13.07.2015 Views

Assessment and Future Directions of Nonlinear Model Predictive ...

Assessment and Future Directions of Nonlinear Model Predictive ...

Assessment and Future Directions of Nonlinear Model Predictive ...

SHOW MORE
SHOW LESS

Create successful ePaper yourself

Turn your PDF publications into a flip-book with our unique Google optimized e-Paper software.

574 M. Fujita et al. CameraCameraTargetObject Manipulator Image Plane 2 Manipulator 2 2 1 1 1 TargetObjectFig. 1. Planar visual feedback systemFig. 2. Schematic diagramapproach proposed by Parisini et al. [6] is based on using a quadratic endpointpenalty <strong>of</strong> the form ax T (t + T )Px(t + T )forsomea>0, some positive definitematrix P <strong>and</strong> a terminal state x(t + T ). Jadbabaie et al. [7] showed that closedloopstability is ensured through the use <strong>of</strong> a terminal cost consisting <strong>of</strong> a controlLyapunov function. Moreover, these results were applied to the Caltech DuctedFan to perform aggressive maneuvers [8, 9]. Visual feedback, however, is notconsidered here. <strong>Predictive</strong> control could be <strong>of</strong> significant benefit when used inconjunction with visual servoing. With the incorporation <strong>of</strong> visual information,the system could anticipate the target’s future position <strong>and</strong> be waiting there tointercept it [10].In this paper, stabilizing receding horizon control is applied to the planarvisual feedback system in [3], a highly nonlinear <strong>and</strong> relatively fast system. Thisrepresents a first step towards high performance visual servoing targeting moreaggressive maneuvers. The main idea is the use <strong>of</strong> the terminal cost derived froman energy function <strong>of</strong> the visual feedback system. By applying the proposedcontrol scheme to a two-link direct drive manipulator with a CCD camera, it isshown that the stabilizing receding horizon control nicely works for the planarvisual feedback system. Furthermore, the experimental results are assessed withrespect to performance.First, passivity-based control <strong>of</strong> a planar visual feedback system is reviewed.Next, a stabilizing receding horizon control for a planar visual feedback systemusing a control Lyapunov function is proposed. Then, the control performance <strong>of</strong>the stabilizing receding horizon control scheme is evaluated through experimentswith a two-link direct drive manipulator with a camera as shown in Fig. 1.2 Visual Feedback System with Planar ManipulatorThe dynamics <strong>of</strong> n-link rigid robot manipulators can be written asM(q)¨q + C(q, ˙q)˙q + g(q) =τ (1)

Hooray! Your file is uploaded and ready to be published.

Saved successfully!

Ooh no, something went wrong!