Agricultural Research Management Information System

Home
Research Summary
Search
About Us
- ARMIS
- Brochure
Contact Us
Report
User Request
Data Input
Help
- Operation Manual
  - PDF
  - Video
- Program Area & Commodity
We have reached 37600 number of research entries at this moment.

- Logout

Research Detail

Home
Research
Detail

Prediction of the Vibration Characteristics of Half-track Tractor Considering a Three-dimensional Dynamic Model

M.A. Rabbani
Graduate School of Bioresources and Bioenvironmental Sciences, Kyushu University, 6-10-1 Hakozaki, Higashi-ku,Fukuoka 812-8581, Japan

T. Tsujimoto
Graduate School of Bioresources and Bioenvironmental Sciences, Kyushu University, 6-10-1 Hakozaki, Higashi-ku,Fukuoka 812-8581, Japan

M. Mitsuoka
Laboratory of Bioproduction Engineering, Faculty of Agriculture, Kyushu University, 6-10-1 Hakozaki, Higashi-ku, Fukuoka, 812-8581, Japan

E. Inoue
Laboratory of Bioproduction Engineering, Faculty of Agriculture, Kyushu University, 6-10-1 Hakozaki, Higashi-ku, Fukuoka, 812-8581, Japan

T. Okayasu
Laboratory of Bioproduction Engineering, Faculty of Agriculture, Kyushu University, 6-10-1 Hakozaki, Higashi-ku,Fukuoka, 812-8581, Japan

Abstract/ Executive Summary:

A dynamic three-dimensional model was constructed for a half-track tractor that considers its bounce, pitch, and roll motions in order to clarify the tractor’s vibration characteristics. Driving experiments were conducted in which the tractor was driven on a solid asphalt road surface in order to investigate its vibration characteristics and to verify the validity of an analysis based on motion equations that were formulated from the proposed dynamic model. The experiments were conducted with a half-track tractor apparatus equipped with twelve accelerometers for the measurement of 6 DoF of acceleration of the tractor’s centre of gravity. The discrete time series of the measured data was resolved and reconstructed by wavelet analysis. The model was verified using the fixed lug phase difference between the left and the right crawler systems for each combination of three location arrangements of the track rollers and seven levels of tractor speed. Results showed that the acceleration of the centre of gravity for the bounce, pitch, and roll motions was at a minimum when the track rollers were set equidistant from one another. The acceleration caused by the bounce and pitch motions decreased with an increase in the lug phase difference, while the acceleration caused by the roll motion increased with an increase in the lug phase difference. The results further suggested that the proposed threedimensional dynamic model could be improved by incorporating into it the lug phase differences that change during actual tractor driving, instead of a constant lug phase difference.

Keywords: Half-Track Tractor, Wheeled Tractor, Track Rollers

Location:

Start Date:

End Date:

Program Area: Farm Mechanization

Commodity: Performance evaluation

Objectives:

To investigate the tractor's vibration characteristics and to verify the validity of an analysis based on motion equations that were formulated from the proposed dynamic model.

Methodology:

