Prof. Morgado Dias Profile

Prof. Morgado Dias

at Univ da Madeira

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Publications (3)

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Proceedings Article | 13 May 2015 Paper

Advanced illumination control algorithm for medical endoscopy applications

Ricardo Sousa, Martin Wäny, Pedro Santos, F. Morgado-Dias

Proceedings Volume 9481, 94810I (2015) https://doi.org/10.1117/12.2176928

KEYWORDS: Cameras, Light emitting diodes, Endoscopy, Light sources and illumination, Field programmable gate arrays, Light sources, LED lighting, Digital cameras, Logic, Surgery

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CMOS image sensor manufacturer, AWAIBA, is providing the world’s smallest digital camera modules to the world market for minimally invasive surgery and one time use endoscopic equipment. Based on the world’s smallest digital camera head and the evaluation board provided to it, the aim of this paper is to demonstrate an advanced fast response dynamic control algorithm of the illumination LED source coupled to the camera head, over the LED drivers embedded on the evaluation board. Cost efficient and small size endoscopic camera modules nowadays embed minimal size image sensors capable of not only adjusting gain and exposure time but also LED illumination with adjustable illumination power. The LED illumination power has to be dynamically adjusted while navigating the endoscope over changing illumination conditions of several orders of magnitude within fractions of the second to guarantee a smooth viewing experience. The algorithm is centered on the pixel analysis of selected ROIs enabling it to dynamically adjust the illumination intensity based on the measured pixel saturation level. The control core was developed in VHDL and tested in a laboratory environment over changing light conditions. The obtained results show that it is capable of achieving correction speeds under 1 s while maintaining a static error below 3% relative to the total number of pixels on the image. The result of this work will allow the integration of millimeter sized high brightness LED sources on minimal form factor cameras enabling its use in endoscopic surgical robotic or micro invasive surgery.

Proceedings Article | 13 March 2015 Paper

Multi-camera synchronization core implemented on USB3 based FPGA platform

Ricardo Sousa, Martin Wäny, Pedro Santos, Morgado Dias

Proceedings Volume 9403, 940306 (2015) https://doi.org/10.1117/12.2082928

KEYWORDS: Cameras, Sensors, Clocks, Field programmable gate arrays, Image sensors, Control systems, Interfaces, 3D vision, Video, Voltage controlled current source

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Centered on Awaiba’s NanEye CMOS image sensor family and a FPGA platform with USB3 interface, the aim of this paper is to demonstrate a new technique to synchronize up to 8 individual self-timed cameras with minimal error. Small form factor self-timed camera modules of 1 mm x 1 mm or smaller do not normally allow external synchronization. However, for stereo vision or 3D reconstruction with multiple cameras as well as for applications requiring pulsed illumination it is required to synchronize multiple cameras. In this work, the challenge of synchronizing multiple selftimed cameras with only 4 wire interface has been solved by adaptively regulating the power supply for each of the cameras. To that effect, a control core was created to constantly monitor the operating frequency of each camera by measuring the line period in each frame based on a well-defined sampling signal. The frequency is adjusted by varying the voltage level applied to the sensor based on the error between the measured line period and the desired line period. To ensure phase synchronization between frames, a Master-Slave interface was implemented. A single camera is defined as the Master, with its operating frequency being controlled directly through a PC based interface. The remaining cameras are setup in Slave mode and are interfaced directly with the Master camera control module. This enables the remaining cameras to monitor its line and frame period and adjust their own to achieve phase and frequency synchronization. The result of this work will allow the implementation of smaller than 3mm diameter 3D stereo vision equipment in medical endoscopic context, such as endoscopic surgical robotic or micro invasive surgery.

Proceedings Article | 2 March 2015 Paper

Image synchronization for 3D application using the NanEye sensor

Ricardo Sousa, Martin Wäny, Pedro Santos, Morgado Dias

Proceedings Volume 9304, 93041N (2015) https://doi.org/10.1117/12.2078271

KEYWORDS: Cameras, Sensors, Clocks, Image sensors, Video, Interfaces, Field programmable gate arrays, Control systems, Imaging systems, 3D vision

Read Abstract +

Based on Awaiba’s NanEye CMOS image sensor family and a FPGA platform with USB3 interface, the aim of this paper is to demonstrate a novel technique to perfectly synchronize up to 8 individual self-timed cameras. Minimal form factor self-timed camera modules of 1 mm x 1 mm or smaller do not generally allow external synchronization. However, for stereo vision or 3D reconstruction with multiple cameras as well as for applications requiring pulsed illumination it is required to synchronize multiple cameras. In this work, the challenge to synchronize multiple self-timed cameras with only 4 wire interface has been solved by adaptively regulating the power supply for each of the cameras to synchronize their frame rate and frame phase. To that effect, a control core was created to constantly monitor the operating frequency of each camera by measuring the line period in each frame based on a well-defined sampling signal. The frequency is adjusted by varying the voltage level applied to the sensor based on the error between the measured line period and the desired line period. To ensure phase synchronization between frames of multiple cameras, a Master-Slave interface was implemented. A single camera is defined as the Master entity, with its operating frequency being controlled directly through a PC based interface. The remaining cameras are setup in Slave mode and are interfaced directly with the Master camera control module. This enables the remaining cameras to monitor its line and frame period and adjust their own to achieve phase and frequency synchronization. The result of this work will allow the realization of smaller than 3mm diameter 3D stereo vision equipment in medical endoscopic context, such as endoscopic surgical robotic or micro invasive surgery.

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