The Experts below are selected from a list of 10041 Experts worldwide ranked by ideXlab platform
Luisa Bastos - One of the best experts on this subject based on the ideXlab platform.
-
hybrid derivative free extended kalman filter for unknown Lever Arm estimation in tightly coupled dgps ins integration
Gps Solutions, 2011Co-Authors: Yanrui Geng, Richard Deurloo, Luisa BastosAbstract:Differential carrier phase observations from GPS (Global Positioning System) integrated with high-rate sensor measurements, such as those from an inertial navigation system (INS) or an inertial measurement unit (IMU), in a tightly coupled approach can guarantee continuous and precise geo-location information by bridging short outages in GPS and providing a solution even when less than four satellites are visible. However, to be efficient, the integration requires precise knowledge of the Lever Arm, i.e. the position vector of the GPS antenna relative to the IMU. A previously determined Lever Arm by direct measurement is not always available in real applications; therefore, an efficient automatic estimation method can be very useful. We propose a new hybrid derivative-free extended Kalman filter for the estimation of the unknown Lever Arm in tightly coupled GPS/INS integration. The new approach takes advantage of both the linear time propagation of the Kalman filter and the nonlinear measurement propagation of the derivative-free extended Kalman filter. Compared to the unscented Kalman filter, which in recent years is typically used as a superior alternative to the extended Kalman filter for nonlinear estimation, the virtue of the new Kalman filter is equal estimation accuracy at a significantly reduced computational burden. The performance of the new Lever Arm estimation method is assessed with simulated and real data. Simulations show that the proposed technique can estimate the unknown Lever Arm correctly provided that maneuvers with attitude changes are performed during initialization. Field test results confirm the effectiveness of the new method.
-
Hybrid derivative-free extended Kalman filter for unknown Lever Arm estimation in tightly coupled DGPS/INS integration
GPS Solutions, 2011Co-Authors: Yanrui Geng, Richard Deurloo, Luisa BastosAbstract:Differential carrier phase observations from GPS (Global Positioning System) integrated with high-rate sensor measurements, such as those from an inertial navigation system (INS) or an inertial measurement unit (IMU), in a tightly coupled approach can guarantee continuous and precise geo-location information by bridging short outages in GPS and providing a solution even when less than four satellites are visible. However, to be efficient, the integration requires precise knowledge of the Lever Arm, i.e. the position vector of the GPS antenna relative to the IMU. A previously determined Lever Arm by direct measurement is not always available in real applications; therefore, an efficient automatic estimation method can be very useful. We propose a new hybrid derivative-free extended Kalman filter for the estimation of the unknown Lever Arm in tightly coupled GPS/INS integration. The new approach takes advantage of both the linear time propagation of the Kalman filter and the nonlinear measurement propagation of the derivative-free extended Kalman filter. Compared to the unscented Kalman filter, which in recent years is typically used as a superior alternative to the extended Kalman filter for nonlinear estimation, the virtue of the new Kalman filter is equal estimation accuracy at a significantly reduced computational burden. The performance of the new Lever Arm estimation method is assessed with simulated and real data. Simulations show that the proposed technique can estimate the unknown Lever Arm correctly provided that maneuvers with attitude changes are performed during initialization. Field test results confirm the effectiveness of the new method.
Yanrui Geng - One of the best experts on this subject based on the ideXlab platform.
-
hybrid derivative free extended kalman filter for unknown Lever Arm estimation in tightly coupled dgps ins integration
Gps Solutions, 2011Co-Authors: Yanrui Geng, Richard Deurloo, Luisa BastosAbstract:Differential carrier phase observations from GPS (Global Positioning System) integrated with high-rate sensor measurements, such as those from an inertial navigation system (INS) or an inertial measurement unit (IMU), in a tightly coupled approach can guarantee continuous and precise geo-location information by bridging short outages in GPS and providing a solution even when less than four satellites are visible. However, to be efficient, the integration requires precise knowledge of the Lever Arm, i.e. the position vector of the GPS antenna relative to the IMU. A previously determined Lever Arm by direct measurement is not always available in real applications; therefore, an efficient automatic estimation method can be very useful. We propose a new hybrid derivative-free extended Kalman filter for the estimation of the unknown Lever Arm in tightly coupled GPS/INS integration. The new approach takes advantage of both the linear time propagation of the Kalman filter and the nonlinear measurement propagation of the derivative-free extended Kalman filter. Compared to the unscented Kalman filter, which in recent years is typically used as a superior alternative to the extended Kalman filter for nonlinear estimation, the virtue of the new Kalman filter is equal estimation accuracy at a significantly reduced computational burden. The performance of the new Lever Arm estimation method is assessed with simulated and real data. Simulations show that the proposed technique can estimate the unknown Lever Arm correctly provided that maneuvers with attitude changes are performed during initialization. Field test results confirm the effectiveness of the new method.
