Showing papers on "Kinematics equations published in 2014"

A Variable Curvature Continuum Kinematics for Kinematic Control of the Bionic Handling Assistant

Abstract: We present a new variable curvature continuum kinematics for multisection continuum robots with arbitrarily shaped backbone curves assembled from sections with three degrees of freedom (DoFs) (spatial bending and extension, no torsion). For these robots, the forward kinematics and the differential forward kinematics are derived. The proposed model approach is capable of reproducing both the constant and variable backbone curvature in a closed form. It describes the deformation of a single section with a finite number of serially connected circular arcs. This yields a section model with piecewise constant and, thus, a variable section curvature. Model accuracy and its suitability for kinematic real-time control applications are demonstrated with simulations and experimental data. To solve the redundant inverse kinematics problem, a local resolution of redundancy at the velocity level through the use of the robot's Jacobian matrix is presented. The Jacobian is derived analytically, including a concept for regularization in singular configurations. Experimental data are recorded with Festo's Bionic Handling Assistant. This continuum robot is chosen for experimental validation, as it consists of a variable backbone curvature because of its conically tapering shape.

Toward parallel continuum manipulators.

Abstract: In this paper, we investigate continuum manipulators that are analogous to conventional rigid-link parallel robot designs. These “parallel continuum manipulators” have the potential to inherit some of the compactness and compliance of continuum robots while retaining some of the precision, stability, and strength of rigid-link parallel robots, yet they represent a relatively unexplored area of the broad manipulator design space. We describe the construction of a prototype manipulator structure with six compliant legs connected in a parallel pattern similar to that of a Stewart-Gough platform. We formulate the static forward and inverse kinematics problems for such manipulators as the solution to multiple Cosserat-rod models with coupled boundary conditions, and we test the accuracy of this approach in a set of experiments, including the prediction of leg buckling. An inverse kinematics simulation of slices through the 6 degree-of-freedom (DOF) workspace illustrates the kinematic mapping, range of motion, and force required for actuation, which sheds light on the potential advantages and tradeoffs that parallel continuum manipulators may bring. Potential applications include miniature wrists and arms for endoscopic medical procedures, and lightweight compliant arms for safe interaction with humans.

Solving time-varying inverse kinematics problem of wheeled mobile manipulators using Zhang neural network with exponential convergence

Abstract: A mobile manipulator is a robotic device composed of a mobile platform and a stationary manipulator fixed to the platform. The forward kinematics problem for such mobile manipulators has a mathematical analytic solution; however, the inverse kinematics problem is mathematically intractable (especially for satisfying real-time requirements). To obtain the accurate solution of the time-varying inverse kinematics for mobile manipulators, a special class of recurrent neural network, named Zhang neural network (ZNN), is exploited and investigated in this article. It is theoretically proven that such a ZNN model globally and exponentially converges to the solution of the time-varying inverse kinematics for mobile manipulators. In addition, the kinematics equations of the mobile platform and the manipulator are integrated into one system, and thus the resultant solution can co-ordinate simultaneously the wheels and the manipulator to fulfill the end-effector task. For comparison purposes, a gradient neural network (GNN) is developed for solving time-varying inverse kinematics problem of wheeled mobile manipulators. Finally, we conduct extensive tracking-path simulations performed on a wheeled mobile manipulator using such a ZNN model. The results substantiate the efficacy and high accuracy of the ZNN model for solving time-varying inverse kinematics problem of mobile manipulators. Besides, by comparing the simulation results of the GNN and ZNN models, the superiority of the ZNN model is demonstrated clearly.

