Microfluidic Cell Transport with Piezoelectric Micro Diaphragm Pumps

The automated transport of cells can enable far-reaching cell culture research. However, to date, such automated transport has been achieved with large pump systems that often come with long fluidic connections and a large power consumption. Improvement is possible with space- and energy-efficient piezoelectric micro diaphragm pumps, though a precondition for a successful use is to enable transport with little to no mechanical stress on the cell suspension. This study evaluates the impact of the microfluidic transport of cells with the piezoelectric micro diaphragm pump developed by our group. It includes the investigation of different actuation signals. Therewith, we aim to achieve optimal fluidic performance while maximizing the cell viability. The investigation of fluidic properties proves a similar performance with a hybrid actuation signal that is a rectangular waveform with sinusoidal flanks, compared to the fluidically optimal rectangular actuation. The comparison of the cell transport with three actuation signals, sinusoidal, rectangular, and hybrid actuation shows that the hybrid actuation causes less damage than the rectangular actuation. With a 5% reduction of the cell viability it causes similar strain to the transport with sinusoidal actuation. Piezoelectric micro diaphragm pumps with the fluidically efficient hybrid signal actuation are therefore an interesting option for integrable microfluidic workflows.

Experimental Study on Anti-Icing Performance of NS-DBD Plasma Actuator

An experimental study was conducted to evaluate the anti-icing performance of NS-DBD plasma actuator under the conditions of airflow speed U = 65 m/s, ambient temperature T = −10 °C, liquid water content LWC = 0.5 g/m3, mean-volume diameter MVD = 25 μm, mainly to clarify the effect of pulse frequency and voltage amplitude of actuation on anti-icing performance. A NACA0012 airfoil model with a chord length of c = 280 mm was used in the tests. The NS-DBD plasma actuator was mounted at the front part of the airfoil. A FLIR infrared (IR) imager and CCD camera were used to record the anti-icing process of the NS-DBD plasma actuator. Two typical discharge conditions were selected for the anti-icing experiments. The first was HV-LF discharge, corresponding to discharge under higher voltage amplitude with lower pulse frequency; the second was LV-HF discharge, corresponding to discharge under lower voltage amplitude with higher pulse frequency. Results reveal that NS-DBD is a very promising method for anti-icing. With the same power consumption, the LV-HF discharge shows a better anti-icing performance compared to HV-LF discharge under the same icing conditions. In view of pulse duration and duty circle, combined with heat dissipation, it is suggested that there is a threshold frequency, corresponding to the voltage amplitude of electric actuation signal and the incoming flow condition, to achieve effective anti-icing performance.

Hierarchical fuzzy-tuned multiobjective optimization control for gantry cranes

This work presents a hierarchical fuzzy-tuned multiobjective optimization control scheme for the horizontal moving process of gantry cranes. Initially, a multiobjective optimization controller is developed based on gantry crane dynamics, which transforms the control issue of gantry crane into a state-tracking optimization problem and accomplishes simultaneous optimization of multiple performance indexes through the weighting matrix configuration. To cope with the multiobjective optimization controller, an actuation signal modulator is designed using a linear interpolation algorithm, which transforms the step signal of terminal position into an asymptotic signal to improve the transient system performance. Furthermore, a PD-type fuzzy logic regulator is developed as the superior of multiobjective optimization controller to adaptively guide the control procedure by tuning and configuring the weighting matrix. Above three components (multiobjective optimization controller, actuation signal modulator, fuzzy logic regulator) compose the complete hierarchical control scheme. Then, stability of the proposed control scheme is testified through Lyapunov stability theorem, and performances of the control scheme are examined through a series of simulations. Finally, conclusions and assessment of the control scheme are summarized and discussed.

Optimal FIR Input Shaper Designs for Motion Control With Zero Residual Vibration

This paper considers the design of input shaping filters used in motion control of vibratory systems. The filters preshape a command or actuation signal in order to negate the effect of vibratory modes. A class of finite impulse response filter satisfying a set of orthogonality conditions that ensure zero residual vibration is introduced. Filter solutions having minimum quadratic gain, both with and without the inclusion of non-negativity (peak gain) constraints, are presented. Unlike impulse-based shapers, the filters have impulse responses with no singularities and therefore automatically remove discontinuities from an input signal. Minimum duration impulse response solutions are also presented. These contain singularities but may also have smooth components. Discrete-time designs can be obtained numerically from system modal parameters, accounting for all modes simultaneously so that convolving single-mode solutions, which leads to suboptimality of the final design, is not required. Selected designs are demonstrated experimentally on a flexible link planar manipulator.

PWM Synchronization for Intelligent Agent Scarce Resource Auction

This paper is focuses on modulating a shared resource, power demand on the electricity grid, among intelligent agents charged with modulating residential HVAC systems. We discuss the use of synchronized control actuation signals (PWM) to simplify scarce resource auctions for control of a network of intelligent home agents. By synchronizing the actuation signal with the auction times, identification and prediction becomes simpler, and modulation of the shared resource is as easy as adjusting the saturation limits of the controller. We show results through simulation.

CHAOS DOES HELP MOTION CONTROL

This work consists in the realization and control of a walking microrobot actuated by piezoelectric materials. Usually, the actuation of robot legs is controlled by square wave signals characterized by fixed amplitude and frequency. In this work the control signals are generated performing a frequency modulation driven by the chaotic evolution of Chua's circuit state variables. The smooth changes of the actuation signal frequency, performed by our chaotic system, enhance the microrobot walking capabilities especially when walking on given surfaces.

Comparative Study of Some New Hybrid Fuzzy Algorithms for Manipulator Control

The robot manipulator is a highly complex system, which is multi-input, multi-output, nonlinear, and time variant. Controlling such a system is a tedious and challenging task. In this paper, some new hybrid fuzzy control algorithms have been proposed for manipulator control. These hybrid fuzzy controllers consist of two parts: a fuzzy controller and a conventional or adaptive controller. The outputs of these controllers are superimposed to produce the final actuation signal based on current position and velocity errors. Simulation is used to test these controllers for different trajectories and for varying manipulator parameters. Various performance indices like the RMS error, steady state error, and maximum error are used for comparison. It is observed that the hybrid controllers perform better than only fuzzy or only conventional/adaptive controllers.