摘要
为克服舰船摇摆所带来的影响,拓宽电视跟踪设备的使用环境,该文提出了一种五自由度具有2层结构的自稳跟踪平台。上层为两自由度的跟踪平台,采用串联式U-U结构,即U型外框绕外环轴(铅垂)旋转,U形内框绕内环轴(水平)旋转;下层为三自由度的自稳平台,采用并联式3UPS/PU结构,3个UPS为驱动分支,中间PU为约束分支。分别建立了跟踪平台和自稳平台的数学模型,推导了跟踪平台引导算法和自稳平台运动学反解算法。试验结果表明:当选用0.5 Hz、5.1?幅值的正弦曲线作为目标跟踪曲线时,自稳跟踪平台跟踪精度优于0.02?;自稳平台的稳定频率优于1 Hz(双十,幅值1.5?);以频率0.1 Hz,幅值30?进行正弦摇摆时,动态自稳精度优于0.3?。该研究将跟踪功能和自稳功能相结合,可为渔船定点撒网、收网以及农作物精准种植、收割等设备的开发提供参考。
In the process of navigation,because of the influence of the waves,ships will generate the movement of rolling,pitching,heading,and so on.This movement will disturb the using of the TV(television)tracking equipment and change the direction and bring some danger to equipment and personnel.In order to overcome the effects of ship swaying,and broaden the application scope of TV tracking equipment,a novel five-degree-of-freedom stabilized tracking platform using two-layer structure is introduced,which is of great significance and illustrates a good prospect of application.The upper layer is the two-degree-of-freedom tracking platform,which uses the series structure of U-U(the U-shaped outer frame revolving around the outer ring axis and the U-shaped inner frame revolving around the inner ring axis).It can ensure that the TV tracking equipment is aimed at the dynamic target in real time.The down layer is the three-degree-of-freedom stabilized platform,which uses the parallel structure of3UPS/PU because of its characteristics of good stiffness,large carrying capacity,high precision,compact conformation,and so on.But control algorithm complexity and poor real-time performance cause the low accuracy of the stable platform,which seriously affects the further development of the stable platform of parallel mechanism.So the RTX(real-time extension)operating system is combined in order to improve the real-time performance of the control system.The stabilized platform can effectively isolate the disturbance of ships and provide a stable erection platform for TV tracking equipment.UPS is the driving branch and PU is the constraint branch.The upper platform’s radius is500mm.The down platform’s radius is700mm.The height of stabilized platform is900mm.The angle of adjacent spherical joints is120°on the upper platform.The angle of adjacent spherical hinges is120°on the down platform.Mathematical models of tracking platform and stabilized platform are established respectively and the algorithm of tracking platform guidance and the kinematics of stabilized platform are derived.A set of IMU(inertial measurement unit)is installed on the outer frame of thetracking platform,which can dynamically acquire the position of the tracking platform.GPS(global position system)signal source is installed on the target and the target information is transmitted to the tracking platform computer through the wireless network.By guiding the solution method,the rolling and pitching angle of the tracking platform are calculated.And then computer controls the outer frame and inner frame axis to achieve dynamic tracking.Now the control strategy of the stable platform of parallel mechanism is based on kinematics or dynamics.By contrast,the control strategy based on kinematics is easier to implement and has a better real-time performance.So the control strategy of the stable platform of parallelmechanism uses the one based on kinematics.The stabilized platform has the motions of2directions i.e.rolling and pitching.The sensitive component installed on stabilized platform is aware of the ship’s rolling,pitching attitude and other parameters.These motion parameters are transmitted to the motion control computer.The motion control computer calculates through the real-time kinematics,and the motion quantity of the electric cylinder is obtained and the control instruction is generated.Thecontrol instruction is output after signal conditioning by the servo control unit,which drives the movement of the servo systemto realize the desired movement attitude.At the same time,the servo control unit can collect the displacement of the electric cylinder in real time,realize the monitoring and protection of the self-stabilized platform,and display the various information.Experimental results show that tracking accuracy of tracking platform is better than that of0.02°,stable frequency of stabilized platform is better than that of1Hz,and dynamic stability precision is better than that of0.3°.It confirms the self-stability and tracking performance of the designed platform.This study combines the tracking function with the stabilizing function,which can provide reference for the development of other ship-borne and vehicle-mounted equipment.
作者
陈立坡
Chen Lipo(Unit 92785 of the Chinese People's Liberation Army (PLA), Qinhuangdao 066200, China)
出处
《农业工程学报》
EI
CAS
CSCD
北大核心
2018年第1期22-27,共6页
Transactions of the Chinese Society of Agricultural Engineering
基金
十二五建设
关键词
稳定
跟踪
结构
混联
平台
设计
控制
试验
stabilization
tracking
structure
hybrid
platform
design
control
experiments
