Closed-loop Position Research Articles

A Design of Position Closed-Loop Control System for Hybrid Stepping Motors Based on Mechanical-Sensorless Rotor Position Detection

In a stepping motor, the flux linkage with a phase winding is a function of rotor position and phase current. Employing inductance saliency to detect rotor position is suitable for hybrid stepping motor (HSM) for its saturation feature. This paper will introduce a position closed-loop control system for HSM with rotor position detection by monitoring chopping characteristics, and present simulation results based on Matlab/Simulink.

The Study on the Control of Open CNC System Accuracy

New scheme of the CNC system software subdivision based on grating signal is discussed; the subdivision error analysis, the hardware circuit and the speed control are discussed. The closed-loop position control system with stepping motor as driving component is implemented.

The Study of Closed-Loop Position Control System Based on CNC Processing

In view of the existing problems of indirect position closed-loop control, a digitized closed-loop control method is presented and a new kind of position control system with fully digitized closed-loop based on that method is developed. In this way, the fully digitized control of cutter trajectory is implemented with the features of digitized driving, digitized measuring and digitized position control, so that the machining accuracy of the NC machine tools is effectively assured. This system has been used on varieties of NC machine tools and very good results have been obtained in the machining of complex precision parts.

Optimal torque coordinating control of the launching with twin clutches simultaneously involved for dry dual-clutch transmission

As for the self-developed six-speed dry dual-clutch transmission (DCT), the optimal torque-coordinated control strategy between engine and dual clutches is proposed to resolve the problem of launching with twin clutches simultaneously involved based on the minimum value principle. Focusing on the sliding friction phase of the launching process, dynamics equations of dry DCT with two intermediate shafts are firstly established, and then the optimal transmitting torque variation rate and the driven plate's rotating speed of dual clutches are deduced by using the minimum value principle, in which the jerk intensity and friction work are taken as the performance indexes, and the terminal constraints of state variables are determined according to the driver's launching intention. Besides, the separating conditions of non-target gear clutch and the torque distributing relations of twin clutches are derived from the launching control targets that guarantee the approximately equal friction extent of two clutches and no power cycle. After the synchronisation of driving and driven plates of on-coming clutch, the output torque of engine is smoothly switched to the driver's demand level. Furthermore, launching the simulation model of the dry DCT vehicle is set up on the Matlab/Simulink platform. Simulation results indicate that the proposed launching control strategy not only can effectively reflect the driver's intention and extend the life span of twin clutches, but also obtain an excellent launching quality. Finally, the torque control laws of two clutches obtained through the simulation are transformed into clutch position control laws for the future realisation in the real car, and the closed-loop position controls of twin clutches in the launching process are conducted on the test bench with two sets of clutch actuator, obtaining preferable tracking effects.

Design and control of a piezoelectric driven reticle assist device for prevention of reticle slip in lithography systems

This paper presents a device for managing the inertial loads on photoreticles of lithography scanners. At high scan accelerations, the reticle inertial load can approach the clamp force limit. As a result, nanometer-level presliding slip can occur. Reticle slip is one limitation on increasing the throughput of the lithography scanners. In this paper, we present a reticle assist device which can eliminate reticle slip by compensating better than 95% of the inertial loads when tested in a bench-top tester. The reticle assist device consists of a coarse approach mechanism, for accommodating reticle load/unload, and a piezoelectric stack for fine actuation. The device utilizes a sensorless control system design. The control system uses a self-sensing contact detection method, which is inspired by self-sensing scanning probe microscopy, to find the reticle edge. It also uses a charge amplifier with a novel hybrid hysteresis compensation technique to linearly control the piezoelectric actuator extension, without the need for closed-loop position control. When tested with a replicated force profile with 60N peak force and 6400N/s force rate, the assist device compensated better than 95% of the inertial load.

