Industrial Motion Control Research Articles

Novel bacterial foraging-based ANFIS for speed control of matrix converter-fed industrial BLDC motors operated under low speed and high torque

In this paper, a novel adaptive neuro-fuzzy inference system (ANFIS)-based control technique optimized by Bacterial Foraging Optimization Algorithm for speed control of matrix converter (MC)-fed brushless direct current (BLDC) motor is presented. ANFIS is considered to be one of the most promising technologies for control of electrical drives fed by MC. Optimizing the training parameters of ANFIS, to improve its performance, is still being considered by several researchers recently. Parameters of the online ANFIS controller such as learning rate (η), forgetting factor (λ) and steepest descent momentum constant (α) are optimized by using the proposed algorithm. For the purpose of comparison, proportional integral derivative controller, fuzzy logic controller, PSO-ANFIS and BAT-ANFIS are considered. Set point tracking performances of the proposed system are carried out at various operating points for an industrial BLDC motor operating at a maximum rated speed of 380 rpm and torque of 6.4 N m. Time domain specifications such as rise time, settling time, peak time, steady-state error and peak overshoot in the presence and absence of load torque disturbances are presented. Time integral performance measures such as integral square error, integral absolute error, and integral time multiplied absolute error are analyzed for various operating conditions. Speed fluctuation in the output of BLDC motor is dependent on the source current harmonics of the inverter/converter. To illustrate this, total harmonic distortion (THD) analysis is carried out for the existing PWM inverter and the proposed MC, and it is proved that MC results in reduced THD, as compared to PWM inverter. Simulation results confirm that the proposed controller outperforms the other existing control techniques under various set speed and torque conditions. Statistical analysis is effectively carried out to prove the effectiveness of the proposed controller. Experimental analysis is performed to validate the performance of the proposed control scheme.

High-performance and high-precision servo control of a single-deck dual-axis PMLSM stage

The inertia of the stacked multi-degree-of-freedom platform imposes limitation on the achievable motion speed. To overcome this barrier, the unstable design becomes very attractive. This research presents a novel single-deck dual-axis linear motor platform that is capable of fast long-range motion. The platform is equipped with air-bearing design to achieve backlash-free operation. As a result, the positioning rigidity depends entirely on the performance of the servo system. A force distribution control is used to decouple the difference axis dynamics. This research also proposes a chain scattering description (CSD) setup to allow a pseudo-derivative feedback (PDF) control framework that is commonly used in industrial motion control for achieving high servo rigidity. An interesting finding is that our experiments show that without the help of complex piggyback piezoelectric stage, the single-deck platform design, with a stroke as large as 20 mm, can already reach a servo accuracy of ±60 and ±80 nm in the x- and y-axis and 600 μarcsec in the yaw axis.

Robust output tracking using disturbance observer with application to industrial servo control

This paper proposes a robust strategy for output tracking in industrial motion control using disturbance observer (DO). The control scheme uses a sliding mode control (SMC) augmented by the estimates of disturbances. The SMC proposed here compensates matched as well as mismatched disturbances. The DO is used to estimate the disturbances and their derivatives for improved performance. The practical stability of the overall system is assured. The robustness is analysed for practical disturbances like backlash and friction. The effectiveness of the proposed strategy is experimentally validated for trajectory tracking in the presence of matched and mismatched disturbance.

Development of an aerodynamic control system for the evaluation of the Open Core Engineering technology

This paper describes the development of an aerodynamic control system used for the evaluation and demonstration of the award winning Open Core Engineering (OCE) technology. The aerodynamic control system was designed with physical properties that allow using it in rapid-control-prototyping (RCP) environments as well as with industrial motion-control components. Open Core Engineering is a quite modern technology invented by Bosch Rexroth AG that supports software development on several platforms for industrial automation applications. A 3D printed alternative design is explained as well.

Extremum-Seeking Control for the Adaptive Design of Variable Gain Controllers

In this paper, we experimentally demonstrate an extremum-seeking control strategy for nonlinear systems with periodic steady-state outputs, for the adaptive design of variable-gain controllers. Variable-gain control can balance the tradeoff between low-frequency disturbance suppression and sensitivity to high-frequency noise in a more desirable manner than linear controllers can. However, the optimal performance-based tuning of the variable-gain controller parameters is far from trivial, and depends on the unknown disturbances acting on the system. The extremum-seeking controller only utilizes output measurements of the plant, and can therefore be used to optimally design the parameters of the variable gain controller, without using direct information on the disturbances acting on the system. Experimental results are presented for the performance-optimal tuning of a variable-gain controller applied to a magnetically levitated industrial motion control setup performing tracking motions. The influence of the different parameter choices on the performance of the extremum-seeking controller is illustrated through experiments.

