Using Multiple MEMS IMUs to form a Distributed Inertial Measurement Unit

MEMS IMUs are readily available in quantity and have extraordinary advantages over conventional IMUs in size, weight, cost, and power consumption. However, the poor performance of MEMS IMUs limits their use in more demanding military applications. It is desired to use multiple distributed MEMS IMUs to simulate the performance of a single, more costly IMU, using the theory behind Gyro-Free IMUs. A Gyro-Free IMU (GF-IMU) uses a configuration of accelerometers only to measure the three accelerations and three angular rotations of a rigid body in 3-D space. Theoretically, almost any configuration of six distributed accelerometers yields sufficient measurements to solve for the translational and angular acceleration. In reality, however, sensor noise corrupts the measurements and good sensor geometry is necessary to obtain an accurate estimate of the translational and angular accelerations. Determining the optimal configuration of accelerometers is an exercise in geometry. This thesis investigates the optimal geometry of an INS constructed of multiple networked IMUs and develops the accompanying mechanization and error equations. Simple simulations are run to test and validate the basic design principles

SALSA: A Novel Dataset for Multimodal Group Behavior Analysis

Studying free-standing conversational groups (FCGs) in unstructured social settings (e.g., cocktail party ) is gratifying due to the wealth of information available at the group (mining social networks) and individual (recognizing native behavioral and personality traits) levels. However, analyzing social scenes involving FCGs is also highly challenging due to the difficulty in extracting behavioral cues such as target locations, their speaking activity and head/body pose due to crowdedness and presence of extreme occlusions. To this end, we propose SALSA, a novel dataset facilitating multimodal and Synergetic sociAL Scene Analysis, and make two main contributions to research on automated social interaction analysis: (1) SALSA records social interactions among 18 participants in a natural, indoor environment for over 60 minutes, under the poster presentation and cocktail party contexts presenting difficulties in the form of low-resolution images, lighting variations, numerous occlusions, reverberations and interfering sound sources; (2) To alleviate these problems we facilitate multimodal analysis by recording the social interplay using four static surveillance cameras and sociometric badges worn by each participant, comprising the microphone, accelerometer, bluetooth and infrared sensors. In addition to raw data, we also provide annotations concerning individuals' personality as well as their position, head, body orientation and F-formation information over the entire event duration. Through extensive experiments with state-of-the-art approaches, we show (a) the limitations of current methods and (b) how the recorded multiple cues synergetically aid automatic analysis of social interactions. SALSA is available at http://tev.fbk.eu/salsa.Comment: 14 pages, 11 figure

Multiple IMU system test plan, volume 4

Operating procedures for this redundant system are described. A test plan is developed with two objectives. First, performance of the hardware and software delivered is demonstrated. Second, applicability of multiple IMU systems to the space shuttle mission is shown through detailed experiments with FDI algorithms and other multiple IMU software: gyrocompassing, calibration, and navigation. Gimbal flip is examined in light of its possible detrimental effects on FDI and navigation. For Vol. 3, see N74-10296

Advanced flight control system study

The architecture, requirements, and system elements of an ultrareliable, advanced flight control system are described. The basic criteria are functional reliability of 10 to the minus 10 power/hour of flight and only 6 month scheduled maintenance. A distributed system architecture is described, including a multiplexed communication system, reliable bus controller, the use of skewed sensor arrays, and actuator interfaces. Test bed and flight evaluation program are proposed

Velocity measurement based on inertial measuring unit

Vehicles technology have been a priority area of research over the last few decades. With the increasing the use of electronic components in the automotive industry to measure conditions around the vehicle, the focus of automotive technology development is now leading to the development of active technology. Information on the speed of conventional vehicles is generally still obtained based on the rotation of the wheel, but there are weakness in the system that is the diference between wheel and road through vehicle also changes wheel radius of the vehicle due to wind tube air preasure that can change at any time. In this research used Inertial Measuring Unit (IMU) 6 axis (accelerometer and gyroscope) which have been done filtering by using Kalman filter in order to make output sensor value more stable, results obtained at the test of 0 m/s had an RMS error of 0.8696 m/s when elevation is +450; 0.0393 m/s when elevation is 00; and 0.3030 m/s when elevation is -450. this research is expected to be an exploration for the development of a decent system that is suitable to be used as vehicle speed estimator which is as reliable as it is by using an existing speedometer on a ground vehicle generally regardless of slippage and changes in wind capacity on wheels

Inertial Motion Tracking for Inserting Humans into a Networked Synthetic Environment

Inertial/Magnetic tracking is based on the use of sensors containing three orthogonally mounted angular rate sensors, three orthogonal linear accelerometers and three orthogonal magnetometers to determine independently the orientation of each link of an articulated rigid body. Inertial/magnetic orientation tracking could be applied to a broad range of problems which require real-time tracking of an articulated structure without being continuously dependent upon an artificially generated source. This research focuses on the goal of developing and demonstrating wireless full body tracking using MARG sensor modules.U.S. Army Research OfficeW911NF-04-1-030

