Dynamic analysis of flexible manipulators, a literature review

Over the last few decades, extensive use of flexible manipulators in various robotic applications has made it as one of the research interests for many scholars over the world. Recent studies on the modeling, sensor systems and controllers for the applications of flexible robotic manipulators are reviewed in order to complement the previous literature surveyed by Benosman & Vey (Robotica 22:533---545, 2004) and Dwivedy & Eberhard (Mech. Mach. Theory 41:749---777, 2006) . A brief introduction of the essential modeling techniques is first presented, followed by a review of the practical alternatives of sensor systems that can help scientists or engineers to choose the appropriate sensors for their applications. It followed by the main goal of this paper with a comprehensive review of the control strategies for the flexible manipulators and flexible joints that were studied in recent literatures. The issues for controlling flexible manipulators are highlighted. Most of the noteworthy control techniques that were not covered in the recent surveys in references (Benosman & Vey Robotica 22:533---545, 2004; Dwivedy & Eberhard Mech. Mach. Theory 41:749---777, 2006) are then reviewed. It concludes by providing some possible issues for future research works.

Review of Control and Sensor System of Flexible Manipulator

In this paper, the n-dimensional discretized model of the two-link flexible manipulator is developed by the assumed mode method (AMM). Subsequently, based on the discretized dynamic model, both full-state feedback control and output feedback control are investigated to achieve the trajectory tracking and vibration suppression. In order to guarantee the stability strictly, uniform ultimate boundedness (UUB) of the closed-loop system is realized by the Lyapunov's stability. Furthermore, through appropriately choosing control parameters, the states of the system will converge to zero within a small neighborhood. Eventually, extensive simulations and experiments on the Quanser platform for a two-link robotic manipulator are carried out to demonstrate the feasibility of the proposed neural network controller.

Neural Network Control of a Two-Link Flexible Robotic Manipulator Using Assumed Mode Method

A review on two-link flexible manipulators

Designing the control strategy for a flexible robotic arm has long been considered a complex problem as it requires stabilizing the vibration simultaneously with the primary objective of position control. A stable state-feedback fuzzy controller is proposed here for such a flexible arm. The controller is designed on the basis of a neuro-fuzzy state-space model that is successfully trained using the experimental data acquired from a real robotic arm. The complex problem of solving stability conditions is taken care of by recasting them in the form of linear matrix inequalities and then solving them using a popular interior-point-based method. This asymptotically stable fuzzy controller is further augmented to provide enhanced transient performance along with maintaining the excellent steady-state performance shown by the stable control strategy. The controller hence designed has been successfully implemented for a real robotic arm to operate over a long angular range of 180 with several payload conditions and, for situations where the system is operated for a long range and with a large variation in payload conditions, it could successfully outperform the recently proposed proportional derivative and strain controller.

Augmented Stable Fuzzy Control for Flexible Robotic Arm Using LMI Approach and Neuro-Fuzzy State Space Modeling

A partial differential equation (PDE) model for a flexible two-link manipulator is derived and transformed to a form appropriate for the development of stable control designs. Stable control of this nonlinear infinite dimensional two-link system is then achieved by a novel control design developed using passivity and Lyapunov-based methods. A two-link hardware experimental setup is used to validate the analytical PDE model and the proposed stable control design scheme.

PDE modeling and control of a flexible two-link manipulator

The swash-plate in a variable displacement pump experiences very large forces and moments that try to dislocate its position; therefore, a large device is required for adequate control. In this paper, the dynamics of an alternative pump design using an indexing valve plate to position the swash-plate are reported. The indexing valve plate design is aimed at controlling the pressure transition for a piston, which is moving from a high-pressure port to a low-pressure port. In this paper, the governing equations for the pump are derived and the detailed open-loop and parametric studies, which are necessary for understanding the overall dynamic characteristics of the pump, are reported. Also, full nonlinear and simplified modelling approaches for the system are compared.

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Dynamic modelling and parametric studies of an indexing valve plate pump

A partial differential equation model for a flexible two-link manipulator is derived using the Hamilton principle. A stable strain feedback control design is then proposed based on insights into the dynamics. Stability is established using a Lyapunov-based design approach. A two-link hardware setup is used to validate the analytical model and the proposed stable control design. This control approach, which is energy based; can also be extended to multi-arm flexible link configurations.

Dynamic modeling related to an alternative method of actuating the swash plate of an axial variable-displacement pump is investigated. The method involves direct control of the indexing valve plate instead of the swash plate. The paper proposes a reduced order nonlinear model for the system, which provides more insight and is useful for control design purposes. The steady state input-output relationship is derived for the design as the valve plate angle /spl delta/ varies. Additionally, some pump design parameters are also investigated to determine their effect on the dynamic response.

Reduced order modeling of the dynamics of an indexing valve plate pump

An, open loop, reduced order model is proposed for the swash plate dynamics of an axial piston pump. The difference from previous reduced order models is the modeling of a damping mechanism not reported previously in the literature. An analytical expression for the damping mechanism is derived. The proposed reduced order model is validated by comparing with a complete nonlinear simulation of the pump dynamics over the entire range of operating conditions.

X. Zhang

Papers

PDE modeling and control of a flexible two-link manipulator

Dynamic modelling and parametric studies of an indexing valve plate pump

PDE modeling and control of a flexible two-link manipulator

Reduced order modeling of the dynamics of an indexing valve plate pump

Damping on the swash plate of an axial-piston pump