Multirate Sampling Technique Research Articles

Input Observer-Based Individual Cylinder Air-Fuel Ratio Control: Modelling, Design and Validation

A general approach is proposed to address the cylinder-to-cylinder air-fuel ratio (AFR) balancing control problem using a single universal exhaust gas oxygen (UEGO) sensor. Using the multirate sampling technique, a control-oriented engine model, well combining the fuel delivery dynamics and exhaust gas dynamics, is established. Gas mixing phenomena is characterized by a gas mixing matrix, which is valid both for equal-length and unequal-length exhaust runners. Based on the developed model, the observability of the individual cylinder AFR estimation problem is analyzed using the input observability concept. An input observer using the one-step forward feedback is proposed to design the estimator. Using the estimated AFR, a decoupled PI compensator is designed for each cylinder to compensate the cylinder-by-cylinder variations. Finally, the proposed approach is verified by simulation and experimental results.

Variable slope pulse pump controller for stepping position servo control system using frequency-locked technique

A stepping position servomotor system based on frequency-locked technique is proposed for high-performance incremental position control. A novel microcomputer-based variable slope pulse pump controller (VSPPC) using multi-rate sampling technique is exploited. The proposed VSPPC can adaptively generate motor motion profile, and it can replace the traditional PID controller for applications in stepping motor position control. System models are constructed for stability study and computer simulation. A prototype is designed and implemented to verify the theoretical studies and examine the performance of the proposed system. Position and speed responses of a realized system for 0-50 cm movement with 10 mm resolution is investigated. With the variable slope technique employed in VSPPC, the acquisition time for long-distance movement is reduced significantly and is close to that of short-range movement. In particular, the position acquisition time has improved about 67-79% compared to the conventional position control system.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

Model-Following Digital Servo Using Multirate Sampling for an Optical Disk Drive

In order to achieve faster seeks, a simple feedback method using classical control needs higher servo bandwidth to reduce the steady state tracking error and to maintain the stability of the objective lens positioning system. In a multi-input multi-output model-following servo controller, however, the tracking error and the instability of the objective lens positioning does not increase even when the faster seek is performed with the same actuators. Both simulation and experimental results show that the disturbances and the model mismatching are well reduced by the four feedback loops in the servo bandwidth. Although such multiple feedback loops makes the controller more complicated, a multi-rate sampling technique helps to decrease the load of the digital-signal-processing task without sacrificing the performance.

An optimized multirate sampling technique for the dynamic variation of vocal tract length in the Kelly-Lochbaum speech synthesis model

How vocal tract length variation may be incorporated in the Kelly-Lochbaum (1962) speech synthesis model through a dynamic variation of the system sampling rate is described. It has been determined that an eight-point four-term Blackman-Harris (1978) window is optimum for designing the FIR interpolation filter for converting from a varying to a fixed sample rate. >

Novel multirate sampling technique for ultrasound electronic sector scanning

We describe a new method of electronic sector scanning by a multirate sampling technique, which is capable of achieving steering and dynamic focusing simultaneously. The technique is based on separate processing of steering and focusing delays, and utilising their symmetry and linearity to implement the multirate sampling clock generator (SCG) independent of the number of scan angles.

Multirate sampling technique in digital control systems simulation

Digital regulators for continuous plants are designed today by means of conventional z-transfer function methods. With these z-transfer functions the value of the system output y(t) can be learned only at instants spaced T seconds apart, where T is the sampling period. A technique is proposed where the value of y(t) can be learned at instants spaced T/n seconds apart, where n is any integer. This technique is based on multirate sampling. First a method to calculate the output multirate sampled sequence is described. Then an efficient algorithm to calculate the multirate sampling discrete transfer function from the normal discrete transfer function is proposed.