Positioning device for outdoor mobile robots using optical sensors and lasers

We propose a novel method for positioning a mobile robot in an outdoor environment using lasers and optical sensors. Position estimation via a noncontact optical method is useful because the information from the wheel odometer and the global positioning system in a mobile robot is unreliable in some situations. Contact optical sensors such as computer mouse are designed to be in contact with a surface and do not function well in strong ambient light conditions. To mitigate the challenges of an outdoor environment, we developed an optical device with a bandpass filter and a pipe to restrict solar light and to detect translation. The use of two devices enables sensing of the mobile robot’s position, including posture. Furthermore, employing a collimated laser beam allows measurements against a surface to be invariable with the distance to the surface. In this paper, we describe motion estimation, device configurations, and several tests for performance evaluation. We also present the experimental positioning results from a vehicle equipped with our optical device on an outdoor path. Finally, we discuss an improvement in postural accuracy by combining an optical device with precise gyroscopes

Comprehensive Development And Control Of A Path-Trackable Mecanum-Wheeled Robot

This paper presents an intuitively straightforward yet comprehensive approach in developing and controlling a Mecanum-wheeled robot (MWR), with decent path tracking performance by using a simple controller as an end objective. The development starts by implementing two computer ball mice as sensors to realize a simple localization that is immune toward wheel slippage. Then, a linearization method by using open-loop step responses is carried out to linearize the actuations of the robot. Open-loop step response is handy, as it directly portrays the non-linearity of the system, thus achieving effective counteraction. Then, instead of creating a lookup table, polynomial regression is used to generate an equation in which the equation later represents an element of the linearizer. Next, a linear angle-to-gain (LA-G) method is introduced for path tracking control. The method is as easy as just linearly maps the summation of two angles-the angle between immediate and desired positions and the MWR's heading angle, into gains to control the wheels. Unlike the conventional control method which involves inverse kinematics, the LA-G method is directly a displacement-controlled approach and does not require the knowledge of parametric values, such as the robot's dimensions and wheel radius. Finally, all the methods are implemented, and the MWR experimentally demonstrates successfully tracking various paths, by merely using proportional controllers

Optical Flow-Based Odometry for Underground Tunnel Exploration

As military operations in degraded or GPS-denied environments continue to increase in frequency and importance, there is an increased necessity to be able to determine precision location within these environments. Furthermore, authorities are finding a record number of tunnels along the U.S.-Mexico border; therefore, underground tunnel characterization is becoming a high priority for U.S. Homeland Security as well. This thesis investigates the performance of a new image registration technique based on a two camera optical- flow configuration using phase correlation techniques. These techniques differ from other image based navigation methods but present a viable alternative increasing autonomy and answering the tunnel based navigation problem. This research presents an optical flow based image registration technique and validates its use with experimental results on a mobile vehicle. Results reveal that further extension to pose estimation yields accuracy within 1.3 cm

Software for Embedded Module for Image Processing

katedra kybernetik

A role for sensory areas in coordinating active sensing motions

Active sensing, which incorporates closed-loop behavioral selection of information during sensory acquisition, is an important feature of many sensory modalities. We used the rodent whisker tactile system as a platform for studying the role cortical sensory areas play in coordinating active sensing motions. We examined head and whisker motions of freely moving mice performing a tactile search for a randomly located reward, and found that mice select from a diverse range of available active sensing strategies. In particular, mice selectively employed a strategy we term contact maintenance, where whisking is modulated to counteract head motion and sustain repeated contacts, but only when doing so is likely to be useful for obtaining reward. The context dependent selection of sensing strategies, along with the observation of whisker repositioning prior to head motion, suggests the possibility of higher level control, beyond simple reflexive mechanisms. In order to further investigate a possible role for primary somatosensory cortex (SI) in coordinating whisk-by-whisk motion, we delivered closed-loop optogenetic feedback to SI, time locked to whisker motions estimated through facial electromyography. We found that stimulation regularized whisking (increasing overall periodicity), and shifted whisking frequency, changes that emulate behaviors of rodents actively contacting objects. Importantly, we observed changes to whisk timing only for stimulation locked to whisker protractions, possibly encoding that natural contacts are more likely during forward motion of the whiskers. Simultaneous neural recordings from SI show cyclic changes in excitability, specifically that responses to excitatory stimulation locked to whisker retractions appeared suppressed in contrast to stimulation during protractions that resulted in changes to whisk timing. Both effects are evident within single whisks. These findings support a role for sensory cortex in guiding whisk-by-whisk motor outputs, but suggest a coupling that depends on behavioral context, occurring on multiple timescales. Elucidating a role for sensory cortex in motor outputs is important to understanding active sensing, and may further provide novel insights to guide the design of sensory neuroprostheses that exploit active sensing context

광 변위센서를 사용한 선체 청소로봇의 위치추정 시스템 개발

An industrial robot has been applied on the hull cleaning method to enhance an operational efficiency of entire cleaning process. Especially, autonomous robotic system is necessary for more efficient cleaning hull cleaning and the position estimation system is indispensible part in this system. Position estimation system of the hull cleaning robot, therefore, was studied for the autonomous hull cleaning process in this paper. Conventional position estimation method with rotary encoders is unsuitable for the hull cleaning robot on account of slippage between the robot wheel and the hull surface. Thus, a novel position estimation system using optical displacement sensors was suggested to solve this problem. Operation environments and drive characteristics of the hull cleaning robot were analyzed to design the position estimation system effectively. Reflecting the results of the analysis, a position estimation algorithm which based on the dead reckoning and instantaneous center of rotation theory was developed. Performance test of the optical displacement sensor that measures the relative displacement with a contact-free optical sensor was implemented to find out the output characteristics according to the operating conditions including direction, speed, acceleration, height and surface type. In the position estimation system, two optical displacement sensors were used to reduce the measurement error and also data selection algorithm which choose more sensitive one in the two measured data was added to error reduction method. Furthermore, the monitoring PC operates the graphical based position estimation program that contains the position estimation algorithm. Consequently, the results of the position estimation are able to be displayed on the user interface screen in real-time and save on the database simultaneously. The developed position estimation system was mounted on the scale model mobile robot which has an identical drive method with hull cleaning robot for experiments because the large scale support units, operation cost, high electric power, wide test area are required to operate the real hull cleaning robot. Experimental results demonstrate that the proposed position estimation system with the optical displacement sensors is more accurate compared to conventional system using rotary encoders.목 차 List of Tables iii List of Figures iv Nomenclatures vi Abstract viii 제 1 장 서 론 1 1.1 연구배경 1 1.2 연구동향 5 1.3 연구내용 및 구성 6 제 2 장 선체 청소로봇 시스템 7 2.1 선체 청소로봇 운용환경 7 2.2 선체 청소로봇 시스템 구성 8 2.2.1 선체 청소로봇 구조 8 2.2.2 청소로봇 지원 장치 9 2.3 선체 청소로봇의 주행특성 11 제 3 장 위치추정 알고리즘 13 3.1 위치추정 개요 13 3.2 평면상에서의 위치추정 알고리즘 14 제 4 장 위치추정 시스템 설계 20 4.1 광 변위센서 20 4.1.1 광 변위센서 개요 20 4.1.2 광 변위센서의 동작 특성 24 4.1.3 광 변위센서 교정 30 4.2 위치추정 시스템 구성 33 제 5 장 실험 및 분석 39 5.1 위치추정 실험 39 5.2 위치추정 실험 결과 42 제 6 장 결 론 50 참고문헌 52 감사의 글 5