Design And Research Of Automatic Leveling System For Forestry Equipment Driving Platform

The results of the eighth national forest resource inventory showed that the area of planted forests in China was 69 million hectares and the accumulated volume was 2.483 billion cubic meters,and the area of planted forests continued to be the world’s largest.In the plan determined during the "Thirteenth FiveYear Plan" period,China’s forest harvesting quota was 254 million cubic meters,of which 80.71% were planted forests.The trend of forest harvesting is shifted to planted forests.Planted forest tending has strict seasonality.In the future,forestry production will shift from labor-intensive to technology-intensive.The use of forestry equipment will revolutionize the efficiency of forestry production.Aiming at the problem that forestry equipment often travels and operates on complicated terrain such as slopes and potholes,which reduces the driver’s operation accuracy,work efficiency,comfort and safety,an automatic leveling system for forestry equipment driving platforms was designed.The six degree of freedom parallel mechanism was used for automatic leveling.Firstly,according to the complex application scenarios in the forest area,a segmented embedded driving platform was designed to reduce the center of gravity and improve safety,while effectively reducing the impact of automatic leveling on driver comfort.The mechanical structure of the whole machine was designed and modeled by Solid Works software,and the specific main parameters was given.Meanwhile,a set of control principles and specific feasible schemes for the automatic leveling system were designed,and a phased automatic leveling control strategy was established based on the main operating conditions of forestry equipment.The kinematics and dynamics of six-degree-of-freedom parallel mechanism including the inverse solution calculation of mechanism position,speed and acceleration were analyzed.Based on the singularity analysis,the structural parameters of the parallel mechanism were further optimized.Finally,a reasonable leg length and distribution circle radius of the upper and lower platforms were determined.And the shape singular trajectory map was drew according to the parameters.After comparing the task workspace with the singular trajectory,a set of hydraulic protection devices in the singular space were designed to ensure absolute safety.The singularity triggering interval and the principle of hydraulic protection were also established.Finally,the ADAMS motion simulation environment was established.The interface of ADAMS motion simulation environment and control module established in MATLAB / Simulink was set up for joint simulation experiments.Finally,the actual test was carried out by the automatic leveling test platform.The results showed that the automatic leveling system can effectively improve the driver’s comfort and safety while maintaining the level of the driving platform,especially in the case of forestry equipment with large fluctuations and obstacles.