In this paper implementation of a control system for high precision applications is presented. The control system is developed for a Piezo LEGS motor, which is a walking piezo motor that can be employed in nanometric precision applications. In the control system structure, two main components are digital signal controller which executes control algorithm and power driver that is generating driving voltages for the motor. The waveforms of the driving voltages are designed using a recently presented coordinate transformation. This transformation enables synthesis of driving waveforms according to design requirements regarding force imposed to the motor's rod and rod's x-direction trajectory profile. In this work, the waveforms are selected to ensure no relative motion between the motor's legs and rod, and constant velocity of the rod within one step. Control algorithm is named as virtual time control. Despite its simplicity, the algorithm allows high precision positioning which is very close to theoretically achievable one.

The most popular control method in the industry is PID control due to its simple structure and effective performance. Although huge numbers of PID controller tuning methods have been proposed so far, existing ones still do not have the desired performances and the simplicity. Complex system dynamics make it challenging for engineers and students to apply these methods on their applications especially in the motion control and robotics areas. Such systems generally include nonlinearity, friction, varying inertia and unknown disturbances which make the conventional tuning methods ineffective and too complex to be used. There is need for simple and effective PID tuning methods in these areas. In order to solve this problem, this paper proposes two novel practical PID tuning methods for motion control systems. These methods bring the superiority of the 2 degree of freedom control approach to simple PID controller structures analytically. They are very effective in motion control and robust both to parameter uncertainty and unknown disturbances, yet very simple. They can be easily used by the engineers in the industry and the students with very basic control knowledge, so little effort and time. The tuning methods of robust PID and PI controllers with velocity feedbacks are proposed, for position and force control problems of servo systems, respectively. The validities of the proposals are verified by the experimental results.

This paper presents a novel current control methodology for grid connected doubly-fed induction generator (DFIG) based wind energy conversion systems. Controller is based on a proportional controller with additional first order low pass filter disturbance observer which estimates the parameter dependent nonlinear feed-forward terms. The results in simulations and experimental test bed obviously demonstrate that decoupled control of active and reactive power is achieved without the necessity of additional machine parameter.

This paper proposes two novel master-slave configurations that provide improvements in both control and communication aspects of teleoperation systems to achieve an overall improved performance in position control. The proposed novel master-slave configurations integrate modular control and communication approaches, consisting of a delay regulator to address problems related to variable network delay common to such systems, and a model tracking control that runs on the slave side for the compensation of uncertainties and model mismatch on the slave side. One of the configurations uses a sliding mode observer and the other one uses a modified Smith predictor scheme on the master side to ensure position transparency between the master and slave, while reference tracking of the slave is ensured by a proportional-differentiator type controller in both configurations. Experiments conducted for the networked position control of a single-link arm under system uncertainties and randomly varying network delays demonstrate significant performance improvements with both configurations over the past literature.

This paper presents a novel robust stator voltage oriented rotor current controller structure for grid connected doubly fed induction generators (DFIG). Controller is based on a proportional controller with first order low pass filter disturbance observer which estimates machine parameter dependent nonlinear terms. Therefore, necessity of accurate knowledge of machine parameters is not required. The results are demonstrated in experimental laboratory setup.

In this paper a novel design for three-dimensional (3-D) contour controller is proposed. This design relies on dynamics projection to the moving Frenet-Serret frame defined for each point on reference trajectory. Contour controller consists of independent joint controller and additional sliding mode controller, added as corrective term. Control task is defined as contour tracking with constant tangential velocity. Contour controller was compared with independent joint controller designed as acceleration controller with first order disturbance observer. Reference trajectory is generated using time based spline approximation to provide smooth reference trajectory. Experimental results showed significant improvement that contour controller provides over independent joint control with relatively high velocity references.

This work presents a modular and reconfigurable desktop microfactory for high precision machining and assembly of micro mechanical parts. Miniature factory is inspired by the downsizing trend of the production tools. The system is constructed based on primary functional and performance requirements such as miniature size, operation with sub-millimeter precision, modular and reconfigurable structure, parallel processing capability, ease of transportation and integration. Proposed miniature factory consists of several functional modules such as two parallel kinematic robots for manipulation and assembly, galvanometric laser beam scanning system for micromachining, camera system for inspection, and a rotational conveyor system for sample part delivery. The overall mechanical structure of the proposed microfactory facilitates modularity and reconfigurability, parallel processing, flexible rearrangement of the layout, and ease of assembly and disassembly of the whole structure. Experiments involve various tasks within a single process such as pick-place of the 3 mm diameter metallic ball, marking a 2D sub-millimeter image on the ball surface with high power laser, and inspection along with verification of the image by means of microscopic camera. Results have shown the possibility of implementation of the desktop microfactory concept for machining and assembly of tiny mechanical parts with microprecision.

