187 research outputs found
Integrating Higher-Order Dynamics and Roadway-Compliance into Constrained ILQR-based Trajectory Planning for Autonomous Vehicles
This paper addresses the advancements in on-road trajectory planning for
Autonomous Passenger Vehicles (APV). Trajectory planning aims to produce a
globally optimal route for APVs, considering various factors such as vehicle
dynamics, constraints, and detected obstacles. Traditional techniques involve a
combination of sampling methods followed by optimization algorithms, where the
former ensures global awareness and the latter refines for local optima.
Notably, the Constrained Iterative Linear Quadratic Regulator (CILQR)
optimization algorithm has recently emerged, adapted for APV systems,
emphasizing improved safety and comfort. However, existing implementations
utilizing the vehicle bicycle kinematic model may not guarantee controllable
trajectories. We augment this model by incorporating higher-order terms,
including the first and second-order derivatives of curvature and longitudinal
jerk. This inclusion facilitates a richer representation in our cost and
constraint design. We also address roadway compliance, emphasizing adherence to
lane boundaries and directions, which past work often overlooked. Lastly, we
adopt a relaxed logarithmic barrier function to address the CILQR's dependency
on feasible initial trajectories. The proposed methodology is then validated
through simulation and real-world experiment driving scenes in real time.Comment: 6 pages, 3 figure
Gas-Purged Headspace Liquid Phase Microextraction System for Determination of Volatile and Semivolatile Analytes
In order to achieve rapid, automatic, and efficient extraction for trace chemicals from samples, a system of gas-purged headspace liquid phase microextraction (GP-HS-LPME) has been researched and developed based on the original HS-LPME technique. In this system, semiconductor condenser and heater, whose refrigerating and heating temperatures were controlled by microcontroller, were designed to cool the extraction solvent and to heat the sample, respectively. Besides, inert gas, whose gas flow rate was adjusted by mass flow controller, was continuously introduced into and discharged from the system. Under optimized parameters, extraction experiments were performed, respectively, using GP-HS-LPME system and original HS-LPME technique for enriching volatile and semivolatile target compounds from the same kind of sample of 15 PAHs standard mixture. GC-MS analysis results for the two experiments indicated that a higher enrichment factor was obtained from GP-HS-LPME. The enrichment results demonstrate that GP-HS-LPME system is potential in determination of volatile and semivolatile analytes from various kinds of samples
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