Pub Date : 2008-05-05DOI: 10.1109/PLANS.2008.4570052
M. Angermann, M. Khider, P. Robertson
Rescue workers, such as fire fighters often face conditions that impose a combination of threats on them: severe physical and mental stress, limited or no visibility, unknown layout of buildings may induce disorientation. Systems capable of continuously locating all members of a rescue team could help to maintain orientation, and in cases of accident, help other team members or team leaders to localize colleagues in danger. The paper points out the discrepancy between state of the art in research projects, primarily in the fields of wearable computing and indoor navigation, and the lack of operational systems that have been fielded or have undergone sustained usage. The paper shows, that a successful operational system for continuous navigation of rescue teams requires a combination of several sensors, motion models, computing, communication means, and human machine interfaces. Based on an analysis of rescue operations and interviews with rescue workers, relevant issues and requirements are derived. A reference architecture for an operational system for continuous navigation of rescue teams is outlined. Its implementation and feasibility aspects are discussed. We discuss in how far the required technological components are available and affordable and where shortcomings have to be resolved by future research and development.
{"title":"Towards operational systems for continuous navigation of rescue teams","authors":"M. Angermann, M. Khider, P. Robertson","doi":"10.1109/PLANS.2008.4570052","DOIUrl":"https://doi.org/10.1109/PLANS.2008.4570052","url":null,"abstract":"Rescue workers, such as fire fighters often face conditions that impose a combination of threats on them: severe physical and mental stress, limited or no visibility, unknown layout of buildings may induce disorientation. Systems capable of continuously locating all members of a rescue team could help to maintain orientation, and in cases of accident, help other team members or team leaders to localize colleagues in danger. The paper points out the discrepancy between state of the art in research projects, primarily in the fields of wearable computing and indoor navigation, and the lack of operational systems that have been fielded or have undergone sustained usage. The paper shows, that a successful operational system for continuous navigation of rescue teams requires a combination of several sensors, motion models, computing, communication means, and human machine interfaces. Based on an analysis of rescue operations and interviews with rescue workers, relevant issues and requirements are derived. A reference architecture for an operational system for continuous navigation of rescue teams is outlined. Its implementation and feasibility aspects are discussed. We discuss in how far the required technological components are available and affordable and where shortcomings have to be resolved by future research and development.","PeriodicalId":446381,"journal":{"name":"2008 IEEE/ION Position, Location and Navigation Symposium","volume":"58 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2008-05-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"128273248","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2008-05-05DOI: 10.1109/PLANS.2008.4570034
I. Nygren
For terrain navigation to be a serious navigation tool in underwater navigation it must be robust and work well in flat bottomed areas. Furthermore it should be easy to incorporate with the vehicle's inertial navigation system (INS) so a bound can be placed on the system's position error. This paper describes the terrain navigation system developed for the Swedish Defence Materiel Administration's autonomous vehicles AUV62F and Sapphires. Both vehicles are battery powered and torpedo shaped with a diameter of 21". From the outset, the terrain navigation system was designed to work in flat bottomed areas; it uses many simultaneous sonar beams (400+) to measure the bottom topography, producing a unique underwater map position for the vehicle. When terrain navigating in flat bottomed areas, bottom topography measurement often gives many possible vehicle positions, i.e., the probability density function of the vehicle position is multimodal, so efficient and robust nonlinear Kalman filtering must be used. The terrain navigation module uses an optimal nonlinear Kalman filter called the FD filter. The FD filter numerically solves the stochastic differential equation that guides the vehicle positioning. The measurement updating is Bayesian. The filtering procedure is characterized by robustness, simplicity, and accuracy. It is also simple to incorporate independent measurements other than the terrain topography into the filter.
