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Discrete-time, linear control systems with specified pointwise-in-time constraints, such as those imposed by actuator saturation, are considered. The constraints are enforced by the addition of a nonlinear ‘reference governor’ that attenuates, when necessary, the input commands. Because the constraints are satisfied, the control system remains linear and(More)
In a previous study, we evaluated six 2D barcodes using eight criteria for standardization potential: omnidirectional symbol reading, support for low-resolution cameras, reading robustness under different lighting conditions, barcode reading distance, error correction capability, security, support for multiple character sets, and data capacity. We also(More)
Two dimensional (2D) barcodes are becoming a pervasive interface for mobile devices, such as camera phones. Often, only monochrome 2D-barcodes are used due to their robustness in an uncontrolled operating environment of camera phones. Most camera phones capture and store such 2D-barcode images in the baseline JPEG format. As a lossy compression technique,(More)
The use of colours in 2D barcodes is challenging. This is even more so in barcodes for mobile devices. Although 2D barcodes are fast becoming the ubiquitous tool for mobile computing, most implementations considered monochromatic 2D barcodes. A few colour 2D barcodes are emerging but these implementations only utilises a limited number of colours. In this(More)
In recent years, a trend has emerged in the use of colour to increase the data capacity of the 2D barcode. However the decoding of such colour barcode can be challenging in a mobile environment due to blurring effect that is commonly found in images captured by camera mobile phone. Blurring affects the synchronisation between the cells. It also causes the(More)
With a camera mobile phone, which has become a "must-have" device, 2D-barcode works as an interface to bridge the physical and digital world. As the notion of ubiquitous computing has permeated, developing a new 2D-barcode and its applications has been a growing trend worldwide. A 2D-barcode symbol consists of two broad areas: data area and guide area. The(More)
As camera phones have permeated into our everyday lives, two dimensional (2D) barcode has attracted researchers and developers as a cost-effective ubiquitous computing tool. A variety of 2D barcodes and their applications have been developed. Often, only monochrome 2D barcodes are used due to their robustness in an uncontrolled operating environment of(More)
In recent years, colour 2D barcodes have emerged to increase the data capacity of the 2D barcode. Similarly, camera-equipped mobile phones have became more popular and their camera could act as an input device for a barcode decoder. In this paper, three Windows Mobile (WM) operated mobile phones are used to test their camera performance in reading the(More)