Soft pneumatic actuators offer great advantages compared to rigid ones, particularly due to their compliant nature, which allows them to adapt to uncertainties in the environment. As such, they ...enable human-safe interactions and are often applied to various applications, such as for example, soft grippers or wearable devices for human motion assistance. The presented research describes the process of design, development and finally control of two cost-effective bellow pneumatic actuators. The properties of the developed devices are experimentally assessed by performing three different types of experiments. In a first instance, the testing of blocking force was performed, followed by experimental assessment of velocity-displacement characteristics, and finally, the dynamical properties for sinusoidally forced motion were examined. It was shown that the actuator can provide over 100 N force and assure a contraction ratio over 40% of its full length, with maximum velocity exceeding 60 mm/s. Experimental responses to a sinusoidally forced motion allowed establishing that no significant change due to the fatigue, creep and relaxation occur in material properties. Finally, the positioning performances of both developed devices were assessed by employing PID and LQR controllers which allowed their precise position control with fast responses and steady-state errors within the 0.2 mm margin. The performed research gives some insights into the future development of the pneumatically driven mechatronics systems used for position control.
Today, we are witnessing an increasing trend in the number of soft pneumatic actuator solutions in industrial environments, especially due to their human-safe interaction capabilities. An interesting ...solution in this frame is a vacuum pneumatic muscle actuator (PMA) with a bellow structure, which is characterized by a high contraction ratio and the ability to generate high forces considering its relatively small dimensions. Moreover, such a solution is generally very cost-effective since can be developed by using easily accessible, off-the-shelf components combined with additive manufacturing procedures. The presented research analyzes the precision positioning performances of a newly developed cost-effective bellow PMA in a closed-loop setting, by utilizing a Proportional-Integral-Derivative (PID) controller and a Linear Quadratic Regulator (LQR). In a first instance, the system identification was performed and a numerical model of the PMA was developed. It was experimentally shown that the actuator is characterized by nonlinear dynamical behavior. Based on the numerical model, a PID controller was developed as a benchmark. In the next phase, an LQR that involves a nonlinear pregain term was built. The point-to-point positioning experimental results showed that both controllers allow fast responses without overshoot within the whole working range. On the other hand, it was discovered that the LQR with the corresponding nonlinear pregain term allows an error of a few tens of micrometers to be achieved across the entire working range of the muscle. Additionally, two different experimental pneumatic solutions for indirect and direct vacuum control were analyzed with the aim of investigating the PMA response time and comparing their energy consumption. This research contributes to the future development of the pneumatically driven mechatronics systems used for precise position control.
GEROLER hydraulic motors are known for their good value for money and their balance between simplicity, robustness, compactness, versatility and noise. Compared to axial hydraulic motors, GEROLER ...motors still represent a research area with the possibility of a significant contribution in terms of nonlinear dynamic behavior analysis. The aim of this research was experimental analysis of GEROLER motor dynamics at uneven load torque. Based on the obtained laboratory measurements, a black-box model for predicting the operating parameters using the artificial neural networks was developed. Two different neural network architectures were used: the simpler static multilayer feed-forward network and the more complex dynamic NARX neural network. From the obtained results, it appears that the multilayer feed-forward neural network provides acceptable results, while the dynamic NARX neural network provides more favorable results due to its flexibility in dealing with nonlinear dynamic systems. The research conducted represents a new approach for modeling and predictive analysis of the GEROLER engine.
In this paper an analysis of the hydraulic hybrid system with parallel architecture is carried out. Based on the different delivery van driving regimes a calculation of the van hydraulic hybrid ...system is conducted and standard hydraulic components are chosen. After that a numerical model of the parallel hydraulic hybrid system is developed using the Matlab/Simulink software. Using a developed numerical model, simulations for breaking and starting modes of the vehicle are performed. Simulation results have proven the real behaviour of the developed numerical model.
River courses play a vital role in preserving unpolluted ecosystems. On the other hand, networks of sensor nodes can be used to measure characteristic parameters in the environment such as ...temperature, pressure, humidity or the concentration of pollutants. In the framework of the EU FP7 project “GOLDFISH”, technical competences of a consortium of 11 institutions are hence employed in designing, manufacturing, validating and operating wireless sensors nodes for tracking pollution in remote rivers. The sensor network is composed of sensor clusters located underwater and gateways on the riverbank with long-distance communication links to the central management and monitoring station. Each sensor node is composed of active electronic devices that have to be constantly powered. Batteries can generally be used for this purpose, but problems may occur when they are to be recharged or replaced, especially in the case of large networks placed in scarcely accessible locations. State-of-the-art energy harvesting technologies can hence constitute a viable powering solution. The possibility to use different small-scale river flow energy harvesting principles is thoroughly studied in this work by the University of Rijeka GOLDFISH team: a miniaturized hydro-generator, a ‘piezoelectric eel’ and a hybrid solution of a rotating shaft plucking a piezoelectric beam. The first two concepts are validated experimentally in a flow channel and in real river conditions. The miniaturized hydro-generator with suitable power management electronics is finally embedded into the wireless sensor node deployed into the river, allowing the GSM transmission of collected data to be successfully performed.
In this work the gear tooth root stress was calculated by means of numerical method 2D FEM (two-dimensional Finite Element Method) and according to two analytical methods, that included the stress ...calculation method B of standard ISO 6336-3 and its modified form - method MAX. In order to evaluate the rim thickness factor introduced by the method B of standard ISO that takes into account the influence of rim thickness on nominal tooth root stress, the stress at a spur tooth root of cylindrical external gearing was determined going from solid towards thin rimmed gear, and considering the gear with various number of teeth.
Stroboscopes are devices for observation of cyclically moving high-speed objects by creating an optical illusion of stopped or slowed motion. The stroboscopic effect relies on the persistence of ...vision in the human eye to achieve the desired effect. In addition to the observation of fast moving objects, stroboscopes can be used in a variety of applications ranging from machinery inspection to turntable pitch control.
This paper compares the volume and mass of two-stage coaxial reduction gears with single-stage and two-stage planetary reduction gears. Single-stage planetary reduction gears have been studied in ...cases with the planet carrier locked and the ring gear locked. As to two-stage planetary reduction gears, only two-stage planetary reduction gears with the ring gear locked have been studied. The purpose of the comparison is to determine at which transmission ratios planetary reduction gears have lower volume and mass than two-stage coaxial reduction gears.
The paper presents basic ways for the development of product feature model. The investigation and improvement of feature modelling, as product modelling that enables geometrical and functional ...information to be stored in a single model, has not been accomplished completely. Along with survey of major shortcomings that accompany current feature modelling systems, consisting of maintenance of feature semantics, the existence of only one product feature model, the limited facilities of collaborative modelling, and the limited shape domain the investigations aimed at solving these shortcomings are also presented.
In this paper an analysis of the hydraulic hybrid system with parallel architecture is carried out. Based on the different delivery van driving regimes a calculation of the van hydraulic hybrid ...system is conducted and standard hydraulic components are chosen. After that a numerical model of the parallel hydraulic hybrid system is developed using the Matlab/Simulink software. Using a developed numerical model, simulations for breaking and starting modes of the vehicle are performed. Simulation results have proven the real behaviour of the developed numerical model.