Implementation and experimental validation of Dynamic Movement Primitives for object handover

Abstract: This article presents the implementation and experimental validation of a control system dedicated to human robot physical interaction during object handovers. Our control law defines the trajectory of the robotic arm towards a previously unknown handover location based on the Dynamic Movement Primitives formalism adapted for human robot object handover. The control law was deployed on a Kuka Light-Weight Arm equipped with the Azzurra anthropomorphic hand. We employed an industrial-like setting involving three different human postures for object handover in order to evaluate the performance and user experience of our control law and its generalizability. The evaluation was conducted over 1000 object handover trials between the human and robot partners, and the kinematic data and subjective experience were gathered for each trial. The outcomes of this evaluation validate the current implementation and guide the next steps towards more efficient and fluid human robot interaction.

A neural-network committee machine approach to the inverse kinematics problem solution of robotic manipulators

Abstract: In robotics, inverse kinematics problem solution is a fundamental problem in robotics. Many traditional inverse kinematics problem solutions, such as the geometric, iterative, and algebraic approaches, are inadequate for redundant robots. Recently, much attention has been focused on a neural-network-based inverse kinematics problem solution in robotics. However, the result obtained from the neural network requires to be improved for some sensitive tasks. In this paper, a neural-network committee machine (NNCM) was designed to solve the inverse kinematics of a 6-DOF redundant robotic manipulator to improve the precision of the solution. Ten neural networks (NN) were designed to obtain a committee machine to solve the inverse kinematics problem using separately prepared data set since a neural network can give better result than other ones. The data sets for the neural-network training were prepared using prepared simulation software including robot kinematics model. The solution of each neural network was evaluated using direct kinematics equation of the robot to select the best one. As a result, the committee machine implementation increased the performance of the learning.

Modeling and computed torque control of a 6 degree of freedom robotic arm

Abstract: This paper presents modelling and control design of ED 7220C — a vertical articulated serial arm having 5 revolute joints with 6 Degree Of Freedom. Both the direct and inverse kinematic models have been developed. For analysis of forces and to facilitate the controller design, svstem dvnamics have been formulated. A non-linear control technique, Computed Torque Control (CTC) has been presented. The algorithm, implemented in MATLAB/Simulink, utilizes the derived dynamics as well as linear control techniques. Simulation results dearly demonstrate the efficacy of the presented approach in terms of traiectory tracking Various responses of the arm joints have been recorded to characterize the performance of the control algorithm. The research finds its applications in simulation of advance nonlinear and robust control techniques as well as their implementation on the physical platform.

Design and implementation of kinematics model and trajectory planning for NAO humanoid robot in a tic-tac-toe board game

Abstract: The ability of NAO robot to play tic-tac-toe board game using its hands is greatly determined by the kinematics model of NAO’s arms and the use of trajectory planning for manipulation tasks In this paper, kinematics models for NAO’s upper body are presented The forward kinematics models are designed by using the modified Denavit-Hartenberg convention The inverse kinematics models of 5-joints NAO’s arms are obtained by using analytical inverse transform technique in which provide unique and feasible solutions The movement of NAO’s arms while playing tic-tac-toe is constructed by using the proposed 3-Dimensional Cartesian Space trajectory planning method The test result shows that the implemented trajectory planning method along with kinematics model are able to make NAO robot plays tic-tac-toe well by using its hands

Kinematic instability in concentric-tube robots: Modeling and analysis

Abstract: In this paper the issue of kinematic instability for concentric tube robots is studied when the following two conditions are considered: (a) the robot consists of more than two concentric tubes, and (b) the tubes consist of straight sections followed by curved sections. In this paper, we use the term “kinematic instability” when the tip position of robot in the Cartesian domain jumps from one equilibrium point to another while having a constant joint space configuration. This implies that in unstable configurations, the “forward kinematics” of the robot will have multiple solutions for one set of joint space variables. In this paper a novel framework is proposed that can calculate the stability condition for the robots consisting of multiple tubes with straight sections without solving the nonlinear ordinary differential equations. The resulting conditions restrict the pre-curvatures and length of the tubes, as a design factor, to guarantee kinematic stability within the whole workspace of the robot.

