Development of a High-Power Capacity Open Source Electrical Stimulation System to Enhance Research into FES-Assisted Devices: Validation of FES Cycling

Since the first Cybathlon 2016, when twelve teams competed in the FES bike race, we have witnessed a global effort towards the development of stimulation and control strategies to improve FES-assisted devices, particularly for cycling, as a means to practice a recreational physical activity. As a result, a set of technical notes and research paved the way for many other studies and the potential behind FES-assisted cycling has been consolidated. However, engineering research needs instrumented devices to support novel developments and enable precise assessment. Therefore, some researchers struggle to develop their own FES-assisted devices or find it challenging to implement their instrumentation using commercial devices, which often limits the implementation of advanced control strategies and the possibility to connect different types of sensor. In this regard, we hypothesize that it would be advantageous for some researchers in our community to enjoy access to an entire open-source FES platform that allows different control strategies to be implemented, offers greater adaptability and power capacity than commercial devices, and can be used to assist different functional activities in addition to cycling. Hence, it appears to be of interest to make our proprietary electrical stimulation system an open-source device and to prove its capabilities by addressing all the aspects necessary to implement a FES cycling system. The high-power capacity stimulation device is based on a constant current topology that allows the creation of biphasic electrical pulses with amplitude, width, and frequency up to 150 mA, 1000 µs, and 100 Hz, respectively. A mobile application (Android) was developed to set and modify the stimulation parameters of up to eight stimulation channels. A proportional-integral controller was implemented for cadence tracking with the aim to improve the overall cycling performance. A volunteer with complete paraplegia participated in the functional testing of the system. He was able to cycle indoors for 45 min, accomplish distances of more than 5 km using a passive cycling trainer, and pedal 2400 m overground in 32 min. The results evidenced the capacity of our FES cycling system to be employed as a cycling tool for individuals with spinal cord injury. The methodological strategies used to improve FES efficiency suggest the possibility of maximizing pedaling duration through more advanced control techniques.

Reinforcement Learning reveals fundamental limits on the mixing of active particles

The control of far-from-equilibrium physical systems, including active materials, requires advanced control strategies due to the non-linear dynamics and long-range interactions between particles, preventing explicit solutions to optimal control problems....

A Data-Driven Identification Procedure for HVAC Processes with Laboratory and Real-World Validation

Linear system identification is a well-known methodology for building mathematical models of dynamic systems from observed input–output data. It also represents an essential tool for model-based control design, adaptive control and other advanced control techniques. Use of linear identification is, however, often limited to academic environment and to research facilities equipped with scientific computing platforms and highly qualified staff. Common industrial or building control system technology rarely uses these advanced design techniques. The main obstacle is typically lack of experience with their practical implementation. In this article, a procedure is proposed, implemented, and tested, that brings the benefits of linear identification into broader control system practice. The open-source DCU control system platform with its advanced control framework is used for implementation of the proposed linear identification procedure. The procedure is experimentally tested in the laboratory setting using a unique model of HVAC system as well as in real-world environment in an experimental two storey family house. Testing this novel feature of the control system has proved satisfactory results, while some of them are presented in graphical and numerical form.

Safety Control Architecture for Ventricular Assist Devices

In patients with severe heart disease, the implantation of a ventricular assist device (VAD) may be necessary, especially in patients with an indication for heart transplantation. For this, the Institute Dante Pazzanese of Cardiology (IDPC) has developed an implantable centrifugal blood pump that will be able to help a diseased human heart to maintain physiological blood flow and pressure. This device will be used as a totally or partially implantable VAD. Therefore, performance assurance and correct specification of the VAD are important factors in achieving a safe interaction between the device and the patient’s behavior or condition. Even with reliable devices, some failures may occur if the pumping control does not keep up with changes in the patient’s behavior or condition. If the VAD control system has no fault tolerance and no system dynamic adaptation that occurs according to changes in the patient’s cardiovascular system, a number of limitations can be observed in the results and effectiveness of these devices, especially in patients with acute comorbidities. This work proposes the application of a mechatronic approach to this class of devices based on advanced control, instrumentation, and automation techniques to define a method to develop a hierarchical supervisory control system capable of dynamically, automatically, and safely VAD control. For this methodology, concepts based on Bayesian networks (BN) were used to diagnose the patient’s cardiovascular system conditions, Petri nets (PN) to generate the VAD control algorithm, and safety instrumented systems to ensure the safety of the VAD system.

