Design, analysis, and validation of an orderly recruitment valve for bio-inspired fluidic artificial muscles

Biological musculature employs variable recruitment of muscle fibers from smaller to larger units as the load increases. This orderly recruitment strategy has certain physiological advantages like minimizing fatigue and providing finer motor control. Recently fluidic artificial muscles (FAM) are gaining popularity as actuators due to their increased efficiency by employing these bio-inspired recruitment strategies such as active variable recruitment (AVR). AVR systems use a multi-valve system (MVS) configuration to selectively recruit individual FAMs depending on the load. However, when using an MVS configuration, an increase in the number of motor units in a bundle corresponds to an increase in the number of valves in the system. This introduces greater complexity and weight. The objective of this paper is to propose, analyze, and demonstrate an orderly recruitment valve (ORV) concept that enables orderly recruitment of multiple FAMs in the system using a single valve. A mathematical model of an ORV-controlled FAM bundle is presented and validated by experiments performed on an ORV prototype. The modeling is extended to explore a case study of a 1-DOF robot arm system consisting of an electrohydraulic pressurization system, ORV, and a FAM-actuated rotating arm plant and its dynamics are simulated to further demonstrate the capabilities of an ORV-controlled closed-loop system. An orderly recruitment strategy was implemented through a model-based feed forward controller. To benchmark the performance of the ORV, a conventional MVS with equivalent dynamics and controller was also implemented. Trajectory tracking simulations on both the systems revealed lower tracking error for the ORV controlled system compared to the MVS controlled system due to the unique cross-flow effects present in the ORV. However, the MVS, due to its independent and multiple valve setup, proved to be more adaptable for performance. For example, modifications to the recruitment thresholds of the MVS demonstrated improvement in tracking error, albeit with a sacrifice in efficiency. In the ORV tracking performance remained insensitive to any variation in recruitment threshold. The results show that compared to the MVS, the ORV offers a simpler and more compact valving architecture at the expense of moderate losses in control flexibility and performance.

APPLICATION OF LEARNING FEED-FORWARD CONTROLLER BASED ON MODEL REFERENCE ADAPTIVE SYSTEM FOR MISSILE STABILIZATION

The article presents the results of research, analysis and how to build learning feed-forward controller based on model reference adaptive system in the remote control loop for missile stabilization. The controller structure is simple, adaptive control law applying Lyapunov stability theory fast convergence and sustainable. The simulation results have shown the advantages of using algorithm, the missile is always stable when there is a parameter change due to the effects of flight conditions.

Design of Energy Saving Controllers for Central Cooling Water Systems

Since fuel prices account for approximately 40% of a ship’s operating costs, shipping companies worldwide have made significant efforts to save energy on board such as introducing new technologies or machine operation methods. Many ship operators have adopted an advanced control system using a variable-speed pump and/or an optimizing control system of a three-way valve on the outlet side of the central cooling system. It is often considered that the best way to control a central cooling system is to integrate the two control systems. However, when applied in practice, there is a frequent uncontrollable phenomenon in which the three-way valve is opened to its minimum and the variable-speed seawater pump is operated at its maximum, resulting in a large amount of energy consumption. Therefore, in this study, the speed of the variable-speed seawater pump is set to the minimum, and the feed-forward controller is adopted for the three-way valve control system. The input variable of the feed-forward controller is the Main Engine load, and it is designed to directly control the bypass openness with the three-way valve controller. Using this design, it was demonstrated that the variable-speed seawater pump was operated at a minimum and energy was saved.

A Fas/FasL mediated Feed-forward Controller of T-cell Differentiation Reconciles MIS-C and Discrepant Youth and Adult Covid-19 Severity

Fas expression is quickly upregulated on CD8+ T cells following stimulation, while FasL expression is limited to Tcm and later. A phenomenon of T cell differentiation via paracrine Fas signal has been previously described. Here, we describe such differentiation in a pool fits the Feed-forward model which can correct for disturbances in the system, as seen during in vitro T cell stimulation. This feed-forward controller exerts control via Fas/ FasL expression, and the effect is uncoupled with use of lz-FasL. Interestingly, the feed-forward model provides us with evolutionary insight as to why Fas stimulation becomes apoptotic at terminal differentiation, in order to exhibit a perfect and extinguished control and response.

Application of Simulink software in vessel design

The article considers different types of controllers and regulators used in industry, laboratories and for daily tasks. In practice, the most commonly used controllers are discrete state controllers, PID controllers, fuzzy and neural controllers. The last two use more sophisticated concepts, such as artificial intelligence. Controllers can be divided into feed-forward and feedback controllers. The feed-forward controller works by giving a result based on waiting for the next step, while the feedback controller works to give an observable result that changes the processing value of the later step. PID controllers are very popular in the design of a ship's main power plant. There is considered a schematic diagram of the PID controller. The description of the ship model in the Simulink environment is presented, the specified model of the diesel engine, the mechanical regulator, areas of restrictions of the engine are illustrated. The model of the turbocharger is analyzed in detail. It consists of a turbine resting on the exhaust gases coming out of the cylinders, due to which the compressor starts and compresses the air at the inlet to the cylinders. There is given the equation formed by the ratio of integral to time. In accordance with the original model of the diesel engine Diesel Engine Module, the nominal efficiency is defined. A model of shaft dynamics based on Newton's second law for rotation is considered. The actual Simulink model is illustrated, which introduces transmission losses and saturation associated with the load capacity of the engine. The model uses three designs of propellers. The characteristics of the propellers on the container ship MSC Caitlin, the tanker “Ivan Poddubny” and the ferry “Olympiad” are given. The general model of the propeller is made and resistance of calm water is simulated. The additional model of wave resistance is presented.

Design of the state feedback-based feed-forward controller asymptotically stabilizing the double-pendulum-type overhead cranes with time-varying hoisting rope length

In this paper we focus our attention on the design of the feedback-based feed-forward controller asymptotically stabilizing the double-pendulum-type (D-P-T) crane system with the time-varying rope length in the desired end position of payload (the origin of the coordinate system). In principle, two cases are considered, in the first case, the sway angle of payload is uncontrolled and second case, when the sway angle of payload is controlled by an external force. Precise mathematical modeling in the framework of Lagrange formalism without the traditional neglect of the important structural parameters of the D-P-T crane system and numerical simulation in the Matlab environment indicate the substantial reduction of the transportation time to the desired end position.

Modeling, Simulation, and Vision-/MPC-Based Control of a PowerCube Serial Robot

A model predictive control (MPC) scheme for a Schunk PowerCube robot is derived in a structured step-by-step procedure. Neweul-M2 provides the necessary nonlinear model in symbolical and numerical form. To handle the heavy online computational burden concerning the derived nonlinear model, a linear time-varying MPC scheme is developed based on linearizing the nonlinear system concerning the desired trajectory and the a priori known corresponding feed-forward controller. Camera-based systems allow sensing of the robot on the one hand and monitoring the environments on the other hand. Therefore, a vision-based MPC is realized to show the effects of vision-based control feedback on control performance. A semi-automatic trajectory planning is used to perform two meaningful experimental studies in which the advantages and restrictions of the proposed (vision-based) linear time-varying MPC scheme are pointed out. Everything is implemented on a slim, low-cost control system with a standard laptop PC.