Position Measurement Method Research Articles

Attitude Measuring for Spinning Air Vehicle Based on Kinematics

The attitude measurement method of satellite navigation for spinning air vehicles is innovatively proposed. As an attitude measurement backup solution for inertial navigation system or magnetometer, based on kinematics principle, the velocity vector from GNSS receiver could be used to measure attitude for spinning air vehicles without any other sensors. The three-dimensional pseudo-attitude kinematics modelling is realized under the condition that the flight angle of attack and sideslip angle are small; the pseudo-attitude is transformed into inertial coordinates through Euler attitude matrix, and its accuracy index meets the actual working requirements.

Spacecraft Attitude Measurement and Control Integration Using a Novel Configuration of Variable Speed Magnetically Suspended Control and Sensing Gyroscope

For the sake of achieving the high-accuracy and high-bandwidth attitude measurement and control integration of flexible spacecraft, an integrated method based on a novel configuration of Variable Speed Magnetically Suspended Control and Sensitive Gyroscope (VSMSCSG) and Radial Basis Function (RBF) neural network control is proposed in this paper. First, the structure and principle of a novel VSMSCSG configuration are given, and its modelling is established. VSMSCSGs are employed as both actuators and attitude-rate sensors. Second, the attitude measurement method based on the configuration is proposed in the case of rotor spin speed and deflection angle changing. Based on the characteristics of the novel configuration, the corresponding RBF neural network attitude control law of spacecraft and the adaptive saturation avoidance steering laws of the VSMSCSGs have been further designed; the rotor can deflect at high frequency and change speed simultaneously to output a high bandwidth attitude control moment which dramatically improves the moment output capability of VSMSCSG configuration. Compared with the traditional method of attitude measurement and control integration, the proposed one not only improves the speed and accuracy of attitude control under high bandwidth disturbance but also greatly improves the accuracy of attitude measurement by fully using the dynamic information of novel configuration. Semiphysical simulation results demonstrate the correctness and superiority of the proposed method.

Position and Direction Measurement of Rock Bolt Hole Using Cross Line Laser and Camera

In this paper, we propose a new position and direction measurement method of rock bolt hole with a cross line laser. A combination of the light-sectioning method and a hole detection in an image is used to estimate a hole position and direction. Experimental results in a tunnel under construction show that the proposed method can measure positions and directions with high accuracy.

Model position sensing method for low fineness ratio models in a magnetic suspension and balance system.

A new model-position-sensing method for the levitation of models with a low fineness ratio (ratio of the longitudinal length to the diameter) in a magnetic suspension and balance system (MSBS) is proposed. MSBS is an ideal model-support device for wind-tunnel testing, which enables the study of flow fields around blunt bodies without flow disturbances introduced by mechanical support devices, with the aerodynamic forces determined from the magnetic forces using a pre-calibrated relationship. The new method allows wind tunnel experiments without mechanical supports with a low fineness ratio model. This method adopts two line sensors placed parallel to the central axis of the model image and measures the position with a resolution finer than 0.06mm or degeven for thin model geometries. In addition, measurement errors were reduced by correcting a second-order term in the depth direction of the camera. A low fineness ratio circular cylinder model was levitated following sensor calibration. The model was supported in conditions with and without freestream flow. This position measurement method was also applied to a reentry capsule model. The model was levitated while keeping its position and attitude stabilized near the origin.

2D absolute position measurement based on the hybrid encoding method.

This paper introduces a new method of absolute position measurement based on the hybrid encoding principle that can precisely measure the absolute position of a two-dimensional (2D) micro displacement table. The method uses pseudo-random sequences and binary codes to generate the long-distance position encoding sequences. It combines the encoding sequences with checkerboards to form a hybrid encoding to complete the design of the 2D encoding of plane positions. Then a 2D encoding disk is designed as a tool to measure 2D absolute position. Among them, the X and Y positions are designed by the modular approach, respectively, to efficiently detect the accuracy of 2D position values during the measurement. Moreover, the designed 2D encoding disk can quickly realize image correction. In order to verify the feasibility of the designed 2D encoding disk for measuring the 2D absolute position, the corresponding measurement system is built using a 2D encoding disk, a CCD camera, and a telecentric lens. The experimental results demonstrate that the average position deviation of the 2D absolute position measurement system is less than ±1 µm.