A three-dimensional dynamic model of a half-track tractor driven over a rigid horizontal surface. In this model, the track rollers are fixed on the track frame and mounted at the hitch point of the tractor. The model parameters k1(t),k3(t), and c(t) represent the actual linear dynamic spring constant, the nonlinear dynamic spring constant, and the viscous damping coefficient beneath the track rollers in actual driving conditions, respectively. For this model, it can be assumed that the track rollers run on the upper surface of the rubber crawler. The experimental system principally consisted of a half-track tractor (KUBOTA, GB 150) driven by an oscillating crawler system. Twelve accelerometers (KYOWA AS-5C) were attached to an acrylic box, based on the method for measuring six-degree-offreedom accelerations. The driver’s seat was removed, and the box was attached in its place in order to measure the translational and rotational accelerations of the machine. Three different track roller arrangements were selected for simulation in order to compare the measured and simulated results under similar experimental conditions. The distance between the first and third track roller was kept identical at 392 mm while the second track roller was shifted from its position at the centre of the track frame by 20 mm backward and forward. Using the main gear, sub-gear, and the number of engine shaft rotations, we varied the running speed, using seven different values of 0.25 m s1, 0.41 m s1, 0.50 m s1, 0.66 m s1, 0.76 m s1, 1.00 m s1, and 1.30 m s1, which were equivalent to frequencies of 2.96 Hz, 4.88 Hz, 5.95 Hz, 7.86 Hz, 9.05 Hz, 11.90 Hz, and 15.48 Hz, respectively. These frequencies indicate the number of lug pitches that a track roller would pass per second. Unmanned driving tests were carried out on a flat, dry asphalt road surface. The measured voltage signals from the accelerometers were amplified using a strain amplifier (KYOWA, YA-506B, 500 mε-2 V). The results were filtered for signals that exceeded 100 Hz and were recorded on a data recorder (GRAPHTECH GL1000). The analysis was carried out on a notebook computer using DADiSP-Pro 4.1 data analysis software. Measurements were carried out three times for each tractor speed and track roller arrangement. For this reason, the experimental data needed to be filtered prior to comparison with the simulated results in order to extract the actual frequency of the crawler driving system. Wavelet analysis has been used to address the nonlinear vibrations in agricultural tractors and to determine their adaptability to unsteady phenomena. A computer program was developed for discrete wavelet transforms in order to extract the frequency elements, using Microsoft Visual Basic 6. No theoretical index was used in selecting the mother wavelet as the basis of the wavelet transform; it was experimentally determined. In this study, Daubechies wavelet (N ¼ 10) was used. The relationships of the predicted RMS of bounce, pitch, and roll accelerations agree reasonably well with those obtained from the measured data at a lug phase of 24 mm. Therefore, a lug phase difference of 24 mm was selected for the comparison of the predicted data with the measured data at a tractor speed of 0.76 m s1 for the zero track roller arrangement. Likewise, other lug phase differences were chosen for different speeds and track roller arrangements for comparison.

Source of Information: Biosystems engineering 110 (2011) 178 to 188, Available at www.sciencedirect.com, journal homepage: www.elsevier.com/locate/issn/15375110 doi:10.1016/j.biosystemseng.2011.07.013

Article Link (Online Journal): www.sciencedirect.com, journal homepage: www.elsevier.com/locate/issn/15375110 doi:10.1016/j.biosystemseng.2011.07.013

Funding Source:

Total Budget (Tk.) :

Achievement/Findings:

In this study, numerical simulation was used to predict the vibration characteristics of a half-track tractor. A threedimensional model for predicting the acceleration of the centre of gravity of the tractor and the analysis method used for prediction were presented and discussed.

- For the entire range of tractor speeds used to predict acceleration, the root mean squares of accelerations were the lowest when zero track roller arrangement was used, as compared to other arrangements of track rollers in the track frame. For all the track roller arrangements tested, the simulated results agreed well with the measured ones at tractor speeds upto 0.76 ms^-1. Beyond this speed, the influence of the nonlinearity of the rubber crawler as well as the overlapping of the rubber crawler caused the simulation results to deviate from the measurements.

- The proposed three-dimensional model enhanced the two-dimensional model to a reasonable degree, as it could adequately predict the acceleration of the centre of gravity due to roll motion, which might be the most dominant source of vibration in a half-track tractor. The proposed model was also able to clarify the deviations of the accelerations of the centre of gravity that were due to changes in the track roller arrangement in the track frame.

- The lug phase difference of the rubber crawler had a significant influence on the accelerations of the half-track tractor. Owing to this lug phase difference, the acceleration of the rolling motion of the centre of gravity was higher than the accelerations of the bounce and pitch motions of the tractor as its speed was increased. Qualitative deviations were observed between the measured and the simulated results because a fixed lug phase difference was used for each given speed and track roller arrangement. It was difficult to identify the model parameters correctly when the displacement due to the loading force on a track roller varied over a wide range, owing to the increased machine vibration at a higher tractor speed. However, we would suggest modification of the three-dimensional model so that it takes into account the lug phase differences that are always changing during actual driving, as well as the overlapping of the rubber crawler, which also takes place in real settings.

Knowledge Management: Journal