100 N·m negative step dynamic torque standard machine is used to calibrate the dynamic characteristics of torque transducer. Through measurement of negative step excitation time τ,it can get the inherent frequency ω_n. The paper describes the working principle, key technology, test data and the uncertainty analysis of the machine. The specification of machine is as follows: measurement range 100 N·m, τ ≤ 5ms, uncertainty U = 2.64%, k=2.

We present an AFM cantilever calibration system: Nano Force Calibrator (NFC), which can provide accurate spring constant calibrations with traceability to SI. Two types of commercial beam-shaped AFM cantilevers (contact and tapping mode) are investigated using the NFC. Uncertainty analysis reveals that the uncertainty of present method is less than 1%. In addition, comparison between other famous calibration methods (dimensional, cantileveron- cantilever, and Sader method) and the NFC method is performed to assess the uncertainties of other three methods. From the comparison results, we estimate that the uncertainties of dimensional, cantilever-on-cantilever, and Sader method are around 10-15%, 10%, and 15-40%, respectively.

An approach for calibrating a low-cost IMU is studied, requiring no mechanical platform for the accelerometer calibration and only a simple rotating table for the gyro calibration. The proposed calibration methods utilize the fact that ideally the norm of the measured output of the accelerometer and gyro cluster are equal to the magnitude of applied force and rotational velocity, respectively. This fact, together with model of the sensors is used to construct a cost function, which is minimized with respect to the unknown model parameters using Newton’s method. The performance of the calibration algorithm is compared with the Cram´er-Rao bound for the case when a mechanical platform is used to rotate the IMU into different precisely controlled orientations. Simulation results shows that the mean square error of the estimated sensor model parameters reaches the Cram´er-Rao bound within 8 dB, and thus the proposed method may be acceptable for a wide range of low-cost applications.

Three Methods for evaluating the dynamic response of force transducers against varying force are described in this paper. In all methods, the inertial force of a mass is used as the known dynamic force, and this reference force is applied to a force transducer under test. The inertial force is measured highly accurately as the product of the mass and the acceleration. An aerostatic linear bearing is used to obtain linear motion with sufficiently small friction acting on the mass (i.e., the moving part of the bearing). Three experimental setups were built for the dynamic calibration against an impact force, an oscillation force and a step force. Ways of establishing dynamic calibration methods are also discussed.

The reliability of the weighing system is becoming more and more important these years. This paper deals with a new approach to load cell soft failure prediction by the application of Grey theory. Grey theory is a theory which studies poor information and sets up a math model to simulate and predict a system behavior. Collecting the historical data of zero and sensitivity drift to set up a grey model GM (1.1) and with this model, the system can not only simulate the zero and sensitivity drifts but also calculates their possible value in the near future. Therefore, a previous action could be taken before zero and sensitivity running out of the acceptable range. This method is hoped to be able to improve the reliability of a system and have a potential future in the field of measurement.