Scheduled controller design for systems with two switching sensor configurations: A frequency-domain approach

In this paper, we consider a hybrid system consisting of a motion stage that exhibits, from a control point-of-view, position-dependent dynamics as a result of varying sensor configurations. A scheduled controller design is proposed that is intuitive for control engineers as all individual filters can be obtained using classical frequency-domain loop-shaping techniques thereby connecting to the industrial motion control practice. Moreover, data-based graphical conditions are provided in the frequency-domain under which closed-loop stability can be verified irrespective of how the switching between the controllers occurs in time. The effectiveness of the proposed scheduling technique, as a way to improve both transient and steady-state performance compared to the current state-of-the-art industrial control solution, is demonstrated by means of experiments on a high-precision industrial motion stage.

Open-loop neuro-fuzzy speed estimator applied to vector and scalar induction motor drives

Scalar and vector drives have been the cornerstones of control of industrial motors for decades. In both the elimination of mechanical speed sensor consists in a trend of modern drives. This work proposes the development of an adaptive neuro-fuzzy inference system (ANFIS) angular rotor speed estimator applied to vector and scalar drives. A multi-frequency training of ANFIS is proposed, initially for a V/f scheme and after that a vector drive with magnetizing flux oriented control is proposed. In the literature ANFIS has been commonly proposed as a speed controller in substitution of the classical PI controller of the speed control loop. This paper investigates the ANFIS as an open-loop speed estimator instead. The subtractive clustering technique was used as strategy for generating the membership functions for all the incoming signal inputs of ANFIS. This provided a better analysis of the training data set improving the comprehension of the estimator. Additionally the subtractive cluster technique allowed the training with experimental data corrupted by noise improving the estimator robustness. Simulations to evaluate the performance of the estimator considering the V/f and vector drive system were realized using the Matlab/Simulink® software. Finally experimental results are presented to validate the ANFIS open loop estimator.

A fast white-beam shutter for hard x-ray topography at beamline 1-BM of the Advanced Photon Source

Beamline 1-BM at the Advanced Photon Source (APS) delivers a white beam from a bending magnet with very intense x-ray photon flux. One important application of this beamline is white-beam x-ray topography imaging for crystal-based x-ray optics development and for industrial characterization of single crystals and epitaxial materials. Due to the intense photon flux from the third-generation synchrotron source of the APS, the exposure time of the imaging process should be accurately controlled down to the millisecond level. For this purpose we have designed and implemented a fast shutter that is vacuum compatible to 10−8 torr. The aperture is a copper block with a 70 mm horizontal and 5 mm vertical opening and is water cooled. The aperture is moved vertically up and down by means of a linear voice-coil actuator. The aperture's position is controlled using encoder feedback in a servo loop running on an industrial motion controller. A shutter opening response time of 32 milliseconds was measured. In this paper, we describe the shutter mechanics and its associated electronics installed at the 1-BM, and we report example white-beam topographs of diamond type IIa crystals.

Dual-Channel Measurement System for Real-Time Ethernet

Real-time Ethernet (RTE) is widely used in industrial automation and high performance motion control field. Its minimum cycle time is down to less than 100μs and cycle jitter is less than 1μs, making many existing network and protocol analyzers cant meet the requirements of time accuracy in measurement system for RTE. In this paper, a low-cost and open measurement system is proposed to analyze the time characteristics (cycle time, cycle jitter, end-to-end delay, etc.) and protocol (Ethernet type, length, detailed info, etc.) of real-time Ethernet. The measurement system is consisting of a FPGA-based hardware device and a PC-based monitor station. The hardware device has dual channels that allow detecting two nodes data frame simultaneously. Ethernet data frames through channels are transmitted immediately; at the same time, all data frames will be duplicated and sent to the monitor station with precise timestamp for frame analysis. A prototype of measurement system has been realized to verify feasibility and performance. Result of the experiment shows that the maximal delay time brought in by measuring device is only 120ns and the accuracy of time stamp is down to 5ns; the parser is created in the monitor PC for analysis the time characteristics and protocols of real-time Ethernet.

