Person:

Book, Wayne J.

Permanent Link

https://hdl.handle.net/1853/71109

Associated Organization(s)

Organizational Unit

George W. Woodruff School of Mechanical Engineering

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Publication Search Results

Now showing 1 - 10 of 186

Compensation for Biodynamic Feedthrough in Backhoe Operation by Cab Vibration Control

(Georgia Institute of Technology, 2011-05) Humphreys, Heather C. ; Huggins, James D. ; Book, Wayne J.

This research investigates and seeks to mitigate the undesirable effects of biodynamic feedthrough in backhoe operation. Biodynamic feedthrough occurs when motion of the controlled machine excites motion of the human operator, which is fed back into the control input device. This unwanted input can cause significant performance degradation, which can include limit cycles or even instability. Backhoe user interface designers indicate that this is a problem in many conventional machines, and it has also proved to degrade performance in this testbed. A particular backhoe control system, including the biodynamic feedthrough, is modeled and simulated. Cab vibration control is selected as a means to mitigate the biodynamic feedthrough effect. Two controller based methods are developed based on these models and presented, both of which use the working implement itself to reduce the cab motion. In this case, the backhoe arm has dual functionality, to perform excavation operations and to cancel cab vibration. Results show that significant reductions in cab motion can be obtained with minimal tracking performance degradation, without additional actuators.
A Robust Nonlinear Observation Strategy for the Control of Flexible Manipulators

(Georgia Institute of Technology, 2011-05) Post, Brian K. ; Book, Wayne J.

Flexibility is often an unavoidable consequence of the desire for high speed and performance manipulators. This paper proposes a method that improves the performance of flexible manipulators through the employment of robust state estimation techniques. These techniques are based on discrete time Kalman filtering and sliding mode principles. A simple model for a single degree of freedom flexible manipulator is derived and a control scheme is chosen and implemented. The latter includes a robust non-linear estimator. Simulation and preliminary experimental results are presented that demonstrate the validity of the proposed control scheme.
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.
An Excavator Simulator for Determining the Principles of Operator Efficiency for Hydraulic Multi-DOF Systems

(Georgia Institute of Technology, 2011-03) Elton, Mark D. ; Book, Wayne J.

This paper discusses an excavator simulator constructed to evaluate the effects of human-machine interfaces (HMIs) on operator productivity. Simulation allows for standardization of the machine and environment and is less time consuming and cheaper than implementing the controller on the machine. The simulator discussed in this paper includes a realistic graphical display that exceeds the current academic simulators, audio, and a new soil model that accounts for all possible trajectories of the bucket through the soil. Two coordinated control schemes were implemented on the simulator and preliminary tests were performed to demonstrate that the simulator can be used to evaluate HMIs.
Biodynamic Feedthrough Compensation and Experimental Results Using a Backhoe

(Georgia Institute of Technology, 2011-03) Heather C. Humphreys ; Book, Wayne J. ; Huggins, James D.

In some operator-controlled machines, motion of the controlled machine excites motion of the human operator, which is fed back into the control device, causing unwanted input and sometimes instability; this phenomenon is termed biodynamic feedthrough. In operation of backhoes and excavators, biodynamic feedthrough causes control performance degradation. This work utilizes a previously developed advanced backhoe user interface which uses coordinated position control with haptic feedback, using a SensAble Omni six degree-of-freedom haptic display device. Backhoe user interface designers and our own experiments indicate that biodynamic feedthrough produces undesirable oscillations in output with conventionally controlled backhoes and excavators, and it is even more of a problem with this advanced user interface. Results indicate that the coordinated control provides more intuitive operation, and the haptic feedback relays meaningful information back to the user. But the biodynamic feedthrough problem must be overcome in order for this improved interface to be applicable. For the purposes of reducing model complexity, the system is limited to a single degree of freedom, using fore-aft motion only. This paper investigates what types of controller-based methods of compensation for biodynamic feedthrough are most effective in backhoe operation, and how they can be implemented and tested with human operators.
Modeling and Simulation of a Pneumatically-Actuated Rescue Robot

(Georgia Institute of Technology, 2011-03) Daepp, Hannes G. ; Book, Wayne J.

A four-legged pneumatically actuated search and rescue robot is presented as a system with potentially enhanced versatility relative to existing rescue robots. The usage of fluid powered actuation, combined with tele-operation of the robot via an operator workstation, enables the twelve degree of freedom robot to better manipulate large objects. A simulation is developed to enable ease of design variation and implementation testing in difficult virtual terrains. The simulation consists of an actuator model, modeled in Simulink, which is interfaced with an open-source dynamic simulation. The simulation calculates the robot dynamics based on actuator inputs. Where previous research has focused on the development of simulation kinematics and simple actuator models, this paper discusses development of a friction model for improved fidelity of the simulator, as well as implementation and verification in the dynamic model. The balance between model performance and the level of realism required for system development is found and discussed.
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.
Automated garment manufacturing system using novel sensing and actuation

(Georgia Institute of Technology, 2010-07) Book, Wayne J. ; Winck, Ryder C. ; Killpack, Marc D. ; Huggins, James D. ; Dickerson, Stephen L. ; Jayaraman, Sundaresan ; Collins, Thomas R. ; Prado, Ronald J.

Attempts to automate the sewing process of garment manufacture have employed substitutes for human guidance of fabric into somewhat conventional sewing machines. A new approach has been proposed and partially verified in prototype form. It consists of several subsystems responsible for 1) gross fabric motion, 2) precision detection of the fabric location and 3) exact placement of the needle in the fabric. Gross motion employs steerable rollers capable of moving the fabric. Fine fabric motion employs vision sensing technology to count threads in the fabric. Exact placement employs servo controlled dogs for moving the fabric to exactly place the needles. This paper will explain the concept and the extent of verification of its realization.