(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.
(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.
(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.