Inertial measurement unit

About: Inertial measurement unit is a research topic. Over the lifetime, 13326 publications have been published within this topic receiving 189083 citations. The topic is also known as: IMU.

A universal approach for processing any MEMS inertial sensor configuration for land-vehicle navigation

Abstract: Recent navigation systems integrating GPS with Micro-Electro-Mechanical Systems (MEMS) Inertial Measuring Units (IMUs) have shown promising results for several applications based on low-cost devices such as vehicular and personal navigation. However, as a trend in the navigation market, some applications require further reductions in size and cost. To meet such requirements, a MEMS full IMU configuration (three gyros and three accelerometers) may be simplified. In this context, different partial IMU configurations such as one gyro plus three accelerometers or one gyro plus two accelerometers could be investigated. The main challenge in this case is to develop a specific navigation algorithm for each configuration since this is a time-consuming and costly task. In this paper, a universal approach for processing any MEMS sensor configuration for land vehicular navigation is introduced. The proposed method is based on the assumption that the omitted sensors provide relatively less navigation information and hence, their output can be replaced by pseudo constant signals plus noise. Using standard IMU/GPS navigation algorithms, signals from existing sensors and pseudo signals for the omitted sensors are processed as a full IMU. The proposed approach is tested using land-vehicle MEMS/GPS data and implemented with different sensor configurations. Compared to the full IMU case, the results indicate the differences are within the expected levels and that the accuracy obtained meets the requirements of several land-vehicle applications.

FOG-based navigation in downhole environment during horizontal drilling utilizing a complete inertial measurement unit: directional measurement-while-drilling surveying

Abstract: Presently used surveying sensors in directional drilling processes include accelerometers and magnetometers arranged in three orthogonal directions. The magnetometers in these setups are negatively affected by external magnetic interferences induced by various sources. Therefore, expensive, heavy and lengthy protective nonmagnetic collars need to be installed. Fiber-optic gyroscopes (FOGs) in an inertial navigation setup have been proposed as an alternative to magnetometer-based downhole surveying. The present study explored the feasibility of utilizing a FOG-based tactical-grade inertial measurement unit (IMU) as a complete surveying sensor for measurement-while-drilling (MWD) processes downhole. Alignment and real-time navigation under laboratory conditions were demonstrated. Analysis of vibrations and temperature as possible factors limiting the accuracy of the navigation process was performed. Severe vibration effects were reduced using software techniques, and a shock-absorbing housing was suggested. The temperature range of the IMU is limited by the optical components of the device, but dynamic temperature changes within this range did not present a major problem. A downhole sub design demonstrated that the actual integration of the IMU requires only minor changes in the presently used drilling tools. The utilization of a tactical-grade IMU eliminates the necessity of nonmagnetic collars, which results in lower costs and improved accuracy.

Proprioceptive localilzatilon for a quadrupedal robot on known terrain

Abstract: We present a novel method for the localization of a legged robot on known terrain using only proprioceptive sensors such as joint encoders and an inertial measurement unit. In contrast to other proprioceptive pose estimation techniques, this method allows for global localization (i.e., localization with large initial uncertainty) without the use of exteroceptive sensors. This is made possible by establishing a measurement model based on the feasibility of putative poses on known terrain given observed joint angles and attitude measurements. Results are shown that demonstrate that the method performs better than dead-reckoning, and is also able to perform global localization from large initial uncertainty

Control Laws For The Tele Operation Of An Unmanned Aerial Vehicle Known As An X4-flyer

Abstract: In this paper, we present a control design for the tele-operation of a miniature unmanned aerial vehicle known as an X4-flyer. A simple dynamic nonlinear model for the vehicle, valid for quasi-stationary flight conditions, is derived as a basis for the control design. An attitude control based on information issued from an Inertial Measurement Unit is designed. In order to control the vehicle altitude, an adaptive controller avoiding the ground effects and based on measurements issued from an ultrasonic low cost sensor is designed. In order to compute the altitude velocity, an estimator based on the proposed modelling is used. At the end of the paper, experimental results are presented.

Detection of anticipatory postural adjustments prior to gait initiation using inertial wearable sensors.

Abstract: Background: The present study was performed to evaluate and characterize the potential of accelerometers and angular velocity sensors to detect and assess anticipatory postural adjustments (APAs) generated by the first step at the beginning of the gait. This paper proposes an algorithm to automatically detect certain parameters of APAs using only inertial sensors. Methods: Ten young healthy subjects participated in this study. The subjects wore an inertial unit containing a triaxial accelerometer and a triaxial angular velocity sensor attached to the lower back and one footswitch on the dominant leg to detect the beginning of the step. The subjects were standing upright on a stabilometer to detect the center of pressure displacement (CoP) generated by the anticipatory adjustments. The subjects were asked to take a step forward at their own speed and stride length. The duration and amplitude of the APAs detected by the accelerometer and angular velocity sensors were measured and compared with the results obtained from the stabilometer. The different phases of gait initiation were identified and compared using inertial sensors. Results: The APAs were detected by all of the sensors. Angular velocity sensors proved to be adequate to detect the beginning of the step in a manner similar to the footswitch by using a simple algorithm, which is easy to implement in low computational power devices. The amplitude and duration of APAs detected using only inertial sensors were similar to those detected by the stabilometer. An automatic algorithm to detect APA duration using triaxial inertial sensors was proposed. Conclusions: These results suggest that the feasibility of accelerometers is improved through the use of angular velocity sensors, which can be used to automatically detect and evaluate APAs. The results presented can be used to develop portable sensors that may potentially be useful for monitoring patients in the home environment, thus encouraging the population to participate in more personalized healthcare.