Orientation Of End-effector Research Articles

Spreadsheet-based neural networks modelling and simulation for training and predicting inverse kinematics of robot arm

This paper is proposed to solve the inverse kinematic (IK) problem of two-degree-of-freedom planar robot arm using neural networks (NN). Several NN model designs of distinct hidden neurons based on the sum of square error function of joint angle are developed and trained with generalised reduced gradient algorithm. The paper is also intended to demonstrate the modelling process of feed-forward NN topology in spreadsheet environment. The spreadsheet functions as INDEX, SUMPRODUCT, EXP, and SUMSQ; the utilities as name manager, data validation, data table, ActiveX controls, answer report, and charts; and the add-in Solver are utilised to develop the models. With the input parameters of link lengths and end-effector position and orientation, two models with the structures 5-12-1 and 5-10-1 are discovered best-capable in predicting first and second joint angles respectively. This NN-based IK technique contributes significantly to the optimal motion control of robot arm for quality processing and assembly tasks.

Pengembangan Wearable Robotic Arm Input dan Virtual Instrument untuk Pengendalian dan Pemantauan Lengan Robot

This paper investigate the integration of wearable robotic arm input (WRAI) with virtual instrument (VI) for controlling and monitoring the manipulator. The WRAI was designed by following the contours of human arms and equipped with five potentiometers as the sensor. The sensors were placed properly on WRAI by considering the ergonomic aspect. Each sensor on WRAI actuate each joint on the manipulator. The manipulator has five degrees of freedom (DOF) which consists of five revolute joints. For monitoring process, control panel of VI was created suitably by LabVIEW, and its block diagram was mainly programmed by following the forward kinematics approach. The VI obtains the input signal from the rotation of potentiometer on WRAI, and then transmitted to the receiver on manipulator to actuate the joints. By monitoring the control panel, the user can observe each angle joint on manipulator and also the position and orientation of end effector. The test results show the WRAI performs good controllability and ergonomic. The WRAI can control the manipulator easier than using remote control and joystick. Further, the control panel of VI is able to simplify the monitoring process by the friendly user interface.

Intuitive adaptive orientation control of assistive robots for people living with upper limb disabilities.

Robotic assistive devices enhance the autonomy of individuals living with physical disabilities in their day-to-day life. Although the first priority for such devices is safety, they must also be intuitive and efficient from an engineering point of view in order to be adopted by a broad range of users. This is especially true for assistive robotic arms, as they are used for the complex control tasks of daily living. One challenge in the control of such assistive robots is the management of the end-effector orientation which is not always intuitive for the human operator, especially for neophytes. This paper presents a novel orientation control algorithm designed for robotic arms in the context of human-robot interaction. This work aims at making the control of the robot's orientation easier and more intuitive for the user, in particular, individuals living with upper limb disabilities. The performance and intuitiveness of the proposed orientation control algorithm is assessed through two experiments with 25 able-bodied subjects and shown to significantly improve on both aspects.

An Approach for Imitation Learning on Riemannian Manifolds

In imitation learning, multivariate Gaussians are widely used to encode robot behaviors. Such approaches do not provide the ability to properly represent end-effector orientation, as the distance metric in the space of orientations is not Euclidean. In this paper, we present an extension of common imitation learning techniques to Riemannian manifolds. This generalization enables the encoding of joint distributions that include the robot pose. We show that Gaussian conditioning, Gaussian product, and nonlinear regression can be achieved with this representation. The proposed approach is illustrated with examples on a two-dimensional sphere, with an example of regression between two robot end-effector poses, as well as an extension of task-parameterized Gaussian mixture model and Gaussian mixture regression to Riemannian manifolds.

Procedure for definition of end-effector orientation in planar surfaces robot applications

Design of user-friendly and at the same time powerful robot programming methods is the subject of significant efforts undertaken by the international robotics community. For the purpose of facilitating robot programming, with regard to the most common present-day applications in industry, it would be useful to develop programming procedures for frequently used manipulator tasks which could be easily implemented and used as ready-made application software. Important class of industrial robot applications involves end-effector trajectories in planar surfaces. Development of robot programming language procedure intended for determination of object plane normal with respect to frame of interest, as well as programming of end-effector orientation is presented in this paper. This procedure can be used as integral part of task oriented robot programing applications as well as a procedure for explicit programming languages, and it is illustrated in practical example with the robot Lola 15.

