| The wheeled tractor is the main mechanical equipment of agricultural production in China,which has the advantages of strong traction,simple operation and convenient maintenance.However,due to the poor performance of its suspension and poor road conditions,the driver suffers from low-frequency rigid vibration for a long time in the driving process,which seriously damages the physical and mental health of the driver and reduces the working efficiency.The research content of this paper is mainly divided into two parts:the information acquisition of tractor road roughness and the research of semi-active control method of seat suspension.Accurate acquisition of road information is the basis of further improving the damping performance of wheeled tractors.In this paper,binocular stereo vision technology is used to reconstruct the three-dimensional road information and accurately obtain the road roughness information by acquiring the two-dimensional road image.A new semi-active control method of wheeled tractors is proposed to improve the damping performance of tractor seats It is of great significance to improve the driving stability of the tractor and the riding comfort of the driver.The specific research contents are as follows:(1)By using the binocular machine stereo vision technology,the road environment during the driving process of the wheeled tractor is sensed,the principle and related technology of binocular stereo vision,the calibration of zed binocular camera image preprocessing,stereo matching and 3D information recovery are studied in detail,and the camera experiment platform is built.The average calibration error of binocular camera is 0.24 pixel,and the experiment recovery is carried out The difference between the threedimensional information and the reality is less than 2.95%,which shows the accuracy and feasibility of binocular machine stereo vision in perceiving the driving environment of wheeled tractor.(2)According to the obtained three-dimensional environment data,the mathematical elevation topographic map is established.Based on the analysis of elevation topographic map by neighborhood analysis method,the information of terrain factors such as terrain slope,fluctuation and elevation is extracted.On this basis,the experiment of obtaining the road condition information of tractor on 100m standard road is carried out,and the road roughness curve during the driving process of the wheeled tractor is extracted,which provides the road excitation for the vibration characteristics analysis of the whole wheeled tractor and the seat.(3)In this paper,a dynamic model of a new type of tractor with plough wheel is proposed and the differential equations are established.The model fully simulates the working condition of tractor with plow.Taking the cf700 wheeled tractor as the research object and the road roughness information obtained as the excitation,the dynamic differential equations of the wheeled tractor system with agricultural tools are solved by MATLAB software,and the vibration characteristics of the wheeled tractor system on the 100m experimental road are simulated.The acceleration and speed information of passive seat,cab and body are obtained,and the analysis shows that the damping effect of passive seat suspension is not good.(4)A new semi-active control method of wheel tractor seat suspension is proposed,which is divided into two parts:parallel stiffness switch strategy and magnetorheological damper ceiling control strategy.The parallel stiffness switch system is designed and its mathematical model is established.Study the characteristics of MR damper,compare the advantages and disadvantages of different semi-active control methods,select the adaptive ceiling damping control algorithm,design the overall and stiffness control system structure of the seat suspension,through the hardware selection,make the physical seats,complete the construction of the seat suspension control platform,and use Lab VIEW to write the seat control program.The experimental results under road excitation show that the displacement response is reduced by 22.5%on average compared with the constant stiffness system,and the overall level of vertical acceleration is reduced by 26.1%,which verifies the effectiveness of the semi-active control strategy of the seat suspension proposed in this paper.The research of this subject has important theoretical significance and practical value for the accurate detection of the road roughness information,the promotion of semi-active control of the wheel tractor seat suspension,and the improvement of the ride comfort of the wheel tractor. |
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