Structural Design of a Cam-Based Tracking Mobile Platform

Abstract

To address the problems of low trajectory accuracy and inability to perform online correction caused by machining errors and ground slip when a pure mechanical steering model car runs on complex tracks, this paper designs a pure mechanical adaptive tracking car based on the cam-rocker mechanism and a front-mounted dual-angle differential fine-tuning device, in accordance with the requirements of the solar car competition. Under the constraints of a 6000 mm × 6000 mm field and a 200 mm × 300 mm body projection boundary, SolidWorks and Matlab are used collaboratively to smoothly fit the entire 14135.51522 mm track with 10 landmarks using high-order Bezier curves. A mapping model from curvature to front wheel steering angle is established, and the theoretical cam profile is generated through a polar coordinate reverse calculation algorithm. The chassis adopts a front-wheel steering and rear-wheel drive layout, with a transmission chain consisting of a DC gear motor, a timing belt, and a four-stage planar expansion gear set, achieving a precise total transmission ratio of 38.13. To overcome the drawback that the cam profile cannot be adjusted once machined and finalized, a tool-free dual-angle fine-tuning steering mechanism is designed. Through independent adjustment of two decoupled variables—the initial deflection angle of the steering rod and the additional torsion angle of the front wheel axle—mechanical precision compensation for zero-position error is achieved. The smoothness of the rocker motion under cam drive and the structural strength are verified through SolidWorks Motion dynamics simulation and static checking of key components. A 3D-printed prototype is fabricated based on the above design, and real vehicle tracking tests are conducted. Experimental results show that the marker recognition success rate reaches 97.5%, and the comprehensive endpoint drift deviation is stabilized within 20 mm after dual-angle fine-tuning compensation. This scheme effectively resolves the contradiction among mechanical compactness, motion stability, and path tracking accuracy under no electronic control conditions, providing an engineering reference for the design of pure mechanical adaptive mobile platforms.