Minimum Settings Calibration Method for Low-Cost Tri-Axial IMU and Magnetometer

Abstract This manuscript presents a minimum settings calibration method for low-cost tri-axial inertial measurement units (IMU) and magnetometers. At ﬁrst, we analyze the major defect of the traditional calibration methods for tri-axial accelerometers and magnetometers. To ﬁx that problem, we just utilize the ellipsoid model to calibrate the tri-axial accelerometer and magnetometer preliminarily, then complete the calibration work with at least two reference angular positions, and prove that two reference angular positions are minimum requirements in the calibration progress. Next, the tri-axial gyroscope is calibrated based on the nonlinear cost function with the aid of the pre-calibrated accelerometer. The simulation and real-world experiment results show that the proposed method is practical and effective, suggesting that this technique is a viable candidate for the IMU and magnetometer applications.

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Optimized Multi-Position Calibration Method with Nonlinear Scale Factor for Inertial Measurement Units

Sensors ◽

10.3390/s19163568 ◽

2019 ◽

Vol 19 (16) ◽

pp. 3568 ◽

Cited By ~ 5

Author(s):

Wang ◽

Cheng ◽

Keyword(s):

Calibration Method ◽

Scale Factor ◽

Inertial Measurement Units ◽

Inertial Measurement ◽

Initial Values ◽

Scale Factors ◽

Calibration Methods ◽

Measurement Units ◽

Position Calibration ◽

Nonlinear Scale

Navigation grade inertial measurement units (IMUs) should be calibrated after Inertial Navigation Systems (INSs) are assembled and be re-calibrated after certain periods of time. The multi-position calibration methods with advantage of not requiring high-precision equipment are widely discussed. However, the existing multi-position calibration methods for IMU are based on the model of linear scale factors. To improve the precision of INS, the nonlinear scale factors should be calibrated accurately. This paper proposes an optimized multi-position calibration method with nonlinear scale factor for IMU, and the optimal calibration motion of IMU has been designed based on the analysis of sensitivity of the cost function to the calibration parameters. Besides, in order to improve the accuracy and robustness of the optimization, an estimation method on initial values is presented to solve the problem of setting initial values for iterative methods. Simulations and experiments show that the proposed method outperforms the calibration method without nonlinear scale factors. The navigation accuracy of INS can be improved by up to 17% in lab conditions and 12% in the moving vehicle experiment, respectively.

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An improved multi-position calibration method for low cost micro-electro mechanical systems inertial measurement units

Proceedings of the Institution of Mechanical Engineers Part G Journal of Aerospace Engineering ◽

10.1177/0954410014562262 ◽

2014 ◽

Vol 229 (10) ◽

pp. 1919-1930 ◽

Cited By ~ 8

Author(s):

Zhijian Ding ◽

Hong Cai ◽

Huabo Yang

Keyword(s):

Low Cost ◽

Mechanical Systems ◽

Calibration Method ◽

Inertial Measurement Units ◽

Micro Electro Mechanical Systems ◽

Inertial Measurement ◽

Measurement Units ◽

Position Calibration

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Testing of the Possibilities of Using IMUs with Different Types of Movements

Geoinformatics FCE CTU ◽

10.14311/gi.12.10 ◽

2014 ◽

Vol 12 ◽

pp. 61-66 ◽

Cited By ~ 2

Author(s):

Pavol Kajánek

Keyword(s):

Inertial Navigation System ◽

Low Cost ◽

Indoor Navigation ◽

Integrated System ◽

Test Results ◽

Inertial Measurement Units ◽

Inertial Measurement ◽

Improve Accuracy ◽

Different Types ◽

Measurement Units

Inertial navigation system (INS) is a self-contained navigation technique. Its main purpose is to determinate the position and the trajectory of the object´s movement in space. This technique is well represented not only as a supplementary method (GPS/INS integrated system) but as an autonomous system for navigation of vehicles and pedestrians, also. The aim of this paper is to design a test for low-cost inertial measurement units. The test results give us information about accuracy, which determine the possible use in indoor navigation or other applications. There are described some methods for processing the data obtained by inertial measurement units, which remove noise and improve accuracy of position and orientation.

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POF-IMU sensor system: A fusion between inertial measurement units and POF sensors for low-cost and highly reliable systems

Optical Fiber Technology ◽

10.1016/j.yofte.2018.04.012 ◽

2018 ◽

Vol 43 ◽

pp. 82-89 ◽

Cited By ~ 4

Author(s):

Arnaldo G. Leal-Junior ◽

Laura Vargas-Valencia ◽

Wilian M. dos Santos ◽

Felipe B.A. Schneider ◽

Adriano A.G. Siqueira ◽

...