Automatic entry point planning for robotic post-mortem CT-based needle placement.

Post-mortem computed tomography guided placement of co-axial introducer needles allows for the extraction of tissue and liquid samples for histological and toxicological analyses. Automation of this process can increase the accuracy and speed of the needle placement, thereby making it more feasible for routine examinations. To speed up the planning process and increase safety, we developed an algorithm that calculates an optimal entry point and end-effector orientation for a given target point, while taking constraints such as accessibility or bone collisions into account. The algorithm identifies the best entry point for needle trajectories in three steps. First, the source CT data is prepared and bone as well as surface data are extracted and optimized. All vertices of the generated surface polygon are considered to be potential entry points. Second, all surface points are tested for validity within the defined hard constraints (reachability, bone collision as well as collision with other needles) and removed if invalid. All remaining vertices are reachable entry points and are rated with respect to needle insertion angle. Third, the vertex with the highest rating is selected as the final entry point, and the best end-effector rotation is calculated to avoid collisions with the body and already set needles. In most cases, the algorithm is sufficiently fast with approximately 5-6s per entry point. This is the case if there is no collision between the end-effector and the body. If the end-effector has to be rotated to avoid collision, calculation times can increase up to 24s due to the inefficient collision detection used here. In conclusion, the algorithm allows for fast and facilitated trajectory planning in forensic imaging.

Solution for a Five Link Industrial Robot Manipulator Inverse Kinematics Using Intelligent Prediction Response Method

Background: Robot kinematics suggests and interprets the relationship exists between the kinematic position connectivity and acceleration of each link. In any of the robot manipulator the kinematics solution may be forward kinematics or inverse kinematics. To determine the joint values for a provided desired end effector orientation and position, the inverse kinematics principle is applied. Inverse kinematics is the usage of kinematics equations of a robot to find out the joint parameters that gives a targeted position of the end-effector. Methods/Statistical Analysis: In this paper, inverse kinematic solution for a five joint robot involving intelligent prediction response method has been developed and the result will be analyzed based on the performance. The intelligent prediction response method will give the performance based result, which shows the five various angles of an industrial robot. The single variation in the joint angle will be analyzed for every joint angles. This method based inverse kinematics solution is much more useful in real-time adaptive robot control where shorter calculation times are required. Findings: The MATLAB 13.0 is used to find the solution for a set of joint parameters. The actual reading and MATLAB program was found acceptable level. Applications/Improvements: To solution provided for the inverse kinematics problem with number of joint angles using the intelligent prediction response method such as artificial neural network is used.

Robot-Assisted Landing of VTOL UAVs: Design and Comparison of Coupled and Decoupling Linear State-Space Control Approaches

This paper addresses the problem of landing a VTOL UAV using a serial robotic manipulator fixed to the landing surface, which assists the UAV during the last, most challenging, landing phase. In this phase, UAV and manipulator are connected via a universal hinge, which decouples the flying vehicle’s and the robot’s end-effector orientation. The main contribution of the paper is the design of a linear state-space controller for position and orientation of the UAV while it is fixed to the manipulator. Furthermore, we compare a coupled and a decoupling realization of the model-based controller with a model-free controller. Both model-based controllers consider the dynamics of an attitude-controlled aerial vehicle and use the acceleration of the robot’s end-effector as control input. All three controllers are validated and compared in experiments using a KUKA/DLR light-weight robot on a nonmoving base and an AR.Drone 2.0 quadrotor. The experimental results show that decoupling is superior to the coupled and the model-free approach, since the orientation of the UAV rotorcraft is controlled more precisely.

A markerless human-manipulators interface using multi-sensors

Purpose – The purpose of this paper is to present a markerless human–manipulators interface which maps the position and orientation of human end-effector (EE, the center of the palm) to those of robot EE so that the robot could copy the movement of the operator hand. Design/methodology/approach – The tracking system of this human–manipulators interface comprises five Leap Motions (LMs) which not only makes up the narrow workspace drawback of one LM but also provides redundancies to improve the data precision. However, because of the native noises and tracking errors of the LMs, the measurement errors increase over time. To address this problem, two filter tools are integrated to obtain the relatively accurate estimation of the human EE, that is, Particle Filter for position estimation and Kalman Filter for orientation estimation. Because the operator has inherent perceptive limitations, the motions of the manipulator may be out of sync with the hand motions, so that it is hard to complete with the high performance manipulation. Therefore, in this paper, an over-damping method is adopted to improve reliability and accuracy. Findings – A series of human–manipulators interaction experiments were carried out to verify the proposed system. Compared with the markerless and contactless methods(Kofman et al., 2007; Du and Zhang, 2015), the method described in this study is more accurate and efficient. Originality/value – The proposed method would not hinder most natural human limb motion and allows the operator to concentrate on his/her own task, making it perform high-precision manipulations efficiently.