This paper introduces a codec scheme for compressing the control and feedback signals in bilateral control systems. The method makes use of Wavelet Packet Transform (WPT) and Inverse Wavelet Packet Transform (IWPT) for coding and decoding operations respectively. Data compression is carried out in low pass filter output by reducing the sampling rate; and in high pass filter output by truncating the wavelet coefficients. The proposed codec works on both directions of signal transmission between a master robot and a slave robot over a networked motion control architecture. Following the formulation of the compression/decompression methodology, experimental validation is conducted on a single degree of freedom (DOF) motion control system. In the experiments, responses from different Wavelet structures are analyzed and a comparative study is carried out considering the factors of compression rate, reconstruction power error and real time computational complexity. It is confirmed that the controller using the proposed compression algorithm performs very close to the uncompressed one while enabling transmission of much less data over network.

This paper proposes a new motion-loading method that utilizes a multilateral control-based scheme for the motion-copying system. The motion-copying system refers to human operator's motion, tracks and preserves it only for being able to reproduce the same result of the motion. Conventionally, only slave system was used for motion-loading phase. The method proposed in this paper offers a way to enable more than one slave side actuator at the phase. With the proposed system, the operator at loading phase can grab the master system which the manipulator was holding at the saving phase. The performance analyses of proposed system are made with the bode plots, and the experiments are held with two degrees-of-freedom actuators. The newly proposed haptic informational reproduction technique can be applied in many areas, especially as the training purposes.

This paper describes FPGA based control system for a piezoelectric motor, commercially available Piezo LEGS motor. Driving voltages waveforms are defined as a combination of linear functions. This definition provides possibility for easy implementation on very simple hardware. Linear functions parameters allow forming of the driving voltages according to desired trajectory of motor's legs. Considering that FPGA technology offers many advantages over the classical microprocessor based systems, it is used as control system implementation hardware. Realized control system can be very easily expanded to control multiple motors, if hardware resources are big enough. Also modularity is provided, making the future application very simple. In the paper control system structure is described in detail along with a very simple control algorithm for Piezo LEGS motor positioning control. Experimental results are given to validate designed control system. They showed satisfying control performance, responses with no overshoot and expected steady state error.

Motion control technologies are introduced in a huge number of products: electric vehicles, robots, mass storage areas, machine tools, etc. Many new products have developed based on previous studies on motion control. Recent achievements in motion control have indicated that innovation in this area is accelerating. For example, many companies have put robots with force sensing to practical use in the past few years. They have a wide variety of applications such as deburring, polishing, and assembling. Further development of haptics is strongly required for telesurgery, rehabilitation, and nursing care support. The development of high-accuracy positioning/tracking control has shortened the access time of mass storage areas. Sophisticated integration of actuators and sensors technologies has created many innovative techniques for new motion control systems. It is quite obvious that motion control is becoming more and more important as one of the key technologies in industrial electronics. Therefore, this "Special Section on New Emerging Technologies in Motion Control Systems - Part I" aims at presenting to the industrial electronics audiences the most advanced and relevant results in the field of motion control. The Guest Editors summarize the 14 articles from, various areas, that comprise the special section.

This “Special Section on New Emerging Technologies in Motion Control Systems-Part II” aims to present to the industrial electronics audience the most advanced and relevant results in the field of motion control. It is our pleasure to present the second part of this special section since many cutting-edge studies have been contributed.

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This work focuses on the design of driver for PiezoLegs actuator used for high precision positioning purposes. Motor is driven with the set of periodical voltages with known frequency, amplitude and phase shift between the phases. Motor's operation has been investigated in detail and clear relationships between the amplitude and phase shifts between the driving voltages and motor step size have been established. According to the motor analysis, set of design requirements for the design of driver is given. Particular solution meeting these requirements and satisfying the given design constraints is presented. Driver is experimentally evaluated for power consumption and analyzed in frequency domain, it's performance is compared to the performance of a commercially available driver for the same motor. Designed driver shows improved performance.

This paper describes configuration space control of a Delta robot with a neural network based kinematics. Mathematical model of the kinematics for parallel Delta robot used for manipulation purposes in microfactory was validated, and experiments showed that this model is not describing “real” kinematics properly. Therefore a new solution for kinematics mapping had to be investigated. Solution was found in neural network utilization, and it was used to model robot's inverse kinematics. It showed significantly better mapping between task space coordinates and configuration (joint) space coordinates than the mathematical model, for the workspace of interest. Consequently positioning accuracy improvement is expected. Neural network is then used as a part of the control system. Applied control strategy was configuration space acceleration control with disturbance observer.