1. Ergonomic evaluation of human–robot collaborative order picking : a combined laboratory and simulation studyMinqi Zhang, Jakob Marolt, Primož Bencak, Eric Grosse, Tone Lerher, 2024, published scientific conference contribution Abstract: Thanks to rapid technological developments in robotics, various automation technologies are being applied in warehouses today. Order picking, as a key process in warehouse operations, has drawn attention in academia and practice for decades. In addition to many studies dedicated to manual and fully automated order picking, efforts have also been made to study semi-automated warehouses in which humans and robots collaborate. However, these studies mostly focused on system efficiency and ignored ergonomic aspects. Order picking was confirmed as a labor-intensive process in an environment in which workers are at a high risk of developing health problems. Therefore, this study addresses the investigation of physical human working conditions in both manual and robot-assisted order picking systems via real-life laboratory experiments and simulation modeling. We used a motion capture system to assess human working postures when working with and without robot assistance. In addition, we estimated the daily workload by applying the energy expenditure concept. Using simulation experiments, we were able to extend the results to various practical scenarios with different design variables, for example warehouse layouts, order sizes, and human-robot team configuration. Our preliminary results reveal that human-robot collaboration can reduce human workload. Posture evaluation also shows a slight improvement.
Keywords: order picking, autonomous mobile robot, human factors, ergonomics, assisted order picking, hybrid order picking, simulation, performance evaluation
Published in DKUM: 21.11.2024; Views: 0; Downloads: 2
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2. Analysing picking errors in vision picking systemsEla Vidovič, Brigita Gajšek, 2020, original scientific article Abstract: Vision picking empowers users with access to real-time digital order information, while freeing them from handheld radio frequency devices. The smart glasses, as an example of vision picking enabler, provide visual and voice cues to guide order pickers. The glasses mostly also have installed navigation features that can sense the order picker's position in the warehouse. This paper explores picking errors in vision systems with literature review and experimental work in laboratory environment. The results show the effectiveness of applying vision picking systems for the purposes of active error prevention, when they are compared to established methods, such as paper-picking and using cart mounted displays. A serious competitor to vision picking systems are pick-to-light systems. The strong advantage of vision picking system is that most of the errors are detected early in the process and not at the customer's site. The cost of fixing the error is thus minimal. Most errors consequently directly influence order picker's productivity in negative sense. Nonetheless, the distinctive feature of the system is extremely efficient error detection.
Keywords: order picking, storage operations, warehousing, smart glasses, error prevention, inventory management, intralogistics
Published in DKUM: 22.08.2024; Views: 83; Downloads: 4
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3. Comparison of lowest-slot and nearest-stack heuristics for storage assignment of steel bar setsJakob Marolt, Tone Lerher, 2018, original scientific article Abstract: Our research objective is to lower intralogistics costs by minimizing the number of shuffling operations in a steel plant company commercial warehouse. The process of dispatching products consists of retrieving set of steel bar (SSB) from a floor stored stack or a special stacking frame by an overhead crane. To retrieve a targeted merchandise all SSB above targeted must be reshuffled. Proper assignment of storage locations is a key logistics problem for efficient order picking. We are comparing two heuristics, that do not require information of dispatching sequence of any stored products. We simulated the problem at hand with both methods. Our objective is to count the number of reshuffles using each heuristic on randomly generated examples and decide which is better in the long run. Our problem has similarities with storage assignment of steel plates or steel coils for minimization of reshuffling operations. The problem is also comparable to storage assignment of containers in a container yard. In our case we are dealing with a special stacking configuration of products, that demands different approach. We want to demonstrate which heuristic should be used in companies that lack necessary storage information infrastructure.
Keywords: order picking, storage operations, warehousing, logistics
Published in DKUM: 22.08.2024; Views: 62; Downloads: 10
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4. Towards productive and ergonomic order picking : multi-objective modeling approachBrigita Gajšek, Simona Šinko, Tomaž Kramberger, Marcin Butlewski, Eren Özceylan, Goran Đukić, 2021, original scientific article Abstract: The logistics sector should strive for sustainability alongside productivity by protecting its order pickers' health and welfare. Existing storage assignment models are mainly based on the criterion of order picking time and, to a lesser extent, the human factor. In the paper, a solution to a storage assignment problem using a multi-objective model based on binary integer linear programing is presented by developing a solution that considers order picking time, energy expenditure and health risk. The Ovako Working Posture Assessment System (OWAS) method was used for health risk assessment. The downside of solely health risk-optimization is that the average order picking time increases by approximately 33 % compared to solely time-optimization. Contrary to this, the developed multi-objective function emphasizing time has proven to be promising in finding a compromise between the optimal order picking time and eliminating work situations with a very-high risk for injuries. Its use increases the time by only 3.8 % compared to solely time-optimization while significantly reducing health risk.
Keywords: productivity, energy expenditure, order picking, order picking system, health risk, OWAS, multi-objective modeling, planning, logistics, ergonomics
Published in DKUM: 13.08.2024; Views: 109; Downloads: 10
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5. Single-tray VLM vs dual-tray VLM : quantitative throughput comparisonGoran Đukić, Tihomir Opetuk, Brigita Gajšek, Tone Lerher, 2021, original scientific article Abstract: In this paper quantitative comparison of resulting throughputs for single-tray and dual-tray VLM devices is presented. Comparison is based on mathematical models for throughput approximating dual command times of VLM's crane, for selected parameters of VLM device (height and crane's velocity) and selected picking times per delivered tray. Analysis showed that throughput increase achieved by using dual-tray VLM's depends mostly on the average picking time relative to the expected dual command time of the VLM's crane. Highest improvements are possible for picking time equal to expected dual command time and amounts over 80%, however for extremely low or high picking times improvements are significantly reduced.
Keywords: order-picking, throughput model, vertical lift module systems, quantitative analysis, intralogistics, dual-tray VLM, single-tray VLM
Published in DKUM: 12.08.2024; Views: 48; Downloads: 9
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6. Bi-objective assignment model for lean order picking in a warehouseBrigita Gajšek, Hrvoje Cajner, Tihomir Opetuk, Goran Đukić, Marcin Butlewski, 2022, original scientific article Abstract: With the introduction of Lean Warehousing, we are committed to using lean principles for more efficient warehousing operations, which are performed with quality and safety. Manual order picking, on which the paper is focused, is currently considered the most unfriendly to humans because, in the long run, it contributes to the appearance of musculoskeletal disorders. We record not only the increase in the average age of employees in warehouses but also in the number and duration of sick leave due to back and muscle pain. This paper explores the possibility of productive work while preventing order pickers from Work-Related Musculoskeletal Disorders. Using a laboratory experiment, we determine retrieval times for units with different characteristics and study required postures by guidelines of Revised NIOSH Lifting Equation. The final goal is to create a bi-objective assignment model.
Keywords: warehousing, order picking, ergonomics, intralogistics, lean logistics, manual order picking, productivity, revised NIOSH lifting equation, warehousing, work-related musculoskeletal disorders
Published in DKUM: 13.06.2024; Views: 105; Downloads: 8
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