Organizational Unit:

Institute for Robotics and Intelligent Machines (IRIM)

Permanent Link

https://hdl.handle.net/1853/70657

Includes Organization(s)

Organizational Unit

Biorobotics and Human Modeling Lab

Organizational Unit

Humanoid Robotics Laboratory

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Publication Search Results

Now showing 1 - 10 of 21

Modeling of biodynamic feedthrough in backhoe operation

(Georgia Institute of Technology, 2009-10) Humphreys, Heather C. ; Book, Wayne J. ; Huggins, James D.

An advanced backhoe user interface has been developed which uses coordinated control with haptic feedback. Results indicate that the coordinated control provides more intuitive operation that is easy to learn, and the haptic feedback also relays meaningful information back to the user in the form of force signals from digging forces and system limitations. However, results show that the current system has significant problems with biodynamic feedthrough, where the motion of the controlled device excites motion of the operator, resulting in undesirable forces applied to the input device and control performance degradation. This unwanted input is difficult to decouple from the intentional operator input in experiments. This research presents an investigation on the effects of biodynamic feedthrough on this particular backhoe control system, using system identification to empirically define models to represent each component. These models are used for a preliminary simulation study on potential methods for biodynamic feedthrough compensation.
A novel approach to fabric control for automated sewing

(Georgia Institute of Technology, 2009-07) Winck, Ryder C. ; Dickerson, Stephen L. ; Huggins, James D. ; Book, Wayne J.

This paper describes a novel fabric manipulation method for fabric control during the sewing process. It addresses issues with past attempts concerning fabric position and tension control. The method described involves replacing the current sewing feed mechanism with a servo controlled manipulator to both feed and control the fabric. The manipulator is coupled with a machine vision system that tracks the threads of the fabric to provide real-time position control that is robust with respect to fabric deformations. A prototype of the manipulator is used to demonstrate the feasibility of the concept, reaching accelerations up to 27 g’s and following a closed loop trajectory with open loop control while operating in coordination with an industrial sewing machine. The system described also offers a general solution to high accuracy and high acceleration position control systems.
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.
Speed Control and Position Estimation of Small Hydraulic Cylinders for Digital Clay Using PWM Method

(Georgia Institute of Technology, 2004-07) Zhu, Haihong ; Book, Wayne J.

Digital Clay is a new generation 3D computer input and output device for surface shape and haptic effects. The device consists of arrays of fluidically actuated cells under the control of valves connected to two pressure reservoirs in a manner ultimately suitable to an implementation in MEMS technology. At the current stage, it is very difficult to implement a tiny position sensor into the tiny cell. This paper presents a control method for the speed and position estimation and control for the cells of digital clay only using low cost pressure sensors and without using any position-sensing device.
Stability in active mass damping control of a flexible robot

(Georgia Institute of Technology, 2004-03) Krauss, Ryan W. ; Book, Wayne J.

Active mass damping has been shown to be an effective method for reducing vibrations in flexible robots by previous researchers working on an experimental test bed at Georgia Tech. Acceleration feedback can cause instability in this test bed. System identification and root locus analysis were used to determine the causes of this instability. Several potential modifications to the system were simulated including: 1) replacing accelerometers with position sensors; 2) removing second order dynamics from the actuator; and 3) adding an additional accelerometer to use modal feedback.
Force reflecting teleoperation with adaptive impedance control

(Georgia Institute of Technology, 2004-02) Love, Lonnie J. ; Book, Wayne J.

Experimentation and a survey of the literature clearly show that contact stability in a force reflecting teleoperation system requires high levels of damping on the master robot. However, excessive damping increases the energy required by an operator for commanding motion. The objective of this paper is to describe a new force reflecting teleoperation methodology that reduces operator energy requirements without sacrificing stability. We begin by describing a new approach to modeling and identifying the remote environment bf the teleoperation system. We combine a conventional Multi-Input, Multi-Output Recursive Least Squares (MIMO-RLS) system identification, identifying in real-time the remote environment impedance, with a discretized representation 'of the remote environment. This methodology generates a time-varying, position dependent representation of the remote environment dynamics. Next, we adapt the target impedance of the master robot with respect to the dynamic model of the remote environment. The environment estimation and impedance adaptation are execute simultaneously and in real time. We demonstrate, through experimentation, that this approach significantly reduces the energy required by an operator to execute remote tasks while simultaneously providing sufficient damping to ensure contact stability.
Modeling and Control of an Improved Dissipative Passive Haptic Display

(Georgia Institute of Technology, 2004) Reed, Matthew R. ; Book, Wayne J.

This paper investigates the modeling and control of a new dissipative passive haptic display that uses magneto rheological (MR) brakes as actuators. The device is energetically passive, meaning that it can only remove energy from the system. All motive force must be generated by the user, which guarantees stability of the system and safety of the human operator. A first order system approach is presented as a tool for modeling MR fluid behavior in a low-speed braking device. A simulation was developed that uses the brake model and the equations of motion to predict robot motion based on force input and actuator commands. The accuracy of these models was demonstrated with comparisons to experimental data. Two forms of path following velocity control were successfully implemented and shown to significantly reduce path error in preliminary experiments with human operators.
Hardware-in-the-Loop Simulation for Control Development in EHPV Applications

(Georgia Institute of Technology, 2003-11) Jung, Sooyong ; Lee, Young J. ; Book, Wayne J.

The creation of a PC-based Hardware-In-the-Loop Simulation facility for testing hydraulic and other drive components and their controllers is described. High performance electric motors are used to produce both drive and load characteristics as commanded by the simulated environment. To enable rapid development of new application scenarios an integrated software environment has been incorporated to rapidly model, program and simulate the environment's behavior and the controlled response. In order to validate the HIL testbed developed, the experiment is pelformed on hydraulic component with wide range of applications. For the next stage, a novel Electro Hydraulic Poppet Valve (EHPV) is targeted to be studied.
Control concepts for digital clay

(Georgia Institute of Technology, 2003-09) Zhu, Haihong ; Book, Wayne J.

Digital Clay is a new generation of 3D computer input and output device for surface shape. Its three control levels are introduced in this paper. The device consists of arrays of fluidically actuated cells under the control of valves, that are connected to two pressure reservoirs in a manner ultimately suitable to an implementation in MEMS technology. Preliminary research on control related behaviour is described including testing of a single cell under a proposed control scheme. Based on these tests, control methods are presented and discussed that achieve elastic, plastic and elastic-plastic material behaviours.