Research on the General NC System of Quasi Flexible Production Line

The general NC (Numerical Control) system of quasi flexible production Line is researched based on motion control card operated by the DSP (Digital Signal Processor) and industrial PC (Personal Computer) running on system platform of Windows. The hardware platform of general NC system of quasi flexible production Line is built with industrial PC and motion control card, and the industrial PC is the upper computer. The software platform of general NC system of quasi flexible production line is compiler environment of Visual C++. Using programming technique of object-oriented and modularized, the network communication of data exchange for coordination and scheduling module in general NC system of quasi flexible production Line is built based on multi-threaded technology.

Model-based decoupling control method for dual-drive gantry stages: A case study with experimental validations

Industrial motion control of dual-drive gantry stages is usually performed by position controllers acting independently on each actuator. This approach neglects the unbalance and the mechanical coupling between actuators, leading to poor positioning performances. To overcome this drawback, a model-based decoupling control is proposed. Initially, a dynamic model of the gantry stage is proposed. Once identified and validated, such model is written in terms of a decoupling basis. Then, by model inversion, a feedback−feedforward decoupling control is presented. Experimental results show that, in comparison to the independent axis control approach, the proposed solution leads to improved motion control.

Exploring the Potential of MEMS Gyroscopes: Successfully Using Sensors in Typical Industrial Motion Control Applications

Since their conception in the 1990s, MEMS gyroscopes have gained increasing popularity over traditional mechanical or optical gyroscopes because of their innate features such as low cost, reduced size, and low power requirements. Market acceptance has grown over the years, thanks to the constant efforts spent by manufacturers in improving key features such as performance, reliability, and cost of the single device. Recently, MEMS gyroscopes have begun to be applied in several automotive, industrial, and consumer electronics applications either as replacements of older, bulkier, and more expensive sensors or as essential components in new applications that require compact, inexpensive solutions for the measurement of the angular rate. Typical motion control applications, such as the stabilization of inertial platforms, the active damping of undesired vibrations, or the motion reconstruction, can undoubtedly benefit from the usage of MEMS gyroscopes. The two motion control applications presented in this article portray, with the support of real experimental data, some of these benefits. Hopefully this article has provided sufficient motivations to the interested reader to further explore the potentials of MEMS gyroscopes and to start planning how to successfully apply them in existing or innovative motion control applications.

Mater-slave Control Technology for Abdominal Minimally Invasive Surgery Robot and Its Experiments

According to task features of RMIS(robot-assisted minimally invasive surgery),based on the functional requirement analyses of master-slave control,a hardware platform of robot master-slave control system is constructed by adopting control architecture of industrial computer and motion control card.A real-time control algorithm of master-slave operation is investigated based on differential transformation method,and then the auxiliary function of master-slave control is designed.Master-slave control experiment,experiment on biological tissue and animal experiment are carried out after robot system integration.Experiments demonstrate that the system has good master-slave control performance,which satisfies the actual demand of minimally invasive surgery.

Modeling and Identification for Lightweight High-Speed Machines with Loads Variation

The positioning performance of high-speed, high-accuracy light-weight motion control systems is usually restricted by the structure flexibility and model parameter-varying caused by load mass variation. It needs to develop novel motion control algorithm to eliminate the residual vibration in the end-effectors, as well as to be robust over the load mass variation. This paper addresses the first and crucial step of this problem, modeling and identification technique. The linear parameter-varying model of the system is constructed and analyzed. The parameters and affine function identification method based on nonlinear least-squares and principle component analysis technique is proposed. The validity of the proposed method is demonstrated through a lightweight machine experimental setup. It is general enough to be applicable to the dynamic behaviors analysis and gain-scheduling robust control design for industrial lightweight vibration suppression and motion control systems that possess flexible elements and variable loads.

Control Module of Laser Metal Deposition Shaping System

The Laser Metal Deposition Shaping (LMDS) is a state-of-the-art technology which correlates the Rapid Prototyping and Manufacturing (RP&M) and laser processing. During this process, a certain alloy is fused onto the surface of a substrate. Laser deposition devices, namely powder feeder, CNC worktable, and laser shutter, are integrated to automatically make any cladding profile possible. Material is deposited by scanning the laser across a surface while injecting metallic powders into the molten pool at the laser focus. The metal part is then fabricated layer by layer. The LMDS system consists of four primary components: energy supply module, motion control module, powder delivery module, and computer control module. These modules of LMDS system individually perform the specified functions, but coordinate with each other. One of them, the control module plays an important role in causing the LMDS system automatic and intelligent. The control module can be divided into hardware and software components. The hardware structure mainly includes industrial computer, motors, and motion control card, which build the overall framework, and are driven by software structure. The software structure, namely the system application program with GUI, can instruct every module of LMDS system to finish the motion cooperatively adjust the processing parameters freely, and fulfill the LMDS technology automatically and intelligently. The hardware and software structures work in harmony with each other, thus flexibly controlling the LMDS system.