Quaternion-Based Algorithm for Direct Kinematic Model of a Kawasaki FS10E Articulated Arm Robot

This article follows a detailed description of development and validation for the direct kinematic model of six degrees of freedom articulated arm robot - Kawasaki FS10E model. The development of the kinematic model is based on widely used Denavit-Hartenberg notation, but, after the initial parameter identification, the mathematical algorithm itself follows an approach that uses the quaternion number system, taking advantage of their efficiency in describing spatial rotation - providing a convenient mathematical notation for expressing rotations and orientations of objects in three-dimensional space. The proposed algorithm concludes with two quaternion-based relations that express both the position of robot tool center point (TCP) position and end-effector orientation with respect to robot base coordinate system using Denavit-Hartenberg parameters and joint values as input data. Furthermore, the developed direct kinematic model was validated using the programming and offline simulation software Kawasaki PC Roset.

Geometric and elastostatic calibration of robotic manipulator using partial pose measurements

The paper deals with the geometric and elastostatic calibration of robotic manipulator using partial pose measurements, which do not provide the end-effector orientation. The main attention is paid to the efficiency improvement of identification procedure. In contrast to previous works, the developed calibration technique is based on the direct measurements only. To improve the identification accuracy, it is proposed to use several reference points for each manipulator configuration. This allows avoiding the problem of non-homogeneity of the least-square objective, which arises in the classical identification technique with the full pose information (position and orientation). Its efficiency is confirmed by the comparison analysis, which deals with the accuracy evaluation of different identification strategies. The obtained theoretical results have been successfully applied to the geometric and elastostatic calibration of a serial industrial robot employed in a machining work cell for aerospace industry.

On generating the motion of industrial robot manipulators

In this study, an intelligent search algorithm is proposed to define the path that leads to the desired position and orientation of an industrial robot's manipulator end effector. The search algorithm gradually approaches the desired configuration by selecting and evaluating a number of alternative robot's configurations. A grid of the robot's alternative configurations is constructed using a set of parameters which are reducing the search space to minimize the computational time. In the evaluation of the alternatives, multiple criteria are used in order for the different requirements to be fulfilled. The alternative configurations are generated with emphasis being given to the robot's joints that mainly affect the position of the end effector. Grid resolution and size parameters are set on the basis of the desired output. High resolution is used for a smooth path and lower for a rough estimation, by providing only a number of the intermediate points to the goal position. The path derived is a series of robot configurations. This method provides an inexperienced robot programmer with flexibility to generate automatically a robotic path that would fulfill the desired criteria without having to record intermediate points to the goal position. Intelligent, grid based search algorithm for generating motion of industrial robot manipulators.The robot path is produced as the result of combining the joints values. The large search space is reduced by applying a set of parameters.The alternative configurations of the robot are generated giving emphasis to the robot's joints that mainly affect the desired target.Multiple-criteria are taken into account for evaluating the generated robot path towards the desired position and orientation.

DESIGN & KINEMATIC ANALYSIS OF AN ARTICULATED ROBOTIC MANIPULATOR

This paper describes the design, fabrication and analysis a five axes articulated robotic manipulator. The current work is undertaken by considering various commercially available robotic kits to design and fabricate a five degree of freedom (D.O.F) arm. Forward kinematic model has been presented in order to determine the end effectors position and orientation. Although this work is still in primary level, this analysis is useful for path tracking of an industrial manipulator with pick-and-place application. Based on this analysis, a researcher can develop path tracking behaviour of an end effector in complicated work space.

