Research On The Safe Working Range Reached Out By The Manipulator Arms Of A Large Rescue Equipment Under A Variety Of Constraints

During the process of disaster rescue,large rescue equipment has a characteristic of single function.Therefore,an equipment with multiple functions becomes an important developing trend of the large rescue equipment.Its manipulator arms are important parts of the large rescue equipment.As a result,it is of great significance to study the safe working range of manipulator arms.At present,the research of manipulator arms of the large rescue equipment mainly focuses on kinematics and dynamics analysis and simulation at typical working positions.There is little research on the force of the hydraulic cylinder and the stress analysis of the arm case under any position,any angular velocity and any angular acceleration of the manipulator arms in the ideal envelope range.In this paper,the relationships between the force of the hydraulic cylinder,the stress of the arm case and the angle,angular velocity and angular acceleration of the manipulator arms are established.The angle range of the manipulator arms satisfying the constraint conditions is analyzed,and the safe working range of the manipulator arms is determined.Specific research contents include the following aspects:First,according to the multi-function requirements of large rescue equipment,the functions are lifting,manned,demolition,excavation and so on.In this paper,some constraint conditions are determined such as the hook of the windlass is perpendicular to the ground,multiple cylinder ultimate elongation,unloading pressure of multi joint cylinder,maximum load,structure and stress of multi arms,limit angular velocity of multistage manipulator arms,limit angular acceleration of multistage manipulator arms.The limit envelope trajectory,the derived trajectory and the ideal envelope range of the manipulator arms under lifting condition are obtained on the basis of ADAMS simulation and spline interpolation.Second,the relationship bewteen the force of the hydraulic cylinder and the angle,angular velocity and angular acceleration of the manipulator arms is established.Based on the D-H matrix method,the relationship between the positions and the angles of the arms,the relationship between the linear velocity(acceleration)of each position and the angular velocity(acceleration)of the manipulator arms are obtained.Based on Kane's equation,the relationship bewteen the force of the hydraulic cylinder and the angle,angular velocity,angular acceleration of manipulator arms is obtained.Accordingly,the force of the hydraulic cylinder is converted to the torque.The first judgement criterion of the working range is the torques of the hydraulic cylinders are less than the unloading pressure.Finally,in view of the coupling force of the box of the boom and the bucket,based on the stress formula,the stress of the cross section of the manipulator arms is connected with the angle,the angular velocity and the angular acceleration of the manipulator arms.The second judgment criterion is the stress of the manipulator arms meeting the requirement of the third strength theory.The safe working range can be obtained by the two judgement criterions using Matlab programme.