Trajectory Tracking Control of Delta-Robot Using 3rd Order Sliding Mode Control
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Date
2016-04
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Addis Ababa University
Abstract
Robots are multi-input multi-output (MIMO) nonlinear systems with uncertainties and high
coupling effects ; this makes the control of Robot more difficult and needs a robust control
system. This thesis describes, the concept of higher order sliding mode control as applied to
trajectory tracking of a 3-DOF Delta Robot using tracking error as the sliding surface. Third
order sliding mode control technique is specifically applied for this purpose.
With the Robot's complicated electromechanical parts, mutual interactions of Robot mechanics
and drives, building the nonlinear dynamic model of the Robot using 3D-CAD (like SolidWorks)
program was the best solution to model the Robot. Real parameters were introduced via 3DCAD
Modeling. The SimMechanics link utility bridges the gap between geometric modeling and
block diagram modeling and simulation. Dynamical model with all the kinematic constraints for
a Robot will simply be found by exporting a 3D-CAD model of the Robot to SimMechanics.
In this thesis a 3-DOF Delta Robot is designed in SolidWorks, the kinematic and dynamic
models of the Robot have been developed, a 3-SMC sliding mode controller is designed and a
circular trajectory tracking is achieved, with X & Z axis rms error of 3mm. The simulation result
shows that the steady state tracking is reached before 3 seconds. Finite time convergence of
sliding function and its first and second derivatives is also achieved. the plant has been subjected
to the effects of joint internal mechanics, mass uncertainty and external disturbances of torques.
The designed third order sliding mode control have fond to be smooth, model independent,
robust and is insensitive to applied model parameter variations, external & internal effects beside
eliminating the chattering effect of the standard SMC..
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Control Engineering