Instantaneous rotation speed measurement and error analysis for variable speed hydraulic system

In order to monitor the working state of piston motor and measure its instantaneous rotation speed accurately, the measuring principle and method of instantaneous rotation speed based on industrial personal computer and data acquisition card are introduced, and the major error source, influence mechanism and processing method of data quantization error are dis- cussed. By means of hybrid programming approach of LabVIEW and MATLAB, the instantaneous rotation speed measurement system for the piston motor in variable speed hydraulic system is designed. The simulation and experimental results show that the designed instantaneous speed measurement system is feasible. Furthermore, the sampling frequency has an important influ- ence on the instantaneous rotation speed measurement of piston motor and higher sampling frequency can lower quantization er- ror and improve measurement accuracy.

Rotation speed measurement of moving particles in a CFB riser

This paper presents a study on measuring rotation speed of moving glass beads with an average diameter of 500 p.m in a pilot-scale circulating fluidized bed （CFB） riser with a high-speed digital imaging system. Two methods have been developed to calculate particle rotation speed from the particle images. The first method consists of a fully automated algorithm based on cross-correlation of gray distribution of particle images for particles whose rotation axes are （nearly） perpendicular to the imaging plane, and the second method calculates the speed of particle rotation by identifying its rotation axis using two or more characteristic points on its surface. The reliability of the two methods is verified by using a small sphere with known speed and direction of rotation. The first method is shown to be capable of measuring accurately the rotation speed for the particle with a rotation axis （nearly） perpendicular to the imaging plane and filtering off other particles using an appropriate threshold of correlation coefficient. The second method is shown to be capable of yielding both the speed and direction of particle rotation, with a measurement error of less than 10%. Results of both methods on real glass beads in a CFB riser are compared against each other.

Experimental Investigation of Electric Drive Dynamics

Induction motor is used in many applications to drive an electromechanical system. Transients of the motor torque and speed are outlined by the inertia of rotating rotor. The paper deals with influence of rotor inertia to transients of motor speed. The method of speed control measurement and experimental equipment is discussed. Simulation and experimental results are compared.

Novel laser Doppler tachometer

In order to improve the accuracy and universality of the rotational speed measurement,an instantaneous rotational speed measurement method based on laser Doppler technology is proposed.The composition and working principle of the new system are discussed in detail.Theoretical and experimental results show that the new rotational speed measurement system belongs to the non-contact method,which eliminates the quantization error of the contact method and greatly improves the applicability and accuracy.Compared to the commonly used method,the measurement accuracy of the new rotational speed measurement system will not be affected by the system’s installation angle deviation,and it does not need to measure the radius of the rotating body,so the influence of the radius fluctuation of the rotating body on the measurement accuracy can be avoided while outputting the rotational speed in real time.The relative error of the rotational speed measurement is less than 0.06%(1σ).