Optimal Kinematic Design Research Articles

Kinematic synthesis and optimization design of a rice pot seedling transplanting mechanism

To achieve the precise operation trajectory and posture required for pot seedling transplanting and solve the problem that the partial reversal of the transplanting arm’s output in the double planet carrier transplanting mechanism, which is unconducive to the realization of the seedling pushing action, a motion synthesis method for a double planet carrier gear train mechanism with attitude constraints based on the output angle and four exact task poses is proposed. First, the ideal transplanting trajectory is planned according to the transplanting agronomic requirements, and the position and attitude information of the four key points on the ideal trajectory are extracted as the constraints of the mechanism design. Then, based on the relative displacement equation, a comprehensive design equation of the motion of the plane 3R mechanism (simplified model of the transplanting mechanism) about the output rotation angle and the precise four pose constraints is established, and the mechanism parameters that meet the constraint requirements are obtained by solving the multicellular homotopy method. A mathematical model of the roundness of the non-circular gear was also established, and the roundness of the transmission non-circular gears in the gear-train transplanting mechanism was optimized by using the genetic algorithm. Finally, the structural design, virtual simulation, and experimental analysis of the double-planet carrier gear train transplanting mechanism were completed. The results show that the actual trajectory and attitude are consistent with the theoretical design, and when then the mechanism was under the transplanting efficiency of 120 and 180 plants/min, the success rates of picking seedlings were 91.53% and 87.46%, respectively, meeting the design requirements.

Optimization design of a parallel surgical robot with remote center of motion

This paper proposes a parallel surgical robot with a remote center of motion, and the kinematic optimization design is studied. The surgical robot is composed of two branches, each of which is a planar mechanism. The kinematics model of the robot is established through spatial geometric analysis. A modified Monte-Carlo sampling method is presented to greatly increase the sampling rate during the workspace calculation of the parallel surgical robot. Further, through the boundary sampling method, the boundary of the workspace is encrypted and sampled, and the accurate workspace is obtained. A dexterity index with clear physical meaning is proposed and the corresponding solution is found. Based on the effective workspace volume index and global dexterity index, a multi-objective optimization is carried out on the parallel surgical robot by using the quantum particle swarm optimization. The optimized robot has a large effective workspace and good dexterity, which meets the needs of surgical robots.

Kinematic Optimization Design and Performance Simulation of Novel 5-DOF Parallel Machining Robots with Spatial Layout

High efficiency and precision machining of complex components with spatial free-form surface features is facing significant scientific challenges, which put forward higher requirements for the design of machining equipment. Considering the requirements of engineering practice on the rotation ability, motion ability, stiffness performance and mass of equipment, two novel parallel five degree of freedom (5-DOF) machining robots with spatial layout are proposed. This kind of robot is approximately centrally symmetric, with reasonable constraint and driving wrench design, and greatly releases the flexibility of the spindle. A multi-objective optimization approach incorporating the NSGA-II algorithm is used to optimize the kinematic performance of the robots. According to the cooperative equilibrium criterion, the optimal virtual prototype parameters for the two types of robots are selected and contrasted. Then, the static performance of the more optimal virtual prototype is verified using finite element analysis. The numerical simulation demonstrates that the designed 5-DOF machining robot offers satisfactory static behavior and flexibility, which is of significant application value.

Kinematic Analysis and Optimal Design of a Novel Schönflies-Motion Parallel Manipulator With Rotational Pitch Motion for Assembly Operations

Abstract This paper presents a novel Schönflies-motion Parallel Manipulator with RotationalPitch motion (SPM-RP) based on a single-platform fully parallel mechanism. An analysis of the position, workspace, velocity, and singularity of the SPM-RP is carried out in detail, and a dimensionless Jacobian is proposed to evaluate the manipulability of the SPM-RP. The analysis shows that the SPM-RP is with position-decoupled kinematics, a large singularity-free workspace, and excellent manipulability. The SPM-RP is actuated by four parallel prismatic actuators, enabling the manipulator to provide the identical kinematic performance at all generic cross sections perpendicular to the prismatic joint axes within its workspace. This paper thus proposes a reduced design optimization formulation, where the traditional optimization over the entire workspace is reduced to the optimization on a representative workspace cross section of the SPM-RP. According to this approach, the design optimization of the SPM-RP is carried out by maximizing its manipulability over the total orientation workspace, which is crucial for precision assembly. Based on the achieved optimal design, an SPM-RP prototype is developed. The mobility, orientation capability, total orientation workspace, and repeatability of the optimal design are tested and verified by the developed SPM-RP prototype. Experiments show that the SPM-RP can achieve a large total orientation workspace with excellent precision performance.

