Tilt Unit Research Articles

Methods and Practices for In Situ Measurements of RF EMF Exposure From 5G Millimeter Wave Base Stations

In this article, a methodology for in situ measurements of the radio frequency electromagnetic fields exposure from 5G base stations (BSs) operating at millimeter wave (mmW) frequencies is presented. Measurements were performed in proximity of two BSs operating around 28 and 39 GHz. The measured power density from the BSs when extrapolated for the maximum transmit power was below 30 mW/m <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> at a distance of about 10 m (i.e., below 1% of the ICNIRP limits). A systematic analysis of the challenges related to in situ measurements of 5G mmW exposure is conducted for the first time. It was found that exposure measurement procedures developed for frequencies below 6 GHz (such as those based on extrapolation of the synchronization signal block) are generally applicable also at mmW. When in line-of-sight, dual-polarized directional antennas can be used to accurately characterize the maximum exposure. The angular variation of the incident power density at the measurement location was studied by means of a motor-controlled panorama tilt unit. At the same time, a network counter was used to monitor the directional time-averaged power transmitted by the BS. The study is of importance to standardization committees addressing measurement techniques to assess exposure from mobile networks.

Результаты лабораторных испытаний подводной навигационной системы для аппаратов экологического контроля

An urgent task facing the developers of unmanned underwater vehicles (UUVs) (autonomous underwater vehicles, remotely operated underwater vehicles) is to improve the accuracy of determining the output navigation parameters: orientation angles, linear velocities and location coordinates. The systems for determining the course and attitude position (Attitude and Heading Reference Systems – AHRS) and spatial positioning systems, which are supposed to equip the UUV, should not be expensive, but technologically suitable for mass production with acceptable coordinate determination accuracy. At the first stage of the research, a prototype of the navigation platform with software for it was developed and manufactured, on which experimental data from the measuring channels were obtained in laboratory conditions, and then their preliminary processing was carried out. The analysis of existing methods for increasing the accuracy of determining the output navigation parameters of unmanned underwater vehicles showed that, despite their dynamic development and constant improvement, the error in calculating coordinates when using MEMS sensors remains high and unstable. The use of an additional hydrostatic tilt unit in the navigation platform will make it possible to compensate for the errors of MEMS sensors, which require constant correction during their stable operation, unfortunately, only for a short period of time. The analysis of typical errors of MEMS sensors is carried out. The deterministic part of the error of these sensors can be eliminated by calibration, and to estimate the stochastic errors, we used the Allan variation. The obtained error values will be used in the future to form the Kalman filter of the resulting system.

Autonomous Mapping of Underwater 3-D Structures: From View Planning To Execution

Three-dimensional mapping of submerged industrial facilities or underwater sites with complex geometries is still a challenge for nowadays autonomous underwater vehicles (AUVs), which are restricted to more simple survey missions. This letter presents a complete framework to plan and execute autonomous missions to map a region of interest, coping with the particularities of the underwater domain. The proposed solution consists of the following steps: First, if a previous model is not available, a preliminary bathymetry of the area to be covered is gathered and an octree representation is created. Next, using this a priori model, an offline view-planner computes a minimum set of sensor configurations to cover the volume of interest by taking into account the mapping sensor and the vehicle safety constraints. It also computes the free path to be followed by the AUV to traverse all these sensor configurations. Finally, the planned mission is executed while an online simultaneous localization and mapping algorithm prevents the AUV from drifting, ensuring that the planned path is correctly followed. Preliminary results regarding the view planner have been obtained in a shipwreck site with the Girona 500 AUV, while results involving the whole framework have been achieved using the Gazebo simulator and a realistic AUV model equipped with a multibeam sonar mounted on a pan & tilt unit.

Automatic Adjustable Spraying Device for Site-Specific Agricultural Application

This paper presents a device for accurate pesticide spraying capable of dealing with amorphous shapes and variable-sized targets. The device includes a single spray nozzle with an automatically adjustable spraying angle, color camera, and distance sensors, all mounted on a pan tilt unit. The site-specific spraying device aims to spray specific targets while reducing the use of pesticides. The spraying diameter is set as the minimum closing circle diameter according to the shape and size of the target. Two preliminary experiments were conducted in order to evaluate the spray nozzle flow rate in relation to the spray diameter and the spray diameter in relation to the nozzle’s angular position. A main outdoor experiment was conducted to evaluate the complete spraying device using artificial targets of varying sizes. The results indicated that the spraying device is capable of reducing the amount of pesticides applied. An economic analysis estimates that up to 45% of pesticide reduction is possible when using the suggested spraying method. Actual savings depend on the spraying durations, target size, and distribution. Note to Practitioners —This paper focuses on the development of a site-specific sprayer solution. The developed device aims to reduce pesticide application by spraying individual targets specifically by setting the diameter of the spraying according to the shape and size of the target. The core of the paper is a detailed description of a spraying device able to change its spraying diameter according to the detected target. A working procedure to calibrate and validate such a device is included. We believe that such a device can be used in modern agriculture and can be combined with a robotic sprayer navigating autonomously along crop fields. Such a device will contribute to reduced pesticide application.

