A method called Feature Extraction by Demands(FED) has been developed to generate object descript... more A method called Feature Extraction by Demands(FED) has been developed to generate object descriptions. Objects are described by surface adjacency graphs containing the surface class and the surface equation at each node. Due to occlusion and the use of 21D range images the generated object description is frequently partial. This paper describes a new method to generate object hypotheses and to recognize and locate viewed objects using partial descriptions of objects bounded by quadric surfaces. The method proceeds in two phases. In phase one, the object location is estimated from matched surface pairs(between an object description and an object model). Depending upon the surface type, each surface may provide partial or complete location information. As long as the location information calculated from matched surface pairs is consistent, that is passes matching feasibility tests, the object model is a candidate for the viewed object. The consistent partial location information is combined into a more complete object location estimation sequentially. The order of location information to be used in object location estimation is decided by whether a more complete object location can be calculated. If a complete location can be calculated or the object location estimation cannot be further refined the hypothesis is verified by phase two. In phase two, each remaining surface which was not used for object location estimation is searched for a matched model surface and the neighboring relations between surfaces are verified. If the hypothesis passes phase two the model is accepted as a matched model. If a complete object location can be calculated from the accepted hypothesis an optimal object location is calculated.
We present the first large-area, all-silicon rib waveguides and fiber guiding U-grooves fabricate... more We present the first large-area, all-silicon rib waveguides and fiber guiding U-grooves fabricated on (110) silicon substrates. Waveguide rib structures with a height of 6.7 micrometers and widths of 5, 10, and 15 micrometer are RIE etched into lightly doped epitaxial silicon layers deposited on heavily doped silicon substrates. Fiber-guiding U-grooves with unique corner compensation structures are anisotropically etched by a 35 wt% KOH solution at 70 degrees C, with and without ultrasonic agitation of the etching solution. Devices fabricated without ultrasonic agitation have a U-groove bottom surface roughness (Ra) of 5606 angstrom, while devices with ultrasonic agitation have a surface roughness (Ra) of 341 angstrom. Ultrasonic etching improves the surface roughness of the U-groove bottoms by a factor of 16.4. We found that the variation of U-groove etch depth is grater than 1 micrometer across the wafer, even with ultrasonic agitation of the etchant. Examination of the waveguide modal structure indicates that devices with 6.7 micrometer tall and 10 micrometer wide rib structures propagate only one waveguide mode at 1550 nm. The total loss of the straight waveguides was as low as 4.88 dB, and the propagation loss was estimated to be 1.68 dB. These loss values indicate waveguide end-faces fabricated by anisotropic etching of (110) silicon do not need to be polished.
An algorithm for object recognition based on the data from various contact and/or non-contact sen... more An algorithm for object recognition based on the data from various contact and/or non-contact sensors is described. The sensors are primarily used for resolving the ambiguities which may be encountered in recognizing the object identity and its pose. The feature vector representing an object-state is partitioned into a finite number of feature subvectors each containing the features extracted from a different sensory source. To perform the recognition task through integration of data from different sensors, an a priori cost value is assigned to each feature. These feature costs and the object models are used for deriving a decision tree based on a sequential pattern, recognition approach. The decision tree guides the system during the recognition phase. General strategies for feature extraction from various sources are implemented as a finite state machine. A coordinator module supervises the coordination of manipulation and recognition processes and the execution of system state changes which are required to successfully implement the recognition algorithm.
IEE Colloquium Intelligent and Self-Validating Sensors, 1999
Torque signals are used today across a broad range of automation applications such as dynamometer... more Torque signals are used today across a broad range of automation applications such as dynamometer test stands and web process lines. Some of the drawbacks to using commercial torque transducers include their cost, reliability, and mechanical stiffness. It is possible to utilize an artificial neural network coupled with the photoelastic effect of many polymers to provide a small, low-cost torque sensor. The availability of low-cost torque sensing opens up many new applications that previously did not cost justify the investment in a commercial torque sensor. The sensor material has a high bandwidth which enables sampling high-frequency torque signals. High frequency torque signals are particularly useful for investigating machinery dynamics and for machinery health assessment.
