EtherCAT Fieldbus Research Articles

Real-Time EtherCAT-Based Control Architecture for Electro-Hydraulic Humanoid

Electro-hydraulic actuators have witnessed significant development over recent years due to their remarkable abilities to perform complex and dynamic movements. Integrating such an actuator in humanoids is highly beneficial, leading to a humanoid capable of performing complex tasks requiring high force. This highlights the importance of safety, especially since high power output and safe interaction seem to be contradictory; the greater the robot’s ability to generate high dynamic movements, the more difficult it is to achieve safety, as this requires managing a large amount of motor energy before, during, and after the collision. No matter what technology or algorithm is used to achieve safety, none can be implemented without a stable control system. Hence, one of the main parameters remains the quality and reliability of the robot’s control architecture through handling a huge amount of data without system failure. This paper addresses the development of a stable control architecture that ensures, in later stages, that the safety algorithm is implemented correctly. The optimum control architecture to utilize and ensure the maximum benefit of electro-hydraulic actuators in humanoid robots is one of the important subjects in this field. For a stable and safe functioning of the humanoid, the development of the control architecture and the communication between the different components should adhere to some requirements such as stability, robustness, speed, and reduced complexity, ensuring the easy addition of numerous components. This paper presents the developed control architecture for an underdeveloped electro-hydraulic actuated humanoid. The proposed solution has the advantage of being a distributed, real-time, open-source, modular, and adaptable control architecture, enabling simple integration of numerous sensors and actuators to emulate human actions and safely interact with them. The contribution of this paper is an enhancement of the updated rate compared to other humanoids by 20% and by 40 % in the latency of the master. The results demonstrate the potential of using EtherCAT fieldbus and open-source software to develop a stable robot control architecture capable of integrating safety and security algorithms in later stages.

The advanced motion control system in HEPS beamline

In synchrotron radiation facilities such as the High Energy Photon Source (HEPS), numerous motorized actuators are equipped on the optics devices of HEPS beamline to manipulate the orientation of crystals and mirrors, thereby altering the position and characteristics of X-rays. The motion control system (MCS) plays an important role in the optics devices of HEPS beamlines, such as monochromator, K-B mirror and sample plants. In order to acquire the specify properties of X-ray and satisfy the complex experimental requirements, MCS must have the ability to handle the complicated control demands. Therefore, HEPS has developed a standardized motion control system for synchrotron radiation applications, which is a distributed system based on EtherCAT fieldbus. The hardware of this system consists of the control unit and driver unit, which has the flexibility to suit for different applications. The software of MCS is designed under the Experimental Physics and Industrial Control System (EPICS), which is very popular in synchrotron radiation facilities all over the world. In this paper, the performance tests of IOC software were demonstrated, and a few flyscan applications were given, which include spiral scan, raster scan and position event trigger, to demonstrate the feasibility and effectiveness of this system.

Solution for real time sensor guided programmable logic controller of galvanometer scanners

This paper introduces PLC (programmable logic controller)-based real-time motion control of 2D galvanometer scanners under consideration of different sensor information. The Fraunhofer IWS developed ESL2-100 module works as a locally separated client of a higher-level machine control to drive the scanner. The EtherCAT field bus supports extensive and constant exchange of information between the control levels. An application example, therefore, is the spatially resolved surface structuring of large areas using a continuous wave laser. In this application, the scanner must move the laser beam to predefined positions, stop there during the processing time, and jump to the next position. Frequencies up to 2 kHz are applicable depending on the scanner performance. The working area of a scanner can be extended by moving the scanner head with Cartesian machine axes. In the presented solution, the scanner control records these movements via encoder signals and captures the geometrical boundaries of the workpiece, i.e., previous operated areas, via cameras. The obtained data are included in the real-time calculation of scanner position data and laser emission signals. These measures maintain precision in positioning the patterns for surface structuring and adapt them to existing contours. The processing of the control data, the 2D-on-the-fly correction, and the correction of the target positions are done on the PLC level. Then, within one control cycle, multiple position data are sent in blocks from the PLC to the ESL2-100 module within one control cycle. At the end, the ESL2-100 module converts the field bus data into the scanner control protocol (here SL2-100 protocol). The approach described enables the deterministic calculation of the scan movement and responds dynamically to changing conditions by linking all necessary sensor information on one control platform.