Signal Averaging for Noise Reduction in Mobile Robot 3D Measurement System

Accurate information from sensors plays an important role in precision measurement. In such measurement small component of a noise can leads to a large variation in the output of the system. For the applications like multi-sensor data integration, sequences of observations from a number of different sensors are used to integrate into a single best estimate of the state of the environment. For integration of sensory information, sensor registration is considered as an important step. This research work is focused upon reduction of a noise from the repetitive motion of the pan tilt unit. The outcome of this paper is implemented on 3D feature extraction of the mobile robot’s environment using a laser range finder. In the proposed work averaging technique is implemented on the Pan Tilt Unit (PTU) of the system where laser range finder is fixed upon the PTU to extract the 3D feature of the target objects. Registration of the angular displacement of PTU and laser range finder is an essential element of the 3D feature extraction. An experimental result of sensor registration shows a substantial improvement in signal to noise (S/N) ratio and quality of 3D feature extraction is also found improved.

Intelligent Control for Visual Servoing System

&lt;p&gt;This paper presents intelligent control for visual servoing system. The proposed system consists of a camera placed on a Pan Tilt Unit (PTU) which consists of two different servo motors. Camera and PTU are connected to a personal computer for the image processing and controlling purpose. Color threshold method is used for object tracking and recognition. Two different control methods, PID and Fuzzy Logic Control (FLC) are designed and the performances are compared through simulation. From the simulation result, the settling time of PID controller is 40 times faster than FLC. Additionally, the rise time of PID is about 20 times faster than FLC. However, the overshoot percentage of PID controller is 4 times higher than FLC. High overshoot value is not preferable in a control system, since it will cause the damage to the system. Real implementation of FLC on a home-built visual servoing system is conducted. Two different types of FLC, 9 and 11 rules of FLC are designed and implemented on the system. The experimental result shows that FLC with different total number of rules give different system performance. The settling time of FLC with 11 rules is 2 times faster than FLC with 9 rules. Additionally, the overshoot percentage of FLC with 11 rules is 2 times lower than FLC with 9 rules.&lt;/p&gt;

Contact-Free Respiration Rate Monitoring Using a Pan–Tilt Thermal Camera for Stationary Bike Telerehabilitation Sessions

One typical remote consultation envisioned for in-home telerehabilitation involves having the patient exercise on a stationary bike. Making sure that the patient is breathing well while pedaling is of primary concern for the remote clinician. One key requirement for in-home telerehabilitation is to make the system as simple as possible for the patients, avoiding, for instance, to have them wear sensors and devices. This paper presents a contact-free respiration rate monitoring system measuring temperature variations between inspired and expired air in the mouth–nose region using thermal imaging. The thermal camera is installed on a pan–tilt unit and coupled to a tracking algorithm, allowing the system to keep track of the mouth–nose region as the patient exercises. Results demonstrate that the system works in real time even when the patient moves or rotates its head while exercising. Recommendations are also made to minimize limitations of the system, such as the presence of people in the background or when the patient is talking, for its eventual use in in-home telerehabilitation sessions.

Multibeam 3D Underwater SLAM with Probabilistic Registration.

This paper describes a pose-based underwater 3D Simultaneous Localization and Mapping (SLAM) using a multibeam echosounder to produce high consistency underwater maps. The proposed algorithm compounds swath profiles of the seafloor with dead reckoning localization to build surface patches (i.e., point clouds). An Iterative Closest Point (ICP) with a probabilistic implementation is then used to register the point clouds, taking into account their uncertainties. The registration process is divided in two steps: (1) point-to-point association for coarse registration and (2) point-to-plane association for fine registration. The point clouds of the surfaces to be registered are sub-sampled in order to decrease both the computation time and also the potential of falling into local minima during the registration. In addition, a heuristic is used to decrease the complexity of the association step of the ICP from to . The performance of the SLAM framework is tested using two real world datasets: First, a 2.5D bathymetric dataset obtained with the usual down-looking multibeam sonar configuration, and second, a full 3D underwater dataset acquired with a multibeam sonar mounted on a pan and tilt unit.