-
Hybrid derivative-free extended Kalman filter for unknown Lever Arm estimation in tightly coupled DGPS/INS integration
GPS Solutions, 2011Co-Authors: Yanrui Geng, Richard Deurloo, Luisa BastosAbstract:Differential carrier phase observations from GPS (Global Positioning System) integrated with high-rate sensor measurements, such as those from an inertial navigation system (INS) or an inertial measurement unit (IMU), in a tightly coupled approach can guarantee continuous and precise geo-location information by bridging short outages in GPS and providing a solution even when less than four satellites are visible. However, to be efficient, the integration requires precise knowledge of the Lever Arm, i.e. the position vector of the GPS antenna relative to the IMU. A previously determined Lever Arm by direct measurement is not always available in real applications; therefore, an efficient automatic estimation method can be very useful. We propose a new hybrid derivative-free extended Kalman filter for the estimation of the unknown Lever Arm in tightly coupled GPS/INS integration. The new approach takes advantage of both the linear time propagation of the Kalman filter and the nonlinear measurement propagation of the derivative-free extended Kalman filter. Compared to the unscented Kalman filter, which in recent years is typically used as a superior alternative to the extended Kalman filter for nonlinear estimation, the virtue of the new Kalman filter is equal estimation accuracy at a significantly reduced computational burden. The performance of the new Lever Arm estimation method is assessed with simulated and real data. Simulations show that the proposed technique can estimate the unknown Lever Arm correctly provided that maneuvers with attitude changes are performed during initialization. Field test results confirm the effectiveness of the new method.
Richard Deurloo - One of the best experts on this subject based on the ideXlab platform.
-
hybrid derivative free extended kalman filter for unknown Lever Arm estimation in tightly coupled dgps ins integration
Gps Solutions, 2011Co-Authors: Yanrui Geng, Richard Deurloo, Luisa BastosAbstract:Differential carrier phase observations from GPS (Global Positioning System) integrated with high-rate sensor measurements, such as those from an inertial navigation system (INS) or an inertial measurement unit (IMU), in a tightly coupled approach can guarantee continuous and precise geo-location information by bridging short outages in GPS and providing a solution even when less than four satellites are visible. However, to be efficient, the integration requires precise knowledge of the Lever Arm, i.e. the position vector of the GPS antenna relative to the IMU. A previously determined Lever Arm by direct measurement is not always available in real applications; therefore, an efficient automatic estimation method can be very useful. We propose a new hybrid derivative-free extended Kalman filter for the estimation of the unknown Lever Arm in tightly coupled GPS/INS integration. The new approach takes advantage of both the linear time propagation of the Kalman filter and the nonlinear measurement propagation of the derivative-free extended Kalman filter. Compared to the unscented Kalman filter, which in recent years is typically used as a superior alternative to the extended Kalman filter for nonlinear estimation, the virtue of the new Kalman filter is equal estimation accuracy at a significantly reduced computational burden. The performance of the new Lever Arm estimation method is assessed with simulated and real data. Simulations show that the proposed technique can estimate the unknown Lever Arm correctly provided that maneuvers with attitude changes are performed during initialization. Field test results confirm the effectiveness of the new method.