Attitude Stabilization Control of a Quadrotor UAV by Using Backstepping Approach

The modeling and attitude stabilization control problems of a four-rotor vertical takeoff and landing unmanned air vehicle (UAV) known as the quadrotor are investigated. The quadrotor’s attitude is represented by the unit quaternion rather than Euler angles to avoid singularity problem. Taking dynamical behavior of motors into consideration and ignoring aerodynamic effect, a nonlinear controller is developed to stabilize the attitude. The control design is accomplished by using backstepping control technique. The proposed control law is based on the compensation for the Coriolis and gyroscope torques. Applying Lyapunov stability analysis proves that the closed-loop attitude system is asymptotic stable. Moreover, the controller can guarantee that all the states of the system are uniformly ultimately bounded in the presence of external disturbance torque. The effectiveness of the proposed control approach is analytically authenticated and also validated via simulation study.

Finite-Time Control for Attitude Tracking Maneuver of Rigid Satellite

The problem of finite-time control for attitude tracking maneuver of a rigid spacecraft is investigated. External disturbance, unknown inertia parameters are addressed. As stepping stone, a sliding mode controller is designed. It requires the upper bound of the lumped uncertainty including disturbance and inertia matrix. However, this upper bound may not be easily obtained. Therefore, an adaptive sliding mode control law is then proposed to release that drawback. Adaptive technique is applied to estimate that bound. It is proved that the closed-loop attitude tracking system is finite-time stable. The tracking errors of the attitude and the angular velocity are asymptotically stabilized. Moreover, the upper bound on the lumped uncertainty can be exactly estimated in finite time. The attitude tracking performance with application of the control scheme is evaluated through a numerical example.

Finite-Time Stabilization Control for a Rigid Spacecraft under Parameter Uncertainties

A novel finite-time control scheme is investigated for a rigid spacecraft in present of parameter uncertainties and external disturbances. Firstly, the spacecraft mathematical model is transformed into a cascading system by introducing an adaptive variable. Then a novel finite-time attitude stabilization control scheme for a rigid spacecraft is proposed based on the homogeneous method. Lyapunov stability analysis shows that the resulting closed-loop attitude system is proven to be stable in finite time without parameter uncertainties and asymptotically stable with parameter uncertainties. Finally, numerical simulation examples are also presented to demonstrate that the control strategy developed is feasible and effective for spacecraft attitude stabilization mission.

Position control with PID regulation for a FES system: preliminary results

For people with quadriplegia at C3 and C7 levels functional electric stimulations (FES) could be a solution to make precision movements using the wrist. Closed loop control for FES systems enables to improve precision, stability and diminishes the impact of external perturbations. The goal of this work is to present a control position of the wrist articulation whenever the movement is produced by FES. In this article, a control design is developed along with the results of its first evaluation process on three voluntary individuals without neurological damage. A PID controller is used and it is adjusted experimentally for each test subject. A Constant reference for the wrist extension angle at sagittal plane and time evaluation of 10 minute was used to probe de PID. For two subjects the regulators responded reasonably with low mean errors and low standard deviations. For subject 3 the designed regulator did not succeed in stabilizing the position as from minute 6 in the second test. Preliminary studies of this work suggest that it could be possible to continue with the study of the closed loop position control with PID strategy in some people with spinal cord injuries whose movements are assisted by FES.

Control Structure Design for Man-Function Humanoid Robot

This paper presents a new humanoid robot control structure - Man-Function humanoid robot. The sensing devices worn on the human body, these devices will produce signals of joints’ change when people move. Computer of the control system receiving the signals and processing them, then issue control signals to the servos of the robot at the same time, control the robot’s behavior. For this reason, a control structure of human’s behavior to determine the robot’s behavior formed. The humanoid robot has 17 servos and two pressure sensors, the rotation of these servos’ steering gears lead to the robot’s behavior changes, and 12 servos corresponding to the human body sensing devices, other 5 servos used for the stability control of the robot combined with the pressure sensors. Based on this control structure, some pilot tests of the sensing device or servo have been done, the closed-loop position control mode has been chosen and the Kalman filter smoothing optimization method been used, the initial static walking control of the robot been realized. DOI: http://dx.doi.org/10.11591/telkomnika.v11i12.3891

Attitude Tracking Control of Rigid Spacecraft With Actuator Misalignment and Fault

A control scheme is developed to address the attitude tracking problem of a rigid spacecraft. A sufficient condition to accommodate actuator misalignment is presented. The controller asymptotically stabilizes the closed-loop attitude tracking system. The desired attitude trajectories can be tracked in finite time, even in the presence of uncertain inertia tensor, external disturbances, actuator fault, and actuator misalignment. The attitude tracking performance of the controller is evaluated through an illustrative example.

