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Merging in the form of a mandatory lane-change is an important issue in transportation research. Even when safely completed, merging may disturb the mainline traffic and reduce the efficiency or capacity of the roadway. In this paper, we consider a Stackelberg game-theoretic driver behavior model where the so-called utilities or payoffs reflect the merging vehicle's aggressiveness as it pertains the decision to merge as the situation stands or to accelerate/decelerate prior to the actual lane-change maneuver. The interaction of the merging vehicle with the mainline traffic is also considered whereby the combination of aggressiveness of the respective vehicles leads to both longitudinal and lateral disturbances to the mainline flow as well as subsequent reduction in the roadway throughput. The present study shows in semi-quantitative form that this impact depends on the level of aggressiveness of the merging and mainline vehicles in an intuitive manner, leading to the potential use of this model in traffic flow analysis and autonomous driving. Index Terms-Naturalistic driving models, lane-changing maneuvers, merging behavior, roadway safety. R. Langari is with Texas A&M University, College Station, TX 77843 (email: rlangari@tamu.edu).

In this paper, we have considered the new extendable modular multi-DOFs link to have a larger reachable workspace and more dexterous manipulability, as compared to a typical link. As a part of the extendable modular robot (EMR), our link is implemented to allow free motion when performing required tasks. In addition, this paper deals with a function of adjusting the link’s length (within 25% of the nominal length). Our investigation also focuses on the dynamics of a multi-DOFs link and the nonlinear controller for a given trajectory. The simulation results show the effectiveness of this control approach.

Purpose – The purpose of this paper is to describe a compact wheelchair, which has two 3-degrees of freedom (DOF) legs and a 1-DOF base (the total DOF of the leg system is 7) for stair-climbing, and wheels for flat surface driving. Design/methodology/approach – The proposed wheelchair climbs stairs using the two 3-DOF legs with boomerang-shaped feet. The leg mechanisms are folded into the compact wheelchair body when the wheelchair moves over flat surfaces. The authors also propose a simple estimation method of stair shape using laser distance sensors, and a dual motor driving system to increase joint power. Findings – The proposed wheelchair can climb arbitrary height and width stairs by itself, even when they are slightly curved. During climbing, the trajectory of the seat position is linear to guarantee the comfort of rider, and the wheelchair always keeps a stable condition to ensure the stability in an emergency stop. Originality/value – The wheelchair mechanism with foldable legs and driving wheels enables smooth stair climbing, efficient flat surface driving and additional useful motions such as standing and tilting.

Driven by the emergence of autonomous/semi-autonomous driving technologies, the mixed situation of autonomous vehicles and human drivers is of considerable significance. Toward this end, it is necessary to better understand human driving characteristics so as to predict the actions of the other cars. In this regard, we develop a basic framework for modeling driver behaviors in view of human prediction ability. Through the game theoretic estimation of the counterpart’s behaviors and the corresponding time-evolution of unsafe collision areas, we compute an objective collision model. In turn, we design a human-like predictive perception model on collision with an adjacent vehicle based on the objective collision model and the driver’s subjective level of safety assurance. Since drivers have different safety requirements, the subjective estimate on the collision was designed as a region in which has less safety than the driver’s own safety requirement in the objective probabilistic collision prediction. The region that is subjectively perceived based on the driver’s own safety standard is regarded as a deterministic unsafe region for the driver. That is to say, the subjective perception acts as a collision area with the collision probability of 1 so that the driver should avoid while driving. In our subsequent work, we will address the issue of controller design to avoid the subjective collision estimation.

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