Parameter Identification and Controller Design for the Velocity Loop in Motion Control Systems

Today the controller commissioning of industrial used servo drives is usually realized in the frequency domain with the open-loop frequency response. In contrast to that the cascaded system of position loop, velocity loop and current loop, which is standard in industrial motion controllers, is described in literature by using parametric models. Several tuning rules in the time domain are applicable on the basis of these parametric descriptions. In order to benefit from the variety of tuning rules an identification method in the time domain is required. The paper presents a method for the identification of plant parameters in the time domain. The approach is based on the auto relay feedback experiment by Åström/ Hägglund and a modified technique of gradual pole compensation. The paper presents the theoretical description as well as the implementtation as an automatic application in the motion control system SIMOTION. The identification results as well as the achievable performance on a test rig with a PI velocity controller will be presented.

Identification of Parametric Models and Controller Design for Cascaded Position Control

AbstractThe standard in industrial motion controllers comprises today a cascaded system of position loop, velocity loop and current loop. Each controller has to be designed according to its subordinated system behavior. The paper presents a method for the identification of plant parameters in the time domain. The approach is based on the auto relay feedback experiment by Åström/ Hägglund and a modified technique of gradual pole compensation. In addition to a theoretical description, the implementation as an automatic application in the motion control system SIMOTION is shown. Finally, the velocity controller and the position controller are adjusted according to the identified systems. Furthermore, the identification results as well as the achievable controller performance on a test rig will be presented.

Design and synthesis of FPGA for speed control of induction motor

The industrial motor control is quickly changing from micro to nanotechnology design with speed and performance based design implementation. Considering accuracy and synchronism of output response, the attention has been brought to fully digitized design to adopt Space Vector Pulse Width Modulation (SVPWM) as a control technique for three phase Induction Motors due to its resulted advantages in harmonic reduction. Very High Speed Hardware Description Language (VHDL) digitized scheme built on the platform of a Field Programmable Gate Array (FPGA) for direct speed control of Induction Motor has been proposed for industrial applications. This paper proposed hybrid hardware model of analog, digital, power and micro-electronics. The model is focused to industrial application with loss minimization and smooth control of flux. Xilinx 8.1i, Spartan-II FPGA Xc2s50-5pq208, IGBT CT60AM18F, 2HP Induction Motor has been used for design and synthesis of model. The result shows 74% occupied slices and 70% total no of 4 look-up-tables (LUTs) have been utilized. The model response has been observed very smooth. Key words: Field Programmable Gate Array (FPGA), look-up-tables (LUTs), Space Vector Pulse Width Modulation (SVPWM), Very High Speed Hardware Description Language (VHDL).

Analysis and applications of the motion message estimator for network control systems

AbstractThe time‐delay effect in network systems is unavoidable because of its limited transmission bandwidth. In real‐time network control systems (NCS), all messages are required to be transmitted or received to meet specifications of the deadline. Therefore, the data dropout may thus occur in NCS due to its time delay in a stochastic nature. In this paper, a motion message estimator is proposed to construct a real‐time motion NCS to significantly reduce the data‐dropout effect. Both simulation and experimental results indicate that a 3rd‐order message estimator based on the Taylor expansion can be properly implemented in NCS for industrial motion control systems. Furthermore, since the uncertainties of the NCS estimator are greatly suppressed by applying the message, experimental results indicate that its integration with the feedforward control leads to significantly improved accuracy for the NCS implemented on an industrial computerized numerical control (CNC) machine tool. Copyright © 2008 John Wiley and Sons Asia Pte Ltd and Chinese Automatic Control Society

Optimized motion control system for semiconductor machines

This paper presents Nyquist's compact, rugged NYCe4000 high-end industrial motion control system with flexible and universal integrated drive technology that is suitable for servo and stepper motors up to 500 W. Thanks to the use of the "clean PC" concept, there is no need for extra network cards for real-time kernel extensions. The system's architecture is dominated by the high-performance machine requirements of semiconductor machines. Features are available for debugging and monitoring synchronized, multitasking machine control applications. The NYCe4000 provides high-end motion control performance with complete tooling support.