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We consider a logistic planning problem for simultaneous optimization of the storage and the delivery. This problem arises in the consolidate shipment using an intermediate storage in a supply chain, which is typically found in the automobile industry. The vehicles deliver the items from the origin to the destination, while the items can be stored at some warehousing facilities as the intermediate storage during the delivery. The delivery plan is made for each day separately, but the storage at a warehouse may last for more than one day. Therefore, the entire logistic plan should be considered over a certain period for the total optimization. We formulate the storage and delivery problem as a mixed integer programming. Then, we propose a relax-and-fix type heuristic method, which incrementally fixes decision variables until all the variables are fixed to obtain a complete solution. Moreover, a semiapproximate model is introduced to effectively fix the variables. Based on the formulation, the delivery plan can be solved for each day separately. This has the advantage especially in the dynamic situation, where the delivery request is modified from the original request before the actual delivery day. Numerical experiments show that the simultaneous optimization gives the effective storage plan to reduce the total logistic cost, and the proposed heuristics efficiently reduce the computational time and are robust against the dynamic situation.
The article presents current trends in the field of intelligent working process control systems for industrial vehicles. This is a background for showing individual work in a domain of automated positioning of multi element vehicles during a back drive process. The results are the effect of research, which has been done in the Division of Off-Highway Vehicle Engineering in the Department of Mechanical Engineering Wroclaw University of Technology together with Technical University of Stuttgart. The paper introduces a subject of working machines automation at the beginning. It shows also, machine/vehicle division into a few main subgroups of systems that can be improved by full or partial automation. Authors present a „world" of autonomous vehicles by showing a potential possibility of using them and give a list of publications that makes it possible to analyze and go deep inside a problem of autonomous machine next. Further parts show the results of research on autonomous vehicle made at Wroclaw University of Technology and Technical University of Stuttgart. There were specified reasons for the necessity of automated loading and automated back drive system creating and tests that allow us to rate usefulness of the system in industrial applications. After a short introduction the authors describe an idea of 1st generation control system created at Technical University of Stuttgart. The idea assumes connecting on optical system and trajectory calculating and keeping system as one control system, which enables automated positioning of rnultielements vehicle in relation to container. The high resolution, non-linear optical system was a reason to build a special CCD camera, which is connected to a very high efficiency digital picture processing system. The system makes it possible to recognize and vehicle position calculating. The control system is able to position lorry and trailer relation to reference system, basing on temporary CCD camera and angle encoders data. This information is used to calculate temporary vehicle trajectory. The trajectory is a most optimum way the vehicle should follow to drive to under container without a collision. The above control system was built and experimentally verified at Stuttgart University of Technology. The experiment's results were very good but it shows that the control system doesn't perform all usefulness tests and it cannot be applicable in industrial solutions. As high scale industrial application of a system is impossible (in spite of positive results of experimental tests) the Division of Off-Highway Vehicle Engineering Department of Mechanical Engineering Wroclaw University of Technology have started work on the 2nd generation of control system, which could be applicable in industrial solutions. The new system was proposed which considerably improved steerability. Additionally, quite new subsystem active, blocking elements were added. It can be used to interference in vehicle trajectory. Parallel to the work, which has to improve steerability the research is being done to improve the digital picture processing algorithm. They have to adapt the optical system to work in a real condition that prevails on a logistic terminal.
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