可折展空间八转动副连杆捕获机构的设计

Design and Analysis of Foldable Capture Mechanism Based on Spatial 8-Rotation Linkages

为实现几何形状未知与运动参数不确定的空间目标捕获,提出了一种由8个转动关节依次连接组成的可折展空间连杆捕获机构。利用螺旋理论对该机构进行自由度分析,得到其在分岔位置的3个瞬时自由度;采用几何法对该捕获机构进行运动学分析,将其运动解耦为球面4转动副机构,建立了其在一般位置下的环路方程以及发生运动分岔的条件方程,进而得到捕获机构的包络空间;采用四元数法建立目标运动的数学模型并得到其运动包络范围,通过对比分析得到该机构实现目标捕获的条件并进行仿真验证;基于运动学模型设计原理样机并开展针对3种不同尺寸目标的捕获试验,验证了该捕获机构的功能。试验结果表明:该空间8个转动副连杆捕获机构能够利用折展功能形成大包络空间以实现对目标的捕获,并具有控制系统可靠性高、对目标定位要求低的特点。

To realize the space target capture with unknown geometry and uncertain motion parameters,a foldable spatial 8-rotation(8 D)linkages capture mechanism is proposed.The spiral theory is used to analyze the degree of freedom(DOF)of the mechanism,and the mechanism has instantaneous 3-DOF in the bifurcation position.The kinematics of the capture mechanism is analyzed by using the geometry method.By decoupling its motion into spatial 4 R mechanism,the loop equation of general position,the condition equation of motion bifurcation and the envelop space of the capture mechanism are obtained.The quaternion method is used to establish the mathematical model of target motion and obtain its motion envelope range.Through comparative analysis,the condition of the target acquisition is obtained and verified by simulation.Based on the kinematics model,the prototype is designed and the capture experiments are carried out for three targets of different sizes to verify the function of the capture mechanism.Experimental results show that the spatial 8 Rlinkages capture mechanism can make use of the folding function to form a large envelope space to achieve the acquisition of the target,and has the characteristics of high reliability of the control system and low requirements for the target positioning.