13 results about "Screw theory" patented technology

The invention discloses a dexterous hand fruit and vegetable grabbing control method based on fuzzy variable impedance control. The method comprises the following steps: firstly, establishing a multi-finger collaborative kinematics model based on a spinor theory, and determining fingertip poses, grabbing force of each finger and multi-finger resultant force distribution; on the basis of force sealing, an optimization model with the minimum contact force as a target is constructed, an NSGA-II algorithm is adopted for solving, and the minimum grabbing force needed by stable and lossless grabbing is obtained; establishing an impedance control model in a Cartesian space, enabling a grabbing system to be equivalent to a mass-spring-damping system, analyzing the influence of an impedance parameter on grabbing performance, and determining an inertial parameter and a damping coefficient as key adjustment objects; fuzzy control is further introduced, the grabbing force error and the change rate of the grabbing force error serve as input and output inertia and damping adjustment amount, a fuzzy self-adaptive variable impedance controller is constructed, and dynamic optimization of impedance parameters and accurate tracking of the grabbing force are achieved. The fruit and vegetable grabbing device can be effectively applied to rapid, stable and lossless grabbing of various fruits and vegetables in an unstructured agricultural environment.

The invention relates to a loader working device control method and system based on a spinor theory, and belongs to the technical field of engineering machinery automation control. According to the method, a positive kinematics model based on the spinor theory is established, and the relation between the pose of the end effector and the joint angle is accurately described; and solving inverse kinematics according to the target pose to obtain a target joint angle, and driving a single-joint controller to realize accurate motion control. The system comprises a working device, an angle sensor, a single-joint controller and a processor. The method effectively solves the problems that a traditional method is complex in modeling, has singularity and is insufficient in precision, and has the advantages that modeling is efficient, control is accurate, stability is good, and an advanced control algorithm is easy to integrate.

The invention discloses a five-axis robot configuration synthesis method integrating a 2R1T parallel mechanism, and belongs to the technical field of robot manufacturing. A two-rotation and one-translation (2R1T) parallel mechanism is a core function module of a five-axis robot, most of the 2R1T parallel mechanisms are parallel mechanisms formed by connecting a plurality of kinematic pairs (such as an R pair, an S pair, a P pair, a U pair and a C pair) in series to form a kinematic branch chain and connecting a plurality of kinematic branch chains in parallel, the two ends of the kinematic branch chain are connected with a static platform and a movable platform respectively, calculation is carried out based on a PRU type kinematic branch chain, and the two-rotation and one-translation (2R1T) parallel mechanism is formed. A series of 2R1T parallel mechanism topological configurations are obtained through the spiral theory, a 2R1T parallel mechanism motion spiral system is analyzed, the 2R1T parallel mechanism and the single-degree-of-freedom joint module are reasonably configured, and it is ensured that the five-axis robot has the motion performance meeting the working requirement.

The invention discloses a gear multi-axis cooperative compensation machining method and device based on spinor error mapping. The method comprises the following steps: collecting actually measured data, and calculating a dynamic transmission error; establishing a gear contact analysis model and a dynamical model, and obtaining an equivalent tooth profile error including a tooth profile / pitch error through inversion under manufacturing realizable constraints; a machining kinematic chain model consistent with an actual gear grinding machine in structure is established based on the spinor theory, various machine tool errors are represented as spinor / displacement parameter disturbance, a linear mapping relation is established, and an error propagation model is established; calculating a sensitivity matrix, and identifying a key machine tool error source and a corresponding motion axis which have the most obvious influence on the tooth profile error; and the synchronous correction amount of each key shaft is calculated and is executed in real time during machining, so that active compensation is realized. According to the method, active compensation and accurate control over manufacturing errors of the humanoid robot joint speed reducer are achieved, the DTE amplitude of the speed reducer is effectively reduced, the local abrasion risk is reduced, and the positioning accuracy is improved.

