Kinematic Analysis of Persian Joint Using 3D Rotation Matrix

This paper has been done on study kinematic problem of Persian joint in a general way. In this study, instead of using simulation analysis method as in the previous researches, the 3D rotation matrix method is applied to present the relationship of angular velocities of input shaft and output shaft. The result shows that when the angle between intersecting shafts changes from 0 to 135°, the angular velocity is maintained constant. This new result completely matches with analysis from kinematic simulation of this mechanism. The obtained result is an important base to solve dynamic problem in order to develop the applicability of this joint in reality.

ENGINEERING REALIZATION OF MULTIPLE ANTENNA GPS IN ATTITUDE DETERMINATION INTEGRATED SYSTEM

A multiple antenna GPS system integrated with MEMS-based INS is proposed by data fusion. The system is applied to attitude determination due to its high accuracy, the high output rate, low latency, quick initialization, and good robustness and redundancy. The mathematical method for realizing the system is given. The system can provide attitude and other navigation information even without GPS measurement for a period of time. Experimental results show that, under the condition of 200 Hz, the attitude, the position, the velocity, the acceleration, and the angular rate can achieve 0. 08°/s, 1.5 m, 0. 1 m/s, 0. 12 m/s^2 and 0. 1°/s.

Adaptive filter for a miniature MEMS based attitude and heading reference system

An extended Kalman filter with adaptive gain was used to build a miniature attitude and heading reference system based on a stochastie model. The adaptive filter has six states with a time variable transition matrix. When the system is in the non-acceleration mode, the accelerometer measurements of the gravity and the compass measurements of the heading have observability and yield good eslimates of the states. When the system is in the high dynamic mode and the bias has converged to an aceurate estimate, the attitude caleulation will be maintained for a long interval of time. The adaptive filter tunes its gain automatically based on the system dynamics sensed by the accelerometers to yield optimal performance,

Research on Open-circuit Fault Tolerant Control of Six-phase Permanent Magnet Synchronous Machine Based on Fifth Harmonic Current Injection

This paper proposes a novel control approach for fault-tolerant control of dual three-phase permanent magnet synchronous motor(PMSM) under one-phase open-circuit fault.A modified six-phase static coordinate transformation matrix and an extended rotating coordinate transformation matrix are investigated considering the influence of the fifth harmonic space on fault-tolerant control. These mathematical models are further analyzed in the fundamental space and the fifth harmonic space after the fault and to eliminate the coupling between the d-q axis voltage equation in the fundamental wave space and the d-q axis voltage equation in the fifth harmonic space, a secondary rotation coordinate transformation matrix is proposed. To achieve the purpose of reducing torque ripple, the fault-tolerant control method proposed in this paper not only takes the minimum copper loss as the constraint condition, but also injects the fifth harmonic current. The experimental result of current and torque is used to verify the accuracy of fault-tolerant control.

Hand-eye calibration with a new linear decomposition algorithm

To solve the homogeneous transformation equation of the form AX=XB in hand-eye calibration, where X represents an unknown transformation from the camera to the robot hand, and A and B denote the known movement transformations associated with the robot hand and the camera, respectively, this paper introduces a new linear decomposition algorithm which consists of singular value decomposition followed by the estimation of the optimal rotation matrix and the least squares equation to solve the rotation matrix of X. Without the requirements of traditional methods that A and B be rigid transformations with the same rotation angle, it enables the extension to non-rigid transformations for A and B. The details of our method are given, together with a short discussion of experimental results, showing that more precision and robustness can be achieved.

Disturbance observer based finite-time coordinated attitude tracking control for spacecraft on SO(3)

To solve the problem of attitude synchronization control for spacecraft formation flying(SFF)suffering from external disturbances under a directed communication topology,a sliding mode disturbance observer(SMDO)based on the finite-time control strategy is developed to observe the time-varying external disturbance via estimating the upper bound of its first derivative.Meanwhile,the rotation matrix is employed to describe the attitude of SFF for the purpose of the avoidance of singularity and unwinding phenomenon.As for the attitude synchronization and the tracking control architecture,a sliding mode surface(SMS)is given such that the control objective can be achieved.The effectiveness and the validity of the proposed method are elaborated via theoretical analysis and numerical simulations.

