Su-Lim Tan

Real-Time Operating Systems for Small Microcontrollers

Real-time operating systems have gained popularity in microcontroller- and processor-based embedded system design. This article discusses differences between RTOSs and generic operating systems, the advantages and disadvantages of using RTOSs for small microcontroller system development, and the benchmarking methods used for RTOSs. Benchmarking results for four RTOSs show no clear winner, with each RTOS performing better on some criteria than others.

Road traffic monitoring using a wireless vehicle sensor network

With the advancement of Micro-Electro-Mechanical Systems (MEMS) technologies, wireless sensor networks have opened new vistas for a wide range of application domains. These sensor nodes usually comprise small, low-power devices that integrate sensors and actuators with limited on-board processing and wireless communication capabilities. One of the most important applications is target tracking and monitoring. Here a novel wireless vehicle monitoring system that is able to detect, classify and determine the direction of travel of vehicles on a two-lane road is proposed. Each vehicle detection node features multiple sensors including magnetometer, accelerometer, infrared and acoustic microphone with a two-node structure for cooperative monitoring. The results show that the system was capable of classifying the vehicle type (using vehicle weight) and their directional of travel with high accuracy.

Combined smart chemFET/resistive sensor array

Here we describe a novel CMOS compatible gas sensor array based on a combined resistive/chemFET sensor cell. We have fabricated an array of 70 sensors with integrated drive, gain and baseline removal circuitry using an AMS 0.6 /spl mu/m CMOS process. The sensing materials are carbon black/polymer composite (CB) thin films, which have been previously reported to have good vapour-sensing properties. Different CB films have been deposited onto the sensor array and have been shown to respond differently to volatile organic compounds. This combined sensing element both reduces silicon area and, more importantly, measures different physical properties of the same gas sensitive material improving discrimination and giving more insight into the sensing mechanism.

Sensor data fusion for attitude stabilization in a low cost Quadrotor system

With the development of low-cost and lightweight Micro-Electro-Mechanical System (MEMS) sensors, it has become possible to efficiently develop an attitude estimator, thus renewing the interests into vertical-take-off and landing (VTOL) aircrafts. A quadrotor with an Attitude Heading Reference System (AHRS) was built from scratch for investigation of heterogeneous sensor data fusion and attitude stabilization. This paper focuses on the system integration through the use of a 16-bit embedded microcontroller and sensor data fusion approach to reduce the gyroscope drift and the impact of vibration noise on measurements. The Quadrotor was able to hover over the ground stably indoors and react to applied disturbances. Attitude stabilization with the implementation of a Kalman Filter and PID controller is verified to be satisfactory through tests and response observed in actual flight data.

Towards an artificial olfactory mucosa for improved odour classification

Here, we report on a biologically inspired analytical system that represents a new concept in the field of machine olfaction. Specifically, this paper describes the design and fabrication of a novel sensor system, based upon the principle of ‘nasal chromatography’, which emulates the human olfactory mucosa. Our approach exploits the physical positioning of a series of broadly tuned sensors (equivalent to the olfactory epithelium) along the length of a planar chromatographic channel (analogous to the thin mucus coating of the nasal cavity) from which we extract both spatial (response magnitude) and temporal (retentive delay) sensor signals. Our study demonstrates that this artificial mucosa is capable of generating both spatial and temporal signals which, when combined, create a novel spatio-temporal representation of an odour. We believe that such a system not only offers improved odour discrimination over a sensor array-based electronic nose, but also shorter analysis times than conventional gas chromatographic techniques.

Emotion-aware technologies for consumer electronics

Emotions pervade in peoplepsilas daily lives. Recently, there is a trend of adding emotional characteristics as new features to electronic devices in order to provide more natural and intelligent interaction with human. Affective computing, a concept that combines computer science with psychology and cognitive science was brought forward to support the idea of making machines aware of humanpsilas affective states. This study focuses on differentiating peoplepsilas emotional states based on arousal and valence using physiological signals with the aim to improve human computer interaction for next generation consumer electronic devices.

Asymmetric Multihop Networks for Multi-capsule Communications within the Gastrointestinal Tract

The advancements in wireless communication and electronic technologies enable novel health monitoring devices to be developed and deployed for in-vivo medical examination and treatment. Wireless capsule which can examine the gastrointestinal tract with many kinds of sensors and send the collected data outside the human body wirelessly is very promising. To the authors’ best knowledge, no previous work has been done for using multihop communication in multi-capsule networks. In this paper, multihop communications through the human body is proved effective for saving energy at a given transmit/receive circuitry power consumption by simulation. The total energy saving ratio can be more than 90%. This paper also proposes a novel topology for multi-capsule networks, which utilizes asymmetric uplink and downlink routes for bidirectional communication. In this way, the network can achieve a better tradeoff between power consumption and delay performance.

Using GA-based feature selection for emotion recognition from physiological signals

Emotion awareness is becoming an increasingly important field for human-computer interaction. Compare to audio-visual techniques, relying on physiological signals reveals a few advantages that inspired several research studies. By using various feature selection and classification algorithms, development on physiological signals based emotion recognition has been gradually broadened. This paper employed GA-based feature set searching algorithm combining with four classification methods for physiological signal based emotion recognition. GA is an optimization tool which has been proven to be quite effective for large-scale feature selection. The results in this paper will support a successful application of using GA-based feature selection.

Real-time operating system (RTOS) for small (16-bit) microcontroller

Real-time operating system (RTOS) is gaining increasing use not only in 32-bit systems but also in 16-bit systems. RTOS is different from generic OS by several unique characteristics and the use of RTOS in embedded system development proves to be more advantageous. In this paper, 9 RTOSes targeting smaller processors have been evaluated and four of the RTOSes have been selected for performance benchmarking on the same M16/62P microcontroller platform to avoid bias. Based on the comparison, the μTKernel RTOS is chosen for porting to the H8S/2377 16-bit microcontroller to demonstrate the ease of RTOS platform migration. The same version of μTKernel RTOS running on different platforms are then compared. Lastly, an application is developed with the RTOS to demonstrate the ease of multi-task application development on such microcontroller platform.

In-vivo wireless capsule for health monitoring

The need for continuous and reliable health monitoring, especially for patients with diagnosed illnesses, is getting increasing attention from the consumers. The advancements in wireless communication and electronic technologies enable novel monitoring devices to be developed and deployed for in-vivo medical examination and treatment. One kind of device called in-vivo wireless capsule is introduced in recent years, which can examine the whole gastrointestinal tract with many kinds of sensors, and send the data outside the body wirelessly. This paper focuses on two research areas of the wireless capsule; localization and multi-capsule network. The different ways to realize position localization is discussed and compared. A new architecture for the multi-capsule network and a new power supply chain scheme are proposed.