{"title":"Robust and efficient terrain navigation of underwater vehicles","authors":"I. Nygren","doi":"10.1109/PLANS.2008.4570034","DOIUrl":"https://doi.org/10.1109/PLANS.2008.4570034","url":null,"abstract":"For terrain navigation to be a serious navigation tool in underwater navigation it must be robust and work well in flat bottomed areas. Furthermore it should be easy to incorporate with the vehicle's inertial navigation system (INS) so a bound can be placed on the system's position error. This paper describes the terrain navigation system developed for the Swedish Defence Materiel Administration's autonomous vehicles AUV62F and Sapphires. Both vehicles are battery powered and torpedo shaped with a diameter of 21\". From the outset, the terrain navigation system was designed to work in flat bottomed areas; it uses many simultaneous sonar beams (400+) to measure the bottom topography, producing a unique underwater map position for the vehicle. When terrain navigating in flat bottomed areas, bottom topography measurement often gives many possible vehicle positions, i.e., the probability density function of the vehicle position is multimodal, so efficient and robust nonlinear Kalman filtering must be used. The terrain navigation module uses an optimal nonlinear Kalman filter called the FD filter. The FD filter numerically solves the stochastic differential equation that guides the vehicle positioning. The measurement updating is Bayesian. The filtering procedure is characterized by robustness, simplicity, and accuracy. It is also simple to incorporate independent measurements other than the terrain topography into the filter.","PeriodicalId":446381,"journal":{"name":"2008 IEEE/ION Position, Location and Navigation Symposium","volume":"41 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2008-05-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"128522063","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2008-05-05DOI: 10.1109/PLANS.2008.4570057
Sunmi Kim, Heedong Choi, Ju-hyun Park, Yongwan Park
This paper discusses an improved method for location in CDMA based cellular communication system. An effective technique is proposed for locating a mobile stationpsilas position based on Time Difference of Arrival (TDOA) technique. This technique is based on estimating the difference in the arrival time of the signal from the source at multiple receivers. The major error sources in the CDMA network location system are nonline-of-sight (NLOS) propagation error and hardware system such as repeater. Proposed algorithm based on probability of mobile station (MS) location in serving cell radius. We adopt an enhanced TDOA (E-TDOA) technique for suppress those timing errors. The performance of proposed algorithm is evaluated for CDMA based location system. Simulation also demonstrates in field environments.
{"title":"Timing error suppression scheme for CDMA network based positioning system","authors":"Sunmi Kim, Heedong Choi, Ju-hyun Park, Yongwan Park","doi":"10.1109/PLANS.2008.4570057","DOIUrl":"https://doi.org/10.1109/PLANS.2008.4570057","url":null,"abstract":"This paper discusses an improved method for location in CDMA based cellular communication system. An effective technique is proposed for locating a mobile stationpsilas position based on Time Difference of Arrival (TDOA) technique. This technique is based on estimating the difference in the arrival time of the signal from the source at multiple receivers. The major error sources in the CDMA network location system are nonline-of-sight (NLOS) propagation error and hardware system such as repeater. Proposed algorithm based on probability of mobile station (MS) location in serving cell radius. We adopt an enhanced TDOA (E-TDOA) technique for suppress those timing errors. The performance of proposed algorithm is evaluated for CDMA based location system. Simulation also demonstrates in field environments.","PeriodicalId":446381,"journal":{"name":"2008 IEEE/ION Position, Location and Navigation Symposium","volume":"55 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2008-05-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"114705484","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2008-05-05DOI: 10.1109/PLANS.2008.4570049
S. Moafipoor, D. Grejner-Brzezinska, C. Toth
The prototype of a personal navigator, which integrates Global Positioning System (GPS), tactical grade inertial measurement unit (IMU), digital barometer, magnetometer, and human pedometry to support navigation and tracking of military and rescue ground personnel has been developed at The Ohio State University Satellite Positioning and Inertial Navigation (SPIN) Laboratory. This paper discusses the design, implementation and performance assessment of the prototype, with a special emphasis on dead-reckoning (DR) navigation supported by a human locomotion model. The primary components of the human locomotion model are step frequency (SF), extracted from GPS-timed impact micro-switches placed on the shoe soles of the operator, step length (SL), and step direction (SD), both determined by predictive models derived by the adaptive knowledge based system (KBS). SL KBS is based on Artificial Neural Networks (ANN) and Fuzzy Logic (FL), and is trained a priori using sensory data collected by various operators in various environments during GPS signal reception. An additional KBS module, in the form of a Kalman Filter (KF), is used to improve the heading information (SD) available from the magnetometer and gyroscope under GPS-denied conditions, as well as to integrate the DR parameters to reconstruct the trajectory based on SL and SD. The current target accuracy of the system is 3-5 m CEP (circular error probable, 50%). This paper provides a performance analysis in the indoor and outdoor environments for two different operators. The systempsilas navigation limitation in DR mode is tested in terms of time and trajectory length to determine the upper limit of indoor operation before the need for re-calibration.
