3,523 research outputs found
Discrete-time sliding mode control of high precision linear drive using frictional model
The paper deals with high precision motion control of linear drive system. The accuracy and behavior of the linear drive system are highly affected by the non-linear frictional component compromising of stiction, viscous and stribeck effect present in the system especially in the vicinity of zero velocity. In order to achieve the high accuracy and motion it is mandatory to drive our system with low velocity resulting in many non linear phenomena like tracking error, limit cycles and undesired stick-slip motion etc. This paper discuss the design and implementation of discrete time sliding mode control along with the implementation of dynamic frictional model in order to estimate and compensate the disturbance arising due to frictional component. Experimental results are presented to illustrate the effectiveness and achievable control performance of the proposed scheme
Force feedback pushing scheme for micromanipulation applications
Pushing micro-objects using point contact provides
more flexibility and less complexity compared to pick
and place operation. Due to the fact that in micro-world
surface forces are much more dominant than inertial forces
and these forces are distributed unevenly, pushing through
the center of mass of the micro-object may not yield a pure
translational motion. In order to translate a micro-object, the
line of pushing should pass through the center of friction. In this
paper, a semi-autonomous scheme based on hybrid vision/force
feedback procedure is proposed to push micro-objects with
human assistance using a custom built tele-micromanipulation
setup to achieve translational motion. In the semi-autonomous
pushing process, velocity controlled pushing with force feedback
is realized along x-axis by the human operator while y-axis
orientation is undertaken automatically using visual feedback.
This way the desired line of pushing for the micro-object
is controlled to pass through the varying center of friction.
Experimental results are shown to prove nano-Newton range
force sensing, scaled bilateral teleoperation with force feedback
and snapshot of pushing operation
Scaled bilateral teleoperation using discrete-time sliding mode controller
In this paper, the design of a discrete-time slidingmode
controller based on Lyapunov theory is presented along
with a robust disturbance observer and is applied to a piezostage
for high-precision motion. A linear model of a piezostage was
used with nominal parameters to compensate the disturbance
acting on the system in order to achieve nanometer accuracy. The
effectiveness of the controller and disturbance observer is validated
in terms of closed-loop position performance for nanometer
references. The control structure has been applied to a scaled
bilateral structure for the custom-built telemicromanipulation
setup. A piezoresistive atomic force microscope cantilever with a
built-in Wheatstone bridge is utilized to achieve the nanonewtonlevel
interaction forces between the piezoresistive probe tip and
the environment. Experimental results are provided for the
nanonewton-range force sensing, and good agreement between
the experimental data and the theoretical estimates has been
demonstrated. Force/position tracking and transparency between
the master and the slave has been clearly demonstrated after
necessary scalin
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