Mark Feldmeier

A Compact, Wireless, Self-Powered Pushbutton Controller

We describe a compact piezoelectric pushbutton and associated minimal circuitry that is able to wirelessly transmit a digital ID code to the immediate region (e.g., 50-100 foot radius) upon a single button push, without the need of batteries or other energy sources. Such devices have the potential of enabling controls and interfaces to be introduced into interactive environments without requiring any wiring, optical/acoustic lines of sight, or batteries.

Energy Metering for Free: Augmenting Switching Regulators for Real-Time Monitoring

We present iCount, a new energy meter design. For many systems that have a built-in switching regulator, adding a single wire between the regulator and the microcontroller enables real-time energy metering. iCount measures energy usage by counting the switching cycles of the regulator. We show that the relationship between load current and switching frequency is quite linear and demonstrate that this simple design can be applied to a variety of regulators. Our particular implementation exhibits a maximum error of less than plusmn20% over five decades of current draw, a resolution exceeding 1 muJ, a read latency of 15 mus, and a power overhead that ranges from 1% when the node is in standby to 0.01 % when the node is active, for a typical workload. The basic iCount design requires only a pulse frequency modulated switching regulator and a microcontroller with an externally-clocked counter.

CargoNet: a low-cost micropower sensor node exploiting quasi-passive wakeup for adaptive asychronous monitoring of exceptional events

This paper describes CargoNet, a system of low-cost, micropower active sensor tags that seeks to bridge the current gap between wireless sensor networks and radio-frequency identification (RFID). CargoNet was aimed at applications in environmental monitoring at the crate and case level for supply-chain management and asset security. Custom-designed circuits and sensors were utilized to minimize power consumption and cost in a practical prototype. The CargoNet nodes are capable of asynchronous multimodal wakeup on exceptional events at extremely low power (Quasi-Passive Wakeup) with adjustable thresholds that adapt to dynamic environments. Accordingly, CargoNet has been seen to monitor, log, and report conditions inside a typical shipping crate while consuming under 25 microwatts of average power. To demonstrate the feasibility of the prototype system, several tests and deployments were conducted in the laboratory and aboard various transport conveyances.

Personalized HVAC control system

We present a novel method of building comfort control, focused around the occupant. Custom sensing, communication, and actuation hardware were developed to locate users in a building, and measure various parameters directly on the body. These signals were used to infer user comfort and control the air-conditioning system to direct air flow where it was needed, when it was needed. A three month study of the system was conducted, with four weeks of this experimental control strategy compared to the previous four weeks of standard control. An improvement in both comfort and energy usage are shown as a result of this user-centric control system.

Giveaway wireless sensors for large-group interaction

We have developed a small, handheld or wearable, wireless motion sensor that sends out a short RF pulse whenever it is jerked. The hardware is minimal, as it mainly includes only a piezoelectric foil accelerometer, a CMOS timer, and a single-transistor 300 MHz RF transmitter. As such, the onboard battery should last for many years, and the cost is low enough (well under US

Wearable wireless sensing for sports and ubiquitous interactivity

1. in large quantity) to be given away with a ticket to an event, enabling it to be used to allow individuals to contribute to a large-group, real-time interaction. We discuss results from experiments using this device to explore collaborative music control, and touch on other applications.

A platform for ubiquitous sensor deployment in occupational and domestic environments

In this paper, we overview recent work from our research group that explores two very different applications of wearable inertial systems. The first project exploits an array of wearable, ultrawide-range, synchronous IMUs to measure the performance of professional baseball players. We describe some special aspects of our hardware (a dual-range, 6-DOF IMU with magnetometer), and show sample data from our current analysis. We also overview another project where we leveraged wearable sensors, including a micropower integrating accelerometer, for mobile personalized comfort control of building HVAC (heating/air conditioning) systems.