proposed vehicle stability enhancement system, especially online balancing of tyre forces in an optimal form with and without an adaptation mechanism, is demonstrated through digital simulations. A comprehensive non-linear vehicle dynamics model is utilized for simulation purposes. The results indicate that the proposed control system can effectively utilize the tyres' frictional forces and significantly improve the vehicle stability and handling performances.

Adaptive super-twisting observer for fault reconstruction in electro-hydraulic systems.

Abstract: An adaptive-gain super-twisting sliding mode observer is proposed for fault reconstruction in electro-hydraulic servo systems (EHSS) receiving bounded perturbations with unknown bounds. The objective is to address challenging problems in classic sliding mode observers: chattering effect, conservatism of observer gains, strong condition on the distribution of faults and uncertainties. In this paper, the proposed super-twisting sliding mode observer relaxes the condition on the distribution of uncertainties and faults, and the gain adaptation law leads to eliminate observer gain overestimation and attenuate chattering effects. After using the equivalent output-error-injection feature of sliding mode techniques, a fault reconstruction strategy is proposed. The experimental results are presented, confirming the effectiveness of the proposed adaptive super-twisting observer for precise fault reconstruction in electro-hydraulic servo systems.

Optimized coordination of brakes and active steering for a 4WS passenger car.

Abstract: Optimum coordination of individual brakes and front/rear steering subsystems is presented. The integrated control strategy consists of three modules. A coordinated high-level control determines the body forces/moment required to achieve vehicle motion objectives. The body forces/moment are allocated to braking and steering subsystems through an intermediate unit, which integrates available subsystems based on phase plane notion in an optimal manner. To this end, an optimization problem including several equality and inequality constraints is defined and solved analytically, such that a real-time implementation can be realized without the use of numeric optimization software. A low-level slip-ratio controller works to generate the desired longitudinal forces at small longitudinal slip-ratios, while averting wheel locking at large slip-ratios. The efficiency of the suggested approach is demonstrated through computer simulations.

Coverage control for mobile sensing networks

Abstract: This paper presents control and coordination algorithms for groups of vehicles. The focus is on autonomous vehicle networks performing distributed sensing tasks where each vehicle plays the role of a mobile tunable sensor. The paper proposes gradient descent algorithms for a class of utility functions which encode optimal coverage and sensing policies. The resulting closed-loop behavior is adaptive, distributed, asynchronous, and verifiably correct.

Structural analysis

Abstract: Structures in Other Domains The methodology of structural analysis discussed in this article has been applied beyond the narrow realm of natural language syntax that we have discussed in this article. Within the study of language, similar methods of analysis have been pervasively applied to the study of sounds (phonology), words (morphology), and meanings (semantics), yielding a range of of abstract structural representations whose properties bear considerable explanatory burden. There are a wealth of cases in each of these domains analogous to those discussed here, though space prevents us from going in these (see Akmajian, Demers, Farmer and Harnish 1995 for a traditional overview, and Jackendo 1994 for one more focused on connections with cognitive science). Additionally, these representations have shed substantial light on the processes of language acquisition and language change. It has been found that variation in the types of sentences that are used, whether during the course of children's acquisition of their native languages or in the centuries-long periods of linguistic change, are best characterized not as super cial and haphazard alterations, but rather in terms of parametric modi cations to the fundamental underlying grammatical rules and constraints. Moving outside the domain of language, one application of these same methods has been in the study of music cognition. Just as the representations of linguistic theory arise out of an attempt to model speakers' intuitions about well-formedness and possible meanings of the sentences of their

Hydraulic Control Systems

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Resolving actuator redundancy: optimal control vs. control allocation

Abstract: This paper considers actuator redundancy management for a class of overactuated nonlinear systems. Two tools for distributing the control effort among a redundant set of actuators are optimal control design and control allocation. In this paper, we investigate the relationship between these two design tools when the performance indexes are quadratic in the control input. We show that for a particular class of nonlinear systems, they give exactly the same design freedom in distributing the control effort among the actuators. Linear quadratic optimal control is contained as a special case. A benefit of using a separate control allocator is that actuator constraints can be considered, which is illustrated with a flight control example.