俄亥俄州立大学卫星定位和惯性导航(SPIN)实验室开发了一种个人导航仪的原型，它集成了全球定位系统(GPS)、战术级惯性测量单元(IMU)、数字气压计、磁力计和人体计步器，以支持军事和救援地面人员的导航和跟踪。本文讨论了原型机的设计、实现和性能评估，重点讨论了基于人体运动模型的航位推算导航。人体运动模型的主要组成部分是步频(SF)，从放置在操作员鞋底的gps定时冲击微开关中提取，步长(SL)和步方向(SD)，两者都由自适应知识系统(KBS)导出的预测模型确定。SL KBS基于人工神经网络(ANN)和模糊逻辑(FL)，在GPS信号接收过程中，使用不同操作员在不同环境中收集的感官数据进行先验训练。另外一个KBS模块，以卡尔曼滤波器(KF)的形式，用于改进在gps拒绝条件下从磁力计和陀螺仪获得的航向信息(SD)，并整合DR参数以基于SL和SD重建轨迹。目前系统的目标精度为3-5 m CEP(圆周误差可能为50%)。本文对两种不同运营商在室内和室外环境下的性能进行了分析。在需要重新校准之前，从时间和轨迹长度方面测试了DR模式下系统的导航限制，以确定室内操作的上限。
{"title":"Multi-sensor personal navigator supported by adaptive knowledge based system: Performance assessment","authors":"S. Moafipoor, D. Grejner-Brzezinska, C. Toth","doi":"10.1109/PLANS.2008.4570049","DOIUrl":"https://doi.org/10.1109/PLANS.2008.4570049","url":null,"abstract":"The prototype of a personal navigator, which integrates Global Positioning System (GPS), tactical grade inertial measurement unit (IMU), digital barometer, magnetometer, and human pedometry to support navigation and tracking of military and rescue ground personnel has been developed at The Ohio State University Satellite Positioning and Inertial Navigation (SPIN) Laboratory. This paper discusses the design, implementation and performance assessment of the prototype, with a special emphasis on dead-reckoning (DR) navigation supported by a human locomotion model. The primary components of the human locomotion model are step frequency (SF), extracted from GPS-timed impact micro-switches placed on the shoe soles of the operator, step length (SL), and step direction (SD), both determined by predictive models derived by the adaptive knowledge based system (KBS). SL KBS is based on Artificial Neural Networks (ANN) and Fuzzy Logic (FL), and is trained a priori using sensory data collected by various operators in various environments during GPS signal reception. An additional KBS module, in the form of a Kalman Filter (KF), is used to improve the heading information (SD) available from the magnetometer and gyroscope under GPS-denied conditions, as well as to integrate the DR parameters to reconstruct the trajectory based on SL and SD. The current target accuracy of the system is 3-5 m CEP (circular error probable, 50%). This paper provides a performance analysis in the indoor and outdoor environments for two different operators. The systempsilas navigation limitation in DR mode is tested in terms of time and trajectory length to determine the upper limit of indoor operation before the need for re-calibration.","PeriodicalId":446381,"journal":{"name":"2008 IEEE/ION Position, Location and Navigation Symposium","volume":"3 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2008-05-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"126303145","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2008-05-05DOI: 10.1109/PLANS.2008.4570111
R. Rowe, P. Duffett-Smith, M. Jarvis, N. Graube
GNSS receivers have been developed over 40 years with increasing levels of integration and performance, and are now able to operate in much more severe signal-degraded environments than before. Despite this, the goal of ubiquitous positioning with GNSS-only receivers is still far away, and GNSS receivers generally need support by combining, loosely or tightly, with other positioning systems. This paper describes the enhanced GPS system (EGPS), a system that tightly couples timing measurements and timing-based positioning made using cellular network signals, with GNSS receivers in cellular telephones. The system is able to achieve a near ubiquitous positioning capability, along with improvements in time to fix.