-
Hybrid derivative-free extended Kalman filter for unknown Lever Arm estimation in tightly coupled DGPS/INS integration
GPS Solutions, 2011Co-Authors: Yanrui Geng, Richard Deurloo, Luisa BastosAbstract:Differential carrier phase observations from GPS (Global Positioning System) integrated with high-rate sensor measurements, such as those from an inertial navigation system (INS) or an inertial measurement unit (IMU), in a tightly coupled approach can guarantee continuous and precise geo-location information by bridging short outages in GPS and providing a solution even when less than four satellites are visible. However, to be efficient, the integration requires precise knowledge of the Lever Arm, i.e. the position vector of the GPS antenna relative to the IMU. A previously determined Lever Arm by direct measurement is not always available in real applications; therefore, an efficient automatic estimation method can be very useful. We propose a new hybrid derivative-free extended Kalman filter for the estimation of the unknown Lever Arm in tightly coupled GPS/INS integration. The new approach takes advantage of both the linear time propagation of the Kalman filter and the nonlinear measurement propagation of the derivative-free extended Kalman filter. Compared to the unscented Kalman filter, which in recent years is typically used as a superior alternative to the extended Kalman filter for nonlinear estimation, the virtue of the new Kalman filter is equal estimation accuracy at a significantly reduced computational burden. The performance of the new Lever Arm estimation method is assessed with simulated and real data. Simulations show that the proposed technique can estimate the unknown Lever Arm correctly provided that maneuvers with attitude changes are performed during initialization. Field test results confirm the effectiveness of the new method.
H. Lee Sweeney - One of the best experts on this subject based on the ideXlab platform.
-
Myosin VI Must Dimerize and Deploy Its Unusual Lever Arm in Order to Perform Its Cellular Roles
Cell reports, 2014Co-Authors: Monalisa Mukherjea, Virginie Ropars, Anne Houdusse, M. Yusuf Ali, Carlos Kikuti, Daniel Safer, Zhaohui Yang, Helena Sirkia, David M. Warshaw, H. Lee SweeneyAbstract:Summary It is unclear whether the reverse-direction myosin (myosin VI) functions as a monomer or dimer in cells and how it generates large movements on actin. We deleted a stable, single-α-helix (SAH) domain that has been proposed to function as part of a Lever Arm to amplify movements without impact on in vitro movement or in vivo functions. A myosin VI construct that used this SAH domain as part of its Lever Arm was able to take large steps in vitro but did not rescue in vivo functions. It was necessary for myosin VI to internally dimerize, triggering unfolding of a three-helix bundle and calmodulin binding in order to step normally in vitro and rescue endocytosis and Golgi morphology in myosin VI-null fibroblasts. A model for myosin VI emerges in which cargo binding triggers dimerization and unfolds the three-helix bundle to create a Lever Arm essential for in vivo functions.
-
Processive Steps in the Reverse Direction Require Uncoupling of the Lead Head Lever Arm of Myosin Vi.
Molecular cell, 2012Co-Authors: Julie Ménétrey, H. Lee Sweeney, T. Isabet, Virginie Ropars, Monalisa Mukherjea, Olena Pylypenko, Xiaoyan Liu, Javier Pérez, Patrice Vachette, Anne HoudusseAbstract:Summary Myosin VI is the only known reverse-direction myosin motor. It has an unprecedented means of amplifying movements within the motor involving rearrangements of the converter subdomain at the C terminus of the motor and an unusual Lever Arm projecting from the converter. While the average step size of a myosin VI dimer is 30–36 nm, the step size is highly variable, presenting a challenge to the Lever Arm mechanism by which all myosins are thought to move. Herein, we present structures of myosin VI that reveal regions of compliance that allow an uncoupling of the lead head when movement is modeled on actin. The location of the compliance restricts the possible actin binding sites and predicts the observed stepping behavior. The model reveals that myosin VI, unlike plus-end directed myosins, does not use a pure Lever Arm mechanism, but instead steps with a mechanism analogous to the kinesin neck-linker uncoupling model.
-
The azimuthal path of myosin V and its dependence on Lever-Arm length.
The Journal of general physiology, 2012Co-Authors: John H. Lewis, John F. Beausang, H. Lee Sweeney, Yale E. GoldmanAbstract:Myosin V (myoV) is a two-headed myosin capable of taking many successive steps along actin per diffusional encounter, enabling it to transport vesicular and ribonucleoprotein cargos in the dense and complex environment within cells. To better understand how myoV navigates along actin, we used polarized total internal reflection fluorescence microscopy to examine angular changes of bifunctional rhodamine probes on the Lever Arms of single myoV molecules in vitro. With a newly developed analysis technique, the rotational motions of the Lever Arm and the local orientation of each probe relative to the Lever Arm were estimated from the probe’s measured orientation. This type of analysis could be applied to similar studies on other motor proteins, as well as other proteins with domains that undergo significant rotational motions. The experiments were performed on recombinant constructs of myoV that had either the native-length (six IQ motifs and calmodulins [CaMs]) or truncated (four IQ motifs and CaMs) Lever Arms. Native-length myoV-6IQ mainly took straight steps along actin, with occasional small azimuthal tilts around the actin filament. Truncated myoV-4IQ showed an increased frequency of azimuthal steps, but the magnitudes of these steps were nearly identical to those of myoV-6IQ. The results show that the azimuthal deflections of myoV on actin are more common for the truncated Lever Arm, but the range of these deflections is relatively independent of its Lever-Arm length.
