Automatic Pallet Research Articles

Automatic Palletizing of Concrete Pavement Blocks: An Algorithm for Near‐Optimal Assembly

Palletizing concrete pavement blocks is a labor‐intensive task that requires high levels of workmanship, skill, and concentration. This article proposes an automatic system in which palettes with required design patterns are assembled automatically off‐site and then shipped to the construction site. The efficiency of the assembly process can be improved by incorporating automatic equipment consisting of assembly heads and feeders. An algorithm was developed to determine the optimal layout of the feeders (of different blocks) around the palette and the exact assembly sequence of each layer of blocks. Experimental results show that the algorithm is near optimal and that the solutions provided by it reduce palletizing cycle time for various patterns and sizes of concrete block by 20 to 30 percent.

“Compact” flexible manufacturing systems

This paper discusses the need to investigate the complex problem domain of flexible manufacturing systems (FMS), and develops potential rule structures for this manufacturing environment. Specifically, a simulation analysis that focuses on the operating characteristics of machine centers using automatic pallet loading queues is performed and results are presented. These types of FMS claim benefits from the ability to ‘stack’ work ahead for unattended processing. This research examines a number of loading or scheduling rules designed to extract benefits from and attenuate the impact of such a system. Results demonstrate the inherent conflict of effectiveness, efficiency, and high utilization performance criteria. The paper discusses rule structures which should aid in characterizing the shop conditions under which such automated queuing systems are desirable.

Model-based object recognition using a large-field passive tactile sensor

The results of a model-driven touch sensor recognition experiment are reported. The touch sensor used is a large-field tactile array. Object features appropriate for touch sensor recognition are extracted from a geometric model of an object, and a dual spherical image is formed. Both geometric and dynamic features are used to identify objects and their position and orientation on the touch sensor. Experiments show that geometric features extracted from the model are effective but that dynamic features must be determined empirically. Correct object identification rates, even for very similar objects, exceed 90%, a success rate much higher than would have been expected from only two-dimensional contact patterns. The position and orientation of objects, once identified, are very reliable. The authors conclude that large-field tactile sensors could prove useful in the automatic palletizing problem when object models (from a computer-aided design system, for example) can be utilized.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

High-throughput and fully automated system for molecular-beam epitaxy

A new high‐throughput and fully automated system for molecular‐beam epitaxy was developed by employing multiple substrate mount pallets and automatic pallet transfer mechanisms. The geometrical configuration between pallet and effusion cells was optimized to achieve the uniformity of thickness and carrier concentration of epitaxial layer better than ±2% within a pallet. The throughput was more than 70 2‐in. wafers per day for the growth of AlGaAs/GaAs two‐dimensional electron gas structure. In a typical two‐dimensional electron gas structure with a 6‐nm spacer layer, the variation of sheet electron mobility closed in 7.5 to 10×104 cm2 /V s at 77 K over growth run to run. By improving the heater structure of the Ga effusion cell, the Ga‐related oval defect density was found to be reduced <1 cm −2. The total surface defect density was reduced to <50 cm−2 by preventing the particulate contamination on the growth surface. Moreover, unintentionally doped GaAs layer was dominated by a donor, whose concentration was lower than 1×1014 cm−3, and electron mobility was 145 000 cm2 /V s at 77 K.

Fifth Paper: The Design of Machining Centres

Design features of a range of machining centres are described. A four-axis horizontal machining centre with a 1 1/2 m diameter table is described in detail. It is fitted with a 60-station tool changer and automatic pallet loading and uses hydrostatic slideway and spindle bearings. The elements of the machine are of modular design and other configurations and sizes of machine can be made from the same modules.