Chassis design and test of the hight-clearance terrain-adaptive unmanned vehicle in hilly and mountainous tea plantation

To address the problems of limited ground clearance, platform attitude fluctuation caused by slope disturbances, and difficulty in maintaining a stable working height during cross-ridge operations in hilly and mountainous tea plantations, a tracked high-clearance terrain-adaptive unmanned chassis was designed. The chassis adopts a boom-type structure, in which the lifting arms on both sides drive a trapezoidal gantry frame to realize lateral leveling and height adjustment. An independent lateral suspension was arranged between the gantry frame and the lifting arms as a key articulation mechanism, so that the track width remained constant during leveling while lateral arm sway was suppressed, thereby improving cross-ridge passability and attitude stability. Mechanical analysis and extreme load calculation were conducted under limiting boundary conditions, including inward-eight, outward-eight, unilateral braking steering, and virtual-leg conditions, and the gantry frame was further verified by finite element analysis using Ansys Workbench. A CAN-bus-based travel and lifting control system centered on the vehicle control unit (VCU) was developed, and a self-balancing strategy with a switchable height-reference side was proposed. The reference side was determined according to the stroke margin of the lifting mechanisms on both sides to align the target platform height, and the target displacement of the opposite side was then calculated from the roll angle measured by the inertial measurement unit (IMU). Real-time leveling was achieved through a position-velocity dual closed-loop PID controller. Indoor and field experiments were conducted to evaluate the leveling performance of the chassis under controllable ridge-height differences and actual terrain disturbances. In the indoor tests, a unilateral slope platform was used to simulate ridge-height differences on both sides of tea rows, with two levels of 250 and 500 mm, and static leveling and dynamic crossing tests were carried out. In the field tests, continuous driving verification was performed along a typical cross-ridge route in a steep-slope tea plantation. The results showed that the chassis could adapt to a maximum ridge-height difference of 500 mm, with a maximum leveling angle of 17.4°. Under dynamic driving conditions in steep-slope tea plantations, the chassis inclination angle was stably controlled within ±1°, while the ground clearance and track width remained constant. The proposed chassis and leveling method can realize static and dynamic leveling and maintain a constant chassis height in hilly and mountainous tea plantations, providing a reference for the platform-based design and engineering application of high-clearance self-propelled tea plantation equipment.