Laboratory stand for multi-axis control of stepper drives via EtherCAT fieldbus

In this paper a laboratory stand is presented that was developed for a multi-axis machine stepper drive control system. Each stepper drive utilizes an EtherCAT communication module based on a development board with software developed by the authors. The modules are used to exchange process data with a higher level controller. The EtherCAT communication standard is described including it’s utilization for stepper drive control. A functional description of the developed communication module is also presented. The aim of the Laboratory stand is to conduct research of cyclic communication (1 milisecond or less) and synchronization between multiple drive slave devices and a supervisory controller. The main focus of the presented results was to determine EtherCAT communication cycle jitter on the developed modules. The main aim of the research was to verify whether the data exchange via EtherCAT bus has an impact on the synchronous operation of the multi-axis system.

Advanced Application of Centralized Control for a Scanning Mirror System Based on EtherCAT Fieldbus

Distributed control is the most popular control strategy for controlling numerous slave devices. However, the performance of slave devices is hard to improve because the control algorithm is handled by the commercial slave devices. Therefore, this paper proposes a hybrid control structure that follows the concept of centralized control strategy and handles part of the control loop on the master computer in a distributed control system through EtherCAT fieldbus. In this study, different advanced control methods such as robust control and learning control were applied to handle the position control loop of a scanning mirror system in a selective laser melting (SLM) system with stringent demand of position error around 40 µm based on EtherCAT fieldbus. By designing a proper controller, the experiment results showed that the tracking performance was significantly improved. The tracking error dropped by about 80% after the proposed hybrid control structure was applied. By applying the proposed hybrid control structure, one can improve the high-performance-requirement devices, while reducing the calculation burden of the master computer for other low-performance-requirement devices by retaining the benefit of distributed control.

Dynamic Modelling and Motion Controller Design for Industrial Palletizing Robot and Collision Detection

The 4-DOF parallelogram industrial palletizing robot is taken as the object of study. This paper designs and develops the real-time industrial controller based on the IPC and high-way EtherCAT fieldbus. What’s more, the control algorithm and structure based on the dynamic feedforward contributes to the compensation of robot dynamics in theory. Experiments on the task switching and master delay show that this control system has a good real time response quality. Based on the kinematics analysis of robot parallelogram structure, this paper builds the robot dynamic model. To increase the computing speed and ensure the real-time performance, the model has been simplied and proved to be effective by simulation contrast verification.

Design of LEAF control system

LEAF is a complicated and integrated facility, which includes several different subsystems. In order to realize the remote control of field equipment and meet the requirements of the beam commissioning, a LEAF control system has been designed. The developed control system includes the following sub-systems: timing systems, data archiving systems, personnel safety systems, and machine protection systems. The control system for LEAF is developed using the EPICS software toolset and the distributed control architecture. This is designed in a three-layer structure. At the equipment layer, the control of the low-level equipment is mainly done by various industrial controllers, including programmable logic controllers, controllers for serial devices, and motion controllers based on EtherCAT fieldbus. At the middle layer, the Ethernet switches are used to implement a Gigabit local area network. At the operation layer, high-level application software has been developed for the beam commissioning and the operation of the accelerator. The designed system can realize remote monitoring and control of field devices, provide synchronous timing and machine protection for key equipment, and automatically archive historical data for on-site running equipment. The complete system has a clear structure and stable operation and has been successfully applied to beam commissioning and operation of the LEAF facility.

