| Aiming at the problem of poor flexibility of the mechanical legs of the current underground rescue and detection robot,this paper combines the advantages of high stiffness,fast response,high precision,and low inertia of parallel mechanisms and the characteristics of self-reorganization and self-reconfiguration of metamorphic mechanisms.Based on the 3-RPS parallel mechanism,a new 3-RPS/(H)metamorphic parallel mechanism is designed as the basic configuration of the mechanical leg of the underground rescue and detection robot.First,the basic structure of the 3-RPS/(H)metamorphic parallel mechanism is designed,and its motion process is divided into four configurations according to its configuration design.The schematic diagram of the 3-RPS/(H)metamorphic parallel mechanism is drawn,the degrees of freedom of the four configurations of the mechanism are analyzed using the screw theory,and the G-K formula is used to verify the correctness of the degrees of freedom in each configuration.The application of 3-RPS/(H)metamorphic parallel mechanism in underground rescue detection robot is presented.Secondly,the kinematics of the 3-RPS/(H)metamorphic parallel mechanism is analyzed by using D-H parameters and X-Y-Z euler angles,and the inverse and forward kinematics operations of the mechanism are completed.On the basis of the inverse kinematic,the limit boundary method is used to obtain its working space,and compared with the 3-RPS parallel mechanism,it is proved that the 3-RPS/(H)metamorphic parallel mechanism has more larger space and discusses the impact of major structural dimensions on workspace.The velocity Jacobian matrix of the 3-RPS/(H)metamorphic parallel mechanism is solved.On this basis,the spatial dexterity distribution of the configuration I and III of the mechanism and the dexterity of the rotation angle are analyzed.The influence of the degree distribution.At the same time,the analysis of the singularity of the mechanism is completed,and it is proved that the mechanism does not have a singular configuration in the aforementioned workspace.Then,the virtual prototype model of the 3-RPS/(H)metamorphic parallel mechanism is established,and the positional simulation of the mechanism is carried out,which proves the correctness of the theoretical analysis.On this basis,the inverse and forward kinematics simulations of the configuration I and III of the mechanism are continued.Through the inverse kinematics simulation,adding a drive to the end of the actuator,the displacement,velocity and acceleration curves of the three branch chains are obtained.Through the forward motion simulation,the three RPS branch chains are added with drive,and the displacement,velocity and acceleration curves of the screw apex are obtained,which provides a reliable basis for the design and structural optimization of the mechanical leg.Finally,the specific structure of the 3-RPS/(H)metamorphic parallel mechanism is designed and processed,and the construction of the experimental prototype of the 3-RPS/(H)metamorphic parallel mechanism is completed.By acquiring and analyzing the output signals of the pull and pressure sensors,the motion control of the electric push rod and the solenoid valve is carried out,and the motion process of the four configurations of the mechanism is realized,which verifies the above theoretical analysis. |
PDF Full Text Request