Showing papers on "Inertial measurement unit published in 1989"

Inertial measurement unit with aiding from roll isolated gyro

Abstract: In the present invention the inertial measurement unit system comprises a basic strapdown inertial measurement unit and an isolated fourth gyro strapped to a rotatable platform which is commanded to rotate at a rate equal to the spin rate of the vehicle body but in an opposition direction. The rotatable platform is controlled substantially by a control signal to cause the rotatable platform to turn at a rate substantially equal to the roll of the vehicle body but in an opposite direction. A signal processing means operates on (i) the output of an inertial navigational system computer representative of the rate of rotation of the inertial measurement unit along the roll axis, (ii), the output of the isolation gyro, and (iii) an output of a counter which counts the complete revolutions of the rotatable platform. In turn, an error signal is provided which is related to the rotation measurement error of the first rotation signal. In turn the error signal is fed into the navigational system computer for correction of the navigational system data for correcting that data affected by scale factor stability of the roll gyro of the inertial measurement unit.

Cost‐Effective, High‐Accuracy Inertial Navigation

Abstract: In spite of the trend towards Global Positioning System (GPS)/ Inertial Navigation System Hybrids, certain applications demand a pure inertial solution to give high-accuracy navigation performance. Modern day Inertial Navigation Systems are dominated by the Ring Laser Gyro technology; however, these systems lie normally in the 1 nautical mile per hour class. To obtain a factor of improvement demands either: • Development of higher accuracy (and hence more expensive) inertial sensors; both gyro and accelerometer • Alternative mechanization of existing inertial sensors. An alternative mechanization which is ideally suited for today's ring laser gyros is one that can be borrowed from the past. This technique is the rate bias technique which solves many of the problems associated with dithered gyros, and in addition attenuates the effects of many of the inertial sensors (both gyro and accelerometer) errors. This paper discusses the design rationale and system design, which together with flight test results demonstrate that a rate bias ring laser gyro Inertial Navigation System provides a cost effective solution to the pure high-accuracy Inertial Navigation System requirement.

Control system for neuro-protheses - has inertial sensors coupled to regulating loop for improved control

Abstract: The measurement and regulation system is used for neuromuscular stimulated systems operated in a closed loop mode. The patient carries gyroscope elements that provide an angular rate measurement as an input to a transformation (52) matrix to provide position data. Acceleration information is provided by inertial sensors (54) that relate to equilibrium of the patient. Transformed values are fed to a filter (68) and the generated outputs are used in a regulating circuit. ADVANTAGE - Improves equilibrium of patients with neuroprotteses.

Geodetic Positioning by Inertial and Satellite Systems: An Overview

Abstract: Once satellite and inertial systems are used for geodetic positioning they offer mainly the advantage of online coordination in geometry and gravity space as well as the unnecessary direct line-of-sight. Here their system analysis is based on the threedimensional network point of view for satellite systems, e.g. GPS or GLONASS, and the traverse network philosophy for inertial systems.

Underwater tracking device

Abstract: PURPOSE:To enable a tracking target body to calculate whether or not the body itself is at the shortest approach distance and in the direction by arranging two receiving circuit parts at a specific distance and acquiring necessary information by two kinds of inertia. CONSTITUTION:One underwater sailing body 10 is equipped with a receiver 11A which receives radiated flying sound from a tracking target frame and a 1st arithmetic circuit 11B which calculates the relative angle and relative speed with the tracking target body. Further, this main body 10 is equipped with an inertia sensor 12 which finds the absolute position of its body, a communication equipment 13 which interchanges information with the other underwater sailing body 20 through a cable K, etc. The other main body 20 is the same as the main body 10 and equipped with a 2nd arithmetic circuit 21B, communication equipment 23, etc. Those main bodies 10 and 20 send and receive information required for the both through the communication equipments 13 and 23 and pieces of information obtained by receiving circuit parts 11 and 21 and inertial sensors 12 and 22 are gathered to a main arithmetic part 15 mounted on the main body 10. The arithmetic part 15 calculates the relative distance, speed, etc., with the tracking target frame and sends the results to motion control circuits 17 and 27.

Comparative Study of Inertial Measurement Systems for Geodetic Applications

Abstract: Inertial measurement systems are being increasingly used for geodetic applications. For this purpose stabilized platform systems have been used almost exclusively up to now, but nowadays strapdown systems with the inertial sensors fixed to the vehicle are becoming more and more important. For both mechanizations mentioned above the basic mechanization equations are derived, which result in a system of coupled, non-linear and inhomogeneous differential equations. The equations are linearized, and with the help of the solved linear incremental system of differential equations the effects on point positioning of different sensor model parameters are discussed.

Realtime Surveying in Close Range Area with Inertial Navigation Systems and Optical Target Tracking Techniques

Abstract: Realtime dynamic surveying methods on construction sites are treated in this paper. With the development of an optoelectronic measurement system the positioning of construction machines becomes possible. The measurement system is realized by the combination of realtime cameras which are equipped with position sensitive devices and classical photogrammetric approaches. A target tracking theodolite with automatic angle measurement capability is used for dynamic positioning of slowly moving objects. For tunneling and pipe jacking techniques a measurement methodology is proposed to determine position and orientation with an inertial measurement system using a special step technique. This technique provides a refractionless measurement tool for bad visible conditions.

Long range tracking from a maneuvering platform using range and azimuth measurements

Abstract: This paper presents the results of investigating the sensitivity of a tracking filter to the inclusion or omission of several types of terms in the state dynamic equations on which the filter is based. These terms arise because the projection of the slant range vector onto the platform local level plane is accelerating even when both the platform and target are flying constant velocity, heading, and altitude flight paths. The focus is on tracking targets from a airborne platform a t long ranges using range and azimuth information. The platform is assumed to have an IMU and a local level navigation algorithm. I t will be allowed to change heading, velocity, and altitude while maintaining track. We shall not be concerned with the physical process whereby one obtains range and azimuth measurements or restrict the orientation of the platform relative to the target. That is, we will not restrict the field of view of the sensors. Our object is to develop a filter which applies to any long range t racking s i tua t ion where r a n g e a n d az imuth measurements are available. These measurements do not have to be made a t the same time, and range measurements may be missed independently from azimuth measurements being missed.

A Model for Highly Precise Inertial-Survey Adjustments (Summary)

Abstract: Post-processing of unfiltered inertial data is usually done in two separate steps; the error velocity correction and, subsequently, the coordinate adjustment (Schwarz and Gonthier, 1982; Huddle, 1986). These techniques are in some cases not sufficient for inertial traverses which extend over time periods of two hours. To overcome this limitation one should consider the dynamics of the platform to get a more realistic model for the error behaviour of the inertial survey system.