{"title":"Enhanced GPS: The tight integration of received cellular timing signals and GNSS receivers for ubiquitous positioning","authors":"R. Rowe, P. Duffett-Smith, M. Jarvis, N. Graube","doi":"10.1109/PLANS.2008.4570111","DOIUrl":"https://doi.org/10.1109/PLANS.2008.4570111","url":null,"abstract":"GNSS receivers have been developed over 40 years with increasing levels of integration and performance, and are now able to operate in much more severe signal-degraded environments than before. Despite this, the goal of ubiquitous positioning with GNSS-only receivers is still far away, and GNSS receivers generally need support by combining, loosely or tightly, with other positioning systems. This paper describes the enhanced GPS system (EGPS), a system that tightly couples timing measurements and timing-based positioning made using cellular network signals, with GNSS receivers in cellular telephones. The system is able to achieve a near ubiquitous positioning capability, along with improvements in time to fix.","PeriodicalId":446381,"journal":{"name":"2008 IEEE/ION Position, Location and Navigation Symposium","volume":"64 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2008-05-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"126446371","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2008-05-05DOI: 10.1109/PLANS.2008.4569970
S. Ali-Loytty
This paper presents a new way to apply Gaussian mixture filter (GMF) to hybrid positioning. The idea of this new GMF (efficient Gaussian mixture filter, EGMF) is to split the state space into pieces using parallel planes and approximate posterior in every piece as Gaussian. EGMF outperforms the traditional single-component positioning filters, for example the extended Kalman filter and the unscented Kalman filter, in nonlinear hybrid positioning. Furthermore, EGMF has some advantages with respect to other GMF variants, for example EGMF gives the same or better performance than the sigma point Gaussian mixture (SPGM) [1] with a smaller number of mixture components, i.e. smaller computational and memory requirements. If we consider only one time step, EGMF gives optimal results in the linear case, in the sense of mean and covariance, whereas other GMFs gives suboptimal results.
{"title":"Efficient Gaussian mixture filter for hybrid positioning","authors":"S. Ali-Loytty","doi":"10.1109/PLANS.2008.4569970","DOIUrl":"https://doi.org/10.1109/PLANS.2008.4569970","url":null,"abstract":"This paper presents a new way to apply Gaussian mixture filter (GMF) to hybrid positioning. The idea of this new GMF (efficient Gaussian mixture filter, EGMF) is to split the state space into pieces using parallel planes and approximate posterior in every piece as Gaussian. EGMF outperforms the traditional single-component positioning filters, for example the extended Kalman filter and the unscented Kalman filter, in nonlinear hybrid positioning. Furthermore, EGMF has some advantages with respect to other GMF variants, for example EGMF gives the same or better performance than the sigma point Gaussian mixture (SPGM) [1] with a smaller number of mixture components, i.e. smaller computational and memory requirements. If we consider only one time step, EGMF gives optimal results in the linear case, in the sense of mean and covariance, whereas other GMFs gives suboptimal results.","PeriodicalId":446381,"journal":{"name":"2008 IEEE/ION Position, Location and Navigation Symposium","volume":"4 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2008-05-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"133386411","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2008-05-05DOI: 10.1109/PLANS.2008.4570014
K. Shallberg, Fang Sheng
Previous papers on the wide area augmentation system (WAAS) provided details on integrity design for such items as clock and ephemeris, signal quality, and ionospheric monitoring. This paper will provide details on GPS measurement processing performed in WAAS that supports these monitoring functions. Measurement processing conducted in the integrity (or safety) processor has evolved during the localizer performance with vertical guidance phase of the WAAS Program. Currently, this processing integrates measurements from all three independent receiving threads at a reference station and performs various cross thread checks to mitigate select multipath and cycle slip events. Underlying this cross thread processing is the assumption that common mode errors caused by environmental conditions are rare and random. The introduction of WAAS reference stations in extreme northern latitudes operating in significant phase scintillation environments, and the design decision to have the receiver operate in very low signal to noise conditions, exposed erroneous measurement conditions that challenged this rare and random assumption. This paper will address the WAAS measurement processing architecture and focus on such erroneous conditions along with the monitoring algorithms WAAS incorporated to mitigate them. The paper also examines potential improvements in WAAS measurement processing during communication outages. Communication outages between reference and master stations that occur primarily from remote reference stations have the potential of causing measurement processing algorithms to reinitialize thus impacting WAAS availability and continuity performance. This paper will investigate algorithms for improving operation through data outage periods without reducing measurement quality.
