Browse Prior Art Database

Extended Capability Location System

IP.com Disclosure Number: IPCOM000004639D
Original Publication Date: 2001-Mar-08
Included in the Prior Art Database: 2001-Mar-08
Document File: 6 page(s) / 51K

Publishing Venue

Motorola

Related People

David P. Hoffman: AUTHOR

Abstract

Abstract: The ability to determine location of user through a personal communication device offers significant improvements in public safety, enhanced user functionality resulting in increased market acceptance/profitability. Conventional methods require the use of gyroscopes in order to establish this functionality but are not cost competitive. Recent advances (Vehicle Location and Navigation Systems: Yilin Zhao 1997) have eliminated the gyroscope but are limited to applications where device orientation is fixed (Autos change location but generally are parallel to the road and are not significantly inclined). The Extended Capability Location System (ECLS) is intended as a low cost answer to obtaining positional updates where external access is limited and mobility is required. The device achieves this technical and cost advantage by avoiding use of a gyro through the use of accelerometer and compass electronic components currently available. The functional advantages include function independent of device orientation, an integrated elevation capability, stand alone capability (no external data) and the ability to couple sources not usable by other technologies and current or future location data streams to minimizing CEP. This represents a significant step forward from a cost and capability standpoint.

This text was extracted from a Microsoft Word 97 document.
This is the abbreviated version, containing approximately 59% of the total text.

Abstract: The ability to determine location of user through a personal communication device offers significant improvements in public safety, enhanced user functionality resulting in increased market acceptance/profitability. Conventional methods require the use of gyroscopes in order to establish this functionality but are not cost competitive. Recent advances (Vehicle Location and Navigation Systems: Yilin Zhao 1997) have eliminated the gyroscope but are limited to applications where device orientation is fixed (Autos change location but generally are parallel to the road and are not significantly inclined). The Extended Capability Location System (ECLS) is intended as a low cost answer to obtaining positional updates where external access is limited and mobility is required. The device achieves this technical and cost advantage by avoiding use of a gyro through the use of accelerometer and compass electronic components currently available. The functional advantages include function independent of device orientation, an integrated elevation capability, stand alone capability (no external data) and the ability to couple sources not usable by other technologies and current or future location data streams to minimizing CEP. This represents a significant step forward from a cost and capability standpoint.

A mobile PCS device must be able to determine orientation and changes in velocity in order to provide location related functionality. In applications requiring orientation a gyroscope is normally the device used. However this adds considerable cost and complexity to the device. To avoid this cost the Extended Capability Location System (ECLS) uses a combination of an accelerometer and a compass to achieve an equivalent result.

The ECLS uses an accelerometer and a compass to resolve orientation. The ECLS uses accelerometers to measure applied force, such as acceleration. Since gravity is an applied external force it can also be measured and used as a orientation in the z plane. It also (by perpendicularity) defines the XY plane (figure 1). The compass further refines the XY reference by establishing external reference (north south) which can be vector projected onto the XY plane to define a complete coordinate system (figures 2 3). A key feature of this device is therefore its ability to ascertain its orientation independent of any device orientation so long as it located in a conventional terrestrial system.

Figure 1. Vector Field

Define Vector field that is fixed with respect to the unit but relative to the environment.

The dual axis accelerometer and compass are both tied into this reference plane via the specific mounting geometry employed internal to a PCS device.

Figure 2. Translational Matrix

Establish Translation Matrix between internal vector field and external environment field.

Figure 3. Location Calculation

Accelerometer input

•If 9.7<(((Xr,Yr,Zr))<9.9

•Then (-ALT) XrYrZr

•And ALT -(XrYrZr)

•And Plane NW f( (ALT)

Compass Input

•Nuncorrected f(Xr,Yr,Zr...