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Article
Publication date: 19 June 2017

Xiaochun Tian, Jiabin Chen, Yongqiang Han, Jianyu Shang and Nan Li

This study aims to design an optimized algorithm for low-cost pedestrian navigation system (PNS) to correct the heading drift and altitude error, thus achieving…

Abstract

Purpose

This study aims to design an optimized algorithm for low-cost pedestrian navigation system (PNS) to correct the heading drift and altitude error, thus achieving high-precise pedestrian location in both two-dimensional (2-D) and three-dimensional (3-D) space.

Design/methodology/approach

A novel heading correction algorithm based on smoothing filter at the terminal of zero velocity interval (ZVI) is proposed in the paper. This algorithm adopts the magnetic sensor to calculate all the heading angles in the ZVI and then applies a smoothing filter to obtain the optimal heading angle. Furthermore, heading correction is executed at the terminal moment of ZVI. Meanwhile, an altitude correction algorithm based on step height constraint is proposed to suppress the altitude channel divergence of strapdown inertial navigation system by using the step height as the measurement of the Kalman filter.

Findings

The verification experiments were carried out in 2-D and 3-D space to evaluate the performance of the proposed pedestrian navigation algorithm. The results show that the heading drift and altitude error were well corrected. Meanwhile, the path calculated by the novel algorithm has a higher match degree with the reference trajectory, and the positioning errors of the 2-D and 3-D trajectories are both less than 0.5 per cent.

Originality/value

Besides zero velocity update, another two problems, namely, heading drift and altitude error in the PNS, are solved, which ensures the high positioning precision of pedestrian in indoor and outdoor environments.

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Article
Publication date: 1 April 2002

Andrzej Tomczyk

Rzeszów University of Technology has undertaken the task of designing and providing of equipment to a flying laboratory. This paper presents basic design principles of the…

Abstract

Rzeszów University of Technology has undertaken the task of designing and providing of equipment to a flying laboratory. This paper presents basic design principles of the Inertial Reference Unit (IRU) which employs measuring signals from the Fiber Optic Gyros (FOG), accelerometers and electronic compass module. A microcomputer follows the algorithm of complementary filtration for of calculating the Euler angles for the aircraft attitude (pitch, roll and heading), angular rates, and linear accelerations. The correction systems that minimize error of the steady‐state measuring have been employed. The results of computer simulations, lab tests and selected flight tests have also been presented. The Inertial Reference Unit μIRU‐1 was tested in flight on board of the general aviation aircraft PZL‐110 “Koliber”. It has been confirmed that metrological properties of the system are appropriate for the purposes of teaching process. Currently, a modified version of the unit is being prepared. The new IRU is planned as a main reference unit for integrated flight control system of general aviation aircraft.

Details

Aircraft Engineering and Aerospace Technology, vol. 74 no. 2
Type: Research Article
ISSN: 0002-2667

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Article
Publication date: 1 June 2008

Martin Langner and David Sanders

Simple and affordable systems are described to assist wheelchair users in steering their wheelchairs across sloping ground. The systems can be attached to many standard…

Abstract

Simple and affordable systems are described to assist wheelchair users in steering their wheelchairs across sloping ground. The systems can be attached to many standard powered wheelchairs. Wheelchairs often steer by having two swivelling caster wheels but problems with this configuration occur when a wheelchair is driven along sloping ground because the casters can swivel in the direction of the slope. Gravity then causes the wheelchair to start an unwanted turn or ‘veer’ and the chair goes in an unintended direction. This situation is exacerbated for switch users, as switches cannot provide fine control to trim and compensate. Early experiments demonstrated that calibrating wheelchair controllers for straight‐line balance and optimising motor‐compensation did not solve this problem. Caster angle was selected to provide feedback to the wheelchair controllers. At the point when veer is first detected, a wheelchair has already begun to alter course and the job of the correction system is to minimise this drift from the desired course. A rolling road was created as an assessment tool and trials with both the test bed and in real situations were conducted to evaluate the new systems. The small swivel detector that was created could be successfully attached to caster swivel bearings. The new system was successful, robust and was not affected by changeable parameters. Although primarily intended for switch users, the methods can be applied to users with proportional controls.

Details

Journal of Assistive Technologies, vol. 2 no. 2
Type: Research Article
ISSN: 1754-9450

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Article
Publication date: 1 January 1962

K. Fearnside

AT the present day the operations of civil transport aeroplanes are severely restricted under conditions of poor visibility and not infrequently flights have to be…

Abstract

AT the present day the operations of civil transport aeroplanes are severely restricted under conditions of poor visibility and not infrequently flights have to be diverted or cancelled. The work of the Blind Landing Experimental Unit of the Ministry of Aviation in the development of a system of automatic landing for military aircraft has been described elsewhere.1 A flight control system is described in this paper, which given the necessary azimuth guidance signals from ground based installations, will extend the advantages of automatic landings into the civil field.