A Review of Position and Orientation Visual Measurement Methods and Applications

A Review of Position and Orientation Visual Measurement Methods and Applications

A Super-High-Accuracy Attitude Measurement Method of SINS Based on PWQHN Algorithm in the High-Dynamic Maneuver Environment

To reduce noncommutative error (NCE) and improve the attitude-update accuracy in the attitude algorithm of the strapdown inertial navigation system (SINS), we assume that angular rate is represented as a polynomial to deduce the relationship between the angular increment sampling sequence and the derivatives of the quaternion. Subsequently, a high-order numerical solution of the quaternion differential equation is obtained by substituting the derivatives of the quaternion into its Taylor expansion. Generally, the quaternion will be constructed with a series of angular increment samples in a constant updating interval. Furthermore, the piecewise quaternion high-order numerical (PWQHN) algorithm is deduced by reconstructing quaternion in each sampling interval to ulteriorly improve attitude accuracy. The simulation results indicate that the PWQHN algorithm is stable in two kinds of simulation conditions. In the coning motion condition, PWQHN algorithm has the highest accuracy. In the high-dynamic condition, the extreme accuracy of PWQHN is not significantly higher than other algorithms. However, PWQHN can still output accurate attitude in the situation without many angular increment subsamples.

Modelling and testing the measurement repeatability of linear and angular positions of a measuring arm (miniature NaviFAST 6D DEVICE)

This paper presents the use of a 6 DoF position measurement method with the NaviFast6D device, which is a short-range measuring arm for linear and angular position measurements. The device is used in the measurement of correct hip prosthesis fixation during hip surgery. The arm is equipped only with accelerometers, which is an innovative application that needs to be verified. The described experimental tests of determining the repeatability of the NaviFast6D demonstrated the correctness of the method. The analysis of the measurement repeatability limitations in the measurement and the dependence of the measurement repeatability on the arm base position, was described in detail. The need for about 400 repetitions of the measurement to obtain repeatability of measurement averaged in the range of 0,1 ÷ 0,2 mm was demonstrated. The applicability of the measuring arm in the case of approaching to the vertical of any axis of the arm joints was determined.

Fiber position measurement method in LAMOST based on external planar target

In the Large Sky Area Multi-Object Fiber Spectroscopic Telescope (LAMOST) project, the fiber should precisely align with the celestial target to obtain the spectrum of the star, and the position accuracy of the fiber in the focal plane directly affects the spectral quality. LAMOST uses photogrammetry to acquire the actual position of the fiber. However, the fiber view camera system without precise internal control points in the focal plane negatively affects measurement precision. To solve this problem, we propose a fiber position measurement method based on the external planar target (EPT) that replaces the internal control points with the external control points; multiview reconstruction and bundle adjustment with additional position constraints are used to calculate the position of the fibers. The validity of the measurement method is verified by the simulation and experiment. The preliminary results show that the method has good stability and the measurement accuracy of the fibers can reach 20 μm. Because the external control points are distributed on the EPT plane, the assembly error of the EPT and focal plane does not affect the measurement accuracy. Therefore, the proposed method can achieve precision measurement under nonprecision installation conditions.

A method of attitude measurement and level assessment for skiers based on wearable inertial measurement

<p>Quantitative analysis of sports is an important development direction of scientific skiing training, and the digital expression of human movement patterns during skiing is the basis for scientific quantitative analysis. A human motion capture and attitude reconstruction system based on a wearable BSBD inertial measurement unit was designed and built, combined with the human multi-rigid body motion model to realize the human body reconstruction during the skiing, and applied to the auxiliary training of slewing movements in alpine skiing. At the same time, for the indoor training scene based on the multi-degree-of-freedom simulated ski training platform, a digital evaluation method suitable for ski slalom is proposed. The method uses motion capture system and posture reconstruction system to extract five kinds of sliding characteristic data of skiers, and realizes the evaluation of skiers’ technical parameters through similarity measurement and linear fitting with high-level athletes’ motion parameters, so as to assist scientific training. Finally, experiments are carried out on the indoor Olymp simulated ski training bench to verify the effectiveness of the method.</p>

Spherical actuator attitude measurement method based on multi-to-one WPT modeling

The measurement system of contact spherical actuator has the disadvantages of large friction resistance and poor rotor positioning accuracy. The structure or calculation of non-contact attitude measurement system is complicated. In order to solve the above problems, a multi-to-one wireless power transmission (WPT) spherical actuator attitude measurement method is proposed. The model of mutual inductance(MI) is built. This method effectively shortens the time of finite element analysis(FEA). Three motion states (spin, yaw and tilt) of actuator rotor are analyzed by using this measurement method. Compared with the micro electro mechanical system (MEMS) and fast complementary filter (FCF), the initial attitude error of this method is about 50% of that of the other two methods. Compared with MEMS method, the average angle error of WPT method is reduced by 35%. Experimental results show that this method has good real-time performance and repeatability.