{"title":"WAAS measurement processing; current design and potential improvements","authors":"K. Shallberg, Fang Sheng","doi":"10.1109/PLANS.2008.4570014","DOIUrl":"https://doi.org/10.1109/PLANS.2008.4570014","url":null,"abstract":"Previous papers on the wide area augmentation system (WAAS) provided details on integrity design for such items as clock and ephemeris, signal quality, and ionospheric monitoring. This paper will provide details on GPS measurement processing performed in WAAS that supports these monitoring functions. Measurement processing conducted in the integrity (or safety) processor has evolved during the localizer performance with vertical guidance phase of the WAAS Program. Currently, this processing integrates measurements from all three independent receiving threads at a reference station and performs various cross thread checks to mitigate select multipath and cycle slip events. Underlying this cross thread processing is the assumption that common mode errors caused by environmental conditions are rare and random. The introduction of WAAS reference stations in extreme northern latitudes operating in significant phase scintillation environments, and the design decision to have the receiver operate in very low signal to noise conditions, exposed erroneous measurement conditions that challenged this rare and random assumption. This paper will address the WAAS measurement processing architecture and focus on such erroneous conditions along with the monitoring algorithms WAAS incorporated to mitigate them. The paper also examines potential improvements in WAAS measurement processing during communication outages. Communication outages between reference and master stations that occur primarily from remote reference stations have the potential of causing measurement processing algorithms to reinitialize thus impacting WAAS availability and continuity performance. This paper will investigate algorithms for improving operation through data outage periods without reducing measurement quality.","PeriodicalId":446381,"journal":{"name":"2008 IEEE/ION Position, Location and Navigation Symposium","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2008-05-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"115349611","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2008-05-05DOI: 10.1109/PLANS.2008.4570069
D. Ilstrup, G. Hugh Elkaim
We evaluate the capabilities of an inexpensive obstacle detection system consisting of a CCD or CMOS optical sensor, synchronously pulsed laser and supporting hardware and software. The goal is to expand the range of feasible autonomous vehicle applications to include those that are currently impractical due to limitations on the price, weight, or power requirements of their sensor suites. This system constitutes an active, mechanically passive sensor, relying on the mechanical activity of its host platform to sweep out samples from its surroundings. We evaluate sensor configurations in two example host platform designs. The first is a handheld obstacle detector to aid users with vision impairment, while the second is a short range detector used as part of the sensor ensemble for an autonomous ground vehicle. Tradeoffs for both continuous laser fan and single laser pointer configurations are evaluated. Since the geometric relation between the optical sensor and laser is fixed, we establish effective distance and angle between the laser and sensor given required minimum and maximum ranges, spatial resolution, platform velocity and expected velocities of potential obstacles. In situations with sufficient ambient light, range data from the laser return is used to speed the computation of well known computer vision techniques for object detection to yield estimates of obstacle positions within the environment. Pulsing the laser synchronously with a short shutter time on the camera allows operation of the device as an ANSI Z 136 class 1 device since the laser's active duty cycle is highly compressed. This approach renders visible wavelengths effectively invisible to the naked eye.
我们评估了由CCD或CMOS光学传感器、同步脉冲激光器和支持硬件和软件组成的廉价障碍物检测系统的能力。其目标是扩大可行的自动驾驶汽车应用范围，包括那些目前由于传感器套件的价格、重量或功率要求而不切实际的应用。该系统由主动、机械被动传感器组成，依靠其主机平台的机械活动从周围环境中清除样本。我们在两个示例主机平台设计中评估传感器配置。第一个是手持障碍物探测器，以帮助视力受损的用户，而第二个是一个短距离探测器，用于自动地面车辆的传感器集合的一部分。评估了连续激光风扇和单激光笔配置的权衡。由于光学传感器与激光器之间的几何关系是固定的，我们根据所需的最小和最大距离、空间分辨率、平台速度和潜在障碍物的预期速度，建立激光器与传感器之间的有效距离和角度。在环境光充足的情况下，激光返回的距离数据用于加速已知的计算机视觉技术的计算，用于物体检测，以产生环境中障碍物位置的估计。脉冲激光与相机上的短快门时间同步允许设备作为ANSI Z 136类1设备的操作，因为激光的有源占空比是高度压缩的。这种方法使肉眼看不到可见的波长。