ABSTRACT This paper describes the fabrication process and preliminary experimental results of a p... more ABSTRACT This paper describes the fabrication process and preliminary experimental results of a polygon mirror microscanner. The fabrication process is established by the integration of polysilicon surface micromachining and electroless plating of nickel. The scanner structures studied are similar to conventional mechanical polygon mirror scanners but utilize micromotors with diameters up to one millimeter. The micromotors are fabricated by polysilicon surface micromachining. The optical elements are hexagonal nickel reflectors up to 20 micrometers tall fabricated by selective electroless plating of nickel on the rotor of the micromotor. Successful fabrication of the micromotors with nickel reflectors on the motor has been demonstrated. Optical measurements have been performed at visible wavelength (633 nm) using multi-mode optical fibers for the source illumination positioned roughly in the plane of the substrate. The scanned, reflected radiation was detected via scattering from the substrate and by a television camera in the plane of the substrate.
Digest IEEE/Leos 1996 Summer Topical Meeting. Advanced Applications of Lasers in Materials and Processing
We describe progress in the development of micro-optomechanical components which are compatible w... more We describe progress in the development of micro-optomechanical components which are compatible with MEMS and integrated circuit processing. Devices which have been developed include polygon and diffraction grating scanners, tunable laser diodes, tunable IR filters, and optical waveguides.
A technique for performing surface-based segmentation of range images using neural nets is introd... more A technique for performing surface-based segmentation of range images using neural nets is introduced. In this approach, multilayered neural nets are used to classify local image patches according to the type of surface they belong to, based on features extracted from range and surface normal information. Central component to the efficiency and robustness is a near orientational invariant local data organization which takes place before features are extracted. This data organization reduces internal complexity by shifting the orientation invariance burden from the dimensionality of the feature spaces and/or from the internal architecture of the networks, to a much simpler sequencing of local data. The result is a well segmented image in which surfaces are properly labeled and delimited, without over segmentation. The approach shows to be robust in front of noise.
Proceedings of International Conference on Robotics and Automation
... 3, No. 6, [6] Marefat, M., M. Sandeep, and RL Kashyap, “Object-Oriented Intelligent Computer ... more ... 3, No. 6, [6] Marefat, M., M. Sandeep, and RL Kashyap, “Object-Oriented Intelligent Computer Integrated Design, Process Planning, and Inspection,” Computer, Vol. 26, No. 3, pp. 54-65, 1993. [7] Merat, F., and G. Radack, “Automatic ...
In this paper, it is shown that supervised learning can be posed as an optimization problem in wh... more In this paper, it is shown that supervised learning can be posed as an optimization problem in which inequality constraints are used to encode the information contained in the training patterns and to specify the degree of accuracy expected from the neural network. Starting from this point, a technique for evaluating the learning capability and optimizing the feature space of a class of higher-order neural networks is developed. The technique gives significant insight into the problem of task learning. It permits establishing whether the structure of the network can effectively learn the training patterns. Should the structure not be appropriate for learning, it indicates which patterns form the minimum set of patterns which cannot be learned with the desired accuracy. Otherwise, it provides a connectivity which produces satisfactory network performance. Furthermore, it identifies those features which can be suppressed from the definition of the feature space without deteriorating network performance. Several examples are presented and results are discussed.
An experiment to study the effect of a meterologically well-characterized atmosphere on near-mill... more An experiment to study the effect of a meterologically well-characterized atmosphere on near-millimeter wave propagation has been designed and is being implemented. The primary emphasis of this experiment is on measurement of atmospheric mutual coherence function (MCF) simultaneously with measurement of temperature/humidity structure parameters C2T C2Q, and CTQ. Quasi-optical techniques, which make use of the Fourier transforming properties of focussing reflective optics, will be applied to measure real and imaginary parts of the MCF, while fast temperature and humidity sensors will provide derived structure parameters. This paper will discuss experimental concepts and range instrumentation.
The remote sensing, transmission, recording and display of visual information using holograms con... more The remote sensing, transmission, recording and display of visual information using holograms continues to be a desired goal, The fundamental problem is that conventional off-axis holograms have high space-spatial frequency bandwidth products which require extremely high resolution recording media. However, much of the essential visual information of a scene is intrinsically low spatial frequency information. In general, high spatial frequency has been required to separate the real and virtual images from the self-interference terms in the hologram. A viable alternative is to selectively eliminate the self-interference terms of the hologram during the recording process. One such method is electronic heterodyne recording where electro-optic modulation is used to introduce a sinusoidal phase shift between the object and reference wave. The resulting temporally modulated holographic interference pattern is scanned by a commercial image dissector camera and rejection of the self-interference terms is accomplished by heterodyne detection at the camera output. The electrical signal representing this processed hologram can then be used to modify the properties of a liquid-crystal light valve or similar device. Such display devices, when illuminated by coherent light, transform the displayed interference pattern into a phase modulated wave front rendering a three-dimensional image. System requirements of holographic display systems will be considered as well as specific requirements for television rate and format systems.