Attitude measurement of multi-DOF actuator based on multiple-inputs and single-output WPT system modeling

Multi-DOF actuators are used in bionics where their flexibility is limited by changing batteries or wired charging methods. In order to realize flexible power supplement and accurate attitude measurement, a multiple-inputs and single-output wireless power transmission (WPT) attitude measurement method is proposed. Traditional contact measurement methods have large friction resistance, and some non-contact measurement methods are complicated in structure or calculation. In order to solve the above problems, the receiving coil is installed inside the rotor. When the rotor rotates, the receiving angle is offset from the multi-transmitting coil outside the stator. The receiving coil can transmit power with multi-angle rotation and has good space tolerance. The rotor position is measured by estimating mutual inductance accurately. This method effectively reduces the time of finite element analysis. Three types of exercise are tested (yaw, spin, and tilt). Compared with micro-electromechanical system and fast complementary filter methods, the average angle error of the proposed WPT method is reduced by 36%, 24% and 40% respectively, and the initial attitude error is about 50% of that of the other two methods. Experiments show that this method can accurately measure the attitude of the rotor of the multi-DOF actuator.

An attitude measurement method of industrial robots based on the inertial technology

AbstractThe attitude control error of the robot end-effector directly affects the manufacturing accuracy. The study aims to develop a real-time measurement method of the industrial robot end-effector attitude in the field environment for improving the control accuracy of robot attitude.In this paper, an attitude measurement method of robot end-effector based on the inertial technology was proposed. First, an inertial measurement system was designed, and the measurement parameters and installation errors were calibrated. Then the inertia measurement principle of robot end-effector attitude was explored, and the robot end-effector attitude measurement was realized with the fourth-order Runge−Kutta algorithm. In addition, the influence of the data processing algorithm and sampling frequency on the attitude accuracy was analyzed. Finally, a test platform was built to experimentally explore the proposed inertial measurement method.The inertial measured data were compared with the data obtained with the laser tracker. The measurement accuracy of the inertial measurement method reached 0.15°, which met the accuracy requirements of real-time measurements of robot end-effector attitude in the manufacturing field.The method proposed in this paper is convenient and can realize the real-time attitude measurement of industrial robot. The measurement results can compensate the attitude control error of the robot end-effector and improve the attitude control accuracy of the robot.

Position and Pose Measurement of 3-PRS Ankle Rehabilitation Robot Based on Deep Learning

Introduction: The position and pose measurement of the rehabilitation robot plays a very important role in patient rehabilitation movement, and the non-contact real-time robot position and pose measurement is of great significance. Rehabilitation training is a relatively complicated process, so it is very important to detect the training process of the rehabilitation robot in real time and accuracy. The method of the deep learning has a very good effect on monitoring the rehabilitation robot state. Methods: The structure sketch and the 3D model of the 3-PRS ankle rehabilitation robot are established, and the mechanism kinematics is analyzed to obtain the relationship between the driving input - the three slider heights - and the position and pose parameters. The whole network of the position and pose measurement is composed of two stages: (1) measuring the slider heights using the CNN based on the robot image and (2) calculating the position and pose parameter using the BPNN based on the measured slider heights from the CNN. According to the characteristics of continuous variation of the slider heights, a regression CNN is proposed and established to measure the robot slider height. Based on the data calculated by using the inverse kinematics of the 3-PRS ankle rehabilitation robot, a BPNN is established to solve the forward kinematics for the position and pose. Results: The experimental results show that the regression CNN outputs the slider height and then the BPNN accurately outputs the corresponding position and pose. Eventually, the position and pose parameters are obtained from the robot image. Compared with the traditional robot position and pose measurement method, the proposed method has significant advantages. Conclusion: The proposed 3-PRS ankle rehabilitation position and pose method can not only shorten the experiment period and cost, but also get excellent timeliness and precision. The proposed approach can help the medical staff to monitor the status of the rehabilitation robot and help the patient rehabilitation in training. Discussion: The goal of the work is to construct a new position and pose detection network based on the combination of the regression convolutional neural network (CNN) and the back propagation neural network (BPNN). The main contribution is to measure the position and pose of the 3-PRS ankle rehabilitation robot in real time, which improves the measurement accuracy and the efficiency of the medical staff work.

Rapid Position and Pose Measurement Method for Segment Girder Formwork in Precast Girder Yard

Rapid Position and Pose Measurement Method for Segment Girder Formwork in Precast Girder Yard

A Position and Attitude Measurement Method Based on Laser Displacement Sensor and Infrared Vision Camera

The position and attitude measurement of objects plays an important role in industrial manufacture and inspection. However, in the existing measurement methods, the challenges brought by the environmental uncertainty to the visual measurement algorithm and the coordinate conversion errors caused by the joint measurement of various precision equipment will lead to poor accuracy and stability. In this paper, a measurement method is proposed to measure the object’s position and attitude based on laser displacement sensor and infrared vision camera. Firstly, when measuring the position and attitude, the combination of infrared vision camera and measurement target is an effective method to solve the challenges brought by environmental changes and measurement target changes in visual measurement methods. In addition, the measurement results and data of the whole system need not be converted between multiple coordinate systems, which avoids the complexity of system calculation and coordinate conversion errors. Through position and attitude measuring experiments, the position measurement error is 2.6 mm and the attitude angle measurement error is 1.1°, which verifies the feasibility and stability of the method.

