To determine the wheel dynamics of the mobile machine, a sensor has been developed, which consists of a three-axis accelerometer, a three-axis gyroscope, and a three-axis magnetometer. The sensor is connected to the microcontroller, which transmits the data received via the 2.4 GHz channel. It is attached coaxially to the center of the wheel. In the first step of processing data from the accelerometer and gyroscope, their values are corrected. The corrected acceleration signal and angular velocities are processed using a Butterworth filter. Madgwick filter determines the angles of orientation of the sensor in space. In the next step, the authors deduct the centrifugal component from accelerations. Further, the gravitational component is subtracted from the accelerations to get its real value. The wheel speed is obtained by integrating accelerations. Angular wheel speed and accelerations are processed with a Kalman filter. The outcomes of experimental studies of the proposed method and sensor to determine the wheel dynamics on the tractors with 4x4 wheel formula have been analyzed.
TopIntroduction
The study of the dynamics of mobile machines functioning requires determining the parameters of its state both as a whole and its individual elements.
The issue of creating measurement systems for the functioning parameters of mobile agricultural machines appeared almost simultaneously with the creation of the tractor. At first, measuring systems were designed to improve the performance of machine-tractor units and were based mainly on mechanical computing elements. The lack of accuracy of these devices makes it impossible to use them effectively on tractors at elevated speeds. Previously (Kodenko M. N., Lebedev, A. T., 1969), the prospects of research on the optimal control of a tractor unit using self-adjusting systems have been proved. In this paper, the dynamics of traction efficiency of the tractor has been first evaluated. This made it possible to optimize its operation modes under unsteady load.
For experimental research of mobile machines, the scientists developed measuring instruments and systems (Debain, C. A, Chateau, T., Berducat, M., Martinet, P., & Bonton, P., 2000; Mojtaba, N., Alimardani, R., Sharifi, A., & Tabatabaeefar, A., 2009; Serrano, J. M., Peça, J. O., Shahidian, S., Nunes, M. C., Ribeiro, L., & Santos F., 2011). Some of them are universal (Drenkow, G., 2006), others are specific (Eremenko, A. V., Maloletov, A. V., & Skakunov, V. N., 2010; Kuvachev, V. P., Ayubov, A.M., & Kotov, O. G., 2007). There are systems that read operating parameters from diagnostic interfaces (Čupera, J., & Sedlak, P., 2011), as well as virtual systems (Kring, J., & Travis, J., 2006).
A group of scientists developed the measuring information system IP-256M for measuring and calculating the data of energy and traction tests of tractors and agricultural machines (Kadochnikov, G. N., 2006). The measuring system has a limited number of analogue (specialized) channels (6), to which temperature sensors, strain-gauge links and 8 discrete inputs can be connected.
Nowadays, manufacturers of semiconductor devices have created a sufficient number of sensors of physical quantities, therefore, the information system IP-256M needs only an analogue-to-digital converter and a microcontroller to collect data from sensors.
A group of scientists has developed a data collection and processing system based on the Dewe-2010 PC industrial data collection system (A., Yahya, M., Zohadie, A. F., Kheiralla, S. K., Gew, B.S., Wee, &. E. B., Ng, 2004). The developed data acquisition system includes a global positioning system with differential correction (DGPS-RTK). In this case, the processing and storage of data in this system occurs in real time. The tractor Massey Ferguson 3060 was equipped with such a measuring system. Additional features of this system are the design of the traction force sensor and the torque sensor on the tractor wheels, which require intervention into the tractor design (Yahya, A., 2000).
A sufficient number of sensors installed on the tractor made it possible to determine: the geographical position of the machine, terrain parameters, tillage quality and the traction characteristics of the tractor.
To determine the longitudinal, lateral and vertical accelerations in the process of taking off and the acceleration of an agricultural unit, a mobile measuring complex was developed which consists of Freescale Semiconductor MMA7260QT acceleration sensors and a laptop for processing and storing the data obtained during the experiment (Artemov, N. P., Lebedev, A. T., Podrygalo, M. A., Polyansky, A. S., & Klets, D. M., 2012).
MEMS accelerometers are used as sensors in the mobile measurement system. The popularity of MEMS accelerometers and gyroscopes is caused by their great potential for use in both domestic and industrial equipment (Sysoev, S., 2009).
MEMS sensors are widely used in the automotive industry to control airbags, burglar alarms and navigation systems to calculate the distance traveled or determine the route.