599 research outputs found

    On the geometry of full points of abstract unitals

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    The concept of full points of abstract unitals has been introduced by Korchm\'aros, Siciliano and Sz\H{o}nyi as a tool for the study of projective embeddings of abstract unitals. In this paper we give a more detailed description of the combinatorial and geometric structure of the sets of full points in abstract unitals of finite order

    Active suspension control design for unmanned ground vehicles

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    This paper presents the design of an active suspension control system for an unmanned ground vehicle (UGV). The purpose is to design an active suspension control for a low-speed (less than 1 m/s) off-road UGV in order to be able to move through rugged terrain with the least pitch and roll motion. Classical active suspension design methods cannot be used for minimizing pitch and roll angles, therefore a new approach is applied. The control design is based on the LQG method. The control system uses only pitch and roll angular rate signals, which ensures a simple and cheap control system, but any bias error on the gyro signals cause some problems in reconstructing angles. The control algorithm consists of an optimal state-feedback fed by an augmented observer for estimating the states and the bias error of the gyro sensors. The appropriate tuning of the observer is introduced, which eliminates the bias error problem and ensures the fast reconstruction of the states for the optimal state-feedback. In simulations, the active suspension control system shows high performance at minimizing pitch and roll angles

    New Steiner 2-designs from old ones by paramodifications

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    Techniques of producing new combinatorial structures from old ones are commonly called trades. The switching principle applies for a broad class of designs: it is a local transformation that modifies two columns of the incidence matrix. In this paper, we present a construction, which is a generalization of the switching transform for the class of Steiner 2-designs. We call this construction paramodification of Steiner 2-designs, since it modifies the parallelism of a subsystem. We study in more detail the paramodifications of affine planes, Steiner triple systems, and abstract unitals. Computational results show that paramodification can construct many new unitals
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