IEEE International Conference on Systems Engineering
A method called vision-taction exploration (VTE) for generating surface descriptions from range v... more A method called vision-taction exploration (VTE) for generating surface descriptions from range vision and tactile sensor data is described. The range vision systems available provide sparse 3D data about surfaces. These data are partially processed to provide primary surface features such as surface points and surface normals. With the use of tactile and force-torque sensors under position control, supplementary data
Micro-Optics/Micromechanics and Laser Scanning and Shaping, 1995
We are developing integrated micro-opto-mechanical systems (MOMS) based upon wafer integration of... more We are developing integrated micro-opto-mechanical systems (MOMS) based upon wafer integration of optical and micro-electromechanical components. In this paper, we describe our developments in micro-opto-mechanical systems in the area of microscanners and moveable optical elements. The microscanners are based upon the fabrication of micro-optical elements on the rotors of large diameter, i.e. 500 to 2,000 micrometers , polysilicon micromotors and have resulted in two approaches to scanning. In the first approach, nickel plating and high-aspect- ratio photolithography were used to produce 175 micrometers diameter, 20 micrometers tall nickel polygon reflectors on the rotors of polysilicon micromotors. These polygon microscanners are suitable for planar scanning as well and other planar applications such as optical fiber and waveguide switches. In a second approach, 2 - 4 micrometers spatial period diffraction gratings were fabricated on the solid rotors of polysilicon micromotors. Such devices are suitable for applications requiring out-of-plane scanning, e.g., bar code readers, and take advantage of planar processing. Chemical-mechanical polishing was used to reduce the polysilicon rotor's average surface roughness (Ra) from 420 angstrom to below 17 angstrom, improving the optical performance of the diffraction gratings. Diffraction grating microscanners using salient pole micromotors have been operated at voltages as low as 45 V, with maximum operational speeds of 1100 rpm. Although microscanners based upon rotating reflectors and diffraction gratings are significant, future MOMS also require linear motion of optical elements and optical waveguides to carry light between optical elements. To this end, we have produced optical reflectors on linear translational comb actuators.
A method called Feature Extraction by Demands(FED) has been developed to generate object descript... more A method called Feature Extraction by Demands(FED) has been developed to generate object descriptions. Objects are described by surface adjacency graphs containing the surface class and the surface equation at each node. Due to occlusion and the use of 21D range images the generated object description is frequently partial. This paper describes a new method to generate object hypotheses and to recognize and locate viewed objects using partial descriptions of objects bounded by quadric surfaces. The method proceeds in two phases. In phase one, the object location is estimated from matched surface pairs(between an object description and an object model). Depending upon the surface type, each surface may provide partial or complete location information. As long as the location information calculated from matched surface pairs is consistent, that is passes matching feasibility tests, the object model is a candidate for the viewed object. The consistent partial location information is combined into a more complete object location estimation sequentially. The order of location information to be used in object location estimation is decided by whether a more complete object location can be calculated. If a complete location can be calculated or the object location estimation cannot be further refined the hypothesis is verified by phase two. In phase two, each remaining surface which was not used for object location estimation is searched for a matched model surface and the neighboring relations between surfaces are verified. If the hypothesis passes phase two the model is accepted as a matched model. If a complete object location can be calculated from the accepted hypothesis an optimal object location is calculated.
We present the first large-area, all-silicon rib waveguides and fiber guiding U-grooves fabricate... more We present the first large-area, all-silicon rib waveguides and fiber guiding U-grooves fabricated on (110) silicon substrates. Waveguide rib structures with a height of 6.7 micrometers and widths of 5, 10, and 15 micrometer are RIE etched into lightly doped epitaxial silicon layers deposited on heavily doped silicon substrates. Fiber-guiding U-grooves with unique corner compensation structures are anisotropically etched by a 35 wt% KOH solution at 70 degrees C, with and without ultrasonic agitation of the etching solution. Devices fabricated without ultrasonic agitation have a U-groove bottom surface roughness (Ra) of 5606 angstrom, while devices with ultrasonic agitation have a surface roughness (Ra) of 341 angstrom. Ultrasonic etching improves the surface roughness of the U-groove bottoms by a factor of 16.4. We found that the variation of U-groove etch depth is grater than 1 micrometer across the wafer, even with ultrasonic agitation of the etchant. Examination of the waveguide modal structure indicates that devices with 6.7 micrometer tall and 10 micrometer wide rib structures propagate only one waveguide mode at 1550 nm. The total loss of the straight waveguides was as low as 4.88 dB, and the propagation loss was estimated to be 1.68 dB. These loss values indicate waveguide end-faces fabricated by anisotropic etching of (110) silicon do not need to be polished.