Keyword(s):

Low Cost ◽

Sensor System ◽

Inertial Measurement Units ◽

Inertial Measurement ◽

System A ◽

Reliable Systems ◽

Measurement Units

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On Using Inertial Measurement Units for Solving the Direct Kinematics Problem of Parallel Mechanisms

Robotics ◽

10.3390/robotics8040099 ◽

2019 ◽

Vol 8 (4) ◽

pp. 99

Author(s):

Stefan Schulz

Keyword(s):

Low Cost ◽

Parallel Mechanisms ◽

Inertial Measurement Units ◽

Inertial Measurement ◽

Sensor Structure ◽

Prismatic Joints ◽

Measurement Units ◽

Linear Actuators ◽

Achievable Accuracy ◽

Direct Kinematics

In this paper, we investigate the accuracy and the computational efficiency of an IMU-based approach for solving the direct kinematics problem of parallel mechanisms with length-variable linear actuators under dynamic conditions. By avoiding to measure the linear actuators’ lengths and by using orientations instead, a comprehensive, low-cost sensor structure can be obtained that provides a unique solution for the direct kinematics problem. As a representative example, we apply our approach to the planar 3-RPR parallel mechanism, where P denotes active prismatic joints and R denotes passive revolute joints, and investigate the achievable accuracy and robustness on a specially designed experimental device. In this context, we also investigate the effect of sensor fusion on the achievable accuracy and compare our results with those obtained from linear actuators’ lengths when the Newton-Raphson algorithm is used to compute the manipulator platform’s pose iteratively. Finally, we discuss the applicability of inertial measurement units (IMUs) for solving the direct kinematics problem of parallel mechanisms.

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Technology in Rehabilitation: Evaluating the Single Leg Squat Exercise with Wearable Inertial Measurement Units

Methods of Information in Medicine ◽

10.3414/me16-02-0002 ◽

2017 ◽

Vol 56 (02) ◽

pp. 88-94 ◽

Cited By ~ 24

Author(s):

Tomás E. Ward ◽

Eamonn Delahunt ◽

Brian Caulfield ◽

Darragh F. Whelan ◽

Martin A. O'Reilly

Keyword(s):

Lumbar Spine ◽

Lower Limb ◽

Low Cost ◽

Objective Evaluation ◽

Inertial Measurement Units ◽

Lower Limb Injury ◽

Inertial Measurement ◽

Increased Risk ◽

Measurement Units ◽

Single Leg Squat

SummaryBackground: The single leg squat (SLS) is a common lower limb rehabilitation exercise. It is also frequently used as an evaluative exercise to screen for an increased risk of lower limb injury. To date athlete/patient SLS technique has been assessed using expensive laboratory equipment or subjective clinical judgement; both of which are not without shortcomings. Inertial measurement units (IMUs) may offer a low cost solution for the objective evaluation of athlete/patient SLS technique.Objectives: The aims of this study were to determine if in combination or in isolation IMUs positioned on the lumbar spine, thigh and shank are capable of: (a) distinguishing between acceptable and aberrant SLS technique; (b) identifying specific deviations from acceptable SLS technique.Methods: Eighty-three healthy volunteers participated (60 males, 23 females, age: 24.68 +/− 4.91 years, height: 1.75 +/− 0.09 m, body mass: 76.01 +/− 13.29 kg). All participants performed 10 SLSs on their left leg. IMUs were positioned on participants’ lumbar spine, left shank and left thigh. These were utilized to record tri-axial accelerometer, gyroscope and magnetometer data during all repetitions of the SLS. SLS technique was labelled by a Chartered Physiotherapist using an evaluation framework. Features were extracted from the labelled sensor data. These features were used to train and evaluate a variety of random-forests classifiers that assessed SLS technique.Results: A three IMU system was moderately successful in detecting the overall quality of SLS performance (77% accuracy, 77% sensitivity and 78% specificity). A single IMU worn on the shank can complete the same analysis with 76% accuracy, 75% sensitivity and 76% specificity. Single sensors also produce competitive classification scores relative to multi-sensor systems in identifying specific deviations from acceptable SLS technique.Conclusions: A single IMU positioned on the shank can differentiate between acceptable and aberrant SLS technique with moderate levels of accuracy. It can also capably identify specific deviations from optimal SLS performance. IMUs may offer a low cost solution for the objective evaluation of SLS performance. Additionally, the classifiers described may provide useful input to an exercise biofeed-back application.

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