Proper Assisted Research Method Solving of the Robots Inverse Kinematics Problem

Abstract: Finding the better solution of the inverse kinematics problem, with the minimum of the trajectory errors, is very difficult because there are many variable parameters and many redundant solutions. The presented paper show the assisted solving of the inverse kinematics with the goal to minimize the final end-effector trajectory errors, by optimizing the distance between the and-effector final position and the target. All obtained results were been verified by applying the proper forward kinematics virtual LabVIEW instrumentation. The paper tries to answer at the inverse kinematics problem for one known mathematical trajectory and identifying the cinematic errors after the establishing and applying the proper assisted solving method using the Cycle Coordinate Descent Method coupled to the proper Neural Network Sigmoid Bipolar Hyperbolic Tangent (CCDM-SBHTNN). We were shown one complete study case to obtain one circle space trajectory using one arm type robot fixed on the ceiling. The presented method is general and can be used in all other robots types and in all other conventional and unconventional space curves.

Preliminary concept and kinematics simulation of a novel Spherical Underwater Robot

Abstract: This paper describes the preliminary concept of a novel Spherical Underwater Robot. The novel SUR employs a spherical hull and equipped with multiple vectored water-jetbased thrusters. This paper focuses on the preliminary design of the structure and the simulation of the robot’s dynamics and kinematics. On the basis of the structural characteristics of the spherical robot, its dynamic model is derived by applying the Lagrange-Routh equations briefly. The simulation model is established based on ADAMS2007 software. A 3D model of robot is built by CATIA and then exported to ADAMS2007 for simulation. The results of simulation by combining MATLAB/ SIMULINK with ADAMS are presented. The dynamic analysis and simulation are given to verify the validity of this design. The simulation results indicate that the proposed virtual prototype system has the capability of simulative demonstration and performance validation, and can provide an innovative approach for AUV graphic simulation.

The development of an innovative two-DOF cylindrical drive: Design, analysis and preliminary tests

Abstract: The quest for ever faster pick-and-place robots has led to ingenious parallel robots with reduced mobility, e.g., capable of producing motions proper of SCARA systems: three independent translations and one rotation about an axis of fixed direction. These robots are also known as Schönflies-motion generators (SMG). Some parallel versions are commercially available, as are serial-parallel designs. The former are provided with four limbs, the latter with three, the fourth degree of freedom being appended in series with a Delta robot. Parallel robots are more attractive than their hybrid counterparts, but the presence of four legs poses serious challenges to their designers, as limb-interference limits the rotatability of the moving plate. A solution to this problem includes a gear train for rotation-range amplification, but this increases the inertial load on the motors and complicates the design - too many parts - and the control - because of inherent gear backlash and Coulomb friction. Recently, a SMG system was proposed that is supplied with two limbs, arrayed in an isostatic structure, which provides high rotatability of its gripper. This robot is driven by one C (cylindrical)-joint at each limb. As this joint allows for two degrees of freedom, it calls for two motors, that might as well be fixed to the base, which poses interesting design challenges. Reported in this paper is a design solution for the drive of a C joint, which is termed the C (cylindrical)-drive, based on a cylindrical differential mechanism of the RHHR type, with R standing for revolute, H for helical (or screw) joint. The design, kinematics and dynamics of the drive are discussed, along with a realization, and preliminary tests.

Surface growth kinematics via local curve evolution

Abstract: A mathematical framework is developed to model the kinematics of surface growth for objects that can be generated by evolving a curve in space, such as seashells and horns. Growth is dictated by a growth velocity vector field defined at every point on a generating curve. A local orthonormal basis is attached to each point of the generating curve and the velocity field is given in terms of the local coordinate directions, leading to a fully local and elegant mathematical structure. Several examples of increasing complexity are provided, and we demonstrate how biologically relevant structures such as logarithmic shells and horns emerge as analytical solutions of the kinematics equations with a small number of parameters that can be linked to the underlying growth process. Direct access to cell tracks and local orientation enables for connections to be made to the underlying growth process.

