5 research outputs found
Study on Predictive Control for Trajectory Tracking of Robotic Manipulator
Model predictive control (MPC) differs from other control methods mainly in implementation of the control actions. In
this paper, the tracking error performance index of rolling optimization of predictive control is designed for a class of
nonlinear systems by the relative degree, then employed to design controller for robot manipulator. In other words, the
robot manipulator’s reference trajectory is based on Taylor expansion, and the actual trajectory is substituted into the
performance cost function which is derivated for minimum to obtain the controller. Then the performance analysis for the
closed system is made. Simulation results demonstrate the effectiveness of the method based on Taylor expansion
Review of sliding mode control application in autonomous underwater vehicles
973-984This paper presents a review of sliding mode control for autonomous underwater vehicles (AUVs). The AUVs are used under water operating in the presence of uncertainties (due to hydrodynamics coefficients) and external disturbances (due to water currents, waves, etc.). Sliding mode controller is one of the nonlinear robust controllers which is robust towards uncertainties, parameter variations and external disturbances. The evolution of sliding mode control in motion control studies of autonomous underwater vehicles is summarized throughout for the last three decades. The performance of the controller is examined based on the chattering reduction, accuracy (steady state error reduction), and robustness against perturbation. The review on sliding mode control for AUVs provides insights for readers to design new techniques and algorithms, to enhance the existing family of sliding mode control strategies into a new one or to merge and re-supervise the control techniques with other control strategies, in which, the aim is to obtain good controller design for AUVs in terms of great performance, stability and robustness
Active compliance control strategies for multifingered robot hand
Safety issues have to be enhanced when the robot hand is grasping objects of
different shapes, sizes and stiffness. The inability to control the grasping force and
finger stiffness can lead to unsafe grasping environment. Although many researches
have been conducted to resolve the grasping issues, particularly for the object with
different shape, size and stiffness, the grasping control still requires further
improvement. Hence, the primary aim of this work is to assess and improve the safety
of the robot hand. One of the methods that allows a safe grasping is by employing an
active compliance control via the force and impedance control. The implementation of
force control considers the proportional–integral–derivative (PID) controller.
Meanwhile, the implementation of impedance control employs the integral slidingmode
controller (ISMC) and adaptive controller. A series of experiments and
simulations is used to demonstrate the fundamental principles of robot grasping.
Objects with different shape, size and stiffness are tested using a 3-Finger Adaptive
Robot Gripper. The work introduces the Modbus remote terminal unit [RTU] protocol,
a low-cost force sensor and the Arduino IO Package for a real-time hardware setup. It
is found that, the results of the force control via PID controller are feasible to maintain
the grasped object at certain positions, depending on the desired grasping force (i.e.,
1N and 8N). Meanwhile, the implementation of impedance control via ISMC and
adaptive controller yields multiple stiffness levels for the robot fingers and able to
reduce collision between the fingers and the object. However, it was found that the
adaptive controller produces better impedance control results as compared to the
ISMC, with a 33% efficiency improvement. This work lays important foundations for
long-term related research, particularly in the field of active compliance control that
can be beneficial to human–robot interaction (HRI)
Robust control of robotic manipulators based on integral sliding mode
For rigid body robot manipulators, the computed torque approach provides asymptotic stability for tracking control tasks. However, the state dependent matrices needed to complete the computed torque algorithm are normally unknown and possibly too complex for a real-time implementation. This paper proposes a simple controller with computed-torque-like structure enhanced by integral sliding mode, having pole-placement capability. For the reduction of the chattering effect generated by the sliding mode part, the integral sliding mode is posed as a perturbation estimator with quasi-continuous control action provided by an additional low-pass filter. The time-constant of the latter tunes the controller functionality between the perturbation compensation and a pure integral sliding mode control, as well as between chattering reduction and system robustness. A comparative simulation study between conventional sliding mode control, integral sliding mode control, and integral sliding mode in form of a perturbation estimator for a two-link robot arm validates the proposed design. copyright 2008 Taylor & Francis [accessed 2014 April 1st