Optimization Of Kinematic Parameters Research Articles

Kinematic Parameter Optimization of a 3-DOF Cable-Driven Parallel Robot with a Kinodynamic Dexterity Index

Kinematic Parameter Optimization of a 3-DOF Cable-Driven Parallel Robot with a Kinodynamic Dexterity Index

Efficient and precision dressing of arc-shaped diamond grinding wheel by laser dressing and electrical discharge dressing

Affected by the characteristics of laser Gaussian beam, the spot size and laser energy irradiated on the grinding wheel surface change at any time with the dressing path, which makes it difficult to realize the dressing of high-precision arc-shaped diamond grinding wheel. In order to achieve high-efficiency and precise dressing of arc-shaped diamond grinding wheels, a composite dressing method using laser rough dressing and electrical discharge precision dressing was first proposed. Laser rough dressing method is used to quickly remove the excess abrasive layer to obtain an arc-shaped profile. Electrical discharge precision dressing not only improved the accuracy of arc-shaped contour, but also realized the grinding wheel sharpening. The optimization of kinematic parameters on the dressing profile accuracy in laser dressing and electrical discharge dressing was explored. An arc-shaped profile with a radius of 13 mm was tested on a diamond grinding wheel with a grain size of 120#. The radius of the final dressed arc-shaped profile is 13,007 μm, and the PV value of the profile error is 10.67 μm. It was found that the abrasive grains on the surface of the grinding wheel were slightly graphitized. The damage degree of the abrasive particles in laser dressing was more serious than that of in electrical discharge dressing. Most of the graphite layer on the surface of abrasive particles could be removed by grinding alumina ceramics. The fitting radius of the arc profile of the workpiece is 13.013 mm, and the profile error PV value is 11.91 μm.

Understanding local cutting features affecting surface integrity of gear flank in gear skiving

In gear skiving, large variations in cutting features significantly affect the cutting condition and surface integrity of a newly formed gear flank (NGF). This study aimed to improve the understanding of the effects of local cutting features on the surface integrity of approach and recess NGFs from the resulting microstructure produced by the multiple radial-infeed (MRI) strategy. For the first time, the boundary of the NGF regime and associated local cutting features were calculated from the uncut chip geometry (UCG) using a novel boundary-based level contour method. The theoretical and experimental results revealed that the local rake angle and uncut chip thickness are the most influential factors altering the plastic deformation conditions of the approach and recess NGFs. For the finishing pass, the uncut chip thickness developments within approach and recess NGFs were elucidated, showing the burnishing regime dominated the recess NGF formation. The strain–stress characteristics of the recess NGF show the strain-hardening effect due to the severe plastic deformation. Kernel average misorientation mapping showed a partial reduction in the misorientation angle under the recess NGF. This points to the accumulated deformation in the interaction between successive skiving passes further facilitating the localized recrystallization. Proposed local cutting feature calculations can be applied for further kinematic parameter optimization and MRI infeed rate design.

Kinematic parameter optimization of a flapping ellipsoid wing based on the data-informed self-adaptive quasi-steady model

This paper constructs an optimization framework based on the data-informed self-adaptive quasi-steady model. The framework aims at achieving a specific aerodynamic force coefficient by optimizing the kinematic parameters of the flapping motion of an ellipsoid wing. All the model coefficients of this quasi-steady model are calibrated empirically by the data-informed training. At each optimization iteration, the data-informed training is implemented by the local ridge regression, where the initial training samples are extracted from simulation examples, and the weight coefficients are calculated by the compactly supported radial basis function with the previous optimal solution as the center point. Furthermore, a numerical simulation is conducted to evaluate the accurate aerodynamic force coefficient corresponding to the current optimal solution. The relative error between the accurate simulation result and optimization objective is calculated as the convergence criteria of the optimization. Then, the effects of the kinematic parameters on the time-averaged lift coefficient are first investigated, which indicate that the in-phase flapping with high flapping angle amplitude and medium geometric angle of attack amplitude is beneficial to the lift coefficient. Moreover, the kinematic optimization is conducted for a three-dimensional flapping ellipsoid wing in the hovering mode. The results demonstrate that the leading-edge vortex is crucial for the force generation. Moreover, in one flapping period, the asymmetrical wake and two unequal lift coefficient peaks emerge under the figure-O motion pattern while the vortex structures are highly symmetrical under the figure-8 motion pattern.

Multifidelity kinematic parameter optimization of a flapping airfoil.

