Flexible manipulator control experiments and analysis

Modeling and control design for flexible manipulators, both from an experimental and analytical viewpoint, are described. From the application perspective, an ongoing effort within the laboratory environment at the Ohio State University, where experimentation on a single link flexible arm is underway is described. Several unique features of this study are described here. First, the manipulator arm is slewed by a direct drive dc motor and has a rigid counterbalance appendage. Current experimentation is from two viewpoints: (1) rigid body slewing and vibration control via actuation with the hub motor, and (2) vibration suppression through the use of structure-mounted proof-mass actuation at the tip. Such an application to manipulator control is of interest particularly in design of space-based telerobotic control systems, but has received little attention to date. From an analytical viewpoint, parameter estimation techniques within the closed-loop for self-tuning adaptive control approaches are discussed. Also introduced is a control approach based on output feedback and frequency weighting to counteract effects of spillover in reduced-order model design. A model of the flexible manipulator based on experimental measurements is evaluated for such estimation and control approaches

Design and Experimental Evaluation of a Tendon-Driven Minimally Invasive Surgical Robotic Tool with Antagonistic Control

The design, implementation and experimental evaluation of a minimally invasive surgical robotic instrument is presented in this article. The tool is constructed using rapid prototyping techniques and each degree-of-freedom is actuated via an antagonistic tendon driven mechanism using servo motors. The accompanying software runs under the Robot Operating System framework. The kinematics of the tool are discussed and the efficiency of the system is investigated in experimental studies, which are showcased in order to assess its potential use in a clinical environment

Fault diagnosis based on set membership identification using output-error models

International audienceSUMMARY The objective of this article is the design of a fault diagnosis method based on set membership identification for systems subject to abrupt parametric faults. The proposed method assumes an output-error, linearly parametrizable model, with unknown but bounded noise corrupting the measurement data. The set membership identification's objective is to compute (a) the smallest volume-wise ellipsoid that contains the nominal parameter vector, which concurrently resides within a data-hypersector and (b) the monotonically nonin-creasing parametric set arisen from the orthotopes that tightly outer bound the ellipsoids. The fault detection mechanism is based on consistency tests between the estimated ellipsoids and the data-hypersectors and the intersection of support orthotopes. At the sample instant of the fault detection, set-theoretic operations are applied for the subsequent fault isolation and identification. The fault isolation is based on the projections of the intersections of orthotopes, while the distance of their centers is used for fault identification. Simulations studies are used to verify the efficiency of the suggested method applied on an electrostatic microactuator subject to several abrupt failure modes

Experimental constrained optimal attitude control of a quadrotor subject to wind disturbances,”

Abstract-A Constrained Finite Time Optimal Controller (CFTOC) for attitude set-point maneuvers of an Unmanned Quadrotor Helicopter (UqH) operating under severe wind conditions is the subject of this article. The UqH's nonlinear dynamics is linearized in various operating points resulting in a set of piecewise models. The CFTOC is designed for set-point maneuvers taking into account the switching between the linear models and the constraints of the actuators. The control scheme is applied in experimental studies in a prototype UqH operating in harsh weather conditions resulting from wind gusts. The UqH rejects the induced wind-disturbances while performing attitude set-point maneuvers