Haptic-enabled Teleoperation of Single-rod Hydraulic Manipulators PDF Download

Author: Vikram Banthia
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ISBN:
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Languages : en
Pages : 0

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Book Description
Hydraulically powered machines such as backhoes, excavators, and underwater manipulators are commonly used in industries and require extensive interaction with highly unstructured environments. Proper operation of these machines with manipulator-like implements depends on the ability of human operators who currently use hand controllers to command in response to various circumstances. This approach, known as teleoperation, combines the strength and accuracy of the manipulator with the intelligence of the human operators who normally use visual information, directly or through cameras, to accomplish a task. Providing haptic sensation about the task environment to operators, augments their ability to perform tele-manipulation. The focus of this thesis is thus on enabling a hydraulic manipulator to interact with the environment using the concept of haptic-enabled teleoperation. The application area is towards the utilization of hydraulic manipulators to perform hazardous and/or difficult tasks such as earth-moving, live-line and underwater maintenance activities. Two main issues in teleoperation control are stability and telepresence. The overall closed-loop control system should be stable irrespective of the behavior of the human operator or the task environment. Although the haptic feedback to the master side enables the human operator to rely on his tactile senses, it can make the overall teleoperation system unstable. Teleoperation control of hydraulic manipulators is generally more challenging than that of their electromechanical counterparts, as hydraulic actuators exhibit significant nonlinear characteristics. In this research, a bilateral control scheme has been developed for haptic teleoperation of single-rod hydraulic actuators considering nonlinear dynamics of hydraulic actuation, haptic device, and the human operator. Stability of the complete control system is confirmed theoretically by building a proper Lyapunov function. In terms of telepresence, haptic sensation is provided to the operator based on the position error between the haptic device end-point and the hydraulic actuator implement displacements. Proposed control scheme can be used in a wide variety of applications where the interaction force between the hydraulic actuator and the task environment cannot be measured. The proposed control scheme is easy to implement as it only requires the measurements of the actuator line pressures and displacements of the master and slave. This control scheme is further improved to incorporate base disturbances of single-rod hydraulic actuators. Stability of this controller with an estimated upper value for the base disturbance is analytically proven. Simulation studies are conducted, which confirms that the developed controllers can effectively stabilize the system while interacting with a task environment. They are further tested experimentally on a hydraulic test rig to verify their practicality and effectiveness in real applications.