Design and Control Strategy of Wedge-type Automatic Leveling Mechanism
The theodolite,an optical instrument utilized for measuring the azimuth and pitch angle of spatial targets,operates on the principle of angle measurement,finding extensive application in aviation,construction,and various other industries.Functioning as a precision optical measuring device,the theodolite necessitates meticulous high-precision leveling through a leveling mechanism prior to operation.This ensures alignment of the vertical axis with the earth's plumb line,thereby guaranteeing the accuracy of azimuth and pitch angle measurements within the geodetic coordinate system.The leveling mechanism within the theodolite predominantly consists of screw jack and wedge types,both manually operated.Employing a cyclic approximation leveling mode,the theodolite achieves semi-locking post-coarse leveling at wide angles,followed by re-locking after fine leveling at narrow angles,thereby completing the leveling process while maintaining adequate stable support.However,in practical engineering applications,the proficiency and experience of the operator significantly impact the time required to adjust the theodolite's vertical axis to an error of ≤5",a process that typically takes around 30 minutes.This duration constitutes 50％of the total deployment time of the theodolite.Attaining a tilt error of ≤2"necessitates additional leveling cycles and prolonged operation time.Consequently,the time-consuming nature of high-precision manual leveling severely impedes the deployment speed of the theodolite.Moreover,the cyclic approximation leveling mode's influence on fine leveling of the locking mechanism,particularly at small angles,relies on the elastic or plastic deformation of transmission components within the leveling mechanism.Repeated leveling cycles hasten the deterioration of the leveling mechanism,significantly undermining the theodolite's reliability.Addressing the challenges associated with high-precision manual leveling,this paper introduces the design of an automatic leveling mechanism of the wedge type,characterized by stable self-locking properties,extensive stroke,and high resolution.Through physical modeling,calculation models for anti-torsion friction force,motor torque transmission,leveling angle resolution,and stroke are established,facilitating the determination of core design parameters.Furthermore,an analysis of the leveling strategy for the wedge-type automatic leveling mechanism is conducted,proposing a parallel leveling control strategy as an alternative to the commonly used serial approach in manual operation.This parallel strategy enhances leveling efficiency by enabling electro-mechanical leveling components to achieve synchronized motion.Experimental validation confirms that the designed wedge-type automatic leveling mechanism achieves leveling within a range of±0.25°,with a resolution of＜0.01".Utilizing the parallel leveling control strategy,the time required to adjust axis tilt within a 2"error range around the X and Y axes is significantly reduced compared to the serial strategy,demonstrating higher efficiency.Additionally,experimental tests affirm the feasibility of achieving a 2"leveling accuracy within the entire leveling range using the parallel leveling control strategy,ensuring stable and reliable performance.
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维普
