Paul Bosscher

Wrench-feasible workspace generation for cable-driven robots

This paper presents a method for analytically generating the boundaries of the wrench-feasible workspace (WFW) for cable robots. This method uses the available net wrench set, which is the set of all wrenches that a cable robot can apply to its surroundings without violating tension limits in the cables. The geometric properties of this set permit calculation of the boundaries of the WFW for planar, spatial, and point-mass cable robots. Complete analytical expressions for the WFW boundaries are detailed for a planar cable robot and a spatial point-mass cable robot. The analytically determined boundaries are verified by comparison with numerical results. Based on this, several workspace properties are shown for point-mass cable robots. Finally, it is shown how this workspace-generation approach can be used to analytically formulate other workspaces

Wrench-based analysis of cable-driven robots

This paper introduces the available net wrench set, which is the set of all wrenches that a cable robot can apply to its surroundings without violating tension limits in the cables. This set is used as a framework for understanding and computing wrench-feasibility of a pose of the robot, allowing wrench-feasibility to be tested in the task space. The geometric properties of the available net wrench set are then exploited to permit simple geometric calculation of the boundaries of the wrench-feasible workspace. This workspace generation is extended to two other workspaces as well. Other design tools, including payload specification and failure analysis, are also presented.

A Concept for Rapidly-Deployable Cable Robot Search and Rescue Systems

This paper introduces a new concept for robotic search and rescue systems. This system uses a rapidly deployable cable robot to augment existing search and rescue mobile robots. This system can greatly increase the range of mobile robots as well as provide overhead views of the disaster site, allowing rescue workers to reach survivors as quickly as possible while minimizing the danger posed to rescue workers. In addition to the system concept, this paper presents a novel kinematic structure for the cable robot, allowing simple translation-only motion (with moment-resisting capability) and easy forward and inverse kinematics for a 3-DOF spatial manipulator. Also, a deployment sequence is described, a rapid calibration algorithm is presented and the workspace of the manipulator is investigated.Copyright

Finger sculpting with Digital Clay: 3D shape input and output through a computer-controlled real surface

The NSF Digital Clay project is focused on the design, prototyping, integration, and validation of a computer-controlled physical device capable of taking any of a wide range of possible shapes in response to changes in a digital 3D model or to changes in the pressure exercised upon it by human hands. Although it clearly is a natural and unavoidable evolution of 3D graphical user interfaces, its unprecedented capabilities constitute a major leap in technologies and paradigms for 3D display, for 3D input, and for collaborative 3D design. In this paper, we provide an overview of the Digital Clay project and discuss the challenges, design choices, and initial solutions for a new finger sculpting interface designed for the Digital Clay and prototyped using conventional 3D I/O hardware.

A novel mechanism for implementing multiple collocated spherical joints

The paper presents the spherical joint mechanism, a new mechanism for implementing multiple collocated spherical joints. The mechanism is designed to be strong, rigid, easy to build and have a large range of motion. Two different design concepts are presented and compared to other implementations of spherical joints previously proposed. Finally, implementation issues and potential applications of the spherical joint mechanism are discussed.

A stability measure for underconstrained cable-driven robots

This paper introduces a slope-based measure of the stability of a pose of an underconstrained cable robot. In order to define this measure, the set of twists that the end-effector can instantaneously undergo is found. The measure is then derived using an energy-based approach to generalize the definition of slope for mixed-dimensional twists. In order to more easily understand and calculate the measure an intermediate space is introduced. An example is worked out for a sample manipulator and the stability measure is used to define a measure of overall manipulator stability.

Digital clay: architecture designs for shape-generating mechanisms

This paper examines the kinematic design of digital clay, a new type of computer interface that creates 3-D shapes that a user can interact with. After enumerating the design specifications for the digital clay, a new set of kinematic architectures is introduced: the formable crust architectures. These formable crust mechanisms can form shapes in much the same way a piece of fabric would and have tremendous potential for shape generation. Two measures, the surface freedom measure and the freedom from ground measure, are introduced to aid in evaluating potential designs. Finally, the various architectures are evaluated and compared.

Haptic Cobot Exoskeleton: Concepts and Mechanism Design

This paper presents a concept for a new type of haptic exoskeleton: REACH, the Robotic Exoskeleton with Advanced Cobot Haptics. This exoskeleton is the first ever concept for integrating cobot technology into a wearable exoskeleton device. This exoskeleton represents a significant improvement in haptic exoskeleton technology by providing high-performance haptic feedback to a user’s whole arm while at the same time guaranteeing the user’s safety. The overall design concept is presented, including the use of a spherical 3RRR parallel mechanism to implement the shoulder joint. The detailed design of the shoulder joint mechanism is then presented. The kinematic parameters of the shoulder joint are selected such that its range of motion matches the motion of a user’s shoulder while also avoiding collisions. In addition, to avoid singularities and maximize dexterity the mechanism design is optimized using the inverse condition number of the Jacobian matrix.Copyright

Cable-Suspended Robotic Contour Crafting System

This paper introduces a new concept for a contour crafting construction system. Contour crafting is a relatively new layered fabrication technology that enables automated construction of whole structures. The system proposed here consists of a mobile contour crafting platform driven by a translational cable-suspended robot. The platform includes an extrusion system for laying beads of concrete as well as computer-controlled trowels for forming the beads as they are laid. This system is fully automated and can be used to construct concrete structures rapidly and economically. The novel attributes of this system enable significant improvements over other proposed contour crafting systems, including easier portability, lower cost, and the potential to build much larger structures. This paper presents the kinematics and statics of the proposed system, and uses the reachable workspace of the robot as well as the corresponding cable tensions to approximate the maximum size structure that can be built using this manipulator.Copyright

Concrete Paving Productivity Improvement Using a Multi-Task Autonomous Robot

ABSTRACT To improve productivity in conventional concrete construction, autonomous robots that perform specific tasks are being developed. Single-task robots are capable of enhancing specific functions, though their impact on the overall productivity remains unclear. A robot that incorporates each task-specific piece of machinery used in the concrete paving process into one fully autonomous unit is evaluated. Assessing potential productivity from the use of a fully automated process is a required step for developing a full scale-system. With the purpose of identifying productivity benefits in an automated concrete paving operation, two concrete paving processes will be compared using simulation tools. One process is the conventional operation using intensive labour, slip form paving machine and auxiliary equipment. The other process is the automated operation using a fully autonomous robot. Applications of this assessment methodology based in simulation will allow for the determination of productivity indicators of automated operations in hazardous environments, using the respective results to complement prototypical tests.