Synchronization of Electrical Drives via EtherCAT Fieldbus Communication Modules

Synchronization between devices (in particular drive systems) is paramount for multi-axis motion control systems used in Computerized Numerical Control (CNC) machines, robots, and specialized technology machines used in many areas of the manufacturing industry. EtherCAT is an Ethernet-based network that is one of the most popular industrial networks for multi-axis motion control systems. EtherCAT is standardized in the IEC 61158 and IEC 61784 standards. In the article, an EtherCAT communication network for electrical drives is presented. The article focuses on the synchronization in the EtherCAT network consisting of one master device and slave servo drive devices. Special attention is given to synchronization mechanisms in EtherCAT, such as distributed clocks in slave servo drives devices. For this purpose, a laboratory stand was built consisting of two prototype servo drive devices with BLDC motors equipped with EtherCAT communication modules. A description of the working developed EtherCAT communication modules is given. Authors in communication modules ware used an EtherCAT Slave Controller (ESC) chip (AX58100) to implement lower EtherCAT layers. EtherCAT application layer was implemented in software form on a 32-bit microcontroller, based on CANopen over EtherCAT (CoE) CAN in Automation 402 (CiA402) profile. This research’s main contribution was to show the time dependencies regarding synchronization in terms of data flow in the EtherCAT communication stack in slave servo drive devices. The research results showed that the synchronous operation of drives is mainly influenced not by the mechanism of distributed clocks that ensures synchronization in the EtherCAT network but the implementation of the highest layer of the communication stack in slave servo drive devices. Experimental results are presented that prove the modules’ adequacy for use in high-performance motion control systems.

Design and Simulation of a Servo-Drive Motor Using ANSYS Electromagnetics

The paper is devoted to determining the output parameters of a servomotor, which belongs to synchronous machines with permanent magnets, in order to further determine the characteristics of transient modes in the software package ANSYS Electromagnetics. RMxprt, part of ANSYS Electromagnetics, allows to determine the parameters of windings, losses, motor performance, but requires filling out a form with a complete set of geometric dimensions and winding data. Of course, such data are not available in the motor data sheet, so the first task solved in the paper is to determine all the necessary and sufficient parameters to perform the calculation in RMxprt. The results of the calculations were compared with the measurements on the experimental servomotor EMG-10APA22. This paper shows how to export a servomotor object from RMxprt to the Simplorer workspace, which is also part of the ANSYS Electromagnetics. According to the simulation results in ANSYS Simplorer, the characteristics of the transient modes of the servomotor powered by a stable three-phase source are obtained. Prospects for further research related to the improvement of the simulation model in ANSYS Simplorer are presented.

Research of Mechanical Resonance Analysis and Suppression Control Method of the Servo Drive System

Transmission mechanisms of the servo drive system are not a pure rigid body, and the existence of the elastic transmission mechanisms will make the system generate mechanical resonance. Aiming at mechanical resonance of the servo drive system, the resonance generation mechanism is analyzed, the four-mass model considering the time-varying meshing stiffness of the gear is established, and the influence of different stiffness parameters on the mechanical resonance of the system is researched in this paper. The composite controller of Model Predictive Control (MPC) with Notch Filter is used to simulate the mechanical resonance suppression of the four-mass servo system considering time-varying meshing stiffness, and it is compared with the mechanical resonance suppression method based on Model Predictive Control. The simulation results show that when the step speed is 200 r/min, the overshoot is reduced from 11.6 r/min to 1.1 r/min, which is reduced by 90.5%. Under the impact load condition, from 10 Nm to 30 Nm, overshoot is reduced from 34.3 r/min to 12.8 r/min, reduced by 62%, and torque oscillation is reduced by 81.5%. Therefore, the composite controller of Model Predictive Control with Notch Filter can suppress the mechanical resonance problem effectively, caused by elastic transmission, and improve the robustness of servo drive system.