Kinematics analysis and numerical simulation of a manipulator based on virtual prototyping

Abstract: Manipulator kinematics refers the analytical study of the motion of manipulator, such as positions, velocities, and accelerations of the links of a manipulator. As formulating the suitable kinematics models for a manipulator is very crucial for analyzing the behavior of manipulators and light weight design of manipulators, many researches have been focused on it in recent decades with a result of many valuable contributions. However, current researches always focus on rigid manipulator, while the manipulator is always a rigid-flexible coupling multibody system, which can affect the accuracy of kinematics analysis and numerical simulation. This paper proposed a model of kinematics analysis of manipulator based on rigid-flexible coupling virtual prototyping. After a model of manipulator kinematics based on the D-H method was proposed, rigid-flexible coupling virtual prototyping-based kinematics simulation and numerical simulation was then put forward. The kinematical experiment is carried out based on manipulator physical prototyping, which demonstrates that the accuracy of the kinematics calculation and the rationality of design based on rigid-flexible coupling virtual prototyping. The design of a five-degrees-of-freedom manipulator is given as an example, which demonstrates that the methodology is obviously helpful to manipulator design.

An application of screw theory to the kinematic analysis of a Delta-type robot

Abstract: This paper reports on the kinematics of a translational parallel manipulator whose topology is close to the architecture of the famous Delta robot. The displacement analysis is presented in closed-form solution by applying a new strategy based on the unknown coordinates of a point embedded to the moving platform. The input-output equations of velocity and acceleration of the robot are systematically obtained by resorting to reciprocal-screw theory. The singularities of the mechanism are explained through the input-output equation of velocity. Finally, a numerical example is provided to show the application of the method.

Task-space position control of concentric-tube robot with inaccurate kinematics using approximate Jacobian

Abstract: Many medical applications can benefit from the new technology of concentric-tube robot (CTR) due to its miniature size, superior steerability, and controllability of the end tool. However, the kinematic modeling of CTR is challenging because of complicated physical phenomena caused by the elasticity interaction between tubes. Existing control methods of CTR are based on inverse kinematics calculation and hence the control performance largely relies on the accuracy of kinematics model used. In this work, we propose a new control method from the actuator level and show that the control design of actuator input in task-space with approximate Jacobian matrix provides more flexibility and robustness in handling inaccuracy in kinematics model. It is shown through simulation study that the proposed control method presents better performance compared with traditional inverse kinematics based control method in face of kinematics inaccuracy.

Predicting kinematic configuration from string length for a snake-like manipulator not exhibiting constant curvature bending

Abstract: We have recently developed a snake-like manipulator for use in orthopaedic environments. One example application is the treatment of osteolysis (bone degradation) due to total hip arthroplasty. Recent literature suggest constant curvature models to define manipulator configuration from string (or actuator cable) length; however, our manipulator does not conform to constant curvature bending. In this paper, we present a two-step model to predict the kinematic configuration directly from string length with no assumptions regarding constant curvature bending. We experimentally identify the model parameters and validate the model on an additional experimental data set. The results indicate our model achieved an average maximum error of 1.0 ± 0.90mm in predicting manipulator configuration compared to the ground truth over the test data set.

Inverse kinematics solution for robot manipulator based on adaptive MIMO neural network model optimized by hybrid differential evolution algorithm

Abstract: In this paper, a new hybrid differential evolution algorithm is proposed, which combines the differential evolution (DE) algorithm and the back-propagation (BP) algorithm. This new hybrid algorithm is used to train an adaptive MIMO neural network (or AMNN) model for identifying the inverse kinematics of the industrial robot manipulator. Simulation results prove that the proposed identification process of the new hybrid algorithm performs faster convergence and better precision than the conventional back-propagation algorithm or the solely differential evolution algorithm. Consequently, the inverse kinematics of the industrial robot manipulator identification based on the AMNM achieves outstanding performance.