-
Myosin VI undergoes a 180° power stroke implying an uncoupling of the front Lever Arm
Proceedings of the National Academy of Sciences of the United States of America, 2009Co-Authors: Jeff G. Reifenberger, H. Lee Sweeney, Erdal Toprak, Hyeongjun Kim, Dan Safer, Paul R. SelvinAbstract:We simultaneously measure both the step size, via FIONA, and the 3-D orientation, via DOPI, of the light-chain domain of individual dimeric myosin VIs. This allows for the correlation of the change in orientation of the light chain domain to the stepping of the motor. Three different pairs of positions were tested using a rigid bifunctional rhodamine on the calmodulin of the IQ domain. The data for all three labeling positions support the model that the light chain domain undergoes a significant rotation of approximately 180°. Contrary to an earlier study [Sun, Y. et al. (2007) Mol Cell 28, 954–964], our data does not support a model of multiple angles of the Lever Arm of the lead head, nor “wiggly” walking on actin. Instead, we propose that for the two heads of myosin VI to coordinate their processive movement, the Lever Arm of the lead head must be uncoupled from the converter until the rear head detaches. More specifically, intramolecular strain causes the myosin VI Lever Arm of the lead head to uncouple from the motor domain, allowing the motor domain to go through its product-release (phosphate and ADP) steps at an unstrained rate. The Lever Arm of the lead head rebinds to the motor and attains a rigor conformation when the rear head detaches. By coupling the orientation and position information with previously described kinetics, this allows us to explain how myosin VI coordinates its heads processively while maintaining the ability to move under load with a (semi-) rigid Lever Arm.
Jason L. Speyer - One of the best experts on this subject based on the ideXlab platform.
-
experimental study on the estimation of Lever Arm in gps ins
IEEE Transactions on Vehicular Technology, 2006Co-Authors: Sinpyo Hong, Man Hyung Lee, Ho-hwan Chun, S.h. Kwon, Jason L. SpeyerAbstract:Lever-Arm uncertainty can be an important error source in the integration of the Global Positioning System (GPS) and inertial navigation system (INS). This paper presents both numerical and experimental studies on the estimation of the Lever Arm in the integration of a very-low-grade inertial measurement unit (IMU) with an accurate single-antenna GPS measurement system. Covariance simulation results showed that maneuvers play an important role on the estimation of the Lever Arm and attitude. The length of the Lever Arm has a rather insignificant effect on the estimation of these. Experimental tests conducted with a low-cost microelectromechanical system (MEMS) IMU and a carrier-phase differential GPS (CDGPS) measurement system showed that the Lever Arm can be estimated with centimeter-level accuracy. The test results confirmed that angular motions and horizontal accelerations improve the estimates of the Lever Arm and yaw angle, respectively.
-
Experimental study on the estimation of Lever Arm in GPS/INS
IEEE Transactions on Vehicular Technology, 2006Co-Authors: Sinpyo Hong, Man Hyung Lee, Ho-hwan Chun, S.h. Kwon, Jason L. SpeyerAbstract:Lever-Arm uncertainty can be an important error source in the integration of the Global Positioning System (GPS) and inertial navigation system (INS). This paper presents both numerical and experimental studies on the estimation of the Lever Arm in the integration of a very-low-grade inertial measurement unit (IMU) with an accurate single-antenna GPS measurement system. Covariance simulation results showed that maneuvers play an important role on the estimation of the Lever Arm and attitude. The length of the Lever Arm has a rather insignificant effect on the estimation of these. Experimental tests conducted with a low-cost microelectromechanical system (MEMS) IMU and a carrier-phase differential GPS (CDGPS) measurement system showed that the Lever Arm can be estimated with centimeter-level accuracy. The test results confirmed that angular motions and horizontal accelerations improve the estimates of the Lever Arm and yaw angle, respectively.