A new optical arrangement is introduced for such applications of machine vision that need to discriminate structured laser lighting from stray ambient lighting. Instead of using transmissive filters that usually have high attenuation, a double reflective filter arrangement is presented. A combination of dielectric and metallic mirrors achieves steep stopband attenuation especially in the near infrared region where Si detectors are sensitive and common blackbody-like radiators have high spectral density. An additional advantage follows from the compact size of such a Maksutov-type mirror telescope. Compared to a corresponding refractive design, the length is reduced to less than half.
This paper describes a practical approach for environment perception using fusion of active ranging with a low-power laser and passive, stereo based ranging. A low-cost, coarse pitch linear detector is used, but still sufficient distance accuracy for mobile robotics is achieved by using a new method of sub-pixel calibration. The device is intended for mobile robot or vehicle perception duties in obstacle detection and target position measurement.
We describe an integrated system developed for use onboard a moving work machine. The machine is targeted to such applications as e.g. automatic container handling at loading terminals. The main emphasis is on the various environment perception duties required by autonomous or semi-autonomous operation. These include obstacle detection, container position determination, localization needed for efficient navigation and measurement of docking and grasping locations of containers. Practical experience is reported on the use of several different types of technologies for the tasks. For close distance measurement, such as container row following, ultrasonic measurement was used, with associated control software. For obstacle and docking position detection, 3D active vision techniques were developed with structured lighting, utilizing also motion estimation techniques. Depth from defocus-based methods were developed for passive 3D vision. For localization, fusion of data from several sources was carried out. These included dead-reckoning data from odometry, an inertial unit, and several alternative external localization devices, i.e. real-time kinematic GPS, inductive and optical transponders. The system was integrated to run on a real-time operating system platform, using a high-level software specification tool that created the hierarchical control structure of the software.
Robust range estimation is one of the most important tasks in mobile robotics. This paper presents a new optical arrangement for utilizing the previously known 'depth from defocus' principle. The arrangement makes it possible to apply standard video lenses and camera modules for making a compact range camera system. Real-time processing is made possible with a single-board DSP card.
This paper describes the characteristics of flat panel displays that use the waveguide principle with liquid crystal (LC) switching. The requirements and previous achievements with respect to the various components of the display are reviewed. Such components include light sensors, modulation methods, planar waveguides, and LC switching methods. The waveguide display approach seems to offer advantages over matrix addressed LC displays, especially for large display area applications. Two novel LC switching methods for efficient deflection of light from the waveguides are described. The other method is based on long-range surface plasmon excitation, and the other on shear addressing.