The Research On Machine-Induced Navigation Technology Of Wheeled Tractor

Wheeled tractor was designed as orchard automation mobile platform to achieve the automation of orchard work, liberate driver from heavy labor, reduce pilot's labor intensity, improve production efficiency and maneuvering security. Machine-induced navigation control system was designed based on mechanical guiding. Machine-induced navigation was adopted, mechanical guide mechanism was increased on wheeled tractor. PD controller of linear walking and fuzzy controller of curve walking were designed according to the established tractor kinematical models, the controllers were simulated in Matlab environment and the real car tests were carried out simultaneously, simulation and the experimental results showed that the navigation system can control tractor walk automatically along the navigation path. The main research contents were summarized as follows:(1) The overall scheme of the tractor navigation system was determined.(2) Mechanical guide mechanism was designed, the corresponding relation between the speeds and swinging rod lengths was established.(3) The tractor kinematical models were established according to different environments, navigation control principles were defined. PD controller of linear walk was designed with lateral deviation error and heading error were as inputs, target front wheel angle was as output; the fuzzy controller of curve walk was designed with installation point'lateral deviation error of guide mechanism and the lateral deviation error of axle center were as inputs, target front wheel angle was as output. The controller was simulated in the Matlab environment, the simulation results show that the designed controller can effectively control the tractor walking automatically, theoretical basis was provided for the real car tests.(4) Navigation control system was developed in vc++ environment. Tests results showed that the maximum lateral deviation of linear walking on cement road surfaces was 0.08m at speed of 0.27m/s, 0.095m at speed of 0.39m/s, 0.1m at speed of 0.53m/s; the maximum lateral deviation of linear walking on the grass was 0.14m at speed of 0.27m/s, 0.015m at speed of 0.39m/s; the lateral deviation of curve walking on the cement road surfaces was 0.25m at speed of 0.27m/s when tractor walked through right-angle corner path, the maximum tracking deviation was 0.30 m when tractor walked through sinusoidal path. The tests results showed that the navigation controllers can control tractor walk along the planning path automatically and had certain reliability and applicability.