Two algorithms of working acceleration generated by a precision centrifuge with two rotating axes

The displacement of the origin of the accelerometer coordinate system relative to the origin of the base coordinate system is calculated by homogeneous transformation. The second order derivative of this displacement is the acceleration of the origin to the accelerometer coordinate system. By means of the attitude relationship between the base coordinate system and the accelerometer coordinate system, the acceleration components on the three coordinate axes is obtained. Utilizing the Coriolis rotation coordinate theorem, the three components are also calculated. The homogeneous transtbrmation method and vector differential method lead to identical results.

Direct calculation of acceleration field through homogeneous transformation for two-axis centrifuge

A precision centrifuge is an inertial navigation test equipment used for calibrating the characteristics of accelerometers with high overloading, and a two axis centrifuge can be used to generate either constant acceleration or harmonic acceleration. The moving trajectory equation about the origin of the accelerometer coordinate system in a two axis centrifuge was directly deduced through homogeneous transformation. The acceleration vector of the origin in accelerometer coordinate system was achieved by making the second derivative of this trajectory equation. The acceleration components were acquired by decomposing this acceleration vector along the three axes of the accelerometer coordinate system. The correctness of the homogeneous transformation was verified through vector analysis.

A Practical Strategy of Unbalance Identification and Correction for 2-DOF Precision Centrifuges

Unbalance existing in the mechanical systems is one of the most common causes which leads to unexpected vibration,nonsmooth motions,uncertain dynamics and even instability. In this paper,the problem of unbalance identification and correction is investigated for the countershaft system of a precision centrifuge with two degrees of freedom. According to the characteristics of the load under test installed on the countershaft,a gradual subdivision algorithm is proposed to identify the phase of the unbalance,and its amplitude is calculated by using a space vector algorithm,where the vibration information of the mainshaft system is obtained by utilizing two axis-layout displacement transducers installed associated to the mainshaft.Based on ADAMS software,some numerical simulations are presented and compared,and further,the validity of the strategy is demonstrated by experimental examples.

Evaluation of Variable Rate Technology for Fertilizer Application in Permanent Pastures

This paper describes the field tests carried out to evaluate the new Vicon RS-EDW centrifugal fertilizer spreader, to be used in Precision Agriculture. The results of initial dynamic calibration tests showed a significant and systematic difference between the application rates of the two discs （about 20%）. This difference had to be corrected by the manufacturer that carried out the necessary changes to the electric actuators. The fertilizer spreader had good distribution homogeneity, considering different working velocities and different positions in the parcel. The pattern distribution curve for 18% super phosphate fertilizer led to an effective working width of 28 meters, with a coefficient of variation of 15%. The longitudinal test, under experimental working conditions led to a machine delay time of 6-7 seconds. The results show an actual fertilization application density between 74%-90% of that determined for each location. These results confirm that the spreader can be used to spread fertilizer differentially in the field.