Implementation of PI and MPC-Based Speed Controllers for a Drive with Elastic Coupling on a PLC Controller

This paper presents some of the issues related to the implementation of advanced control structures (PI controller with additional feedback, Model Predictive Controller) for drives with elastic coupling on a programmable logic controller (PLC). The predominant solutions to electric drive control include the use of rapid prototyping cards, signal processors or programmable matrices. Originally, PLC controllers were used to automate sequential processes, but for several years now, a trend related to their implementation for advanced control objects can be observed. This is mainly due to their compact design, immunity to disturbances and standard programming languages. The following chapters of the paper present the mathematical model of the drive and describe the implementation of the proposed control structures. A PI controller with additional feedback loops and a predictive controller are taken into consideration. Their impact on the CPU load was analysed, and the work was summarised by a comprehensive experimental study. The presented results confirm that it is possible to implement advanced control structures on a PLC controller for drives with elastic coupling while maintaining a sufficiently low load on its CPU.

Four Channel 6.5 kV, 65 A, 100 ns-100 µs Generator with Advanced Control of Pulse and Burst Protocols for Biomedical and Biotechnological Applications

Pulsed electric fields in the sub-microsecond range are being increasingly used in biomedical and biotechnology applications, where the demand for high-voltage and high-frequency pulse generators with enhanced performance and pulse flexibility is pushing the limits of pulse power solid state technology. In the scope of this article, a new pulsed generator, which includes four independent MOSFET based Marx modulators, operating individually or combined, controlled from a computer user interface, is described. The generator is capable of applying different pulse shapes, from unipolar to bipolar pulses into biological loads, in symmetric and asymmetric modes, with voltages up to 6.5 kV and currents up to 65 A, in pulse widths from 100 ns to 100 µs, including short-circuit protection, current and voltage monitoring. This new scientific tool can open new research possibility due to the flexibility it provides in pulse generation, particularly in adjusting pulse width, polarity, and amplitude from pulse-to-pulse. It also permits operating in burst mode up to 5 MHz in four independent channels, for example in the application of synchronized asymmetric bipolar pulses, which is shown together with other characteristics of the generator.

MEANS, STANDS AND MACHINES FOR TESTING GEAR WHEELS AND GEAR TRAINS OF HELICOPTER REDUCTION TRAINS

The production and repair of such high-tech and important products as helicopters‟ reduction trains is impossible without comprehensive testing of these products, starting with the manufacture of their individual parts and assemblies and ending with the delivery of reduction trains to the customer. Various means for testing of gear wheels‟ rims and gear trains of helicopter‟s reduction trains, which have found application in testing equipment, are presented. Devices, testers, stands and machines for various tests are considered in order to control the characteristics of gear trains of aviation reduction trains after certain periods of their operation and repair, aimed at achieving better performance during further operation. The considered traditional metrological means of control of gear rims, gear measuring machines and complexes, some stands and machines for testing of reduction trains, pulse controllers and roll machines give an idea of various methods and means of control of gear wheels and gear trains of helicopters‟ reduction trains. The main method of experimental research of gear trains of reducers is stand tests both on movable gear wheels and on roll machines. Until recently, the most common method for monitoring and diagnosing gear trains has been vibrography, however, existing techniques do not give an accurate picture of the train condition, especially the contact surface of the teeth. During the operation of the gear train as a part of the helicopter‟s reduction train, signals from other sources (rotors, blades, shafts, bearings) are superimposed on the vibration signal generated by the gear train which significantly complicates the extraction and processing of the desired vibration signal. One of the most effective methods for monitoring and diagnosing the technical condition of kinematic chains of different complexity, which includes gear trains of helicopters„ reducers is kinematometry. The disadvantage of traditional kinematometry is the need to use high-precision sensors for the frequency and phase of the rotor rotation. Control of vibration from the early 1990s to the present time is the most advanced control, the means and methods of which are well developed in the aviation industry.