Design of servo drive system for machine vision inspection platform

With the more application of machine vision technology in production practice, most machine vision systems are based on passive vision to measure the target, which has some limitations. Based on the requirements of machine vision platform, a three-dimensional servo movement scheme based on active positioning vision is proposed in this paper. In this paper, the parts of the servo drive system of the platform are selected, calculated and checked, the three-dimensional modeling of the machine vision platform is completed in SolidWorks, and the motion simulation of the servo control system is carried out.

Development of Servo Drive Positioning Control System Using PID Controller and Fuzzy Logic Controller

Servo drives are one of the most widely utilized devices in various mechanical systems and industrial applications to provide precise position control. The study of servo driver produc-tiveness and performance index is the important task. In this work, PID controller and fuzzy log-ic controller (FLC) were developed to control the position of a DC servo drive. The MATLAB Simulink program was investigated and implemented to calculate the values of servo drive pa-rameters, and a scheme for simulating the operation of a servo drive using different controllers was presented. A mathematical model of a DC servo drive for a positioning control system has been proposed. The control characteristics of the PID controller, fuzzy logic controller and fuzzy PID controller are compared. The simulation results have shown that the PID controller allows for an overshoot of about 1 % with a settling time of about 4 sec. The use of the fuzzy PID con-troller reduces the maximum overshoot to 1 % and decreases the settling time to 2 sec. As a re-sult, the fuzzy PID controller allows for better performance and efficiency compared to other controllers.

A Semi-recumbent Eccentric Cycle Ergometer Instrumented to Isolate Lower Limb Muscle Contractions to the Appropriate Phase of the Pedal Cycle

Eccentric (ECC) cycling is used in rehabilitation and sports conditioning settings. We present the construction and mode of operation of a custom-built semi-recumbent ECC cycle designed to limit the production of lower limb muscle activity to the phase of the pedal cycle known to produce ECC contractions. A commercially available semi-recumbent frame and seat (Monarch, 837E Semi-recumbent Bike, Sweden) were used to assemble the ergometer. An electrical drive train system was constructed using individual direct drive servo motors. To avoid active muscle activation occurring during the non-ECC pedaling phase of cycling, a “trip” mechanism was integrated into the drivetrain system using a servo-driven regenerative braking mechanism based on the monitoring of the voltage produced over and above a predetermined threshold produced by the motors. The servo drive internal (DC bus) voltage is recorded and internally monitored during opposing (OPP) and non-opposing (N-OPP) phases of the pedal cycle. To demonstrate that the cycle functions as desired and stops or “trips” when it is supposed to, we present average (of 5 trials) muscle activation patterns of the principal lower limb muscles for regular ECC pedal cycles in comparison with one pedal cycle during which the muscles activated outside the desired phase of the cycle for a sample participant. This semi-recumbent ECC cycle ergometer has the capacity to limit the occurrence of muscle contraction only to the ECC phase of cycling. It can be used to target that mode of muscle contraction more precisely in rehabilitation or training studies.

Neuroadaptive Robust Speed Control for PMSM Servo Drives with Rotor Failure

In this paper, a neuroadaptive robust trajectory tracking controller is utilized to reduce speed ripples of permanent magnet synchronous machine (PMSM) servo drive under the presence of a fracture or fissure in the rotor and external disturbances. The dynamics equations of PMSM servo drive with the presence of a fracture and unknown frictions are described in detail. Due to inherent nonlinearities in PMSM dynamic model, in addition to internal and external disturbances; a traditional PI controller with fixed parameters cannot correctly regulate the PMSM performance under these scenarios. Hence, a neuroadaptive robust controller (NRC) based on a category of on-line trained artificial neural network is used for this purpose to enhance the robustness and adaptive abilities of traditional PI controller. In this paper, the moth-flame optimization algorithm provides the optimal weight parameters of NRC and three PI controllers (off-line) for a PMSM servo drive. The performance of the NRC is evaluated in the presence of a fracture, unknown frictions, and load disturbances, likewise the result outcomes are contrasted with a traditional optimized PID controller and an optimal linear state feedback method.