Study On The Adaptive Control System Of Sugarcane Harvester Based On Cutting Height Detection

China’s sugarcane is mainly planted in Guangxi,Yunnan,and other karst areas.The topography of sugarcane fields is undulating,with a planting agronomy of once every three years.According to industry standards,the sugarcane harvester needs to be cut 3 cm into the soil be considered qualified.If the cutting height is too low,the blade will damage the ratoons,and excessive soil will increase the impurity of the sugarcane and power consumption of the equipment,potentially leading to clogging of the channel and damaging the cutting mechanism.On the other hand,a cutting height that is too high will result in harvesting loss and an increase in the rate of perennial root breakage,making the incision vulnerable to pests and diseases and thus reducing the yield in the subsequent year.In addition,potential rock damage to the blade and jamming of the harvesting channel occur from time to time,reducing the efficiency and safety of the operation.Sugarcane branches and leaves are lush,and the presence of weeds,sugarcane stems and leaves,and other disturbances on the ground during harvesting,as well as the presence of a large number of stones,render existing terrain-detection methods difficult to apply.As a result,sugarcane harvesters are unable to meet the needs of precise cutting with minor damage and high quality and still rely on experience to manually adjust the cutting height frequently;this is not only labour-intensive but also hinders the process of mechanised sugarcane harvesting.To address this problem,this thesis examines sugarcane terrain,stone detection,and the adaptive control of harvester cutting height.Specifically,theoretical analysis,numerical simulations,and experimental validation are used to study contact and non-contact terrain-detection methods and strategies for the adaptive control of cutting height.The main research work is as follows.This thesis analyses the planting terrain and harvesting agronomic requirements of the main sugarcane-producing areas in China.Taking the small chopper sugarcane harvester as the research object,the working principle and the cutting height and damage mechanism of the sugarcane harvester were analysed.The dynamic and kinematic models of the cutting mechanism as well as the state space equations of the cutting mechanism were established,allowing the control relationship of the cutting height error to be obtained,which provided a theoretical basis for terrain height detection and adaptive control.In response to the current lack of an effective terrain-height detection method for sugarcane harvester,a contact terrain-height detection sensor based on a drag plate was designed based on an analysis of the advantages and disadvantages of existing contact terrain-detection methods.The contact drag plate was designed according to the theoretical analysis,and using coupled simulations,it was verified from a microscopic point of view that the sensor caused little disturbance to the vertical and horizontal soil,confirming its applicability and accuracy.Indoor tests were conducted to investigate the effects of different moving speeds,rotational damping,and pre-pressure on the response performance of the sensor,and the results were compared with the detection results of the infrared sensor.The results showed that the optimal ranges of moving speed and rotational damping were 1.5–1.8 km/h and 0.7–0.9 Nm respectively.The terraindetection height exhibited a linear relationship with the swing angle of the drag plate,and the performance was stable,providing a simple,reliable,and low-cost terrain-height detection method for the adaptive control of cutting height of sugarcane harvesters.To target the issue of stones in sugarcane fields,which easily damage blades and are difficult to detect,a non-contact stone-detection method based on ground-penetrating radar was proposed by taking advantage of the large differences in the dielectric constants of stones,air,and soil.The principle of ground-penetrating radar detection was employed,and its response time(10 ms)was obtained to meet the real-time detection requirements of the harvester.According to the structural characteristics of the harvester,the optimal installation position of the ground-penetrating radar antenna was determined.The signal-processing method was designed,and forward and inverse simulation tests were carried out.The ground-penetrating radar electromagnetic waves could accurately obtain the ground-layer information under the influence of different high-lying terrain,slope topography,sugarcane proximity and density,and moisture content of the soil.With this foundation,the response characteristics of groundpenetrating-radar electromagnetic waves to stones of different sizes and heights were studied.The results showed that the electromagnetic waves of stones differed greatly from those of air and soil layers.Ground-penetrating radar can detect and visualise stones on the soil surface with a height and size detection error of less than 2 cm,and high recognition rate,demonstrating it as a promising method to improve the efficiency and safety of sugarcane harvesters.A control strategy based on the combination of stone detection and contact terrain-height detection was proposed to achieve adaptive control of the cutting height of the sugarcane harvester.Integrating the interrelationships between cutting height and the terrain,chassis posture,and angle of the cutting mechanism,a terrain-detection method with multiple angle sources was determined.The transfer-function model of the hydraulic system of the cutting mechanism was established,and the optimal PID parameters were researched by using the sparrow search algorithm with three-dimensional(3D)Tent chaotic mapping.The control simulation was carried out using the electromechanical–hydraulic co-simulation model,and the results showed that the pressure fluctuation of the cutting mechanism hydro-cylinder was small,and the response time was ≈0.25 s,which provides a reliable reference for the selection of adaptive-cutting-height control parameters in the field.Based on the terrain-detection method and control strategy,a set of adaptive control systems for the cutting height of sugarcane harvesters was developed.The control system was retrofitted on the TSP-GS15 A chopper sugarcane harvester manufactured by Xi’an Transpower,and the optimal PID parameters were configured.Indoor tests were conducted using the cutting mechanism test rig,and the effectiveness of the contact terrain-height detection method and control strategy were verified using different terrain models.A field experiment was carried out in the youth branch of the Guangxi Jinguang Farm,and the results showed that the cutting mechanism can adjust the height in real time according to the topography of the cane field and maintain the set value of the cutting height,thereby realising the function of terrain adaptive control.Meanwhile,the ground-detecting radar can effectively penetrate interfering objects and detect stones on the soil surface with a detection-height error of 0.6 cm.These results confirm the ability of the method to effectively identify stones in sugarcane fields,which can easily damage the blade and jam the harvesting channel,and verifies the effectiveness of the adaptive control system for cutting height.The proposed contact terrain-detection sensor based on a drag plate,stone-detection method based on ground-penetrating radar,and cutting height adaptive control system not only solve the problem of cutting height detection and control during mechanised sugarcane harvesting but also provide a reference for terrain detection by other agricultural machinery and the detection of foreign objects on the ground.