Oka Mahendra

A survey on robust Repetitive Control and applications

Tracking and rejecting periodic signals are common tasks in many control applications. A well-known use of Repetitive Control (RC) is to both track a periodic reference signal and reject periodic disturbance. This paper reviews various designs of RC that are classified into basic RC design and robust RC design. The recent applications of RC are also presented in this paper.

Design and implementation of data storage system using USB flash drive in a microcontroller based data logger

Although Universal Serial Bus (USB) Flash Drives are commonly used as a portable storage medium, the use of them for a remote microcontroller based data logger are still rare. This paper discusses the design and implementation of data storage system using a USB Flash Drive on a microcontroller-based data logger. An expandable data logger was made based on microcontrollers with a master-slave system. A master board handles the entire processes that are including data acquisition, storage, and communication. The data storage system board acts as a slave using ALFAT OEM board and a USB Flash Drive. Its electronic schematic is described and its algorithm is explained. Some tests carried out to prove the design and implementation works properly. The test result showed 3.6% error in 2 minutes saving interval and 2.4% error in 5 minutes saving interval.

Design of decoupled repetitive control for MIMO systems

This paper introduces the design of decoupled repetitive control (RC) for multi-inputs multi-outputs (MIMO) system. The design is started by decoupling the MIMO system into separate single-input single-output (SISO) models. Then, a set of low order and causal RC compensator is designed for each single-input single-output (SISO) model obtained from decou-pling. The compensators that ensure the RC stability condition, are obtained by solving optimization problems. Simulation results are given to demonstrate the effectiveness of the proposed design.

Method of storing time-based data using sector number references

Time-based data are recorded values which have a timestamp for each datum. Conventional database usually using time data type to store this value This paper proposes a method for storing time-based data using storage sector number as data timestamp and do not require any file system such as FAT, NTFS, EXT, etc. This paper describes the hardware and algorithms to write and read the time-based data by using sector number references. The number of sector is the differences between the time stamp data and time references. The calculation can be done with the epoch time difference calculation or year, month, and day difference. This method uses very little RAM, simpler circuit, and the code execution is faster than using a file system like FAT/Linux file system. With the proposed method, small microcontrollers that have RAM less than 2Kbytes can access (read/write) SD/MMC without any problem.

Performance of non-orthogonal BFSK with a zero crossing demodulator in AWGN channel

Although non-orthogonal Frequency Shift Keying modulation with zero crossing detection is currently used in some practical applications, no reference discusses its performance analysis in the time domain. This paper will cover it. In this paper, probability of error detection in the modulation system is derived. We performed time domain analysis by sampling the signal around ideal zero crossing and count the probability of signal may have positive or negative value. By defining zero crossing as changing in value from positive to negative and vice versa, we derived the probability of zero crossing occurs at certain sampling time. Probability of symbol error is derived from probability zero crossing at certain sampling time. This paper demonstrates that the performance of non-orthogonal FSK modulation with a zero crossing demodulator is directly related to the carrier frequency difference, signal power, and noise power. Another factor affecting the performance of the modulation system is frequency sampling of the demodulator.