Active Compensation Control of Wind Force and Wire Roughness for Current Collector Using Optical Fiber Sensor

For railways speed up such as 350km/h, it is particularly important to reduce noise caused by current collector for environmental problem. For a solution, a diamond shaped low-noise current collector has been developed. However, it becomes difficult for the current collector to maintain the predetermined contact force between the contact strip and the trolley-wire. Therefore, it is necessary to apply the active control to keep the contact force uniform. However, there is a serious problem for the active control that it is difficult to put sensors in high voltage region. In this paper, an application of plastic optical fiber sensor is devised and it is applied to the control system. In the experiment, the usefulness of the proposed sensor and control system is demonstrated.

Adaptive Decentralized Vibration Control of a Cable-Stayed Bridge in the Presence of Seismic Excitation

In this paper, an adaptive decentralized controller is presented to attenuate the transversal vibration of a flexible cable-stayed bridge induced by seismic excitation, in which only local sensor information has been used to generate the control signal that is sent to the actuator. The dynamic behavior of the beam structure is characterized by a nonlinear mathematical model with interconnection terms, which was obtained by using technique of finite element. The controller design is made based on the principle of sliding mode such that a priori knowledge on the exact value of system parameters, structural disturbances and the seismic excitation is not required. In particular, it is assumed that the upper and lower bounds for the seismic excitation are also unknown. The closed-loop robust stability has been achieved through the generation of a sliding motion in the system. Numerical simulation is done to illustrate the effectiveness of the proposed control scheme for a scaled model of the bridge subject to the Taft earthquake.

Decentralized Control of a Tower Crane

This paper deals with modeling and control of a crane mounted on a tower-like flexible structure. A fast transfer of the load causes the sway of the load rope and the vibration of the flexible structure. Our object is to control both the sway and the vibration by the inherent capability of the tower crane. This paper makes its three-dimensional models for simulation and reduced-order-model in order to design the decentralized control system. Then, we design the decentralized H∞ compensator and verify the efficiency by simulations and experiments.

Development of a Pipe Positioning System Using a 5-DOF Suspension Mechanism

Decreasing the number of skilled workers and utilization of automated machines is becoming a general trend at plant construction sites. For this reason, an automated pipe positioning system using a 5-DOF suspension mechanism has been developed as an important automated tool for power plant construction sites. This device is expected to be used for not only assisting less skilled operators, but also making operations more efficient at plant construction sites. This paper mainly focuses on the control system design and the control performance of the proposed positioning system. The controller is designed based on the disturbance observer concept. The pipe positioning system has a 5-DOF suspension mechanism which consists of five stepping motors and chains. A relationship between the actuator space (chain length) and the task space (position and attitude of the pipe center of gravity) is expressed using the Jacobian matrix, and each element of this Jacobian matrix is generally a nonlinear function in space. Therefore the plant in this system is nonlinear. In this study, a disturbance observer concept is used to remove this nonlinearlity, then a conventional linear feedback control low is applied to the control system. The control performance is verified through experiments using a pipe with a diameter of 0.3m. In the experiments, trajectories of the pipe center of gravity with the Jacobian nonlinearly compensation is compared to the trajectories without Jacobian compensation case, and the effectiveness of this pipe positioning system is shown.

Adaptive Motion and Force Control of Robots Performing a Complete Task

In this work, we consider adaptive motion and force control of a robot performing a complete task. By a complete task we mean that the robot desired task contains both free motion and constrained motion. Further, we also consider transition from free motion to constrained motion. We divide the motion of the robot into three phases: (i) inactive phase, where the robot is in free motion, (ii) transition phase, where the transition from free motion to constrained motion takes place, and (iii) active phase, where the robot is in constrained motion with simultaneous force and position control. Uncertainty of the constraint results in the impact of robot with the constraint surface when transition from free motion to constrained motion. We design stable control laws for the three phases that results in an efficient algorithm for robots performing a complete task. Extensive experiments are conducted to show the validity of the proposed control designs.

A Design Method of TDOF Controller for Sampled-Data Control System: A Method Using Dynamical Model of Feedback Controller

It has been proposed the design method of the two-degree-of-freedom (TDOF) controller which use the dynamical model of the feedback controller. In this study, we apply this design method to the sampled-data control system. The TDOF controller is obtained so that the output of the TDOF system follows the output of the model transfer function considering the intersample behaviors.

Optimal Control of a Flexible Mechanism Using a Combined Feedforward-Feedback Strategy: Simulation and Experiment

Due to the elasticity of the links in modern high speed mechanisms, increasing operating speeds often lead to undesirable vibrations, which may render a required accuracy unattainable or, even worse, lead to a failure of the whole process. The dynamic effects e.g. may lead to intolerable deviations from the reference path or even to the instability of the system. Instead of suppressing the vibration by a stiffer design, active control methods may greatly improve the system performance and lead the way to a reduction of the mechanism’s weight. We investigate a four-bar-linkage mechanism and show that by introducing an additional degree of freedom for a controlled actuator and providing a suitable control strategy, the dynamically induced inaccuracies can be substantially reduced. The modelling of the four-bar-linkage mechanism as a hybrid multi body system and the modelling of the complete system (including the actuator) is briefly explained. From the combined feedforward-feedback optimal control approach presented in (v. Stein, Ulbrich, 1998) a time-varying output control law is derived that leads to a very good system performance for this linear discrete time-varying system. The experimental results show the effectiveness of the applied control strategy.

Design of a Highly Integrated Active Magnetic Bearing With Six Coupled Actuators for High Precision Rotation Applications

This paper presents the design and the implementation of a contact free Active Magnetic Bearing (AMB) for high precision rotation applications. For controlling five Degrees of Freedom (DOF) of the rotor six coupled reluctance force actuators (creating radial and axial forces at the same time) are used. A method for designing the actuators in order to meet the specifications is described. Two different controller schemes using different sensor configurations have been implemented on a functional prototype: On the one hand a conventional decentralized PID controller, on the other hand a more centralized structure.

Tension and Speed Regulation of Axially Moving Materials

In this paper, the tension and speed of an axially moving material system are regulated using control torques applied to rollers at each end of a controlled span. Given a distributed parameter model, Lyapunov-type arguments produce a model-based boundary control law that exponentially stabilizes the material tension and speed at the desired setpoints. Dynamic simulation results compare the tension and speed setpoint regulation provided by the proposed control strategy with standard PID approaches.

Self-Powered Active Vibration Control With Continuous Control Input: Application to a Cab Suspension of a Heavy Duty Truck

Active vibration control using regenerated vibration energy, i.e., self-powered active control, is proposed. In the self-powered active control system, vibration energy is regenerated by an electric generator, which is called an energy regenerative damper, and is stored in the condenser. An actuator achieves active vibration control using the energy stored in the condenser. The variable-value resistance whose value can be controlled by a computer is utilized to control output force of the actuator. The authors examine the performance of the self-powered active vibration control on experiments and propose to apply this system to cab suspensions of a heavy duty truck. Through experiments, it is shown that the self-powered active vibration control system has better isolation performance than a semi-active and a passive control system. Numerical simulations demonstrate better isolation performance of the self-powered active vibration control in cab suspensions of a heavy duty truck.