A Joint Physical Constraints Avoidance Method for Inverse Kinematics Problem of Redundant Humanoid Manipulator

Abstract: There are innumerable inverse kinematics solutions that can meet the demand of end-effector position and orientation for the redundant humanoid manipulator. Also each manipulator joint has its physical constraints for the connecting rod structure and figuration design. In order to make the inverse kinematics solution away from the joint position limitation maximization, an algorithm that combines geometry method and numerical iterative method is proposed to solve the inverse kinematics problem of redundant humanoid manipulator(8-DOF). Based on the derived geometric formula of the inverse kinematics problem, the "Away Limitation Level" of the humanoid manipulator is adopted as fitness function and optimization goal, and then particle swarm optimization(PSO) is used to search for the optimal combination of the redundant joint, and the optimal inverse kinematics solution can be obtained in this method. The proposed method can not only solve the multiple inverse kinematics solutions problem of the redundant humanoid manipulator, but also have some advantages, i.e., the solution no theoretical error, fast solving speed and the large margin away from the joint position limitation. Numerical simulation results demonstrate the effectiveness of this algorithm.

Adaptive backstepping control for parallel robot with uncertainties in dynamics and kinematics

Abstract: It is common in robot tracking control that controllers are designed based on the exact kinematic model of the robot manipulator. However, because of measurement errors and changes of states in practice, the original kinematic model is often no longer accurate and will degrade the control result. An adaptive backstepping controller is designed here for parallel robot systems with kinematics and dynamics uncertainties. Backstepping control is used to manage the transformation between the errors in task space and joint space. Adaptive control is utilized to compensate for uncertainties in both dynamics and kinematics. The controller demonstrated good performance in simulation.

Kinematics, Dynamics, Control and Accuracy of Spherical Parallel Robot

Abstract: This paper deals with the kinematical and dynamical properties of parallel spherical manipulators with three degrees of freedom. Accelerations, dynamics, control and accuracy are considered. Algorithm of control is based on the inverse problem of dynamics and allows minimizing deviations of coordinates, velocities and accelerations.

Method for determining position of kinematics, such as multi-axis kinematics as robot arm, involves positioning kinematics for interaction with object, and positioning another kinematics in line of sight to former kinematics

Abstract: The method involves positioning a kinematics (10) for the interaction with an object, and positioning another kinematics (11) in a line of sight to the former kinematics. A relative position of the former kinematics to the latter kinematics is determined based on the radiation (15). The positioning of a multi-axis kinematics for the interaction with the object has a movement of the multi-axis kinematics along the object. A position of the latter kinematics is stationary during the movement of the former kinematics. An independent claim is included for a device for determining the position of a kinematics, such as a multi-axis kinematics as a robot arm.

ANFIS based Jacobian for a parallel manipulator mobility assistive device

Abstract: Nowadays parallel manipulators are used widely in bioengineering applications; this leads to many exciting expectations as well as challenges. The kinematic analysis of parallel manipulators with their differential kinematics yielding the Jacobian in a closed form is not a trivial task. In this paper a parallel manipulator based mobility assistive device called EJADII is analyzed to determine forward kinematics, inverse kinematics and closed-form Jacobian. An Adaptive Neuro-Fuzzy Inference System (ANFIS) is trained to estimate the Jacobian. This system would be useful when determination of the Jacobian in a closed-form is difficult to determine. The human motion during sit to stand captured by VICON experiment is used with two assisting scenarios to train and verify this system. Computer simulations show relatively good results of the proposed system.

