22 research outputs found
A covering projection for robot navigation under strong anisotropy
No full textPath planning can be subject to different types of optimization. Some years ago a German researcher, U. Leuthausser, proposed a new variational method for reducing most types of optimization criteria to one and the same: minimization of path length.
This can be done by altering the Riemannian metric of the domain, so that optimal paths (with respect to whatever criterion) are simply seen as shortest. This method offers an extra feature, which has not been exploited so far: it admits direction-dependent criteria.
In this paper we make this feature explicit, and apply it to two different anisotropic settings. One is that of different costs for different directions: E.g. the situation of a countryside scene with ploughed fields. The second is dependence on oriented directions,
which is called here "strong" anisotropy: the typical scene is that of a hill side. A covering projection solves the additional difficulty. We also provide some experimental results on synthetic data
A New Architecture for TOF-based Range-finding Sensor
No full textThis paper describes the design and characterization of a linear array for three-dimensional measurements based on both multiple-pulse Indirect-Time-Of-Flight (ITOF) and Optical Triangulation (OT) techniques. The 128-pixel array has been fabricated in a standard 0.35um, 3.3-V CMOS technology and the chip dimensions are 4.5x3.3-mm2. The distance measurement with cooperative targets in the 2-8 m range has been successfully performed with a worst case precision better than 4 cm in the ITOF modality. Preliminary test confirmed also the validity of the OT mode, reporting a depth resolution of 100 um at 1
A CMOS Smart Pixel for Active 3D Vision Applications
No full textA CMOS smart pixel aimed at three-dimensional vision applications is introduced. It is suitable for scannerless laser ranging systems which employ the indirect Time-Of-Flight measuring technique to recover distance information. The pixel is operated with trains of light pulses generated by an external source to illuminate the scene and contains most of the processing electronics to perform signal accumulation and noise reduction operations. The smart pixel architecture includes a N-well photodiode plus a self-biasing voltage amplifier and a switched-capacitor fully differential stage. The pixel is fabricated in standard CMOS 0.6um technology and measures 180x160um2 (including the photodiode) with a fill factor of 14%. Electro-optical test results confirm the smart pixel functionality in a range of distance from 3m to 9m, and the accuracy achieved for preliminary distance measurements is 15cm. Both the accuracy and the extension of the range of distance are supposed to be improved by reducing setup and environmental noise contributions that limit the pixel performance
A Linear CMOS Sensor for 3D Vision with Merged I-TOF and OT Techniques
No full text3DJAM is a novel 3D image sensor, implemented with a 3.3V, 0.35μm CMOS technology, that combines the Optical Triangulation (OT) and the Indirect Time of Flight (ITOF) techniques in a single chip for range finding scanners. It has been designed to cover very large depth scenes (up to 20 meters), achieving sub-millimeter resolution over the OT range (below 2 meters), working with a single pulsed laser source and also taking advantage of ambient light removal. The chip embeds also a programmable logic unit, which supervises over all the internal functions (like timing, pipelining, data transfer), a power supply unit (for both the analogue and the digital subsystems) and an analogue output buffer that can drive an external ADC for data acquisitio
A CMOS Sensor based on Single Photon Avalanche Diode for Distance Measurement Applications
No full textThis paper describes the design of a 64x2-pixel array, fabricated in a conventional industrial high-voltage 0.8um CMOS technology, and aimed at three dimensional measurements based on the Time-Of-Flight technique. Light signals are detected using a photodiode biased above its breakdown voltage so that an extremely high sensitivity can be achieved exploiting the intrinsic multiplication effect of the avalanche phenomenon. A single photon avalanche diode and dedicated read-out electronics for light pulses arrival-time estimation have been implemented in a 38x180-um2 pixel with an expected power consumption of about 20 uW. To increase the distance measurement resolution a multiple pulse measurement is used, extracting the mean value of the light pulse arrival-time directly in each pixel; this innovative approach dramatically reduces the dead-time of the pixel read-out, allowing a high frame rate imaging to be achieve
A 16 x 16-Pixel Range-Finding CMOS Image Sensor
No full textThis paper describes the design and characterization of a 16x16-pixel image sensor, fabricated in a 0.35 um, 3.3 V CMOS technology for real time three dimensional measurements based on multiple-pulse indirect Time-of-Flight technique. Owing to an innovative fully differential pixel (FDP) architecture, which allows for the detection of very short and low intensity light pulses, the sensor array provides a range map from 2m to 9m with a precision of ¡Ó4.0% at 2m and ¡Ó1.7% at 9m. The pixel power consumption is 100 ƒÝW, whereas the overall power consumption of the chip is 47 mW in real time operation (30 fps)
A 50x30-pixel CMOS Sensor for TOF-based Real Time 3D Imaging
No full textA 50x30-pixel CMOS sensor aimed at real time three-dimensional vision applications is presented along with characterization results. The sensor is realized on a single mixed-signal chip fabricated in a 0.35-um, 3.3-V, 4-metal/2-poly CMOS technology. The distance measurement relies on the pulsed indirect time of flight (ITOF) technique, and a precision of 4 % is obtained in the 2-8 m range. The real time mode of operation is proved at 20 frames per second with non-cooperative target
CMOS distance sensor based on single photon avalanche diode
No full textThis paper reports on a novel distance sensor employing an avalanche photodiode (APD) in a single photon counting configuration for Time-Of-Flight 3D imaging applications. An active pixel containing a single photon detector and a read-out channel has been designed. An averaging circuit is included in the pixel, allowing an increased resolution with a reduction of the overall measurement time. A 64x2 pixel linear array has been fabricated in a conventional industrial high-voltage 0.8-μm CMOS technology, together with an APD test structure. A preliminary electro-optical characterization of the test structure is reported
A Novel 3D Staring System for Driver Assistance
No full textThis paper reports the development of an intelligent electro-optical device for drive scenarios detection and object recognition, finalised to automotive functions, such as pre-crash, in which the obstacles classification is very important. The system is based on a new CMOS image sensor able to enhance the passive vision by integration on pixel of the distance information. The scene detection is based on a new active 3D imaging techniqu
Cephalometric changes of pushing splints 3 compared to rapid maxillary expansion and facemask therapy on the airway space in class III growing patients: A randomized clinical trial
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