The invention discloses a class-k type tensegrity robot shape finding method based on spinor, belongs to the field of statics analysis and rigid-flexible hybrid robots, and aims to solve the problems that a class-k type tensegrity robot shape finding process is complex, node coincidence constraint is difficult to maintain, and numerical calculation stability is difficult to maintain. The method comprises the following steps: initializing structural parameters; constructing a system pseudo-kinetic equation based on the speed spinor and the force spinor; establishing a node coincidence constraint matrix according to the topological relation, and deducing a multi-level constraint equation of positions, speeds and acceleration levels; and the angular velocity and the linear velocity of each rigid rod piece at the current moment are obtained by solving the augmented velocity spinor. And further updating the node coordinates of the rigid rod piece according to the speed spinor to realize iterative form-finding calculation. And when the free space spinor is smaller than a preset threshold value, the structure reaches a balanced configuration, and shape finding is completed.

The present invention belongs to the technical field of parallel mechanisms and provides a six-degree-of-freedom fully decoupled serial-parallel mechanism containing closed-loop units, including a 2R parallel mechanism and a 3T1R parallel mechanism. The 2R parallel mechanism includes a first moving platform, a first fixed platform, and a first mechanism branch disposed between the first moving platform and the first fixed platform. The 3T1R parallel mechanism includes a second moving platform, a second fixed platform, and a second mechanism branch disposed between the second moving platform and the second fixed platform, wherein the first fixed platform is connected to the second moving platform via the second mechanism branch. Based on screw theory, the present invention adopts a method of constructing closed-loop units by decoupling sub-mechanisms. The overall parallel mechanism is split into multiple sub-parallel mechanisms for design based on the motion characteristics of the degrees of freedom. The branches contain closed-loop units to achieve independent output of force and torque in the X, Y, and Z directions of the moving platform. The present invention also provides a method for constructing a six-degree-of-freedom fully coupled parallel mechanism, simplifying the method and process for designing a fully coupled parallel mechanism.

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 relates to the technical field of robot state analysis, and discloses a robot sensor degradation analysis method and device based on the spinor theory, and the method comprises the steps: constructing an observation feature measurement model corresponding to a target sensor according to an equivalent mechanism model corresponding to the target sensor; constructing a feature constraint model corresponding to the target sensor according to the observation feature measurement model, and constructing a degradation analysis model corresponding to the robot according to the feature constraint model; performing numerical analysis on the degradation analysis model to obtain candidate motion primitives of the robot; and determining a robust discrimination function corresponding to the candidate motion primitive, and performing degradation detection on the candidate motion primitive through the robust discrimination function to discriminate whether an application scene where the robot is located degrades towards the candidate motion primitive, so that the constraint effect of the sensor in state estimation is analyzed by using a spinor theory, and the state estimation accuracy is improved. The influence of scene noise and environment scale is reduced, and the degradation detection accuracy of the robot sensor is improved.

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.

The application discloses a hard and brittle material curved surface grinding preparation method, product, medium and equipment, relates to the technical field of ultra-precision machining, and comprises the following steps: acquiring a geometric model of a hard and brittle material curved surface to be machined and an error value of a grinding preparation process; determining three-dimensional coordinates of a tool position contact point in a grinding tool path based on the geometric model; determining a rigid body conversion matrix by adopting a screw theory according to structural parameters of a grinding preparation machine tool; obtaining an ideal grinding motion model of the machine tool based on the three-dimensional coordinates and the rigid body conversion matrix; compensating the ideal grinding motion model according to the error value of the grinding preparation process to obtain a compensated grinding motion model; and completing the preparation of the hard and brittle curved surface by adopting the compensated grinding motion model. The hard and brittle material curved surface grinding preparation method, product, medium and equipment can effectively improve the machining efficiency and machining quality of the hard and brittle material curved surface.

The application relates to a kind of mechanical arm admittance control method and system, wherein the method comprises: according to the joint current of mechanical arm, the environmental external force suffered by mechanical arm is calculated;By the screw theory unification mechanical arm end tool position and posture, according to environmental external force, and the preset pose trajectory of end tool, the expected pose screw of end tool is calculated;According to the expected pose screw of end tool, the expected joint angle of mechanical arm is calculated, finally control mechanical arm, execute the action corresponding to expected joint angle.It is calculated that external force based on dynamics model and joint current by the present application, without installing high-cost force sensor to measure external force;Based on the description of screw theory unification position and posture, the dimension of pose space is minimized, the complexity of admittance control algorithm is simplified, compared with the separate description of position and posture, it is more accurate and stable, solve the problem of how to realize the accurate, stable, low-cost admittance control of mechanical arm.

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.