We construct a multifidelity framework for the kinematic parameter optimization of flapping airfoil. We employ multifidelity Gaussian process regression and Bayesian optimization to effectively synthesize the aerodynamic performance of the flapping airfoil with the kinematic parameters under multiresolution numerical simulations. The objective of this work is to demonstrate that the multifidelity framework can efficiently discover the optimal kinematic parameters of the flapping airfoil with specific aerodynamic performance using a limited number of expensive high-fidelity simulations combined with a larger number of inexpensive low-fidelity simulations. We efficiently identify the optimal kinematic parameters of an asymmetrically flapping airfoil with various target aerodynamic forces in the design space of heaving amplitude, flapping frequency, angle of attack amplitude, and stroke angle. Notably, it is found that the angle of attack can significantly affect the magnitude of aerodynamic forces by facilitating the generation of the leading-edge vortex. In the meanwhile, its combination effect with the stroke angle can determine the attitude and trajectory of the flapping airfoil, thus further affect the direction of the aerodynamic forces. With the influence of the streamwise in-line motion, the asymmetrical vortex structures emerge in the wake fields because the streamwise velocities of shedding vortices are different in the upstroke and downstroke. Furthermore, we conduct the kinematic parameter optimization for a three-dimensional asymmetrically flapping wing. Compared to the two-dimensional simulations, we further investigate the flow induced by the vortex ring and its unsteady effects on the vortex structure and aerodynamic performance.

An Algorithm to Design Redundant Manipulators of Optimally Fault-Tolerant Kinematic Structure

One measure of the global fault tolerance of a redundant robot is the size of its self-motion manifold. If this size is defined as the range of its joint angles, then the optimal self-motion manifold size for an n-degree-of-freedom (DoF) robot is n × 2π, which is not typical for existing robot designs. This letter presents a novel two-step algorithm to optimize the kinematic structure of a redundant manipulator to have an optimal self-motion manifold size. The algorithm exploits the fact that singularities occur on large self-motion manifolds by optimizing the robots kinematic parameters around a singularity. Because a gradient for the self-motion manifold size does not exist, the kinematic parameter optimization uses a coordinate descent procedure. The algorithm was used to design 4-DoF, 7-DoF, and 8-DoF manipulators to illustrate its efficacy at generating optimally fault-tolerant robots of any kinematic structure.

Kinematic arrangement optimization of a quadruped robot with genetic algorithms

Background: As research on quadruped robots grows, so does the variety of designs available. These designs are often inspired by nature and finalized around various technical, instrumentation-based constraints. However, no systematic methodology of kinematic parameter selection to reach performance specifications is reported so far. Kinematic design optimization with objective functions derived from performance metrics in dynamic tasks is an underexplored, yet promising area. Methods: This article proposes to use genetic algorithms to handle the designing process. Given the dynamic tasks of jumping and trotting, body and leg link dimensions are optimized. The performance of a design in genetic algorithm search iterations is evaluated via full-dynamics simulations of the task. Results: The article presents comparisons of design results optimized for jumping and trotting separately. Significant dimensional dissimilarities and associated performance differences are observed in this comparison. A combined performance measure for jumping and trotting tasks is studied too. It is discussed how significantly various structural lengths affect dynamic performances in these tasks. Results are compared to a relatively more conventional quadruped design too. Conclusions: The task-specific nature of this optimization process improves the performances dramatically. This is a significant advantage of the systematic kinematic parameter optimization over straight mimicking of nature in quadruped designs. The performance improvements obtained by the genetic algorithm optimization with dynamic performance indices indicate that the proposed approach can find application area in the design process of a variety of robots with dynamic tasks.

Geometric parameter identification of a dual-arm robot by using closed-chain constraint and optimization technique

The positioning accuracy of the empirical robot manipulators is determined by various factors, such as kinematic accuracy, structure rigidity, and controller performance. Here, we report on the development of a new and straightforward technique to calibrate the kinematic parameters of a dual-arm robot under uncertainty. In comparison with other techniques, which generally rely on using other instruments to calibrate the manipulators, the proposed method utilizes the intrinsic characteristics of the dual-arm robot for calibration. In particular, when the two arms grasp each other, a formed closed chain can be operated as the constraint equation for the kinematic parameter optimization of the two arms. In the optimization process, the dual-arm robot has to pose in various configurations to yield better performance, and thus a motion generation strategy of the dual-arm robot is proposed, where one arm serves as the master to track the designated trajectory and the other arm serves as the slave to track the motion of the master arm by using a compliance control strategy. The proposed calibration method was experimentally validated, and the results confirm that the positioning accuracy of both arms can be improved.