Dynamic Modeling and Error Analysis of a Cable-Linkage Serial-Parallel Palletizing Robot

The efficiency and accuracy for parallel robot play a significant role in the industrial production process. In order to further improve the motion performance of parallel robot, this paper focuses on the study of mechanism design, dynamic modeling and error analysis of a cable-linkage serial-parallel palletizing robot (CSPR). Firstly, the CSPR is designed as a series-parallel hybrid mechanism driven by flexible cables, which can effectively reduce the inertia and improve the dynamic response. As is known that kinematic design optimization of compliant mechanisms requires accurate yet efficient mathematical models, the kinematics and dynamic models are established by the homogeneous coordinate transformation method and Lagrange equation. Based on the dynamic mathematical model of the robot, a variety of sensors are chosen to construct the hardware control system and the sliding mode variable structure control strategy is also designed based on motion errors. Then, the motion performance and load carrying capacity of the CSPR were analyzed and compared in different operating conditions respectively, and the results verify the validity and efficiency of the mechanism.

Kinematic modeling and optimal design of a partially compliant four-bar linkage using elliptic integral solution

This paper deals with the kinematic modeling and optimal design of compliant mechanisms with one flexible joint designed from a rigid four-bar linkage. An equivalent mechanism is proposed to describe the large-deflection motion of a compliant four-bar linkage. In light of the elliptic integral solution, the kinematics and strain energy of the compliant four-bar linkage are derived and verified by a numerical comparison study. Then, by taking the path deviation and strain energy as two objectives, the multi-objective optimization problem is solved at a given initial configuration of the rigid mechanism, followed by a discussion of the best initial configuration where the rigid joint is replaced by elastic flexures. Both the finite element analysis and experimental verification are carried out. The results show that the output motion of the optimized compliant mechanism matches the desired path very well, which demonstrates the feasibility of designing compliant mechanisms by this approach.

Kinematic Chain Optimization Design Based on Deformation Sensitivity Analysis of a Five-Axis Machine Tool

This paper focuses on optimization of kinematic chain to reduce force-induced error in the scheme design phase of a five-axis machine tool. After conducting process planning on the machining target, local deformation of motion units in cutting positions is considered using a geometric way. A mathematical model is then established describing the influence of local deformation error on the general machining error through homogeneous transformation matrices. Conceptual model of the machine tool is constructed to obtain deformation distribution using static FEA. Error sensitivity coefficients are then calculated and compared among all alternative kinematic chains to select the optimized scheme. The proposed method is verified through a designing example of a five-axis vertical machining center. The optimized kinematic chain could lower the magnitude of deformation sensitivities by 9.69% and increase error equalization variance by 71.25% compared to the conventional method.

Kinematic analysis and optimal design of a novel 3-PRR spherical parallel manipulator

This paper introduces a novel three degree-of-freedom spherical parallel manipulator with 3-PRR topology, where P and R denote a curved prismatic joint and a revolute joint, respectively. The first revolute joint of each PRR leg is actuated via a double Rzeppa-type driveshaft, and hence underlined. The manipulator has at most eight working modes and eight assembly modes. However, only one working mode and one assembly mode of the manipulator are acceptable during its motion which can be easily identified. Singularity and kinematic dexterity analyses reveal that the proposed 3-PRR spherical parallel manipulator has no forward kinematic singularity for a wide range of rotation of the moving platform around its central axis. An optimal design of the manipulator is also presented having a workspace with good kinematic dexterity.

Semi-Isotropically Optimized Stewart Platform Manipulator Design with Actuator Stroke Constraint

The isotropic property has been a general use in the context of kinematic design optimization of robotic manipulators. In this paper, the semi-isotropic home or neutral configuration of a semi-regular Stewart platform manipulator has been designed by introducing the stroke constraint of all the legs through the assessment of new actuator variable termed as ‘fractional excess margin’ of actuation. The constrained optimization problem structured with the quadratic functions relating all the rotational and translational motion of the tool center point and the actuator stroke. The numerical solution obtained from the system of nonlinear equations has been interpreted graphically through the analysis of the ‘fractional excess margin’ for prescribed single degree of motions of Stewart platform manipulator. Finally, a trade-off has been made between the goals of optimum semi-isotropic design configuration and that of the configuration with the actuators in the legs of the least stroke requirement.

