4 results about "Screw theory" patented technology

This invention discloses a method for predicting the motion straightness of an L-shaped worktable on a mortise and tenon broaching machine. The method includes: acquiring the motion pose error of the top surface of the slider, the form and position tolerances of the assembly surface, and the structural dimensions of the worktable; calculating the pose error of the tool holder mounting surface considering the superposition of worktable form and position errors based on the aforementioned motion pose error, assembly surface form and position tolerances, and worktable structural dimensions; and calculating the motion straightness of the tool holder mounting surface of the L-shaped worktable based on the pose error of the tool holder mounting surface considering the superposition of worktable form and position errors. Based on the deformation coordination principle and the small displacement screw theory, and utilizing error propagation modeling techniques, factors such as guide rail straightness and parallelism errors, and worktable form and position errors are mapped into the motion straightness prediction model of the L-shaped worktable on the mortise and tenon broaching machine. This effectively solves the problem of accurately predicting the motion straightness of a worktable supported by multiple non-coplanar guide rails.

The invention discloses a stability control method for continuous reconstruction motion of a metamorphic robot based on nonlinear analysis, which comprises the following steps of: 1, establishing a continuous reconstruction kinematics model of the metamorphic robot by using a spinor theory so as to obtain homogeneous coordinates of centroids of all motion components; 2, establishing a pitch angle-vertical displacement two-degree-of-freedom nonlinear vibration model for continuous reconstruction of the metamorphic robot, and deducing an improved ZMP criterion containing foot wheel nonlinear vertical stiffness; and 4, converting the complex continuous reconstruction nonlinear dynamic model of the metamorphic robot into a simple linear system model for adjusting a centroid mechanism through a sliding block expected displacement deviation solver, and further converting the motion control of each leg joint with continuous reconstruction stability into the displacement control of a sliding block in the centroid mechanism. Therefore, stability control over the metamorphic robot in the continuous reconstruction process is achieved through the LQR controller optimized based on the artificial bee colony algorithm.

The application discloses a dexterous hand fruit and vegetable grabbing control method based on fuzzy variable impedance control. First, a multi-finger cooperative kinematics model is established based on the screw theory to determine the fingertip pose, the grabbing force of each finger and the multi-finger force distribution; an optimization model with the minimum contact force as the target is constructed based on force closure, and the NSGA-II algorithm is used for solving to obtain the minimum grabbing force required for stable and lossless grabbing; an impedance control model is established in the Cartesian space, the grabbing system is equivalent to a mass-spring-damper system, the influence of the impedance parameters on the grabbing performance is analyzed, and the inertia parameter and the damping coefficient are determined as the key adjustment objects; further, fuzzy control is introduced, the grabbing force error and its change rate are taken as the inputs, the inertia and the damping adjustment amount are taken as the outputs, a fuzzy adaptive variable impedance controller is constructed, and dynamic optimization of the impedance parameters and accurate tracking of the grabbing force are realized. The application can be effectively applied to the fast, stable and lossless grabbing of various fruits and vegetables in unstructured agricultural environments.

This invention relates to the field of mechanical design and manufacturing technology, specifically to a method and system for sensitivity analysis of shaft tolerances based on virtual assembly. The method includes: establishing a part deviation model using small displacement screw theory, constructing an assembly pose transfer chain, and establishing a linear mapping equation between part source deviations and assembly errors using the Jacobian matrix; extracting the sensitivity index of each tolerance term by performing partial derivative analysis on the mapping equation, thereby identifying key geometric elements and optimizing tolerance allocation. This invention significantly improves analysis efficiency by replacing large-scale random sampling with analytical differentiation. It can accurately characterize the cumulative effect of spatial nonlinear tolerances such as coaxiality and perpendicularity. While ensuring assembly accuracy, it effectively relaxes non-critical tolerance requirements, reduces manufacturing accuracy requirements and production costs, and achieves a scientific balance between assembly quality and economy.