An algorithm for object recognition based on the data from various contact and/or non-contact sen... more An algorithm for object recognition based on the data from various contact and/or non-contact sensors is described. The sensors are primarily used for resolving the ambiguities which may be encountered in recognizing the object identity and its pose. The feature vector representing an object-state is partitioned into a finite number of feature subvectors each containing the features extracted from a different sensory source. To perform the recognition task through integration of data from different sensors, an a priori cost value is assigned to each feature. These feature costs and the object models are used for deriving a decision tree based on a sequential pattern, recognition approach. The decision tree guides the system during the recognition phase. General strategies for feature extraction from various sources are implemented as a finite state machine. A coordinator module supervises the coordination of manipulation and recognition processes and the execution of system state changes which are required to successfully implement the recognition algorithm.
IEE Colloquium Intelligent and Self-Validating Sensors, 1999
Torque signals are used today across a broad range of automation applications such as dynamometer... more Torque signals are used today across a broad range of automation applications such as dynamometer test stands and web process lines. Some of the drawbacks to using commercial torque transducers include their cost, reliability, and mechanical stiffness. It is possible to utilize an artificial neural network coupled with the photoelastic effect of many polymers to provide a small, low-cost torque sensor. The availability of low-cost torque sensing opens up many new applications that previously did not cost justify the investment in a commercial torque sensor. The sensor material has a high bandwidth which enables sampling high-frequency torque signals. High frequency torque signals are particularly useful for investigating machinery dynamics and for machinery health assessment.
ABSTRACT This paper describes the fabrication process and preliminary experimental results of a p... more ABSTRACT This paper describes the fabrication process and preliminary experimental results of a polygon mirror microscanner. The fabrication process is established by the integration of polysilicon surface micromachining and electroless plating of nickel. The scanner structures studied are similar to conventional mechanical polygon mirror scanners but utilize micromotors with diameters up to one millimeter. The micromotors are fabricated by polysilicon surface micromachining. The optical elements are hexagonal nickel reflectors up to 20 micrometers tall fabricated by selective electroless plating of nickel on the rotor of the micromotor. Successful fabrication of the micromotors with nickel reflectors on the motor has been demonstrated. Optical measurements have been performed at visible wavelength (633 nm) using multi-mode optical fibers for the source illumination positioned roughly in the plane of the substrate. The scanned, reflected radiation was detected via scattering from the substrate and by a television camera in the plane of the substrate.
Digest IEEE/Leos 1996 Summer Topical Meeting. Advanced Applications of Lasers in Materials and Processing
We describe progress in the development of micro-optomechanical components which are compatible w... more We describe progress in the development of micro-optomechanical components which are compatible with MEMS and integrated circuit processing. Devices which have been developed include polygon and diffraction grating scanners, tunable laser diodes, tunable IR filters, and optical waveguides.
A technique for performing surface-based segmentation of range images using neural nets is introd... more A technique for performing surface-based segmentation of range images using neural nets is introduced. In this approach, multilayered neural nets are used to classify local image patches according to the type of surface they belong to, based on features extracted from range and surface normal information. Central component to the efficiency and robustness is a near orientational invariant local data organization which takes place before features are extracted. This data organization reduces internal complexity by shifting the orientation invariance burden from the dimensionality of the feature spaces and/or from the internal architecture of the networks, to a much simpler sequencing of local data. The result is a well segmented image in which surfaces are properly labeled and delimited, without over segmentation. The approach shows to be robust in front of noise.
Proceedings of International Conference on Robotics and Automation
... 3, No. 6, [6] Marefat, M., M. Sandeep, and RL Kashyap, “Object-Oriented Intelligent Computer ... more ... 3, No. 6, [6] Marefat, M., M. Sandeep, and RL Kashyap, “Object-Oriented Intelligent Computer Integrated Design, Process Planning, and Inspection,” Computer, Vol. 26, No. 3, pp. 54-65, 1993. [7] Merat, F., and G. Radack, “Automatic ...