A neural-network committee machine approach to the inverse kinematics problem solution of robotic manipulators

Abstract: In robotics, inverse kinematics problem solu- tion is a fundamental problem in robotics. Many traditional inverse kinematics problem solutions, such as the geo- metric, iterative, and algebraic approaches, are inadequate for redundant robots. Recently, much attention has been focused on a neural-network-based inverse kinematics problem solution in robotics. However, the result obtained from the neural network requires to be improved for some sensitive tasks. In this paper, a neural-network committee machine (NNCM) was designed to solve the inverse kinematics of a 6-DOF redundant robotic manipulator to improve the precision of the solution. Ten neural networks (NN) were designed to obtain a committee machine to solve the inverse kinematics problem using separately prepared data set since a neural network can give better result than other ones. The data sets for the neural-network training were prepared using prepared simulation software including robot kinematics model. The solution of each neural network was evaluated using direct kinematics equation of the robot to select the best one. As a result, the committee machine implementation increased the perfor- mance of the learning.

Robot control using high dimensional neural networks

Abstract: In this paper, we propose a position control scheme for actual robot system using high dimensional neural networks. Complex-valued neural network and quaternion neural network learn inverse kinematics of the robot systems. Control objectives are two dimensional SCARA robot and three dimensional robot. Tip of these robots are controlled by the high dimensional neural networks. Some results by an actual robot system are shown to confirm feasibility of these high dimensional neural networks as robot controllers.

A Hybrid Solution for the Inverse Kinematic on a Seven DOF Robotic Manipulator

Abstract: This paper presents a solution for the inverse kinematics in a human arm kinematics model of seven degrees of freedom applying Genetic Algorithms in the shoulder joint and the Piper method in the whole arm in order to make the algorithm response faster and accurate. The Genetic Algorithm's code explores a set of initial solutions and optimizing it until find an angular response that satisfies the positional and rotational restrictions proposed to the model with a minimal error and a considerably speed. The accuracy and reliability of the applied algorithm is evaluated applying a statistical analysis upon a set of answers using SPSS Statistics.

Dynamics analysis of a novel over-constrained three-DOF parallel manipulator

Abstract: In this paper, a novel over-constrained three degree-of-freedom (DOF) spatial parallel manipulator (SPM) is proposed. The architecture of the SPM is comprised of a moving platform attached to a base through two revolute- prismatic-universal jointed serial linkages and one spherical-prismatic-revolute jointed serial linkage. The prismatic joints are considered to be actively actuated. Kinematics and dynamics of the SPM are studied systematically. Firstly, both of the inverse and forward displacements are derived by analytic formulae. Then, the velocities and the accelerations of the moving platform and each limb are obtained. Finally, dynamics of the mechanism is derived based on the principal of the virtual work. The results are illustrated by numerical examples.

Analysis and simulation of kinematics of 5-DOF nuclear power station robot manipulator

Abstract: To analyze kinematic characteristics of the 5-DOF nuclear robot, the forward kinematics equations are established through Denavit-Hartenberg (D-H) method. The working space of robot is drawn out in Matlab according to Monte Carlo method and the inverse kinematic equations are established through the Paul's inverse transforms. In view of the missing solutions and redundant solutions that may appear in the process of solution for inverse kinematics equations, the paper describes different treatments. In order to test the kinematic model of manipulator, the test procedures are designed and there is a simulation for door-open planning based on the forward and inverse kinematics in a multibody dynamics simulation software Recurdyn to monitor the motion of the manipulator. The simulation experiments in this paper verify the rationality of motion algorithm and link design parameters, and provide a reliable basis for the study of dynamics, control and planning of robot.

Forward kinematics analysis of a 5-axis RV-2AJ robot manipulator

Abstract: This paper presents the forward kinematics analysis for the Mitsubishi Melfa RV-2AJ industrial robot with a five degree of freedom (DOF) revolute joints. The kinematics problem is defined as the transformation from the joint space to the Cartesian space and vice versa. An analytical solution using Denavit-Hartenberg (D-H) representation to describe the position and orientation of the robot end-effector is presented. Several lab experiments to verify the developed kinematics equations have been conducted. In this study, the developed kinematics solutions were found to be accurate (98.68%) compared to the real robot. These findings have important implication for developing dynamic simulation model that can be used to evaluate position and force control algorithm.