Papers by Keyword: Sensor Calibration

Abstract: Impact type grain flow sensor for crop yield monitoring is known to have problem of some thrown grain by the elevator conveyor in a combine not hitting the sensing impact plate. New technology of microwave solid flow sensor was used to solve the problem of impact-type sensor. A calibration stand with its instrumentation systems to stimulate the actual operation of the clean grain auger in a rice combine had been designed and constructed in this study for the purpose of conducting the calibration and evaluation study of the sensor. Two different solid flow sensor orientations and three different solid flow sensor extrusions were investigated in order to find the best positioning of the sensor on the chute for the measurement. Results from the conducted tests indicates that the best sensor positioning is on totally flat ground at 180^o orientation and 8 cm extrusion of the chute cross section (R²=0.9400). Then, the solid flow sensor was tested at seven chute pitch angle positions (i.e-4.5^o, -3.0^o, -1.5^o, 0^o, +1.5^o, + 3.0^o, and +4.5 ^o), seven chute roll angle positions (i.e-4.5^o,-3.0^o, -1.5 ^o, 0^o, +1.5^o, +3.0 ^o, and +4.5^o). Finally, accuracy tests undertaken to compare the real time measurements against the average flow measurements. ANOVA test shows that both pitch angle and roll angle positions have significant effects on the measurement accuracy of the sensor. The measurement errors increased with increasing roll angles and increasing pitch angle. Conclusively, this conducted laboratory study was able to quantify the measurement accuracy of the SWR Solid Flow sensor for real-time measurement of grain flow under a simulated laboratory rice combine test set-up.

Abstract: This paper proposed a calibration method of sheet-of-light vision measurement sensor based on light plane constraint. Through capturing 12 images of different direction from homemade circular calibration target, the center of the circle and the light stripe is extracted based on Halcon platform of Germany. The experimental results obtained the intrinsic parameters, extrinsic parameters and radial distortion coefficient of the nonlinear model. At the same time the light plane constraint equation is got based on PCA plane fitting method. The results show that the calibration method is simple and reliable, and the method does not need any auxiliary adjustment. The work laid the better foundation for hard disk planeness vision measurement.

Abstract: This paper presents a calibration procedure for a Kinect RGB-D sensor and its application to robot simultaneous localization and mapping(SLAM). The calibration procedure consists of two stages: in the first stage, the RGB image is aligned with the depth image by using the bilinear interpolation. The distorted RGB image is further corrected in the second stage. The calibrated RGB-D sensor is used as the sensing device for robot navigation in unknown environment. In SLAM tasks, the speeded-up robust features (SURF) are detected from the RGB image and used as landmarks in the environment map. The depth image could provide the stereo information of each landmark. Meanwhile, the robot estimates its own state and landmark locations by mean of the Extended Kalman filter (EKF). The EKF SLAM has been carried out in the paper and the experimental results showed that the Kinect sensors could provide the mobile robot reliable measurement information when navigating in unknown environment.

Abstract: This paper deals with attitude determination, parameter identification and reference sensor calibration simultaneously. A LEO satellite’s attitude, inertia tensor as well as calibration of Three-Axis-Magnetometer (TAM) are estimated during a maneuver designed to satisfy persistency of excitation condition. For this purpose, kinematic and kinetic state equations of spacecraft motion are augmented for the determination of inertia tensor and TAM calibration parameters including scale factors, misalignments and biases along three body axes. Attitude determination is a nonlinear estimation problem. Unscented Kalman Filter (UKF) as an advanced nonlinear estimation algorithm with good performance can be used to estimate satellite attitude but its computational cost is considerably larger than the widespread, low accuracy, Extended Kalman Filter (EKF). Reduced Sigma Points Filters provide good solutions and also decrease run time of UKF. However, in contrast to nonlinear problem of attitude determination, parameter identification and sensor calibration have linear dynamics. Therefore, a new Marginal UKF (MUKF) is proposed that combines the utility of Kalman Filter with Modified UKF (MMUKF). The proposed MMUKF utilizes only 14 sigma points to achieve the complete 25-dimensional state vector estimation. Additionally, a Monte Carlo simulation has demonstrated a good accuracy for concurrent estimation of attitude, inertia tensor as well as TAM calibration parameters in significantly less time with respect to sole utilization of the UKF.

Abstract: According to industry and agriculture domain which applied temperature sensor need calibration. It is proposed the temperature calibration system design which based on the environmental of the LabVIEW programming to complete the parameter calibration and characteristics analysis of temperature sensor. The design communicates to serial bus by VISA programming interface to complete setting the temperature of the FLUKE9171 temperature calibrator, and get the temperature informations of the Multi-channel DS18B20 temperature sensor. It demarcates the collected data by using the method of the curve fitting, to complete the accurate calibration of the the temperature which collected by temperature sensor. The whole system design is parameters custom, intelligent, self-adaption, which has been applied on a sensor calibration system.

Abstract: In recent years with the development of MEMS and NEMS, various micro and nano scale experiments are required. In general, the smaller the sample, the smaller the force is in the measurement. But it is difficult to load and measure such small force. We developed a probe-type loading and force sensor system to measure micro/nano samples. The system employs a semiconductor strain gauge of a cantilever type sensor and a micro manipulator. A highly sensitive, stable sensing cantilever beam made of single crystal silicon is ion implanted to form the P-type resistor (strain sensor). A tungsten probe with 100 nm radius of curvature was attached to the end of the cantilever as the micro loading tip. We constructed the measurement system and investigated its properties, such as linearity, dynamic response and stability. We also employed microspeckle interferometry to calibrate the force sensor. In preliminary experiments, we successfully obtained the force resolution 0.7 μN and applied our probe-type microforce sensor to calibrate an atomic force microscope (AFM) probe beam and test a single silkworm filament.