OBSERVATION ALGORITHM FOR ESSENTIALLY NONLINEAR MOBILE ROBOTS

This paper is about a new approach of integration of the non-linear observer based on Luenberger, backstepping and disturbance approximation with Unscented Kalman filter for estimate of a state vector of essentially non-linear robots which have a complicated dynamics.Key words: essentially non-linear systems, robots, unscented filter, unscented smoother, observer, estimatio

SELF-TUNING LOW-NOISE AMPLIFIER

A low-noise amplifier with a phase control loop is described in this paper. In the proposed circuit, the resonant frequency is auto-tuned to the input signal frequency. In that way, high gain (20 dB), a phase shift of -180o between input and output signals, and good selective characteristics are obtained. The amplifier is robust to parameter variations, ensuring maximal amplification of the input signal regardless of its frequency as long as it is within a specified frequency range (880-950 MHz). Hence, the proposed circuit possesses self-tuning properties. The stability of the phase loop is analyzed by using Lyapunov's control theory

KALMAN FILTER AND NARX NEURAL NETWORK FOR ROBOT VISION BASED HUMAN TRACKING

Tracking human is an important and challenging problem in video-based intelligent robot systems. In this paper, a vision-based human tracking system is supposed to provide sensor input for vision-based control of a mobile robot that works in a team helping the human co-worker. A comparison between NARX neural network and Kalman filter in solving the prediction problem of human tracking in robot vision is presented. After collecting video data from a robot, simulation results obtained from the Kalman filter model are used to compare with the simulation results obtained from the NARX Neural network.Key words: robot vision, Kalman filter, neural networks, human trackin

IMPROVED PSEUDORANDOM ABSOLUTE POSITION ENCODER WITH RELIABLE CODE READING METHOD

Pseudorandom position encoders enable an absolute position measurement using one code track based on a pseudorandom binary sequence (PRBS). Both serial and parallel pseudorandom code reading methods can be applied in these encoders. A reliable solution of an absolute position encoder that uses two mutually shifted pseudorandom code tracks is presented. The proposed solution is easier for practical realization, and has better performances regarding redundancy and reliability. The practical realization of this code reading method is also shown

CONTENTION RESOLUTION MECHANISM FOR RECEIVER-DRIVEN TDMA-BASED WIRELESS SENSOR NETWORKS

TDMA-based protocols that have been proposed for wireless sensor networks (WSNs) use two opposite strategies of assigning slots to nodes. The transmitted-driven slot assignment schemes, which assign slots to nodes for message transmission, eliminate collisions of data messages, but waste energy due to message overhearing. The receiver-driven schemes, which assign slots to nodes for message reception, eliminate message overhearing, but the neighbors of slot owners have to contend for the medium. The existing proposals of the receiver-driven TDMA protocols employ CSMA-based contention resolution mechanisms, which suffer from both hidden- and exposed-terminal problem, thus limiting the applicability of the protocol to low traffic load conditions. In this paper, we propose a contention resolution mechanism, named TONE, specifically designed for receiver-driven TDMA protocols, which alleviates both the hidden- and exposed-terminal problem, given that a reception slot is not reused within a 2-hop neighborhood. TONE resolves contentions in successive elimination rounds by using a two-phase tone-based signaling mechanism in every round. We also propose a group splitting algorithm, which governs the elimination process in the manner that minimizes the number of tone transmissions, thereby improving the energy-efficiency. Our analysis, verified by simulation results, demonstrates that TONE outperforms the CSMA-based contention resolution mechanism and it can greatly improve the performance of receiver-driven TDMA-based WSNs under heavy traffic load. Also, our simulations show that the receiver-driven TDMA protocol with TONE outperforms transmitter-driven TDMA protocol in energy-efficiency, although with a limited drop in data throughput.Key words: wireless sensor network, MAC protocols, TDMA protocols, contention resolution mechanis