Optimisation of different concrete mix designs for 3D Printing by utilising 6DOF industrial robot

Additive Manufacturing (AM) technologies are becoming increasingly viable for commercial and research implementation into various applications. AM refers to the process of forming structures layer upon layer and finds application in prototyping and manufacturing for building construction. It has recently begun to be considered as a viable and attractive alternative in certain circumstances in the construction industry. This paper focuses on the utilisation of different concrete mixtures paired with extrusion techniques facilitated by a six Degree of Freedom (DOF) industrial robot. Using methods of Damp Least Squares (DLS) in conjunction with Resolved Motion Rate Control (RMRC), it is possible to plan stable transitions between several waypoints representing the various print cross-sections. Calculated paths are projected via 'spline' interpolation into the manipulator controlled by custom software. This article demonstrates the properties of different concrete mixture designs, showing their performance when used as a filament in 3D Printing and representing a comparison of the results that were found. In this study, the prepared materials consist of ordinary Portland cement, fine sand between (425-450) micron, coarse aggregate ranges (3) mm and chemical admixtures which have been used to accelerate setting times and reduce water content. Numerous tests were performed to check the buildability, flowability, extrudability and moldability of the concrete mixtures. The horizontal test was used to determine the flowability and consistency, while the vertical and squeeze-flow tests were used to determine the buildability of the layers. The extrudability and moldability of the concrete mixtures were controlled by the robot and associated extruder speeds

Slip Modelling, Estimation and Control of Omnidirectional Wheeled Mobile Robots with Powered Caster Wheels

Ph.DDOCTOR OF PHILOSOPH

Trajectory tracking control of an aerial manipulator in presence of disturbances and modeling uncertainties

Development and dynamic validation of control techniques for trajectory tracking of a robotic manipulator mounted on a UAV. Tracking performances are evaluated in a context of simulated dynamic disturbance on manipulator base

Force feedback in remote tele-manipulation

PhD ThesisIt is becoming increasingly necessary to carry out manual operations in environments which are hazardous to humans - using remote manipulator systems that can extend the operators reach. However, manual dexterity can become severely impaired due to the complex relationship that exists between the operator, the remote manipulator system and the task. Under such circumstances, the introduction of force feedback is considered a desirable feature, and is particularly important when attempting to carry out complex assembly operations. The dynamic interaction in the manmachine system can significantly influence performance, and in the past evaluation has been largely by comparative assessment. In this study, an experimental remote manipulator system, or tele-manipulator system, has been developed which consists of three electrically linked planar manipulator arms, each with three degrees of freedom. An articulated 'master' arm is used to control an identical 'slave' arm, and independently, a second kinematically and dynamically dissimilar slave arm. Fully resolved Generalized Control has been demonstrated using a high speed computer to carry out the necessary position and force transformations between dissimilar master and slave arms in realtime. Simulation of a one degree of freedom master-slave system has also been carried out, which includes a simple model of the human operator and a task based upon a rigid stop. The results show good agreement with parallel experimental tests, and have provided a firm foundation for developing a fully resolved position/position control scheme, and a unique way of backdriving the master arm. Preliminary tests were based on a peg-in-hole transfer task, and have identified the effect on performance of force reflection ratio. More recently a novel crank-turning task has been developed to investigate the interaction of system parameters on overall performance. The results obtained from these experimental studies, backed up by simulation, demonstrate the potential of computer augmented control of remote manipulator systems. The directions for future work include development of real-time control of tele-robotic systems and research into the overall man-machine interaction

Manned remote work station development article

The two prime objectives of the Manned Remote Work Station (MRWS) Development Article Study are to first, evaluate the MRWS flight article roles and associated design concepts for fundamental requirements and embody key technology developments into a simulation program; and to provide detail manufacturing drawings and schedules for a simulator development test article. An approach is outlined which establishes flight article requirements based on past studies of Solar Power Satellite, orbital construction support equipments, construction bases and near term shuttle operations. Simulation objectives are established for those technology issues that can best be addressed on a simulator. Concepts for full-scale and sub-scale simulators are then studied to establish an overall approach to studying MRWS requirements. Emphasis then shifts to design and specification of a full-scale development test article

Singularity analysis and handling towards mobile manipulation

Ph.DDOCTOR OF PHILOSOPH

Proceedings of the NASA Conference on Space Telerobotics, volume 5

Papers presented at the NASA Conference on Space Telerobotics are compiled. The theme of the conference was man-machine collaboration in space. The conference provided a forum for researchers and engineers to exchange ideas on the research and development required for the application of telerobotics technology to the space systems planned for the 1990's and beyond. Volume 5 contains papers related to the following subject areas: robot arm modeling and control, special topics in telerobotics, telerobotic space operations, manipulator control, flight experiment concepts, manipulator coordination, issues in artificial intelligence systems, and research activities at the Johnson Space Center

Study of robotics systems applications to the space station program

Applications of robotics systems to potential uses of the Space Station as an assembly facility, and secondarily as a servicing facility, are considered. A typical robotics system mission is described along with the pertinent application guidelines and Space Station environmental assumptions utilized in developing the robotic task scenarios. A functional description of a supervised dual-robot space structure construction system is given, and four key areas of robotic technology are defined, described, and assessed. Alternate technologies for implementing the more routine space technology support subsystems that will be required to support the Space Station robotic systems in assembly and servicing tasks are briefly discussed. The environmental conditions impacting on the robotic configuration design and operation are reviewed

Research and technology

Summaries are presented of the research in the development of the space shuttle. Propulsion, materials, spacecraft and thermal control, payloads, instrumentation, data systems, and mission planning are included

The 24th Aerospace Mechanisms Symposium

The proceedings of the symposium are reported. Technological areas covered include actuators, aerospace mechanism applications for ground support equipment, lubricants, latches, connectors, and other mechanisms for large space structures