Organizational Unit:

George W. Woodruff School of Mechanical Engineering

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https://hdl.handle.net/1853/70728

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College of Engineering

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Advanced Mechanical Bipedal Experimental Robotics Lab

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Computational Reactor and Medical Physics Laboratory

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Cryo Lab

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Environmentally Conscious Design and Manufacturing

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Fusion Research Center

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https://finding-aids.library.gatech.edu/agents/corporate_entities/120

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Publication Search Results

Now showing 1 - 9 of 9

Recursive Algorithm for Motion Primitive Estimation

(Georgia Institute of Technology, 2011-05) Enes, Aaron R. ; Book, Wayne J.

The need for knowing future manipulator motion arises in several robotics applications, including notification or avoidance of imminent collisions and real-time optimization of velocity commands. This paper presents a real-time, low overhead algorithm for identification of future manipulator motions, based on measurements of prior motions and the instantaneous sensed actuator velocity commanded by an operator. Experimental results with a human-controlled, two degree of-freedom manipulator demonstrate the ability to quickly learn and accurately estimate future manipulator motions.
Auto-Calibration Based Control for Independent Metering of Hydraulic Actuators

(Georgia Institute of Technology, 2011-05) Opdenbosch, Patrick ; Sadegh, Nader ; Enes, Aaron R. ; Book, Wayne J.

This paper describes a novel auto-calibration state-trajectory-based control method and its application to electronic flow control for independent metering systems. In this paper, the independent metering architecture that is considered uses five Electro-Hydraulic Poppet Valves (EHPV’s). The proposed control method is applied to four of these valves, arranged in a Wheatstone bridge configuration, to regulate the flow of hydraulic oil coming into and out of an actuator. For simplicity, the fifth valve is operated via open-loop to control the supply pressure. Experimental data presented herein demonstrate that the control method learns the valve’s conductance characteristics (i.e. the inverse input-state dynamic map of the valve) while simultaneously controlling the motion of the hydraulic actuator.
Sharing Control Can Increase Excavation Productivity

(Georgia Institute of Technology, 2011-03) Enes, Aaron R. ; Book, Wayne J.

Researchers at the Georgia Institute of Technology have demonstrated that the completion time of common excavation tasks is decreased when an operator and an electronic agent share control of the actuator velocity commands. In this Blended Shared Control architecture, the intended operator task is estimated with a recursive algorithm; the task is optimized in real time; and a command perturbation is computed which results in a lower task completion time when summed with the operator command. Experimental results compare Blended Shared Control to conventional manual control and manual control supplemented with haptic feedback. Trials indicate that Blended Shared Control decreases task completion time by up to 15 percent.
Optimizing Point to Point Motion of Net Velocity Constrained Manipulators

(Georgia Institute of Technology, 2010-12) Enes, Aaron R. ; Book, Wayne J.

The architecture of many hydraulic manipulators, such as excavators common in the earthmoving industry, have constraints on the net sum of actuator speeds. This paper gives the necessary conditions for minimum-time velocity commands for point to point motion. A kinematic model of the manipulator is used. The optimal solution is not always unique. We propose a particular optimal solution, u*, that is stationary. The optimality of inputs unequal to u* is evaluated by the position of u* in the input domain. Several examples are given to demonstrate the analysis.
Towards Shared Control of Hydraulic Excavators

(Georgia Institute of Technology, 2010-06) Enes, Aaron R. ; Book, Wayne J.

Presently, excavator operators manually control all functions of the machine. Decreases to a task's time or energy cost are historically achieved by designing better systems and components or through operator training. In contrast, the approach discussed here allows the human and machine to share control of the end effector to improve machine performance. The paper will introduce the idea of blended shared control in the context of excavation, and will show methods of describing the operator task. A filter that increases the robustness of the task identification is presented. Examples using experimental data are presented to illustrate the results. This approach can potentially decrease task completion time without requiring modification of the machine hardware.
Blended Shared Control of Zermelo's Navigation Problem

(Georgia Institute of Technology, 2010) Enes, Aaron R. ; Book, Wayne J.