중첩 관성 센서에서 레버암 효과 완화의 새로운 기법

학위논문 (석사) -- 서울대학교 대학원 : 공과대학 항공우주공학과, 2021. 2. 박찬국.This masters thesis presents two novel methods to mitigate lever arm effect in Redundant Inertial Measurement Units (RIMUs), each with different approaches. With the presence of a lever arm for each sensing axis, the unexpected accelerations such as Euler and centrifugal accelerations are added to the measurements through rotational motion, resulting in an estimation error of linear acceleration. Therefore, it was previously considered as the best option to minimize the length of the lever arm and compensate the lever arm effect from the accelerometer measurements. However, this approach cannot completely remove the estimation error as the compensated value is based on the estimated angular rates, where the magnitude of the error becomes more apparent with a RIMU composed of low-grade gyroscopes that shows a higher noise level. In order to solve this problem, we propose two methods that can mitigate estimation error using the specific arrangement of the lever arm vectors and the concentrated likelihood method-based nonlinear least squares (NLS). By the proposed methods, the accuracy in compensating the lever arm effect can be increased by placing the lever arm vectors symmetrically or using the information from accelerometers when estimating angular rates. Besides, the suggested methods each have their own advantages in computational efficiency and overall navigation performance, compared to previous method. The effectiveness of the proposed methods is verified through simulations including misalignments of each redundant sensor.본 논문에서는 중첩 관성 센서에서 발생하는 레버암 효과를 완화하기 위한 두 가지 새로운 기법을 제안한다. 중첩 관성 센서에서는 각 센서에 존재하는 레버암에 의해 회전 운동이 가해질 때 마다 오일러 힘이나 원심력과 같이 원치 않는 비력이 가속도 측정치에 섞여 추정 오차를 유발하게 된다. 따라서, 이를 해결하기 위해 제시된 최선의 방법은 길이가 최소화된 레버암에 의한 항 가속도 측정치로부터 보상한 값으로 추정하는 것이었다. 그러나, 보상하는 값이 노이즈가 섞인 각속도 추정치에 기반하기 때문에 기존 접근법은 추정 오차를 완전하게 제거할 수 없으며, 저가형 IMU와 같이 자이로스코프의 잡음 수준이 큰 경우에 대해 오차가 더 커지는 것을 확인할 수 있다. 이러한 문제를 해결하기 위해, 레버암 벡터를 특정한 형태로 배치시키거나 집중 우도 방법에 기반한 비선형 최소 자승 방식을 사용하여 추정 오차를 제거할 수 있는 방식을 제안한다. 제안된 방법에 따르면, 레버암의 대칭적인 배치 형태를 사용하거나 가속도계의 정보를 사용하여 각속도의 추정 오차를 우선적으로 줄여 궁극적으로 가속도 추정에 사용하는 보상하는 값의 정확도를 높이는 방식으로 레버암 효과를 줄일 수 있다. 또한, 제안된 방법은 각각 연산량의 효율성과 전반적인 관성항법 성능의 향상에서 추가적인 이점이 있다. 제안한 방식의 효과는 비정렬 오차를 포함한 시뮬레이션으로 검증하였다.Chapter 1 Introduction 1 1.1 Motivation and background 1 1.2 Objectives and contributions 3 Chapter 2 Related Works 6 2.1 Inertial navigation system 6 2.1.1 Frame mechanization 7 2.1.2 Attitude update algorithm 10 2.1.3 Velocity and position update algorithm 16 2.2 Redundant inertial measurement units (RIMU) 19 2.2.1 Sensing axes configuration for optimal navigation performance 19 2.2.2 Sensing axes configuration for optimal FDI performance 24 Chapter 3 Inertial Navigation based on RIMU 27 3.1 Navigation performance analysis 28 3.1.1 Performance enhancement according to the number of redundant sensors 28 3.1.2 Performance degradation due to the presence of the lever arm 30 3.1.3 Lever arm optimization for minimizing the lever arm effect 33 Chapter 4 Mitigating Lever Arm Effect in RIMU 37 4.1 Symmetric lever arm configuration based on least squares method 37 4.1.1 Lever arm configuration 37 4.1.2 Measurement fusion 39 4.1.3 Performance analysis 42 4.2 Nonlinear least squares method 43 4.2.1 Lever arm configuration 43 4.2.2 Measurement fusion 45 4.2.3 Performance analysis 48 4.3 Simulation results 51 4.3.1 RIMU configuration 51 4.3.2 Navigation performance comparison 53 Chapter 5 Conclusion 62 5.1.1 Conclusion and summary 62 5.1.2 Future works 63 Bibliography 64 국문초록 68Maste

Viking navigation

A comprehensive description of the navigation of the Viking spacecraft throughout their flight from Earth launch to Mars landing is given. The flight path design, actual inflight control, and postflight reconstruction are discussed in detail. The preflight analyses upon which the operational strategies and performance predictions were based are discussed. The inflight results are then discussed and compared with the preflight predictions and, finally, the results of any postflight analyses are presented