77 research outputs found
Technical approaches for measurement of human errors
Human error is a significant contributing factor in a very high proportion of civil transport, general aviation, and rotorcraft accidents. The technical details of a variety of proven approaches for the measurement of human errors in the context of the national airspace system are presented. Unobtrusive measurements suitable for cockpit operations and procedures in part of full mission simulation are emphasized. Procedure, system performance, and human operator centered measurements are discussed as they apply to the manual control, communication, supervisory, and monitoring tasks which are relevant to aviation operations
Control of multiple model systems
This thesis considers the control of multiple model systems. These are systems for which only one model out of some finite set of models gives the system dynamics at any given time. In particular, the model that gives the system dynamics can change over time. This thesis covers some of the theoretical aspects of these systems, including controllability and stabilizability. As an application, ``overconstrained' mechanical systems are modeled as multiple model systems. Examples of such systems include distributed manipulation problems such as microelectromechanical systems and many wheeled vehicles such as the Sojourner vehicle of the Mars Pathfinder mission. Such systems are typified by having more Pfaffian constraints than degrees of freedom. Conventional classical motion planning and control theories do not directly apply to overconstrained systems. Control issues for two examples are specifically addressed. The first example is distributed manipulation. Distributed manipulation systems control an object's motion through contact with a high number of actuators. Stability results are shown for such systems and control schemes based on these results are implemented on a distributed manipulation test-bed. The second example is that of overconstrained vehicles, of which the Mars rover is an example. The nonlinear controllability test for multiple model systems is used to answer whether a kinematic model of the rover is or is not controllable
Discrete-time supervisory control of input-constrained neutrally stable linear systems via state-dependent dwell-time switching
This paper presents a discrete-time supervisory control scheme for an input-constrained neutrally stable linear plant in the presence of modelling uncertainties. The small gain control is employed as the multi-controller, and is shown to stabilize the plant in the sense of integral-input-to-state stability. As the switching logic, a state-dependent dwell-time switching is employed. The proposed supervisory control guarantees that all signals in the closed loop are bounded and the state of the uncertain plant converges to the origin.
Proceedings of the Seventeenth Annual Conference on Manual Control
Manual control is considered, with concentration on perceptive/cognitive man-machine interaction and interface
Control of underactuated fluid-body systems with real-time particle image velocimetry
Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 2012.Cataloged from PDF version of thesis.Includes bibliographical references (p. 141-153).Controlling the interaction of a robot with a fluid, particularly when the desired behavior is intimately related to the dynamics of the fluid, is a difficult and important problem. High-performance aircraft cannot ignore nonlinear stall effects, and robots hoping to fly and swim with performance matching that seen in birds and fish cannot treat fluid flows as quasi-steady. If we wish to match the level of performance seen in nature several major hurdles must be overcome, with one of the most difficult being the poor observability of the fluid state. Fluid dynamicists have long contended with this observability problem, and have used computationally intensive Particle Image Velocimetry (PIV) to gain an understanding of the fluid behavior after the fact. However, improvement in available computational power is now making it possible to perform PIV in real-time. When PIV provides real-time awareness of the fluid state it is no longer just an analysis tool, but rather a valuable sensor that can be integrated into the control loop. In this thesis I present methods for controlling fluid-body systems in which the fluid plays a vital dynamical role, for performing real-time PIV, and for interpreting the output of PIV in a manner useful to control. The utility of these methods is demonstrated on a mechanically simple but dynamically rich experimental platform: the hydrodynamic cartpole. This system is analogous to the well-known cart-pole system in the controls literature, but through its relationship with the surrounding fluid it captures many of the fundamental challenges of general fluid-body control tasks, including: nonlinearity, underactuation, an important and unknown fluid state and a dearth of accurate and tractable models. The first complete demonstration of closed-loop PIV control is performed on this system, and there is a statistically significant improvement in the system's ability to reject fluid disturbances when using real-time PIV for closed-loop control. These results suggest that these new techniques will push the boundaries of what we can expect a robot in a fluid to do.by John W. Roberts.Ph.D
A flexible manufacturing system for lawnmower cutting cylinders
The thesis is concerned with the conception and design of a FLEXIBLE
MANUFACTURING SYSTEM (FMS) for the automation of the manufacture of
lawnmower cutting cylinders at Suffolk Lawnmowers Ltd. A review of FMS
definitions, planning methods and current systems is carried out for the
development of a suitable FMS configuration for the final stages of
manufacture of grass cutting cylinders having 21 different design
specifications. This involves examination of the capabilities of
robotics and microcontrollers to automate the technologies used in
cylinder production.
The company's current manual batch production system is analysed to
determine the suitable form and requirements of the FMS. This includes
analyses of annual volumes, throughputs, batch sizes, product and process
mixes. Long term objectives to automate the system are identified from
which short term objectives are derived. The FMS recommended for
immediate development encompasses the short term objectives for the
welding, hardening, grinding and transfer processes of 8 cutting cylinder
specifications.
It is shown that the MIG (Argon/C02) are welding, progressive flame
hardening and wide-face cylindrical grinding processes can be developed
successfully to automate cylinder production. The recommended system
integrates these processes into an FMS through the'automatic handling
of cylinders (through three process routes) by a robotic manipulator
utilising a double gripper. 'A robotic welding station, manually loaded,
is also recommended. ' The system is controlled overall by a 32K microcontroller
with the process machines individually controlled by programmahle
logic controllers with up to 6K of memory each.
The economic appraisal of the FMS indicates a 4.4 year payback based on
direct labour and material cost savings. The company's application for
grant aid to implement the FMS design has led to an offer of a Department
of Industry grant to cover 50% of all capital and revenue costs. The
grant of £166,943 reduces the payback period to 2.3 years
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