Kinematic analysis and optimal design of a novel parallel pointing mechanism

Pointing mechanisms are widely used in aerospace fields. In order to make the pointing mechanism more adaptable and make the structure more compact and lightweight, a novel six degrees of freedom (6-DOF) parallel mechanism is proposed in this paper, which can provide wide range three-dimensional rotational movement and precise three-dimensional translational movement. Firstly, the description of the novel parallel mechanism is addressed and the equivalent motion to 3-RRR+3-CPR serial-parallel mechanism is demonstrated. Then, the kinematics are studied. Finally, using the performance atlas of motion/force transmission index, an optimal design of the structure parameters is conducted. Based on the kinematic simulation in ADAMS software, the kinematic analysis is verified correct. The novel mechanism has the advantages of wide rotation range, compact structure and decoupling of rotation and translation, which can be well applied in aerospace fields where both the pointing and position adjustment are necessary.

Occupant-centered optimization framework to evaluate and design new dynamic shading typologies.

Dynamic solar shading has the potential to dramatically reduce the energy consumption in buildings while at the same time improving the thermal and visual comfort of its occupants. Many new typologies of shading systems that have appeared recently, but it is difficult to compare those new systems to existing typologies due to control algorithm being rule-based as opposed to performance driven. Since solar shading is a design problem, there is no single right answer. What is the metric to determine if a system has reached its optimal kinematic design? Shading solutions should come from a thorough iterative and comparative process. This paper provides an original and flexible framework for the design and performance optimization of dynamic shading systems based on interpolation of simulations and global minimization. The methodology departs from existing rule-based strategies and applies to existing and to complex shading systems with multiple degree-of-freedom mobility. The strategy for control is centered on meeting comfort targets for work plane illuminance while minimizing the energy needed to operate space. The energy demand for thermal comfort and work plane daylight quantity (illuminance) are evaluated with Radiance and EnergyPlus based on local weather data. Applied to a case study of three typologies of dynamic shading, the results of the methodology inform the usefulness and quality of each degree-of-freedom of the kinematic systems. The case study exemplifies the iterative benefits of the methodology by providing detailed analytics on the behavior of the shades. Designers of shading systems can use this framework to evaluate their design and compare them to existing shading systems. This allows creativity to be guided so that eventually building occupants benefit from the innovation in the field.

Synthesis and methodology for optimal design of a parallel remote center of motion mechanism: Application to robotic eye surgery

This work reports on the synthesis of a parallel Remote Center of Motion (RCM) mechanism, and an optimized design for the use-case of robot-assisted vitreoretinal surgery. A 2-DoF planar RCM mechanism is proposed and synthesised as part of a 4-DoF RCM mechanism. The proposed design substantially reduces the occupied volume at the end-effector. This solves a major problem present in related state-of-the-art, which poses limitations on sterile end-effector design and surgical instrument compatibility. Subsequently, an optimal design algorithm is proposed and implemented for the given use-case. The workspace is determined within mechanism constraints, after which performance parameters such as workspace coverage, potential energy, manipulability, reflected stiffness are determined for specific areas of interest within a desired workspace. Subsequently, these parameters are combined in a score function identifying an optimal kinematic design. When compared with the closely-related prior art, the resulting design shows improvements in relevant workspace coverage, reduced gravity compensation effort, and more isotropic manipulability. Overall reflected stiffness is reduced and should be taken into account in future design phases. Future work includes the integration of the kinematic design into a detailed conceptual design and a first prototype development.

Kinematic Design Analysis and Optimization of Mobility System Using MATLAB

In this research work, several sophisticated types of equipment and automation have been studied, points taken and considered to realise the locomotion of modern territory of all uneven environments. One of the most main mission and structure of this study is the preferred simplicity of the bipedal walking locomotion system. The study included from simple to complicated legs as like single-legged, like humanoid and up to sixteen legs like a caterpillar. Most of the bipedal walking robots are with research study and we concentrated to emphasizes the significance of robotic legged motion stability in the compact. These bipedal walking robots can walk on rough surfaces, turn efficiently and climb staircase if needed. In particular, a suitable bipedal walking model having an upper link and a lower link will make the system to the desired motions, which has been experimentally exposed to provide a stable walking system. The MATLAB software tool is used to optimize the mechanical constraints and to compare, analyse and investigate the influence of motion stability. The simulation results show a possible performance of projected leg bipedal walking mechanism.