In this paper, it is shown that supervised learning can be posed as an optimization problem in wh... more In this paper, it is shown that supervised learning can be posed as an optimization problem in which inequality constraints are used to encode the information contained in the training patterns and to specify the degree of accuracy expected from the neural network. Starting from this point, a technique for evaluating the learning capability and optimizing the feature space of a class of higher-order neural networks is developed. The technique gives significant insight into the problem of task learning. It permits establishing whether the structure of the network can effectively learn the training patterns. Should the structure not be appropriate for learning, it indicates which patterns form the minimum set of patterns which cannot be learned with the desired accuracy. Otherwise, it provides a connectivity which produces satisfactory network performance. Furthermore, it identifies those features which can be suppressed from the definition of the feature space without deteriorating network performance. Several examples are presented and results are discussed.
An experiment to study the effect of a meterologically well-characterized atmosphere on near-mill... more An experiment to study the effect of a meterologically well-characterized atmosphere on near-millimeter wave propagation has been designed and is being implemented. The primary emphasis of this experiment is on measurement of atmospheric mutual coherence function (MCF) simultaneously with measurement of temperature/humidity structure parameters C2T C2Q, and CTQ. Quasi-optical techniques, which make use of the Fourier transforming properties of focussing reflective optics, will be applied to measure real and imaginary parts of the MCF, while fast temperature and humidity sensors will provide derived structure parameters. This paper will discuss experimental concepts and range instrumentation.
The remote sensing, transmission, recording and display of visual information using holograms con... more The remote sensing, transmission, recording and display of visual information using holograms continues to be a desired goal, The fundamental problem is that conventional off-axis holograms have high space-spatial frequency bandwidth products which require extremely high resolution recording media. However, much of the essential visual information of a scene is intrinsically low spatial frequency information. In general, high spatial frequency has been required to separate the real and virtual images from the self-interference terms in the hologram. A viable alternative is to selectively eliminate the self-interference terms of the hologram during the recording process. One such method is electronic heterodyne recording where electro-optic modulation is used to introduce a sinusoidal phase shift between the object and reference wave. The resulting temporally modulated holographic interference pattern is scanned by a commercial image dissector camera and rejection of the self-interference terms is accomplished by heterodyne detection at the camera output. The electrical signal representing this processed hologram can then be used to modify the properties of a liquid-crystal light valve or similar device. Such display devices, when illuminated by coherent light, transform the displayed interference pattern into a phase modulated wave front rendering a three-dimensional image. System requirements of holographic display systems will be considered as well as specific requirements for television rate and format systems.
IEEE International Conference on Systems Engineering
A method called vision-taction exploration (VTE) for generating surface descriptions from range v... more A method called vision-taction exploration (VTE) for generating surface descriptions from range vision and tactile sensor data is described. The range vision systems available provide sparse 3D data about surfaces. These data are partially processed to provide primary surface features such as surface points and surface normals. With the use of tactile and force-torque sensors under position control, supplementary data
Micro-Optics/Micromechanics and Laser Scanning and Shaping, 1995
We are developing integrated micro-opto-mechanical systems (MOMS) based upon wafer integration of... more We are developing integrated micro-opto-mechanical systems (MOMS) based upon wafer integration of optical and micro-electromechanical components. In this paper, we describe our developments in micro-opto-mechanical systems in the area of microscanners and moveable optical elements. The microscanners are based upon the fabrication of micro-optical elements on the rotors of large diameter, i.e. 500 to 2,000 micrometers , polysilicon micromotors and have resulted in two approaches to scanning. In the first approach, nickel plating and high-aspect- ratio photolithography were used to produce 175 micrometers diameter, 20 micrometers tall nickel polygon reflectors on the rotors of polysilicon micromotors. These polygon microscanners are suitable for planar scanning as well and other planar applications such as optical fiber and waveguide switches. In a second approach, 2 - 4 micrometers spatial period diffraction gratings were fabricated on the solid rotors of polysilicon micromotors. Such devices are suitable for applications requiring out-of-plane scanning, e.g., bar code readers, and take advantage of planar processing. Chemical-mechanical polishing was used to reduce the polysilicon rotor's average surface roughness (Ra) from 420 angstrom to below 17 angstrom, improving the optical performance of the diffraction gratings. Diffraction grating microscanners using salient pole micromotors have been operated at voltages as low as 45 V, with maximum operational speeds of 1100 rpm. Although microscanners based upon rotating reflectors and diffraction gratings are significant, future MOMS also require linear motion of optical elements and optical waveguides to carry light between optical elements. To this end, we have produced optical reflectors on linear translational comb actuators.
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Papers by Frank Merat