Determining the Shortest Path for Inner Warehouse Transportation

Environment-Behaviour Proceedings Journal

Fulfilling the customer requirement has always been of utmost concern to logistics service companies, namely those providing warehouse and transportation services. In the warehouse, inner transportation problem affects its performance. Order picker problem is one of the problems that involves the transportation problem within the warehouse. The problem can be handled properly by having proper storage assignment, proper tasking allocation and optimal routing for inner warehouse vehicles' movement. This study proposed a modified Dynamic Programming model to determine the shortest route for the order pickers in completing and fulfilling the customers' orders. The model shows stable solutions for numerous orders.

2014

Warehouses' management is becoming more important inside the logistics' world lately, an optimal management implies a working time reduction and it leads to a cost reduction. The objective of this thesis is to discover the world of warehouses' management, and especially the warehouse order picking field. For that reason it will be divided into two parts. The first one will be theoretical, and the goal is to acquire a theoretical base. The second one will be more practical, firstly a statistical analysis will be carried out through a factorial design in order to understand the performance of the different routing strategies and when is better to use each. Secondly, the relationship between the response and the travel time will be studied through a correlation study.

2015

Warehouse operational costs are heavily influenced by the efficiency in which workers are able to traverse the warehouse and gather items on orders around the warehouse that must be shipped to customers; this action accounts for over 50% of warehouse operations expenses. The act of traversing the warehouse is greatly optimized by following a designated pick path; however, algorithms for pick path generation are complex and heavily unexplored by the industry. Generating pick paths involves solving two common place graph theory problems: the shortest path problem and the traveling salesperson problem. We will analyze algorithms used for solving both of these problems and discuss the feasibility of generating pick paths through the use of the algorithms. We also introduce a simplified implementation to illustrate the viability of the described approaches.

IIE Transactions, 1998

In this paper the problem of ®nding ecient orderpicking routes is studied for both conventional warehouses, where pickers have a central depot for picking up and depositing carts and pick lists, and modern warehouses, where orderpicking trucks can pick up and deposit pallets at the head of every aisle without returning to the depot. Such environments can be found in many warehouses where paperless picking is performed from pallet locations with pickers having mobile terminals receiving instructions one by one. In order to ®nd orderpicking routes with a minimal length in both the situations of a central depot or decentralized depositing, we extend the well-known polynomial algorithm of Ratli and Rosenthal [1] that considered warehouses with a central depot. In practice, the problem is mainly solved by using the so-called S-shape heuristic in which orderpickers move in a S-shape curve along the pick locations. The performance of the new algorithm and the S-shape heuristic are compared in three realistic orderpicking systems: (1) narrow-aisle high-bay pallet warehouse; (2) picking in shelf area with decentralized depositing of picked items; and (3) conventional orderpicking from wide-aisle pallet locations. The new algorithm gives a reduction in travel time per route of between 7 and 34%. It turns out that the reduction in travel time strongly depends on the layout and operation of the warehouse.

WIT transactions on engineering sciences, 2016

The ability to present information in a meaningful way is vital within the organizational context. This paper deals with business processes and productivity improvement in order to reduce costs of any kind, especially by eliminating the wastes in the warehouse. Automation of logistic processes is very important, and in this case is the source of reducing one of the biggest wastes of all: inner transportation. There are several models of routes selecting in practice and, the main aim of this paper is to compare them delving into the development of just one: the shortest path algorithms. Calculating the optimal route for forklifts, in fact means both to shorten transportation routes and to reduce "dead time" in the warehouses.

2021

The order picking problem is one of the key elements in warehouse management. The challenge increases during the new norm when orders can be made by going to the shop and also via online that results in high uncertainty in order volume. Despite that, customer expectation remains on fast delivery which requires the selling organizations to be able to provide fast and efficient service to meet the demand from customers. In achieving this, among the contributing factors is efficient warehouse management especially in order picking, storage assignment, sufficient resource allocation, adequate manpower handling and proper tasking allocation. Thus, in this paper, a model for order picking is modified by considering the limited picking capacity of the Order Pickers (OP), the S-shaped route in the warehouse plan and the need for complete order (all demanded items are picked). The modified model is adapted as a Dynamic Programming problem with the objective of minimizing the time taken (thro...

Innovative Applications in Smart Cities, 2021

This chapter explores the relationship among different routing policies for order picking and the features of the problem (describing both warehouse layout and orders), the results obtained by simulation show that some policies are especially sensitive to the presence of certain conditions that are likely to be present in real-world cases. Moreover, the routing policies are represented for the first time in the literature as far as our knowledge-on structured algorithms. This contribution can facilitate their implementation because the features of the policies are modeled by formal mathematical structures, laying the foundations to standardize the way they operate.

The International Journal of Advanced Manufacturing Technology, 2016

This paper considers the layout design problem of a single block order-picking rack-based warehouse that employs turnover-based storage assignment in both vertical and horizontal dimensions. An analytical expression for vertical travel distance is derived which is incorporated in the pick distance model. The effect of inventory staggering on storage space requirement is considered in arriving at warehouse dimensions. A model that incorporates area cost along with handling cost in optimizing warehouse design is developed and a solution algorithm is presented. The analytical model for vertical travel and the optimization model are applied to data from a real life case. It was found that the model would offer considerable operational cost savings, especially when space costs are high. Computational experiments show that the effect of inventory staggering is quite significant in the estimated storage space. Experiments also demonstrated the importance of segregating products based on turnover in the vertical dimension.

From literature review and deep understanding on the practical industry, it is understood that the proper use of storage assignment policies can use minimum storage space to reach the purpose of minimum total traveling distance, and this has a direct impact on enhancing the order picking performance. At the same time, proper routing planning can minimize overall order picking cost, and finally reach the goal of picking performance enhancement in unit time. Therefore, this paper considers the effects on the order picking system performance for factors such as quantity and layout type of cross aisles in a warehouse system, storage assignment policy, picking route, average picking density inside an aisle, and order combination type, etc. A software, eM-plant, will be used as a simulation and analysis tool, a warehouse design database will be developed, which is based on the minimum overall traveling distance as the optimum performance index, the cross aisle quantity, warehouse layout, storage assignment, picking route planning, picking density and order combination type will be optimally integrated and planned in the warehouse system. Finally, we provide this database to the industry as a reference in the warehouse planning or warehouse design improvement in the future.

This paper evaluates various routing policies (s-shape, largest gap, return and composite policies) and introduces a novel heuristic called Minimum Heuristic (MinH) to solve the picker routing problem. The performance of the routing policies and the MinH heuristic is validated by an experimental design, varying the number of aisles, locations per aisle and pick list size. The experimental results show the travel distance savings of MinH heuristic over routing policies, highlighting that for all of the instances, the MinH heuristic performs 14,3% better than the existing routing policies.