Workspace Visualization Research Articles

Intuitive teleoperation with hand-tracking in VR: a study on master–slave system virtualization and 3D workspace visualization

Intuitive teleoperation with hand-tracking in VR: a study on master–slave system virtualization and 3D workspace visualization

A Workspace Visualization Method for a Multijoint Industrial Robot Based on the 3D-Printing Layering Concept

The workspace of a robot provides the necessary constraint information for path planning and reliable control of the robot. In this paper, a workspace visualization method for a multijoint industrial robot is proposed to obtain a detailed workspace by introducing the 3D-printing layering concept. Firstly, all possible joint-angle groups of one pose in the joints’ ranges are calculated in detail according to the POE (product of exponential) theory-based forward-kinematics expressions of the multijoint industrial robot. Secondly, a multisolution selection method based on the key degree of the joint is proposed to select the appropriate joint-angle groups. The key degrees of all joints and their key order are obtained according to the sensitivity expressions of all joint angles, calculated from the Jacobian matrix of the robot. One principle based on the smallest differences of the nominal angle is established to select the possible solutions for one joint from the possible solutions for the joint with the smaller key order. The possible solutions for the joint with the highest key order are the appropriate joint-angle group. Thirdly, a workspace visualization method based on the layering concept of 3D printing is presented to obtain a detailed workspace for a multijoint industrial robot. The boundary formula of each layer is derived by forward kinematics, which is expressed as a circle or a ring. The maximum and minimum values of the radius are obtained according to the travel range of the joint angles. The height limitations of all layers are obtained with forward kinematics. A workspace boundary-extraction method is presented to obtain the array of path points of the boundary at each layer. The proposed postprocessing method is used to generate the joint-angle code of each layer for direct 3D printing. Finally, the effectiveness of the multisolution selection method and the workspace visualization method were verified by simulation and experiment.

Constrained Manipulability for Humanoid Robots Using Velocity Polytopes

Robot performance measures are important tools for quantifying the ability to carry out manipulation tasks. Generally, these measures examine the system’s kinematic transformations from configuration to task space. This means that environmental constraints are neglected in spite of the significant effects they may have on the robot’s admissible motions. In this paper, we propose a new measure called the constrained manipulability polytope (CMP) that considers the system’s kinematic structure, including closed chains or composite sub-mechanisms, joint limits and the presence of obstacles. For an illustrative planar case, we demonstrate how the CMP can evaluate a robot’s performance in a cluttered scene and how this evaluation can be extrapolated to obtain a workspace visualization. Additionally, we show the advantages and limitations of the CMP compared to the state of the art. Furthermore, the method is demonstrated both in simulation and experimentally for NASA’s Valkyrie robot. We show how the CMP provides a measure for single-arm and dual-arm manipulation tasks, analyze the workspace and be used to optimize the robot’s posture.

Global Redundancy Resolution via Continuous Pseudoinversion of the Forward Kinematic Map

This paper presents a novel approach to kinematic redundancy resolution for redundant robots, which have more degrees of freedom than workspace dimensions. It introduces the concept of a global redundancy resolution, which has the convenient property that whenever the robot returns to the same workspace point, it uses the same joint-space pose. The problem is cast, as a continuous pseudoinversion of the forward kinematic map. Continuity and smoothness should be attained if possible, but otherwise the volume of the discontinuity boundary should be minimized. A sampling-based approximation technique is presented that constructs roadmaps of both the domain and image, and minimizes discontinuities of the inverse function using a maximum satisfiability problem. Applications of this map include teleoperation, dimensionality reduction in motion planning, and workspace visualization. Results are demonstrated on toy problems with up to 20 DOF and on several robot arms. Note to Practitioners —Determining whether a robot manipulator can cover a range of movement in a Cartesian workspace under joint limits and collision constraints is typically addressed by an engineer’s intuition and trial and error. This paper presents an algorithm to solve this problem systematically. The method optimizes a mapping from workspace to joint space to minimize the number of discontinuities. The resulting maps can be used to select continuous inverse kinematic solutions to follow workspace paths, and their visualizations can aid in workcell design, robot selection, and robot placement.

A Study on Kinematics and Workspace Determination of a General 6-P US Robot

The 6-UP S parallel manipulator known as Stewart platform is the most common type of 6-DOF parallel robots. Most industrial applications such as the motion simulators and applications requiring high load and high workspace use this structure. However, the 6-UP S has its disadvantages as the actuated joint is located in the second place in the kinematic chain. The 6-P US is another 6-DOF structure and when compared with the 6-UP S, offers several advantages by allowing to mount the heavy and the vibration inducing actuated prismatic joint on the ground. This offers the added benefit of transferring the majority of the payload to the ground, resulting in lowering of the overall costs. The question is: Can we find a 6-P US architecture that meets or exceeds the prescribed workspace while meeting the same kinematics footprint requirement of a given 6-UP S? In the present paper, a recently constructed 6-UP S mechanism for a metro station is selected and using an optimization method based on a genetic algorithm (GA), a 6-P US mechanism that meets or exceeds the required workspace is identified. To do this, first, the various architectures of the 6-P US parallel robot are presented. The inverse kinematics solution for a general 6-P US architecture is obtained. To fully define the architecture, three additional kinematics parameters are selected and employed to define the cost function used for the optimization. The cost function acts as a penalizing mechanism which ignores unwanted architectures of the 6-P US. Finally, a new concept for 6-DOF workspace visualization representation, called workspace spheres, is presented. The new concept aids the user by offering quantitatively data and visualization tool for simultaneous description of rotational and translational workspace.