A Sea Wave Surge Base Alignment Test Device Based on the EtherCAT Fieldbus

A sea wave surge base alignment test device consisting of a linear motion guide rail, a stewart platform, a rotating mechanism, a cantilever beam and an electronic control system based on an EtherCAT fieldbus is designed. The linear motion guide and the stewart platform provide the seven movement dimensions for the whole device. the rotating mechanism, the cantilever beam and the linear motion guide widen the movement dimension and amplitude of the device.the EherCAT fieldbus effectively satisfies the real-time, synchronization and accuracy of the whole device. the whole system effectively satisfies the requirements of multi-degree, large amplitude, low frequency, large acceleration combined superimposed rocking motion and simulation motion in the sea wave surge simulation motion.

Design and Control of an Assistive Device for the Study of the Post-stroke Sit-To-Stand Movement

Every year more than 5 million people worldwide become hemiplegic as a direct consequence of stroke. This neurological deficiency, often leads to a partial or a total loss of standing up abilities and /or ambulation skills. In order to propose new supporting solutions lying between the wheelchair and the walker, this paper presents a technological strategy for designing an assistive device for a biomechanical study of the Sit-To-Stand movement (STS). The control algorithms are implemented in TwinCAT runtime environment. The communication between the component and the control computer is ensured via the EtherCAT fieldbus. The aim of this architecture lies in the fact that it allows a quick development of a research prototype with the same safety issues found on an industrial machine. An experimental test of the STS strategy is presented and discussed in order to evaluate the strategy.

An ARM-based Multi-channel CNC Solution for Multi-tasking Turning and Milling Machines

ARM-based CNC systems are used as a low-cost solution for controlling 2-3 axis machines. The increase of computing power of ARM processors facilitated their application to controlling multi-tasking and multi-axis machines with several independent control channels. The paper presents the results of the exploratory investigation of the transition from the PC-based to the ARM-based CNC solution. The cross-platform architecture of CNC systems, the porting of CNC kernel software to the single-board computers Raspberry Pi 2 with the Linux operating system and the control of servo drives and PLC I/O over EtherCAT fieldbus with cycle time of 2ms are investigated as well.The dual-channel configuration of ARM-based CNC designed to control the multi-tasking turning and milling machine with inclined layout is presented. The paper illustrates the kinematic scheme and the network architecture of NAKLON 535 machining center for ARM-based CNC solution.

Design of the Three-Dimension Motion Platform Control System Based on EtherCAT

This design contains the EtherCAT fieldbus system and the PLCopen technology. The control system can not only achieve the motion target but also simulate the Computer Numerial System effectively. Hardware is constituted by embedded IPC, SanyoDenki servo drive and motor system, EtherCAT communication module and I/O module. The PLC program run under the Windows XP system, which install Codesys RTE, so that the whole control system improve the real-time character. Paper focuses on the structure of the control system and the design of the PLC program. The experiments and program results have proved that the control system working well，reaching the pre-set target．

The Application of EtherCAT Fieldbus in Pure-Software Open CNC System

EtherCAT fieldbus is widely used in the NC field for its superior performance. Based on ADX CNC, a pure-software open CNC system designed by Amoy Dynamics (Xiamen) CO., LTD，this paper comprehensively compares VersioBus with EtherCAT which are two communication platforms supported by ADX CNC and explicitly introduces the application of EtherCAT fieldbus in pure-software open CNC system with a real example. The application results show that the system is stable, fast response and high precision.

Porting of EtherCAT Soft Master and Developing of a New Type of Open Motion Controller

It is an expectation of most of the numerical control products manufacturer that have a powerful controller with whole won intellectual property and without restriction from other companies. The paper introduces a new type of motion controller that based on ARM and EtherCAT field bus. It concludes the analysis and porting method of the EtherCAT soft master source code, and how to modify the driver of dm9000 to make EtherCAT master works correctly. It also gives an example to confirm the reliability of the controller. Since ARM has an open architecture, EtherCAT soft master does not depend on any special hardware card, and Linux OS is an open source system, this controller has open and flexible characteristic both on hardware and software.