Maximum Time Error Research Articles

Multi-body dynamics modeling and energy consumption optimization of electromagnetic mechanical fully variable valve system

Electromagnetic Mechanical Variable Valve Actuation (EMVVA) technology has the capability to improve engine performance and decrease pollutant emissions. A new type of EMVVA composed of electromagnetic driver and mechanical transmission is proposed to realize the flexible adjustment of valve parameters whether the valve is open or closed process. The geometric mathematical model of the mechanical transmission is developed based on the motion laws of the valve and the geometrical construction of the mechanical transmission, and the conjugate cam curve is solved. A multi-body dynamic model is constructed to calculate the driving torque and energy consumption needed by the mechanical transmission based on the mass, rotational inertia, centroid position of the parts, combining the normal contact force model and the friction model of the clearance contact pair at the same time. Based on the geometric model and multi-body dynamics model, the test platform is established. The test results demonstrated that within the specified valve lift, EMVVA system could accomplish variable valve lift, variable valve timing, and variable valve duration at maximum lift. The maximum timing error does not exceed 1° crank angle, and the maximum valve lift error does not exceed 0.25 mm at 11 mm valve lift. In addition, the error of driving torque between the multi-body dynamics model and the test is less than 0.3 [Formula: see text].Low energy optimization of mechanical transmission was completed using the NSGA-II method and multi-body model. According to the results of the optimization, energy consumption was reduced by 14%, and the peak driving torque was decreased by 54.3%.

Path Perception Synchronization Trigger Method for Dual Mode Multiplexing Mechanical Vibration Wireless Sensor Networks

Synchronization triggers for mechanical-vibration wireless sensor networks play an important role in data acquisition and the analysis of multiple nodes. At present, most nodes are designed using a single protocol, which makes it difficult to achieve a balance between network establishment and synchronization. Meanwhile, such synchronization trigger methods rely on a clock, beacon, or communication between nodes. A method based on a clock and beacon requires frequent timestamps, which reduces the synchronization trigger accuracy and increases the power consumption. The communication between nodes requires these nodes to be at a close distance; otherwise, the node cannot receive synchronization information. Aiming at the above problems, a path perception synchronization trigger method based on dual-mode multiplexing and cluster networks is proposed. First, the node is designed using dual mode multiplexing. Second, an adjoint networking method is proposed to construct the cluster network topology. Next, a path perception time measurement method based on the terminal device and terminal assistant measurement without clock synchronization, beacon synchronization, and communication between nodes is discussed. Finally, a maximum time deviation compensation and time block synchronization trigger measurement method are proposed to solve the problems of a time delay compensation and system instruction interruption. The experimental results show that the maximum time error of the path perception synchronization trigger is between 50 and 60 ls, and the minimum time error is between 10 and 16 ls, which significantly improves the synchronization triggering accuracy under conditions that do not rely on clock synchronization, beacon synchronization, or communicating between nodes.

A Time-Robust Digital Self-Interference Cancellation in Full-Duplex Radios: Receiver Design and Performance Analysis

In full-duplex radios, precise time synchronization between the received and reconstructed self-interference (SI) is the basis of the effective SI cancellation (SIC). However, due to the impacts of the hardware imperfections and the propagation environment, perfect time synchronization is impossible. More seriously, the time-varying SI propagation channel aggravates the difficulty of time synchronization. To overcome the above problems, a time-robust digital SIC (TR-DSIC) is proposed in this article, as a novel scheme to address the time synchronization error (timing error). Firstly, by comprehensively considering nonlinear distortion and multipath propagation with different time delays and time-varying gains, a revised general memory polynomial (RGMP) model of the received SI is presented. Then, based on the RGMP model of the received SI, the TR-DSIC is proposed to cancel the SI in the digital domain, which is robust to arbitrary timing error and no need additional processing for it. Finally, the performance of the proposed TR-DSIC is analyzed under imperfect estimations of the polynomial coefficients. The analytical expression of the variance of the estimation error is presented here, and the closed-form expression of the residual SI power introduced by imperfect estimations of the polynomial coefficients is derived. Simulation results reveal that the TR-DSIC is capable of eliminating the influence of arbitrary timing error. Specially, when the maximum timing error is $0.5T_{s}$ for the SI multipath channel, the TR-DSIC outperforms the traditional DSIC without considering the timing error between the reconstructed and received SI by 5.2 dB.

High Precision Timing of the Copying Control System Based on Windows 2000

A design proposal for developing a high-precision timer of the real-time digital copying control system is put forward by analyzing the real-time characteristics of Windows 2000 operating system. Proposals of using information systems timer—WM_TIMER, multimedia timer, VxD and hardware to achieve high-precision timing in Windows operating system are analyzed and compared. Based on computer high-frequency timer and multi-thread technology, timing function provided by Microsoft Visual C++ is used to achieve a high-precision software timer of the system. Finally, the researched timing method is tested in Advantech IPC-610 host with Intel Pentium 4 processor, and the maximum timing error is less than 5μs which meets the system timing requirements.

A 252-Channel Recorder and Analyzer for Large Acoustic Array Studies

A multichannel recording and analysis system is now in use for beamforming, signal processing, and noise-field studies on large acoustic arrays. Each of the 252 data channels records and reproduces signals from dc to 20 kHz with a reproduced-signal to system-noise level difference of more than 40 dB and a maximum timing error between channels of less than 3 μsec. Timing signals giving 1-μsec time resolution and digital signals with housekeeping and manually set information are also recorded. A real-time playback system reproduces the original time and voltage relationships for all 252 channels simultaneously. A second playback system processes 40 channels at a time through a 40-channel A-to-D converter and a 40-channel 1024-point FFT processor. This system produces digital tapes containing the signal samples the auto-spectral-density data and the cross-spectral data for the 40 input channels. The data on these tapes is either plotted, further processed by a computer, or combined with other output tapes to produce the cross spectra between any pairs of the 252 input channels. Examples of current rises of this system are given.