Intersection workspace visualization of multi-finger hands

The intersection workspace of multi-finger hands means the overlapping workspace in 3D Euclidean space where several fingertips can reach together, and is very valuable for grasp space planning, motion control and mechanical design for multi-finger hands. But, the intersection workspaces usually have sophisticated forms, which are really hard for robotic experts to image them. We present a general approach to visualize and analyze the intersection workspace of multi-finger hands. We firstly deduce the displacement equation of the fingertip, then generate 3D workspace of the fingertip and lastly obtain the intersection workspace of the multi-finger hands. This approach can visualize intersection workspaces with integrated forms and contours, and analyze the volume of the intersection workspaces. The vivid form and volume analysis of intersection workspaces are useful for robotic experts to accurately and intuitionally understand the fingertip motion ranges, plan the motion routes of fingers and avoid the motion collision among fingers.

Contributions to the kinematics of pointing

Pointing consists in orienting a line OP of a rigid body, with its point O fixed, P mobile. The operation can thus be achieved in two steps, one to provide P with the desired longitude on the sphere centered at O, of radius OP¯, the other to provide P with the desired latitude. While this operation is simpler than a full rigid-body rotation, its kinematics is not yet fully recorded in the literature. In fact, the kinematics of pointing cannot be considered as being included in the kinematics of spherical motion, because the latter is known to form a Lie group, while pointing operations do not. This paper is an effort to shed light on the kinematics of pointing by means of the visualization of the workspace of the mechanism used for its realization. In doing this, a strategy is proposed for the planning of pointing trajectories using a three-revolute spherical wrist. The contributions proposed by the authors thus target the workspace visualization and the path-planning of three-axis wrists when used for pointing operations.

Workforce location tracking to model, visualize and analyze workspace requirements in building information models for construction safety planning

Abstract Safety as well as productivity performance in construction is often poor due to congested site conditions. We lack a formalized approach in effective activity-level construction planning to avoid workspace congestion. The purpose of this research is to investigate and prototype a new Building Information Modeling (BIM) enabled approach for activity-level construction site planning that can pro-actively improve construction safety. The presented method establishes automated workspace visualization in BIM, using remote sensing and workspace modeling technologies as an integral part of construction safety planning. Global Positioning System (GPS) data loggers were attached to the hardhats of a work crew constructing cast-in-place concrete columns. Novel algorithms were developed for extracting activity-specific workspace parameters from the recorded workforce location tracking data. Workspaces were finally visualized on a BIM platform for detecting potential workspace conflicts among the other competing work crews or between material lifting equipment. The developed method can support project stakeholders, such as engineers, planners, construction managers, foremen and site supervisors and workers with the identification and visualization of the required or potentially congested workspaces. Therefore, it improves the foundation on how decisions are made related to construction site safety as well as its potential impact on a productive and unobstructed work environment.

A Three-Dimensional-Printed Home-Based Flexible Nasopharyngeal Explorer With Diamond Cuts1

A Three-Dimensional-Printed Home-Based Flexible Nasopharyngeal Explorer With Diamond Cuts1

Numerical Methods for Reachable Space Generation of Humanoid Robots

In view of the importance of workspace to robotic design, motion planning and control, we study humanoid reachable spaces. Due to the large number of degrees of freedom, the complexity and special characteristics of humanoid robots that conventional robots do not possess, it would be very difficult or impractical to use analytical or geometric methods to analyze and obtain humanoid reachable spaces. In this paper, we develop two numerical approaches — the optimization-based method and the Monte Carlo method — to generate the reachable space of a humanoid robot. We first formulate the basic constraints (including kinematic constraint and balance constraint) that a humanoid robot must satisfy in manipulation tasks. We then use optimization techniques to build mathematical models for boundary points by which the reachable boundary is formed. This method gives rise to an approximation of the reachable space with accurate boundary points. On the other hand, the Monte Carlo method is relatively simple and more suitable for the visualization of robotic workspace. To utilize the numerical results by the Monte Carlo method, we propose an approach to build a database. We present the algorithms with these two methods and provide illustrating examples conducted on the humanoid HRP-2.

Workspace zone differentiation and visualization for virtual humans

Human performance measures such as discomfort and joint displacement play an important role in product design. The virtual human Santos™, a new generation of virtual humans developed at the University of Iowa, goes directly to the computer-aided design model to evaluate a design, saving time and money. This paper presents an optimization-based workspace zone differentiation and visualization. Around the workspace of virtual humans, a volume is discretized to small zones and the posture prediction on each central point of the zone will determine whether the points are outside the workspace as well as the values of different objective functions. Visualization of zone differentiation is accomplished by showing different colours based on values of human performance measures on points that are located inside the workspace. The proposed method can subsequently help ergonomic design. For example, in a vehicle's interior, the controls should not only lie inside the workspace, but also in the zone that encloses the most comfortable points. Using the palette of colours inside the workspace as a visual guide, a designer can obtain a reading of the discomfort level of product users.

Using Cognitive Task Analysis (CTA) to Seed Design Concepts for Intelligence Analysts Under Data Overload

This paper describes how a Cognitive Task Analysis (CTA) was used to jumpstart the exploration of useful design aids to combat data overload in intelligence analysis. During a simulated analysis task, we observed how professional intelligence analysts were vulnerable to making inaccurate statements when they were under time pressure and working in a topic area outside their area of expertise. From these observations, we generated design recommendations and criteria for evaluating the usefulness of any effort aimed at reducing data overload. Then, we used CTA insights to trigger the development of modular design concepts, or “design seeds,” that leverage advances in machine processing to address vulnerabilities. Nine design seeds were integrated into a “Visual Narratives” workspace visualization concept. Feedback about the usefulness of the design seeds was obtained during an elicitation session following an animated fly-through, or “Ani-mock,” demonstration.