Active camera stabilization to enhance the vision of agile legged robots

SUMMARYLegged robots have the potential to navigate in more challenging terrains than wheeled robots. Unfortunately, their control is more demanding, because they have to deal with the common tasks of mapping and path planning as well as more specific issues of legged locomotion, like balancing and foothold planning. In this paper, we present the integration and the development of a stabilized vision system on the fully torque-controlled hydraulically actuated quadruped robot (HyQ). The active head added onto the robot is composed of a fast pan and tilt unit (PTU) and a high-resolution wide angle stereo camera. The PTU enables camera gaze shifting to a specific area in the environment (both to extend and refine the map) or to track an object while navigating. Moreover, as the quadruped locomotion induces strong regular vibrations, impacts or slippages on rough terrain, we took advantage of the PTU to mechanically compensate for the robot's motions. In this paper, we demonstrate the influence of legged locomotion on the quality of the visual data stream by providing a detailed study of HyQ's motions, which are compared against a rough terrain wheeled robot of the same size. Our proposed Inertial Measurement Unit (IMU)-based controller allows us to decouple the camera from the robot motions. We show through experiments that, by stabilizing the image feedback, we can improve the onboard vision-based processes of tracking and mapping. In particular, during the outdoor tests on the quadruped robot, the use of our camera stabilization system improved the accuracy on the 3D maps by 25%, with a decrease of 50% of mapping failures.

1A1-G09 人との協調による自動駐車システムに関する研究 : 指示デバイスと雲台付車載カメラとの連携

In this paper, we propose the automatic parking system using human cooperation. Also, we describe cooperation with parking position indicating device and the in-vehicle camera with pan tilt unit. The in-vehicle camera with pan tilt unit tracks the device and measure that position. Realization of advanced automatic parking system in recent years has a problem to be dependent on the infrastructure of the parking lot. So, not dependent on infrastructure of the parking lot system is required. Than the results of the present experiment, parking position indicating devices and stereo camera of cooperation, has been shown to be effective in the proposed system.

ExoMars Rover PanCam: Autonomous &amp; Computational Intelligence [Application Notes

As a part of the Aurora programme for Mars exploration, funded by the United Kingdom Space Agency (UKSA) and European Space Agency (ESA), the UK contributes to the Exobiology on Mars (ExoMars) rover science and engineering programme, with a scheduled launch in 2018; Hence, our Panoramic Camera (PanCam) [9][15] research and development (R&D) is timely. PanCam consists of two stereo Wide Angle Cameras (WAC) and one High Resolution Camera (HRC). While the development is still ongoing, we used funding awarded by the University College London (UCL) Graduate School to conduct investigations in the Himalayas and at Mount Everest Base Camp (EBC), according to the ExoMars rover Reference Surface Mission (RSM). The investigations included capturing stereo and high resolution images using stereo WAC emulators and HRC emulator at altitudes 3490 m, 5150 m and above. Images from different WAC filters, and color images from HRC were acquired at various Pan and Tilt Unit (PTU) mast positions. Our investigation results show significant reduction in data volume with minimum loss in image quality. Furthermore, we introduce a novel autonomous and computational intelligent system called Mission-Specific Data Processor (MSDP) for the rover. It includes Pan-Cam, Visual Data Fusion (VDF), Learning-enabled Object Detection (LOD), Self-Learning Agent (SLA) [22], and Environment Model Library (EML) as part of the rover's computational intelligence [7].

Development of a Laser Scanner-based Navigation System for a Combine Harvester

The objective of this study was to develop an autonomous navigation system for a combine harvester using a laser scanner. The laser scanner was attached to the top of the harvester cabin through a pan tilt unit that tilted the laser scanner in the vertical plane to obtain 3D information on the field. A field profile was modeled by investigating the spatial distribution of range data measured by the laser scanner in a soybean field. A crop row localization method used a cross correlation algorithm to calculate the relative position and direction between the vehicle and crop rows. Field experiments were conducted in a row-planted soybean field during harvesting season. Results showed that the combine harvester had RMS errors of 0.02 m and 0.8 degrees in terms of lateral offset and heading deflection, respectively, in detecting the soybean row localized between cut and uncut areas under static conditions. The corresponding RMS errors were 0.07 m and 3 degrees when the combine harvester was autonomously guided to perform soybean harvesting along crop rows at a speed of 0.97 m/s in the field.