탄성체의 에너지 변환을 이용한 점프 로봇의 기구변수 최적화

탄성체의 에너지 변환을 이용한 점프 로봇의 기구변수 최적화

Research on Optimization of Kinematic Parameters of Pectoral Fin

Since the propulsion performance of fish pectoral fin is directly related to its kinematic parameters, for improving the propulsion performance of pectoral fin, the kinematic model of propulsion motion of pectoral fin was established, the hydrodynamic force acted on the pectoral fin during propulsion motion was calculated and the mathematic model which optimized the propulsion performance of pectoral fin was established. Then MATLAB was used to write the genetic algorithm program which is used to get the optimal solution of kinematic parameters of pectoral fin. Finally, the simulation analysis of the propulsion performance of pectoral fin was developed. From the simulation result, it can be got that the optimal model established and the optimal algorithm adopted can play an important role in improving the propulsion performance of pectoral fin. Therefore, the optimal analysis developed in this paper is reasonable and effective as well as provides theoretical reference to the research on the bionic pectoral fin and the new underwater maneuvering vehicle.

Coupled linkage system optimization for minimum power consumption

This paper presents the dynamic analysis and kinematic parameter optimization of a coupled linkage system for the purpose of employing the system in construction industry. So far, the kinematic optimization of wheel loaders was approached heuristically rather than utilizing elaborate theoretical examinations due to the complexity of coupled linkage structures. The results of the theoretical analysis and kinematic parameter optimization are presented in this paper. A wheel loader with Z-bar linkage was analyzed. For a given end-effector path, the linkage system was optimized to carry out effective motion while exhibiting minimum power consumption during operation. A modified principle of reduced system was applied in order to execute the dynamics analysis of the coupled linkage system. As a result, an optimal Z-bar linkage structure and a distribution of power consumption within the given conditions were obtained.

On aerodynamic modelling of an insect–like flapping wing in hover for micro air vehicles

This theoretical paper discusses recent advances in the fluid dynamics of insect and micro air vehicle (MAV) flight and considers theoretical analyses necessary for their future development. The main purpose is to propose a new conceptual framework and, within this framework, two analytic approaches to aerodynamic modelling of an insect-like flapping wing in hover in the context of MAVs. The motion involved is periodic and is composed of two half-cycles (downstroke and upstroke) which, in hover, are mirror images of each other. The downstroke begins with the wing in the uppermost and rearmost position and then sweeps forward while pitching up and plunging down. At the end of the half-cycle, the wing flips, so that the leading edge points backwards and the wing's lower surface becomes its upper side. The upstroke then follows by mirroring the downstroke kinematics and executing them in the opposite direction. Phenomenologically, the interpretation of the flow dynamics involved, and adopted here, is based on recent experimental evidence obtained by biologists from insect flight and related mechanical models. It is assumed that the flow is incompressible, has low Reynolds number and is laminar, and that two factors dominate: (i) forces generated by the bound leading-edge vortex, which models flow separation; and (ii) forces due to the attached part of the flow generated by the periodic pitching, plunging and sweeping. The first of these resembles the analogous phenomenon observed on sharp-edged delta wings and is treated as such. The second contribution is similar to the unsteady aerodynamics of attached flow on helicopter rotor blades and is interpreted accordingly. Theoretically, the fluid dynamic description is based on: (i) the superposition of the unsteady contributions of wing pitching, plunging and sweeping; and (ii) adding corrections due to the bound leading-edge vortex and wake distortion. Viscosity is accounted for indirectly by imposing the Kutta condition on the trailing edge and including the influence of the vortical structure on the leading edge. Mathematically, two analytic approaches are proposed. The first derives all the quantities of interest from the notion of circulation and leads to tractable integral equations. This is an application of the von Kármán-Sears unsteady wing theory and its nonlinear extensions due to McCune and Tavares; the latter can account for the bound leading-edge vortex and wake distortion. The second approach uses the velocity potential as the central concept and leads to relatively simple ordinary differential equations. It is a combination of two techniques: (i) unsteady aerodynamic modelling of attached flow on helicopter rotor blades; and (ii) Polhamus's leading-edge suction analogy. The first of these involves both frequency-domain (Theodorsen style) and time-domain (indicial) methods, including the effects of wing sweeping and returning wake. The second is a nonlinear correction accounting for the bound leading-edge vortex. Connections of the proposed framework with control engineering and aeroelasticity are pointed out.