High Update Rate Attitude Measurement Method of Star Sensors Based on Star Point Correction of Rolling Shutter Exposure.

Attitude update rate is one of the important indicators of star sensor performance. In order to resolve the problem of the low attitude update rate of star sensors, this paper proposes a star sensor attitude update method based on star point correction of rolling shutter exposure. Based on the characteristics of the asynchronous exposure of the rolling shutter, recursive estimation of the motion attitude and the corrected star point information were combined to realize multiple updates of the attitude in a single frame of the star map. Simulation and experimental results proved that the proposed method could increase the attitude update rate of a star sensor by 15 times, up to 150 Hz.

Development of Integrated Innovation Experiment Platform Based on 3- PRS Parallel Mechanism

Background: The parallel mechanism plays an important role in various fields. The multifunctional integrated innovation experiment platform can improve the utilization rate of the mechanism and be applied in many fields. Objective: The main objective of the study is to establish an integrated innovation experiment platform based on the 3-PRS parallel mechanism, which can be used in typical application and related technology development. Methods: The integrated innovation experiment platform is established and analyzed based on the 3-PRS parallel mechanism. According to the 3D model of the experiment platform, the kinematics and dynamics are analyzed. The force/position control strategy of the system is adopted. According to the function of the experiment platform, two kinds of application and the position and pose measurement technology are developed. The experiment platform is developed by the following methods: (1) The XY table is set up on the fixing platform of the 3-PRS parallel mechanism, so that the mechanism has five degrees of freedom, and the many kinds of workpiece can be easily processed. (2) By selecting the impedance parameter, the experiment platform can realize the compliant control of plantar flexion/dorsiflexion and varus/eversion simultaneously. (3) The binocular vision position and pose measurement method is used to obtain the marked images of the experiment platform through dual cameras, and the position and pose is obtained through image processing, 3D reconstruction and stereo matching, etc. (4) The position and pose detection based on deep learning is divided into two parts: one is to detect the slider height using the regression Convolutional Neural Network (CNN); the other is to compute the position and pose using the Back Propagation Neural Network (BPNN). Results: The experiment results show that the function of the 3-PRS parallel mechanism integrated innovation experiment platform can be effectively realized. The position and pose can be accurately measured in real time using the proposed two measurement methods. The impedance parameters are selected to achieve the rehabilitation training function of the 3-PRS ankle rehabilitation robot and the characters are processed to verify the function of the 3-PRS-XY series-parallel machine tool. Conclusion: The integrated innovation experiment platform based on the 3-PRS parallel mechanism can achieve the function of mechanical processing and rehabilitation training, and can also measure the state of motion in real time through machine vision and deep learning.

Target Positioning Optimization Method in Power System

This thesis presents a method that a position measurement method for moving targets is proposed based on the positioning method based on the time difference of arrival (TDOA) which is based on the research on the positioning problem of station inspection operators and equipment in complex working conditions. The probability error method is introduced to optimize the traditional positioning method that realizes the target node positioning by optimizing the distance difference between the target node to be located in the network domain environment and different base stations, which can effectively improve the positioning accuracy of staff and equipment in the station. Through experiments in a complex power frequency electric field environment, the test results show that the results calculated by the optimization method are better than the existing traditional positioning methods, and can effectively improve the positioning accuracy under the condition of line-of-sight, and realize the substation space Mobile target positioning to ensure the safety of operators.

Infrared focal plane array attitude measurement method based on adaptive fault-tolerant extended Kalman filter

To improve the anti-jamming ability of infrared attitude measurement methods, the infrared focal plane array (IRFPA) fault diagnosis method was investigated with regard to small-region and full-region infrared interference, respectively. An adaptive fault-tolerant extended Kalman filter algorithm is proposed to actively remove the infrared interference data in the case of small-region infrared interference and carry out attitude estimation with the mathematical model under full-region infrared interference. The results reveal that the adaptive fault-tolerant extended Kalman filter has stronger anti-jamming ability compared with the conventional extended Kalman filter. Additionally, the adaptive fault-tolerant extended Kalman filter can maintain the attitude estimation accuracy of ±0.8° when full-region infrared interference doesn't exist or if most IRFPA data are reliable. Apart from missile navigation, the framework of the adaptive fault-tolerant extended Kalman filter can be applied to almost all applications using extended Kalman filter, such as aircraft, vehicular navigation, indoor positioning, and target tracking, etc.