Solving the correspondence problem in stereo vision by internal simulation

We present a computational model for object matching in a pair of stereo images based on internal sensorimotor simulation. In our study, we use pairs of retinal images, i.e. the resolution is higher towards the image center and low in the periphery, which stem from two cameras, each one mounted on a pan–tilt unit (PTU). The internal simulation is driven by two internal models: a saccade controller (SC) which generates a fixation movement to a certain point in either image, and a visual forward model (VFM) that models the effect on camera movements (by the PTU) onto the image. The SC takes as sensory input the current position of a salient point (in image coordinates) and generates a motor command that would lead to the fixation of that point. The VFM takes as sensory input a current camera image and a motor command, i.e. a saccade, and generates an image that appears as if the saccade was executed. By using the internal models, the salient objects are virtually fixated in both images. These fixated views are matched against each other using a simple difference-based matching approach. The performance of the model is evaluated through a large number of experiments on an image database and compared to a widely used approach from computer vision. In addition, a comparison on a commonplace scene is presented.

Long-Range Gaze Tracking System for Large Movements

In the vision-based remote gaze tracking systems, the most challenging topics are to allow natural movement of a user and to increase the working volume and distance of the system. Several eye gaze estimation methods considering the natural movement of a user have been proposed. However, their working volume and distance are narrow and close. In this paper, we propose a novel 2-D mapping-based gaze estimation method that allows large-movement of user. Conventional 2-D mapping-based methods utilize mapping function between calibration points on the screen and pupil center corneal reflection (PCCR) vectors obtained in user calibration step. However, PCCR vectors and their associated mapping function are only valid at or near to the position where the user calibration is performed. The proposed movement mapping function, complementing the user's movement, estimates scale factors between two PCCR vector sets: one obtained at the user calibration position and another obtained at the new user position. The proposed system targets a longer range gaze tracking which operates from 1.4 to 3 m. A narrow-view camera mounted on a pan and tilt unit is used by the proposed system to capture high-resolution eye image, providing a wide and long working volume of about 100 cm × 40 cm × 100 cm. The experimental results show that the proposed method successfully compensated the poor performance due to user's large movement. Average angular error was 0.8° and only 0.07° of angular error was increased while the user moved around 81 cm.

The Application for Underwater Special Monitoring Equipment Based on the PELCO-D Protocol

Aiming at integrating Tritech Company’s Typhoon color zoom camera and Kongsberg Company’s underwater pan and tilt unit OE10-102 to build the underwater monitoring system, this paper designs a method, which uses STM32F103C8 as the core chip to design a protocol converter. The protocol converter could receives and analyses the PELCO-D data frames from RS-485 bus, and then produces corresponding commands to control the cameras and rotator units. Besides, this paper provides a new online program update method based on RS-485 channel, which could make full use of the existing 485 channel to complete user application program updating for the protocol converter without disassembling the deceives. Practice has proved that the methods mentioned are practical and stable.

DISCRETE INTEGRAL SLIDING MODE CONTROL IN VISUAL OBJECT TRACKING

Object tracking is an important process for many applications in computer vision. This process must be implemented in a discrete manner because the images are available only at certain periods. A discrete integral sliding mode algorithm is proposed to control a stereo vision system and perform the aforementioned second task. The kinematic model of the structure is obtained using geometric algebra. The performance of the controller is compared with proportional-integral-derivative control via simulation. The implementation for a pan tilt unit is presented in real time. The algorithm presents a good and robust performance.

Differential and inverse kinematics of robot devices using conformal geometric algebra

In this paper, the authors use the conformal geometric algebra in robotics. This paper computes the inverse kinematics of a robot arm and the differential kinematics of a pan–tilt unit using a language of spheres showing how we can simplify the complexity of the computations.This work introduces a new geometric Jacobian in terms of bivectors, which is by far more effective in its representation as the standard Jacobian because its derivation is done in terms of the projections of the involved points onto the line axes. Furthermore, unlike the standard formulation, our Jacobian can be used for any kind of robot joints.In this framework, we deal with various tasks of three-dimensional (3D) object manipulation, which is assisted by stereo-vision. All these computations are carried out using real images captured by a robot binocular head, and the manipulation is done by a five degree of freedom (DOF) robot arm mounted on a mobile robot. In addition to this, we show a very interesting application of the geometric Jacobian for differential control of the binocular head. We strongly believe that the framework of conformal geometric algebra can generally be of great advantage for visually guided robotics.

Baywatch practical automatic detection of intrusion over water

This paper describes one solution to the problem of providing Perimeter Intruder Detection, (PIDS), for sites whose boundary includes direct access from uncontrolled water. Two surveillance heads were proposed, each consisting of a TI camera and a Colour CCTV camera mounted on a pan and tilt unit.