Rajeevlochana G. Chittawadigi

Identification of Denavit-Hartenberg Parameters of an Industrial Robot

Kinematic identification of a serial robot has been an active field of research as the need for improving the accuracy of a robot is increasing with time. Denavit-Hartenberg (DH) parameters of a serial robot, which are typically used to represent its architecture, are usually provided by its manufacturer. At times these parameters are not the same and hence they need to be identified. An analytical method proposed elsewhere was used here for identification of an industrial robot by noting the values of the point on the end-effector due to rotation of each joint, locking all other joints, were found out using singular value decomposition. The DH parameters of the robot determined using the proposed methodology, matched satisfactorily with the robot specifications. Also, the bounding volume for the joint ranges infers that a smaller measurement volume relative to the robot workspace is required thus facilitating the use of measurement devices which have smaller range of measurement.

Robot kinematics made easy using RoboAnalyzer software

RoboAnalyzer is a software based on 3D model of robots. It was developed primarily for teaching and learning of robot mechanics, although it is robust enough for the use by researchers as well. The motive behind the development of RoboAnalyzer was mainly to help teachers and students get started with teaching/learning of robotics using template‐based skeleton models or CAD models of serial robots. This minimizes the time otherwise spent on modeling, programming, and simulating the robots from scratch. In this article, we focus on the visualization of the Denavit Hartenberg (DH) parameters used to define a robots architecture, and the modeling of the robots input‐output motion characteristics, that is, robot kinematics, using them. The advantages of using RoboAnalyzer to overcome several challenges of learning robotics in a classroom environment are also discussed.

An analytical method to detect collision between cylinders using dual number algebra

Cylinder, a common geometric entity has a discontinuity at the joining of cylindrical surface and circular-disks. Hence, collision detection between two cylinders in space is a difficult task and few have reported formulations to solve it. In this paper, a novel analytical methodology is proposed to detect collision or intersection between two cylinders. The configuration, i.e., position and orientation, between the cylinders was represented using the four Denavit-Hartenberg (DH) parameters plus two extra parameters. Dual Number Algebra was used to extract these six parameters. Tests involved in collision detection between the cylinders were between the lines and rectangles in a plane, thus considerably simplifying the problem of collision detection. As an illustration, an one-DOF arm modeled as a cylinder with cylindrical shaped obstacles were modeled and tested for their collisions. The results were validated with an analytical method available in the literature and a commercial software.

Geometric Model Identification of a serial Robot

Robots find their applications in various fields and are used to perform repetitive and adaptive tasks very accurately. This requires exact kinematic parameters of the robot. Generally, for a serial robot, these parameters are represented using the Denavit-Hartenberg (DH) parameters, whose nominal values are provided by the robot manufacturers. In this paper, a technique is proposed to determine the exact DH parameters of a serial robot. For this, each joint of the robot is rotated while the others are locked. Hence, the end-effector moves in a circle, which can be measured using external measurement devices, say a theodolite, a vision system or a laser scanner. From these measurements, the axis and center of the circles traced by the points are determined. If the joint axes are represented using dual vectors, the exact DH parameters can be extracted with the help of Dual Vector Algebra proposed here. The proposed technique has an advantage that it does not require any calibration of base frame of the robot with the measurement frame. Since, the technique allows one to determine the exact DH parameters at the site of installed robot, the robot need not to be taken to a separate calibration section. The proposed measurement methodology is simulated in a CAD software environment using the CAD model of a KUKA KR5 robot.

Virtual Experiments for Integrated Teaching and Learning of Robot Mechanics Using RoboAnalyzer

Increasing number of universities are offering robotics courses at undergraduate and graduate level. Introductory courses on robot mechanics involve topics from matrix multiplication, coordinate transformations and multivariate equations. Often, the physical meaning of concepts in kinematics and dynamics are lost behind the complicated mathematics involved in them. Hence, it may be the case that some fundamental concepts in robot mechanics may not be very intuitive to teach or learn. In order to appreciate the same, robotics teaching/learning software can be integrated into the curriculum. In this paper, the use of RoboAnalyzer, a 3D model based software for teaching and learning a course in robot mechanics is discussed. An integrated coursework that involves virtual experiments and projects in robot mechanics using RoboAnalyzer is also proposed in the paper. The foreseen advantages of using RoboAnalyzer in classroom and laboratory sessions are also discussed.

Kinematic analysis of MTAB robots and its integration with RoboAnalyzer software

Robotics has emerged as a research interest to find its place in various applications such as industries, automobile, space robots, health care, etc. The thrust in robotics research has resulted in increasing number of courses being introduced in the engineering curriculum. Fundamental concepts in robot mechanics are difficult to visualize using text books alone and hence, require either a physical robot or a simulation software to demonstrate the same. Effective robotics education can be achieved using serial robots and a visualization software. In this paper, affordable serial chain robots developed by MTAB are presented along with its integration with a simulation software named RoboAnalyzer. The forward and inverse kinematic analyses of the MTAB Mini and Aristo robots, and the implementation of the same in RoboAnalyzer software is also presented for comprehensive learning of the robotics topics.

Virtual robots module: an effective visualization tool for robotics toolbox

An introductory level robotics course mainly comprises the topics like geometry, kinematics, and dynamics of serial-chain robots. The description of the robot geometry using the Denavit-Hartenberg parameters and the kinematic and dynamic analyses require advanced mathematical concepts and are computationally intensive for robots with higher degrees-of-freedom. This calls for the use of robotics learning software, which would effectively aid the instructor to explain the concepts lucidly, and help the students in analyzing the mechanics of the robot. Robotics Toolbox is one such commonly used software, which is a collection of MATLAB-based functions that support various dedicated mathematical operations required in mechanical analysis of robots. RoboAnalyzer is another attempt towards the same goal, which focuses on the learning of robotics concepts from the physics of the robot motion. In this paper the integration of the Virtual Robots Module of RoboAnalyzer with the Robotics Toolbox is presented. With multiple number of industrial robot models, the Virtual Robots Module acts as an effective visualization add-in for the analysis performed using the Robotics Toolbox. The proposed visualization add-in can be used from software like MATLAB, MS-Excel, etc. The Virtual Robots Module allows improved visualization and easy simulation of industrial robot models for robotics research and education.

RoboAnalyzer: Robot Visualization Software for Robot Technicians

Robots have become an irreplaceable part of various industries which has led to an increasing demand for well-trained robot operators or technicians to operate and maintain these robots. The concepts of robotics are difficult to understand from pure mathematical standpoint which has led to the development of various robot visualization software for better understanding of the robot motion. RoboAnalyzer is one such software. In this paper, the features of RoboAnalyzer and how they can be used to teach robotics concepts to robot technicians are discussed.

A teach pendant to control virtual robots in Roboanalyzer

Teach programming is an interactive way to program industrial robots. It involves usage of a handheld control unit called teach pendant that can be used to control the motion of a robot. It provides a very convenient method to teach trajectories to the robot. One of the advantages of teach pendant programming is that an operator is not required to learn any special programming language. Hence, teach pendants can be used as an effective tool in educational robotics as well. These devices are generally proprietary and work for a specific robot. As few institutes have robots, the teach pendants are not available to a lot of students to use and control robots. In this paper, a generic ‘teach pendant’ has been reported that can be used to control the motion of virtual robots available in RoboAnalyzer, a 3D model based robotics learning software. The teach pendant can be used by students to program virtual robots.