Comparative Kinematic Analysis and Design Optimization of Redundant and Nonredundant Planar Parallel Manipulators Intended for Haptic Use

SUMMARYThis paper investigates a comparative kinematic analysis between nonredundant and redundant 2-Degree Of Freedom parallel manipulators. The nonredundant manipulator is based on the Five-Bar mechanism, and the redundant one is a 3-RRR planar parallel manipulator. This study is aimed to select the best structure for a haptic application. This latter requires a mechanism with a desired workspace of 10 cm × 10 cm and an admissible force of 5 N in all directions. The analysis criteria are the accuracy of the forward kinematic model and the required actuator torques. Thereby, the geometric parameters of the two structures are optimized in order to satisfy the required workspace such that parallel singularities are overcome. The analysis showed that the nonredundant optimally designed manipulator is more suitable for the haptic application.

Optimal kinematic design of a single-DOF planar grasper based on metaheuristic optimization

A method is proposed for optimal synthesis of a grasper mechanism for circular objects. A single-DOF linkage-type grasper is developed considering the geometry of the target objects. The mechanism consists of successive coupled four-bar linkages and is capable of grasping circular objects with desirable range of diameter. The synthesis problem is formulated as a constraint optimization problem, while adaptive inertia weight particle swarm optimization (AIW-PSO) approach is used to carry out the solutions. Biomechanical and industrial applications for the mechanism are suggested and investigated by simulations as case studies. To demonstrate the effectiveness of AIW-PSO on the problem, a comparison with two other well-known metaheuristic algorithms namely PSO and genetic algorithm is done. The results show the efficiency of the proposed algorithm and the performance of the mechanism.

Kinematic Design Optimization of an Eight Degree-of-Freedom Upper-Limb Exoskeleton

SummaryThis paper studies the problem of optimizing the kinematic structure of an eight degree-of-freedom upper-limb rehabilitation exoskeleton. The objective of optimization is achieving minimum volume and maximum dexterity in the workspace of daily activities specified by a set of upper-arm configurations. To formulate the problem, a new index is proposed for effective characterization of kinematic dexterity for wearable robots. Additionally, a set of constraints are defined to ensure that the optimal design can cover the desired workspace of the exoskeleton, while singular configurations and physical interferences are avoided. The formulated multi-objective optimization problem is solved using an evolutionary algorithm (Non-dominated Sorting Genetic Algorithm II) and the weighted sum approach. Among the resulted optimal points, the point with least sensitivity with respect to the variations of design variables is chosen as the final design.

Correction to: Kinematic design optimization for anthropomorphic robot hand based on interactivity of fingers

Correction to: Kinematic design optimization for anthropomorphic robot hand based on interactivity of fingers

Kinematic design optimization for anthropomorphic robot hand based on interactivity of fingers

The human hand provides excellent grasp capabilities by using the interaction of the thumb and other fingers, and thus, how to dextrously interact with each other can represent the performance of the robot hand. This paper presents the kinematic design optimization for an anthropomorphic robot hand based on the interactivity of fingers. We propose a new performance index, called ‘interactivity of fingers (IF),’ which is useful for quantifying the multifingered precision grasping capability of the robot hand. Using the IF, the kinematic model of an anthropomorphic robot hand is optimized. The optimization is performed by using the genetic algorithm, and position and orientation of the thumb’s saddle joint are systematically determined. In order to verify the usefulness of the proposed performance index, IF of existing hands and that of the optimized model are compared. As a result, the IF of the optimized robot hand is almost five times larger than those of the other hands and the effectiveness of the proposed method is discussed.

Kinematic modeling and design optimization of flexure-jointed planar mechanisms using polynomial bases for flexure curvature

Kinematic design optimization of compliant mechanisms requires accurate yet efficient mathematical models of elastic behavior. A method to predict large-deflection behavior of flexure joint elements using polynomial curvature functions is described in this paper. The method is generalized and extended for kinematic prediction and design optimization of planar multi-flexure mechanisms. It is shown that the kinostatic configuration problem may be solved efficiently and accurately via an energy-based constrained relaxation approach. A class of design optimization problems is further considered where prescribed link positions must be achieved within an overall motion path. Case studies are introduced and theoretical solutions presented. The first of these involves a double Hoeken’s linkage, designed to achieve rectilinear translation of an end link. The second involves an X-Y motion stage mechanism, designed to achieve translational motion of a platform over a targeted workspace while minimizing its rotation. Experimental results involving a realization of the optimized X-Y motion stage design are reported and compared with numerical predictions. To complete the paper, a sensitivity analysis for assembly errors is undertaken via a Monte Carlo simulation. This gives further insight on expected mechanism performance and confirms the efficiency and practical utility of the proposed methods.

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.