Independent Control Scheme Research Articles

Hybrid Codec-Based Intra-Frame Joint Rate Control for Stereoscopic Video

An intra-frame joint rate control scheme is first proposed for a hybrid coder to encode stereoscopic video, which is based on an optimization framework with a gradient-based quadratic rate-quantization model and a gradient-based linear distortion-quantization model. The proposed rate control scheme jointly works on the left and right encoders for stereoscopic video input by controlling the output bit rates of both encoders in the sense that the sum of the two decoded video qualities is maximized and the quality difference is maintained around a desired level for a given target bit budget at the same time. In experiments, the proposed intra-frame joint rate control scheme for the hybrid coder produces the average 0.62 dB gain in PSNR, 64.93% reduction in the mean PSNR differences and 72.04% reduction in the MSE of PSNR difference, compared with the independent rate control schemes of the MPEG-2 TM5 and H.264 JM 16.

DC/DC pre-regulator for input current ripple reduction and efficiency improvement

The cascade connection of a low-ripple voltage doubler pre-regulator and a classical boost converter regulator is proposed to improve the efficiency of the full system due to the reduction in average currents of all boost converters and the smaller duty cycle required for the conventional boost regulator. The pre-regulator inherent low input current ripple, which operates at a 50% duty cycle in complementary interleaving mode, makes the system suitable for current ripple sensitive power generators such as fuel cells or photovoltaic modules. In addition, the proposed solution increases the maximum voltage conversion ratio achievable, and the independent control schemes of the pre-regulator and the boost stage do not increase the control complexity of the system.

Implementation of Shape – Based Matching Vision System in Flexible Manufacturing System

This research is regarding the application of a vision algorithm to monitor the operations of a system in order to control the decision making concerning jobs and work pieces recognition that are to be made during system operation in real time. This paper stress on the vision algorithm used which mainly focus on the shape matching properties of the product. The main focus of this paper is on the development of an adaptive training phase of the vision system, which is the creation of a flexible Region of Interest capability that is able to adapt to various type of applications and purposes depending on the users’ requirements. Additionally, an independent stand-alone control scheme was used to enable this system to be used in various types of manufacturing configurations. The system was tested on a number of different images with various characteristics and properties to determine the reliability and accuracy of the system in respect to different conditions and combination of different training traits.

2B11 Adaptive control for a rewinding process of a high-speed roll-to-roll system

In this paper, transverse vibration control and transport velocity control of a moving web in a rewinding section of a roll to roll system are investigated. The moving web is modeled as an axially moving beam. Two independent adaptive control schemes are proposed. The first control scheme using a control force exerted from a hydraulic actuator is to suppress transverse vibrations of the moving web of unknown mass per unit length under a spatially varying tension and a time-varying transport velocity. The second control scheme using a control torque applied to the rewind roller is to maintain the transport velocity levels of the moving web in spite of disturbances such as the variations of rotating elements and unknown bearing friction. From the decentralized control viewpoint, the uniformly exponential stability for suppressing the transverse vibrations and the uniformly asymptotic stability for maintaining the transport velocity are achieved. However, as a whole, the uniformly asymptotic stability is concluded. Simulations for demonstrating the effectiveness of the proposed control schemes are presented.

Feedforward control of capacity and superheat for a variable speed refrigeration system

This paper deals with an independent control method for the refrigeration system based on general PI control law. In the variable speed refrigeration system (VSRS), the capacity and superheat are respectively controlled by inverters and electronic expansion valves for saving energy and improving performance as well. At first, the decoupling model has been proposed to eliminate the interfering loops, and then the transfer functions are obtained from numbers of experimental tests. Once the new PI controller is designed, the system performance is evaluated by numerical simulations as well as extensive experimental works. Finally, it is found that the independent control scheme can guarantee not only precise control performance but also high COP for the VSRS.

Query based model learning and stable tracking of a robot arm using radial basis function network

In the context of a robot manipulator, a generalized neural emulator over the complete workspace is very difficult to obtain because of dimensionally insufficient training data. A query based learning algorithm is proposed in this paper that can generate new examples where control inputs are independent of states of the system. This algorithm is centered around the concept of network inversion using an extended Kalman filtering based algorithm. This is a novel idea since robot manipulator is an open loop unstable system and generation of control input independent of state is a research issue for neural model identification. Two trajectory independent stable control schemes have been designed using the neural emulator. One of the control schemes uses forward-inverse-modeling approach to update the controller parameters adaptively following Lyapunov function synthesis technique. The proposed scheme is trajectory independent unlike the back-propagation scheme. The second type of controller predicts the minimum variance estimate of control action using recall process (network inversion) and the control law is derived following a Lyapunov function synthesis approach so that the closed loop system consisting of controller and neural emulator remains stable. The simulation experiments show that the model validation approach is efficient and the proposed control schemes guarantee stable accurate tracking.

PD-Type Control Schemes for Cooperative Manipulator Systems

ABSTRACTKinematic control of cooperative manipulator systems is based on the solution of an inverse kinematics problem providing the single-arm reference joint trajectories corresponding to the assigned cooperation task. If an independent joint control scheme is used to realize the desired joint trajectories, tracking error components causing violation of closed-chain constraints lead to building of large internal forces. A simple PD-type control law is presented in this article which is based on kineto-static filtering of the joint error components causing internal forces. The control law retains the simplicity of independent joint control schemes and achieves null internal force at steady state. The addition of internal-force feedback is also analyzed. A case study for a planar cooperative system is developed which shows the effectiveness of the proposed kineto-static filtering and makes a comparison with classical PD control.

Robust design of independent joint controllers with experimentation on a high-speed parallel robot

A linear independent joint control scheme is proposed. The design is made robust by closing another feedback loop that uses acceleration information besides the typical position and velocity loops. Reconstruction of acceleration measurements is performed via a suitable state-variable filter. Linear feedforward compensation is used to improve tracking performance of the closed-loop scheme. The control algorithm is tested first in a discrete-time simulation on a single-joint drive system with imposed disturbance torques. Then, real-time implementation on a high-speed parallel robot is presented. The experimental results demonstrate the effectiveness of the proposed technique.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

Real-time implementation and evaluation of the computed-torque scheme

Experimental results on the real-time performance of model-based control algorithms are presented. The computed-torque scheme which utilizes the complete dynamics model of the manipulator was compared to the independent joint control scheme, which assumes a decoupled and linear model of the manipulator dynamics. The two manipulator control schemes have been implemented on the Carnegie-Mellon University DD (direct-drive) Arm II with a sampling period of 2 ms. The authors discuss the design of controller gains for both the computed-torque and the independent joint control schemes and establish a framework for comparing their trajectory-tracking performances. It is shown that the computed-torque scheme outperforms the independent joint control scheme as long as there is not torque saturation in the actuators. Based on the experimental results, the authors conclusively establish the importance of compensating for the nonlinear Coriolis and centrifugal forces even at low speeds of operation.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>