Details

Aircraft Engineering and Aerospace Technology, vol. 34 no. 1
Type: Research Article
ISSN: 0002-2667

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Article
Publication date: 1 January 1948

H.L. Price

IT is readily understood that no instrument or measuring device can be entirely free from errors duo to physical imperfections of manufacture. Gyroscopes in particular are…

Abstract

IT is readily understood that no instrument or measuring device can be entirely free from errors duo to physical imperfections of manufacture. Gyroscopes in particular are affected in this way, requiring, as they do, complete absence of bearing friction if use is to be made of their property of preserving fixity in space of the direction of their spin axis when free from external forces. The impossibility of achieving this ideal condition results in a small degree of drift of the gyro‐axis, and detracts from the value of a gyroscope as a direction indicating device. In spite of this deficiency, in cases where steadiness of pointer reading is of prime importance, standard gyroscopic directional instruments serve a very useful purpose, provided the necessity of applying corrections at appropriate time intervals is recognized and observed. Latterly, development along the lines of automatic compensation has overcome this defect, and has led to the advent of the ‘monitored’ gyroscopic compass.

Details

Aircraft Engineering and Aerospace Technology, vol. 20 no. 1
Type: Research Article
ISSN: 0002-2667

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Article
Publication date: 1 September 1975

Airscrew Howden Ltd

The Westland Lynx helicopter is a particularly fine example of the use of advanced fan technology in modern aircraft applications. The firm of Airscrew Howden have come a…

Abstract

The Westland Lynx helicopter is a particularly fine example of the use of advanced fan technology in modern aircraft applications. The firm of Airscrew Howden have come a long way from their original manufacture of the wooden ‘prop’ but they still continue to play a very essential part in all types of aircraft flying today; this takes the form of sophisticated fan designs to cover a wide variety of special air‐movement requirements that can arise in this sector.

Details

Aircraft Engineering and Aerospace Technology, vol. 47 no. 9
Type: Research Article
ISSN: 0002-2667

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Article
Publication date: 16 March 2015

Shengbo Sang, Ruiyong Zhai, Wendong Zhang, Qirui Sun and Zhaoying Zhou

This study aims to design a new low-cost localization platform for estimating the location and orientation of a pedestrian in a building. The micro-electro-mechanical…

Abstract

Purpose

This study aims to design a new low-cost localization platform for estimating the location and orientation of a pedestrian in a building. The micro-electro-mechanical systems (MEMS) sensor error compensation and the algorithm were improved to realize the localization and altitude accuracy.

Design/methodology/approach

The platform hardware was designed with common low-performance and inexpensive MEMS sensors, and with a barometric altimeter employed to augment altitude measurement. The inertial navigation system (INS) – extended Kalman filter (EKF) – zero-velocity updating (ZUPT) (INS-EKF-ZUPT [IEZ])-extended methods and pedestrian dead reckoning (PDR) (IEZ + PDR) algorithm were modified and improved with altitude determined by acceleration integration height and pressure altitude. The “AND” logic with acceleration and angular rate data were presented to update the stance phases.

Findings

The new platform was tested in real three-dimensional (3D) in-building scenarios, achieved with position errors below 0.5 m for 50-m-long route in corridor and below 0.1 m on stairs. The algorithm is robust enough for both the walking motion and the fast dynamic motion.

Originality/value

The paper presents a new self-developed, integrated platform. The IEZ-extended methods, the modified PDR (IEZ + PDR) algorithm and “AND” logic with acceleration and angular rate data can improve the high localization and altitude accuracy. It is a great support for the increasing 3D location demand in indoor cases for universal application with ordinary sensors.

Details

Sensor Review, vol. 35 no. 2
Type: Research Article
ISSN: 0260-2288

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Article
Publication date: 11 June 2019

Shijia Wang

This paper aims to improve shearer positioning accuracy. Shearer positioning using an inertial navigation system (INS) is a highly useful technology; however, positioning…

Abstract

Purpose

This paper aims to improve shearer positioning accuracy. Shearer positioning using an inertial navigation system (INS) is a highly useful technology; however, positioning accuracy is seriously hindered by INS attitude error, particularly heading drift.

