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This paper presents flocking control algorithm for a group of Autonomous Underwater Vehicles (AUVs). A leaderfollower flocking where, some AUVs are chosen as leaders which have global knowledge of desired track and other AUVs are chosen as followers which have only sensory capability to find the positions of neighbor AUVs without any global knowledge of desired path. The leader AUVs are desired to track the desired trajectory with the application of the proposed flocking controller and the follower vehicles are gradually attracted towards the leader vehicles so that the whole group tracks desired trajectory. In order to keep connected, the group approaches towards the flocking center whose position is estimated applying consensus algorithm with respect to the positions of the neighbor AUVs. The controller is developed using artificial potential functions (APF) such that the inter vehicle collision between AUVs is avoided. The efficacy of the developed controller is verified through simulation of four AUVs flocking in a group.

Effects of sliding surface on the performances of adaptive sliding mode slip ratio controller for a HEV BASANTA KUMAR DASH and BIDYADHAR SUBUDHI Slip ratio control of a ground vehicle is an important concern for the development of antilock braking system (ABS) to avoid skidding when there is a transition of road surfaces. In the past, the slip ratio models of such vehicles were derived to implement ABS. It is found that the dynamics of the hybrid electric vehicle (HEV) is nonlinear, time varying and uncertain as the tire-road dynamics is a nonlinear function of road adhesion coefficient and wheel slip. Sliding mode control (SMC) is a robust control paradigm which has been extensively used successfully in the development of ABS of a HEV. But the SMC performance is influenced by the choice of sliding surface. This is due to the discontinuous switching of control force arising in the vicinity of the sliding surface that produces chattering. This paper presents a detailed study on the effects of different sliding surfaces on the performances of sliding mode based adaptive slip ratio control applied to a HEV.

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Directional response of a vehicle implies changing its direction when sustaining lateral acceleration while moving on the road. From this response, the vehicle's explicit capabilities as well as its contribution to the system performance of the driver/vehicle combination are obtained. In vehicle control literature, handling is often used interchangeably with cornering, turning, or directional response. This paper focuses one aspect of the handling i.e. directional response. Two different controllers, namely a PID controller and a Fuzzy Logic Controller (FLC) for a hybrid electric vehicle (HEV) are designed in this paper to control the vehicle's steering in a smooth lane change maneuver. The performances of the aforesaid two controllers have been studied extensively in this paper. For achieving an improved path tracking and directional response, parameters of both the PID and FLC have been tuned and their performances have been compared. Further, the effect of changing the scale factors in the fuzzy logic approach to obtaining directional response is presented. To validate the above two control performances, a nonlinear simulation model of a HEV is developed and is used in simulation studies. Both the controllers track the desired directional signal efficiently. Both PID and Fuzzy controllers provide competitive performances. Although with the assumption of all parameters of the vehicle available PID controller exhibits slightly better dynamic performance but in the real-world scenario the fuzzy controller is preferred due to its robustness i.e. it does not depend on the parameters of the vehicle.