Many machines–from hydraulic excavators to mobile wheelchairs–are manually controlled by a human operator. In practice, the operator assumes responsibility for completing a given task at maximum utility, even though the optimal inputs may be unknown to the operator. Here we introduce a simple technique termed Blended Shared Control, whereby the human operator commands are continually merged with the commands of a robotic agent. This approach is shown to result in a lower task completion time than manual control alone when applied to a problem motivated by Zermelo’s navigation problem. Experimental results are presented to compare blended shared control to other types of controllers including manual control, heads up display, and haptic feedback. Trials indicate that the shared control does in fact decrease task completion time when compared to fully manual operation.
A virtual reality operator Interface station with hydraulic hardware-in-the-loop simulation for prototyping excavator control systems

(Georgia Institute of Technology, 2009-07) Elton, Mark D. ; Enes, Aaron R. ; Book, Wayne J.

A multimodal operator interface station is developed to display a realistic virtual reality depiction of a compact excavator performing general digging tasks. The interface station includes engine audio feedback and a near life-size operator display attached to a full-size cab. The excavator dynamics are determined by models of the hydraulic system, the linkage system, and the soil digging forces. To maximize the fidelity of the hydraulic model, certain ldquovirtualrdquo components of the model are replaced with real-time hardware-in-the-loop (HIL) simulations of the actual hardware. HIL simulation is done in a geographically isolated facility, with Internet based communication between HIL and the remote operator interface. This is the first reported high-fidelity operator interface to be combined with remote hydraulic HIL simulations.
A hardware-in-the-loop simulation testbed for emulating hydraulic loads representing the complete dig cycle of a construction machine

(Georgia Institute of Technology, 2008) Enes, Aaron R. ; Book, Wayne J.

A hardware-in-the-loop (HIL) simulation testbed is designed to be capable of emulating the entire domain of hydraulic workport loads incident on a test valve during normal work cycle operations of a certain hydraulic construction machine, such as a backhoe or excavator. The HIL testbed is a useful tool during rapid prototyping of control algorithms for the test valve, and for performing controlled experiments with the valve in the context of developing valve control algorithms to improve the overall energy efficiency of hydraulic systems. This paper discusses four key topics: the architecture of the real-time simulation and testbed control process, the modeling and validation of the emulated machine dynamics, the controller development for the HIL testbed, and some initial performance testing of the HIL testbed.
New command shaping methods for reduced vibration of a suspended payload with constrained trolley motion

(Georgia Institute of Technology, 2007-11) Enes, Aaron R. ; Hsu, Timothy Y. ; Sodemann, Angela A.

In manufacturing environments, a common task is to quickly move a suspended payload point-to-point along a fixed overhead conveyor track without inducing significant payload vibration. Recent research in command shaping has shown remarkably effective ways to reduce the swing of a suspended payload providing the motion of the trolley is not constrained. However, the development of a command shaper where the trajectory of the trolley is constrained to follow a fixed curvilinear path has not been explored. This paper will present the development of a simple feedforward command shaper for fast, low vibration, point-to-point movement of a payload suspended from a trolley constrained to follow a fixed generalized path. The command shaping method involves modifying the command signal by convolving it with a series of impulses. Prior work has suggested command shaping to be very effective for fast, low-vibration movement of flexible systems. In this paper, command shaping methods are applied to an overhead conveyor system constrained to move along a fixed curvilinear path. Two new command shapers are presented for canceling payload vibration induced by motion of the trolley along the path. The designed Tangential Vibration (TV) shaper reduces payload vibrations induced by tangential accelerations of the trolley along the path, while the Centripetal-Tangential Vibration (CTV) shaper reduces vibrations induced by both tangential and centripetal accelerations. A key result of this study is that a command shaper having at least three impulses is required to yield zero residual vibration for motion along a curvilinear path. A simple pendulum payload attached to an actual small-scale overhead trolley following a constrained path is used to evaluate the performance of the designed command shapers. It is shown that the designed shapers significantly reduce payload swing compared to unshaped performance. An experimental sensitivity analysis shows the designed shapers are robust to system modeling errors and variations in path parameters.