An MRI-powered and controlled actuator technology for tetherless robotic interventions

This paper presents a novel actuation technology for robotically assisted MRI-guided interventional procedures. In the proposed approach, the MRI scanner is used to deliver power, estimate actuator state and perform closed-loop control. The actuators themselves are compact, inexpensive and wireless. Using needle driving as an example application, actuation principles and force production capabilities are examined. Actuator stability and performance are analyzed for the two cases of state estimation at the input versus the output of the actuator transmission. Closed-loop needle position control is achieved by interleaving imaging pulse sequences to estimate needle position (transmission output estimation) and propulsion pulse sequences to drive the actuator. A prototype needle driving robot is used to validate the proposed approach in a clinical MRI scanner.

Real-time position control of intelligent pneumatic actuator (IPA) system using optical encoder and pressure sensor

Purpose – Intelligent pneumatic actuator (IPA) is a new generation of actuator developed for Research and Development (R&D) purposes in the academic and industrial fields. The purpose of this paper is to show the application of optical encoder and pressure sensor in IPA, to develop a real-time model similar to the existing devices, and to assess the position control performance using a proportional-integrative (PI) controller and a bang-bang controller in real-time. Design/methodology/approach – A micro optical encoder chip is used to detect cylinder rod position by reading constructed laser stripes on a guide rod, whereas a pressure sensor is used to detect the chamber pressure reading. To control the cylinder movements by manipulating pulse-width modulation (PWM) cycles, two unit valves of two ports and two positions were used. A PI controller and a bang-bang controller are used with suitable gain value to drive the valve using PWM to achieve the target actuator position. Findings – The results show the experimental results of the closed-loop position tracking performance of the system using a data acquisition (DAQ) card over MATLAB software. Originality/value – This paper presents a real-time model used to replace the microcontroller-based system from previous IPA design. The paper proposes two control strategies, PI and bang-bang, to control position using encoder and pressure reading.

Dynamic Positioning of Underwater Robotic Vehicles with Thruster Dynamics Compensation

The development of accurate control systems for underwater robotic vehicles relies on the adequate compensation of thruster dynamics. Without compensation, the closed-loop positioning system can exhibit limit cycles. This undesired behaviour may compromise the overall system stability. In this work, a fuzzy sliding-mode compensation scheme is proposed for electrically actuated bladed thrusters, which are commonly employed in the dynamic positioning of underwater vehicles. The boundedness and convergence properties of the tracking error are analytically proven. The numerical results suggest that this approach shows a greatly improved performance when compared with an uncompensated counterpart.

Dynamic control allocation for spacecraft attitude stabilization with actuator uncertainty

A dynamic control allocation approach is presented to address the attitude stabilization problem of a rigid spacecraft. The approach is developed by using a least-square support vector machine. Actuator uncertainty including misalignment and magnitude deviation is explicitly addressed. A dynamic inverse control law is firstly designed. A least-square support vector machine-based adaptive compensator is then designed to handle actuators uncertainties, external disturbances and unknown moment of inertia. Lyapunov stability analysis shows that the closed-loop attitude system is asymptotically stable. More specifically, constrained quadratic programming-based robust dynamic control allocation is implemented to manage the redundancy actuators. The goal of minimizing the assumption of total energy is achieved. A numerical example is provided to demonstrate the effectiveness of the proposed scheme.