ROTATION CONSTELLATION FOR DIFFERENTIAL UNITARY SPACE-TIME MODULATION

A new constellation which is the multiplication of the rotation matrix and the diagonal matrix ac- cording to the number of transmitters is proposed to increase the diversity product, the key property to the performance of the differential unitary space-time modulation. Analyses and the simulation results show that the proposed constellation performs better and 2dB or more coding gain can be achieved over the traditional cyclic constellation.

Rotation Estimation for Mobile Robot Based on Single-axis Gyroscope and Monocular Camera

The rotation matrix estimation problem is a keypoint for mobile robot localization, navigation, and control. Based on the quaternion theory and the epipolar geometry, an extended Kalman filter (EKF) algorithm is proposed to estimate the rotation matrix by using a single-axis gyroscope and the image points correspondence from a monocular camera. The experimental results show that the precision of mobile robot s yaw angle estimated by the proposed EKF algorithm is much better than the results given by the image-only and gyroscope-only method, which demonstrates that our method is a preferable way to estimate the rotation for the autonomous mobile robot applications.

Method for Workspace Calculation of 6R Serial Manipulator Based on Surface Enveloping and Overlaying

Aiming at the workspace calculation problem of multi-joint serial manipulators,a surface enveloping and overlaying (SEO) method is presented to identify and visualize the manipulator workspace.The SEO method is composed of two stages:the first stage is to choose reference points of the manipulator and calculate their boundary surfaces using the nth enveloping method;the second stage is to overlay these boundary surfaces to identify the final workspace.The SEO method is basically a combination of the analytic method and the numerical method.By delineating the graphic representation of the workspace step by step,the SEO method is easy to analyze the existence and the shape of voids and holes.The basic theory of the SEO method and formulas for workspace calculation are presented based on a 6R serial manipulator.By showing the workspace calculation results,the SEO method is proved working correctly.

Column-orthogonal designs with multi-dimensional stratifications

The orthogonal Latin hypercube design and its relaxation,and column-orthogonal design,are two kinds of orthogonal designs for computer experiments.However,they usually do not achieve maximum stratifications in multi-dimensional margins.In this paper,we propose some methods to construct column-orthogonal designs with multi-dimensional stratifications by rotating symmetric and asymmetric orthogonal arrays.The newly constructed column-orthogonal designs ensure that the estimates of all linear effects are uncorrelated with each other and even uncorrelated with the estimates of all second-order effects(quadratic effects and bilinear effects)when the rotated orthogonal arrays have strength larger than two.Besides orthogonality,the resulting designs also preserve better space-filling properties than those constructed by using the existing methods.In addition,we provide a method to construct a new class of orthogonal Latin hypercube designs with multi-dimensional stratifications by rotating regular factorial designs.Some newly constructed orthogonal Latin hypercube designs are tabulated for practical use.

Detecting the filamentary structure of 3D point clouds:Proposal of a wavelet-based method

The analysis of the filamentary structure of the cosmo as well as that of the internal structure of the polar ice suggests the development of models based on three-dimensional(3D)point processes.A point process,regarded as a random measure,can be expressed as a sum of Delta Dirac measures concentrated at some random points.The integration with respect to the point process leads the continuous wavelet transform of the process itself.As possible mother wavelets,we propose the application of the Mexican hat and the Morlet wavelet in order to implement the scale-angle energy density of the process,depending on the dilation parameter and on the three angles which define the direction in the Euclidean space.Such indicator proves to be a sensitive detector of any variation in the direction and it can be successfully implemented to study the isotropy or the filamentary structure in 3D point patterns.