Design/methodology/approach

A shearer positioning model with double-INS based on extended Kalman filter was proposed. The constant distance between two INSs (INS 1 and INS 2) was selected as the observation vector. Allan variance was used to identify the noise type of the vertical-axis gyroscope, and the stochastic process of heading drift for two INSs was obtained and divided into incongruous drift and concurrent drift.

Findings

Simulation was then carried out to determine the optimal arrangement of the two INSs. For incongruous drift, the optimal arrangement satisfied the condition that the line connecting INS 1 and INS 2 was perpendicular to the shearer lateral axis (in the shearer coordinate frame) and parallel to the east-north plane (in the east-north-up coordinate frame). Under optimal arrangement, the positioning accuracy increased against the distance between INS 1 and INS 2. For concurrent drift, the double-INS positioning model had no effect. Under the circumstances, the number of INSs should be increased so that the uncertainty of INS drift was reflected as much as possible.

Originality/value

A new double-INS positioning model was proposed with the constant distance between the two INSs. The optimal arrangement for double-INS was obtained.

Details

Sensor Review, vol. 39 no. 4
Type: Research Article
ISSN: 0260-2288

Keywords

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Article
Publication date: 8 March 2010

David A. Sanders, Martin Langner and Giles E. Tewkesbury

The purpose of this paper is to present powered‐wheelchair transducers and systems that provide more control, reduced veer on slopes, and improved energy conservation…

Abstract

Purpose

The purpose of this paper is to present powered‐wheelchair transducers and systems that provide more control, reduced veer on slopes, and improved energy conservation, while reducing effort. They are especially significant for people with movement disorders who lack sufficient hand‐grasp and release ability or sufficient targeting skill to use joysticks.

Design/methodology/approach

Laboratory test rigs are created to test proportional switches and teach potential users. Then, trials are conducted with a rolling road and in real situations. Caster angle‐measurement is selected to provide feedback to minimize drift away from a chosen course and an electronic solution was created to match driver control to caster‐steering‐position. A case study is described as an example.

Findings

Results and advantages are presented from changing from using a set of digital‐switches to a set of new variable‐switches and then adding a sensor system to prevent veer on slopes. Systems have been tested for nearly two years and shown to assist powered‐wheelchair‐users with poor targeting skills.

Research limitations/implications

The research used wheelchairs with caster‐wheels but the systems could easily be used on other wheelchairs.

Practical implications

Simple input‐devices are presented that isolate gross motor function and are tolerant to involuntary movements (proportional‐switches). A sensor system is presented that assists users in steering across sloping or uneven ground.

Originality/value

Proportional‐switches and sensors are shown to reduce veer and provide more control over turn and forward speed and turn radius while reducing frustration and improving energy conservation. The simple and affordable systems could be created and attached to many standard powered‐wheelchairs in many organisations.

Details

Industrial Robot: An International Journal, vol. 37 no. 2
Type: Research Article
ISSN: 0143-991X

Keywords

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Article
Publication date: 19 January 2015

Wen Liu, Yingjun Zhang, Xuefeng Yang and Shengwei Xing

The aim of this article is to present a PIN (pedestrian inertial navigation) solution that incorporates altitude error correction, which eliminates the altitude error…

Abstract

Purpose

The aim of this article is to present a PIN (pedestrian inertial navigation) solution that incorporates altitude error correction, which eliminates the altitude error accurately without using external sensors. The main problem of PIN is the accumulation of positioning errors due to the drift caused by the noise in the sensors. Experiment results show that the altitude errors are significant when navigating in multilayer buildings, which always lead to localization to incorrect floors.

Design/methodology/approach

The PIN proposed is implemented over an inertial navigation systems (INS) framework and a foot-mounted IMU. The altitude error correction idea is identifying the most probable floor of each horizontal walking motion. To recognize gait types, the walking motion is described with angular rate measured by IMU, and the dynamic time warping algorithm is used to cope with the different dimension samples due to the randomness of walking motion. After gait recognition, the altitude estimated with INS of each horizontal walking is checked for association with one of the existing in a database.

Findings

Experiment results show that high accuracy altitude is achieved with altitude errors below 5 centimeters for upstairs and downstairs routes in a five floors building.

Research limitations/implications

The main limitations of the study is the assumption that accuracy floor altitude information is available.

Originality/value

Our PIN system eliminates altitude errors accurately and intelligently, which benefits from the new idea of combination of gait recognition and map-matching. In addition, only one IMU is used which is different from other approach that use external sensors.

Details

Sensor Review, vol. 35 no. 1
Type: Research Article
ISSN: 0260-2288

Keywords

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