{"title":"Low cost, low power structured light based obstacle detection","authors":"D. Ilstrup, G. Hugh Elkaim","doi":"10.1109/PLANS.2008.4570069","DOIUrl":"https://doi.org/10.1109/PLANS.2008.4570069","url":null,"abstract":"We evaluate the capabilities of an inexpensive obstacle detection system consisting of a CCD or CMOS optical sensor, synchronously pulsed laser and supporting hardware and software. The goal is to expand the range of feasible autonomous vehicle applications to include those that are currently impractical due to limitations on the price, weight, or power requirements of their sensor suites. This system constitutes an active, mechanically passive sensor, relying on the mechanical activity of its host platform to sweep out samples from its surroundings. We evaluate sensor configurations in two example host platform designs. The first is a handheld obstacle detector to aid users with vision impairment, while the second is a short range detector used as part of the sensor ensemble for an autonomous ground vehicle. Tradeoffs for both continuous laser fan and single laser pointer configurations are evaluated. Since the geometric relation between the optical sensor and laser is fixed, we establish effective distance and angle between the laser and sensor given required minimum and maximum ranges, spatial resolution, platform velocity and expected velocities of potential obstacles. In situations with sufficient ambient light, range data from the laser return is used to speed the computation of well known computer vision techniques for object detection to yield estimates of obstacle positions within the environment. Pulsing the laser synchronously with a short shutter time on the camera allows operation of the device as an ANSI Z 136 class 1 device since the laser's active duty cycle is highly compressed. This approach renders visible wavelengths effectively invisible to the naked eye.","PeriodicalId":446381,"journal":{"name":"2008 IEEE/ION Position, Location and Navigation Symposium","volume":"75 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2008-05-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"115396450","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2008-05-05DOI: 10.1109/PLANS.2008.4570003
Pengfei Guo, Haitao Qiu, Yunchun Yang, Z. Ren
The calibration method of the soft iron and hard iron distortion based on attitude and heading reference system (AHRS) can boil down to the estimation of 12 parameters of magnetic deviation, normally using 12-state Kalman filter (KF) algorithm. The performance of compensation is limited by the accuracy of local inclination angle of magnetic field and initial heading. A 14-state extended Kalman filter (EKF) algorithm is developed to calibrate magnetic deviation, local magnetic inclination angle error and initial heading error all together. The calibration procedure is to change the attitude of AHRS and rotate it two cycles. As the strapdown matrix can hold high precision after initial alignment of AHRS in short time for the gyropsilas short-term precision, the magnetic field vector can be projected onto the body frame of AHRS. The experiment results demonstrate that 14-state EKF outperforms 12-state KF, with measurement errors exist in the initial heading and local inclination angle. The heading accuracy (variance) after compensation is 0.4 degree for tilt angle ranging between 0 and 60 degree.
{"title":"The soft iron and hard iron calibration method using extended kalman filter for attitude and heading reference system","authors":"Pengfei Guo, Haitao Qiu, Yunchun Yang, Z. Ren","doi":"10.1109/PLANS.2008.4570003","DOIUrl":"https://doi.org/10.1109/PLANS.2008.4570003","url":null,"abstract":"The calibration method of the soft iron and hard iron distortion based on attitude and heading reference system (AHRS) can boil down to the estimation of 12 parameters of magnetic deviation, normally using 12-state Kalman filter (KF) algorithm. The performance of compensation is limited by the accuracy of local inclination angle of magnetic field and initial heading. A 14-state extended Kalman filter (EKF) algorithm is developed to calibrate magnetic deviation, local magnetic inclination angle error and initial heading error all together. The calibration procedure is to change the attitude of AHRS and rotate it two cycles. As the strapdown matrix can hold high precision after initial alignment of AHRS in short time for the gyropsilas short-term precision, the magnetic field vector can be projected onto the body frame of AHRS. The experiment results demonstrate that 14-state EKF outperforms 12-state KF, with measurement errors exist in the initial heading and local inclination angle. The heading accuracy (variance) after compensation is 0.4 degree for tilt angle ranging between 0 and 60 degree.","PeriodicalId":446381,"journal":{"name":"2008 IEEE/ION Position, Location and Navigation Symposium","volume":"19 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2008-05-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"115930168","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2008-05-05DOI: 10.1109/PLANS.2008.4569971
W. Dillard, K. Narayanan, V. Trent, M. Greene
Wearable inertial sensors present designers with additional challenges not seen in conventional systems where power at fixed voltage is abundant. This work discusses the critical concerns in designing a wearable inertial sensor including component selection, power distribution and the use of sleep/shutdown modes.
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