Algorithm to obtain inverse kinematics matrix from the 3D curve and to apply to glue shoe sole

Nowadays, manipulator is widely used in industrial applications. The trajectories of manipulator are more and more complicated. In order to do good tracking performance, the end effector position and orientation have to be determined. This paper describes a method to determine position and orientation of manipulator’s end effector base on a reference path. This method will be applied for manipulator 6 DOF to glue shoe sole. Firstly, assume the reference path is arbitrary curve, the path was then discrete to become multi-point. Secondly, the roll – pitch – yaw vectors of the end effector will be determined at each point. Finally, Euler angles and interpolation method in 3D space will be applied to determine inverse kinematics matrix of manipulator for each point on the reference path. In addition, this paper also gives an example of reference path of shoe sole to apply the presented method. To verify the tracking performance of manipulator and reference path, a PID controller was designed for simulation. The result of simulation proved the correction of the algorithm.

Analytical inverse kinematics for 5-DOF humanoid manipulator under arbitrarily specified unconstrained orientation of end-effector

SUMMARYThis paper proposes an analytical method of solving the inverse kinematic problem for a humanoid manipulator with five degrees-of-freedom (DOF) under the condition that the target orientation of the manipulator's end-effector is not constrained around an axis fixed with respect to the environment. Since the number of the joints is less than six, the inverse kinematic problem cannot be solved for arbitrarily specified position and orientation of the end-effector. To cope with the problem, a generalized unconstrained orientation is introduced in this paper. In addition, this paper conducts the singularity analysis to identify all singular conditions.

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

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.

Estimation of Cartesian Space Robot Trajectories Using Unit Quaternion Space

The ability to estimate Cartesian space trajectories that include orientation is of great importance for many practical applications. While it is becoming easier to acquire trajectory data by computer vision methods, data measured by general-purpose vision or depth sensors are often rather noisy. Appropriate smoothing methods are thus needed in order to reconstruct smooth Cartesian space trajectories given noisy measurements. In this paper, we propose an optimality criterion for the problem of the smooth estimation of Cartesian space trajectories that include the end-effector orientation. Based on this criterion, we develop an optimization method for trajectory estimation which takes into account the special properties of the orientation space, which we represent by unit quaternions. The efficiency of the developed approach is discussed and experimental results are presented.

A novel augmented reality-based interface for robot path planning

Intuitive and efficient interfaces for robot task planning have been a challenging issue in robotics as it is essential for the prevalence of robots supporting humans in key areas of activities. This paper presents a novel augmented reality (AR) based interface for interactive robot path and end-effector (EE) orientation planning. A number of human-virtual robot interaction methods have been formulated and implemented with respect to the various types of robotic operations needed in different applications. A Euclidean distance-based method is developed to assist the users in the modification of the waypoints so as to update the planned paths and/or orientation profiles within the proposed AR environment. The virtual cues augmented in the real environment can support and enhance human-virtual robot interaction at different stages of the robot tasks planning process. Two case studies are presented to demonstrate the successful implementation of the proposed AR-based interface in planning robot pick-and-place tasks and path following tasks.

A New Full Pose Measurement Method for Robot Calibration

Identification of robot kinematic errors during the calibration process often requires accurate full pose measurements (position and orientation) of robot end-effectors in Cartesian space. This paper proposes a new method of full pose measurement of robot end-effectors for calibration. This method is based on an analysis of the features of a set of target points (placed on a rotating end-effector) on a circular trajectory. The accurate measurement is validated by computational simulation results from the Puma robot. Moreover, experimental calibration and validation results for the Hyundai HA-06 robot prove the effectiveness, correctness, and reliability of the proposed method. This method can be applied to robots that have entirely revolute joints or to robots for which only the last joint is revolute.

Motion planning for redundant prismatic-jointed manipulators in the free-floating mode

This paper investigates the motion planning of redundant free-floating manipulators with seven prismatic joints. On the earth, prismatic-jointed manipulators could only position their end-effectors in a desired way. However, in space, the end-effectors of free-floating manipulators can achieve both the desired orientation and desired position due to the dynamical coupling between manipulator and satellite movement, which is formally expressed by linear and angular momentum conservation laws. In this study, a tractable algorithm particle swarm optimization combined with differential evolution (PSODE) is provided to deal with the motion planning of redundant free-floating prismatic-jointed manipulators, which could avoid the pseudo inverse of the Jacobian matrix. The polynomial functions, as argument in sine functions are used to specify the joint paths. The coefficients of the polynomials are optimized to achieve the desired end-effector orientation and position, and simultaneously minimize the unit-mass-kinetic energy using the redundancy. Relevant simulations prove that this method provides satisfactory smooth paths for redundant free-floating prismatic-jointed manipulators. This study could help to recognize the advantages of redundant prismatic-jointed space manipulators.