Control Structure Design for Man-Function Humanoid Robot

This paper presents a new humanoid robot control structure - Man-Function humanoid robot. The sensing devices worn on the human body, these devices will produce signals of joints’ change when people move. Computer of the control system receiving the signals and processing them, then issue control signals to the servos of the robot at the same time, control the robot’s behavior. For this reason, a control structure of human’s behavior to determine the robot’s behavior formed. The humanoid robot has 17 servos and two pressure sensors, the rotation of these servos’ steering gears lead to the robot’s behavior changes, and 12 servos corresponding to the human body sensing devices, other 5 servos used for the stability control of the robot combined with the pressure sensors. Based on this control structure, some pilot tests of the sensing device or servo have been done, the closed-loop position control mode has been chosen and the Kalman filter smoothing optimization method been used, the initial static walking control of the robot been realized. DOI: http://dx.doi.org/10.11591/telkomnika.v11i12.3891

Analysis and Modeling of Linear-Switched Reluctance for Medical Application

This paper focuses on the analysis, the modeling and the control of a linear-switched reluctance motor. The application under consideration is medical, and the actuator is to be used as a left ventricular assist device. The actuator has a cylindrical or tubular shape, with a mechanical unidirectional valve placed inside the mover, which provides a pulsatile flow of blood. The analytical expression of the effort based on the linear behavior of the actuator is given. The identification of the characteristics of the prototype actuator and the principle of position control is performed. A modeling of the actuator is proposed, taking into account the variation of inductance with respect to the position. The closed-loop position control of the actuator is performed by simulation. A controller with integral action and anticipatory action is implemented in order to compensate the effects of disturbing efforts and tracking deviations. Moreover, a magic switch is performed in the controller to avoid overshoots. The results show that the closed-loop response of the actuator is satisfactory.

Experimental Analysis of Laser Interferometry-Based Robust Motion Tracking Control of a Flexure-Based Mechanism

This paper presents experimental analysis of laser interferometry-based closed-loop robust motion tracking control for flexure-based four-bar micro/nano manipulator. To enhance the accuracy of micro/nano manipulation, laser interferometry realized robust motion tracking control is established with the experimental facility. This paper contains brief discussions about the error sources associated with the laser interferometry-based sensing and measurement technique, along with detailed error analysis and estimation. Comparative error analysis of capacitive position sensor-based system and laser interferometry-based system is also presented. Robust control demonstrates high precision and accurate motion tracking of the four-bar flexure-based mechanism. The experimental results demonstrate precise motion tracking, where resultant closed-loop position tracking error is of the order of $\pm$ 20 nm, and a steady-state error of about $\pm$ 10 nm. With the experimental study and error analysis, we offer evidence that the laser interferometry-based closed-loop robust motion tracking control can minimize positioning and tracking errors during dynamic motion.

Dynamic velocity feed-forward compensation control with RBF-NN system identification for industrial robots

A dynamic velocity feed-forward compensation control (DVFCC) approach with RBF neural network (RBF-NN) dynamic model identification was presented for the adaptive trajectory tracking of industrial robots. The proposed control approach combined the advantages of traditional feedback closed-loop position control and computed torque control based on inverse dynamic model. The feed-forward compensator used a nominal robot dynamics as accurate dynamic model and on-line identification with RBF-NN as uncertain part to improve dynamic modeling accuracy. The proposed compensation was applied as velocity feed-forward by an inverse velocity controller that can convert torque signal into velocity in the standard industrial controller. Then, the need for a torque control interface was avoided in the real-time dynamic control of industrial robot. The simulations and experiments were carried out on a gas cutting manipulator. The results show that the proposed control approach can reduce steady-state error, suppress overshoot and enhance tracking accuracy and efficiency in joint space and Cartesian space, especially under highspeed condition.

Modelling and control of a springless resonant linear permanent magnet oscillomotor

Several configurations of resonant linear permanent magnet (PM) oscillomotors have been proposed lately for different devices. Higher efficiency for competitive costs and weight, in comparison with rotary actuators containing rotary to linear transmission, can be secured by operation at resonance (mechanical eigenfrequency is equal to electrical frequency). This study proposes a closed-loop position control system for a new, springless, resonant linear permanent magnet oscillomotor and demonstrates through digital simulations its capability to deliver precise and wide levels of output power under good efficiency conditions not only at a given (resonant) frequency, but for ±10% frequency range around it.