In this paper, we develop a new type of snake-like robot using screw-drive units connected by active joints. The screw drive units enable the robot to generate propulsion on any side of the body in contact with environments. Another feature of this robot is the omni-directional mobility by combinations of screws' angular velocities. We also derive a kinematic model and apply it to trajectory tracking control. Furthermore, we design a front-unit-following controller, which is suitable for manual operations. In this control system, operators are required to command only one unit in the front, then commands for the rest of the units are automatically calculated to track the path of the preceding units. Asymptotic convergence of the tracking error of the front-unit-following controller is analyzed based on a Lyapunov approach for the case of constant curvature. The effectiveness of the control method is demonstrated by numerical examples and experiments.Index Terms-snake-like robot, screw drive mechanism, path tracking, search and rescue
This study examines a driver assistance system to predict driving behavior considering the pre-preceding vehicle behavior. The authors have defined an anticipation index called PRE3 and proposed a driving assistance system that indicates the PRE3 to the driver in real-time during a car-following. The proposed system indicates the evaluation index considering the relations not only between the preceding and following vehicles, but also between the pre-preceding and following vehicles. This paper aims to evaluate the performance of PRE3 by a test track field experiment that employs three passenger cars as the test vehicles. The test cars are equipped with various sensors and communication system including the camera and the target for headway distance measurement and the CAN data of the vehicles. Five drivers which participated in the experiment are instructed to follow the preceding and the visible pre-preceding vehicles with and without the driving assistance system. The field test showed that the proposed system is succeeded in reducing the relative velocity with the pre-preceding vehicle. Also, the positive high acceleration rate is infrequent when installing the PRE3 assistant system. It was concluded that the proposed assistance system is helpful to reduce the relative velocity with the pre-preceding vehicle, unnecessary positive acceleration and the variance of collision risk to the preceding vehicle.
The present study aims to clarify how four different combinations of input and output resources affect driving performance, because usage of information devices based on non-visual and non-manual interface during driving is configured as distracter recently. The primary task consisted of following a lead vehicle at a constant headway while that vehicle changed speed according to a predefined rhythm. The secondary task, which involved using a surrogate user interface, consisted of four different tasks to assess interference with the driver's attentional resource during driving. To achieve the objective, we conducted a field experiment on a test track using 14 participants. The results suggest that the smallest effects on drivingrelevant metrics were for the combination of auditory stimuli and verbal response, and that the greatest effects were for the combination of visual stimuli and manual response.
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