Richard W. Wall

Simple methods for detecting zero crossing

Affects of noise, harmonics, and multi-frequency signal make frequency and period measurements difficult for synchronizing control events. Various methods are presented to minimize errors in period and phase measurements. Both frequency and amplitude domain approaches are analyzed. Post detection processing allows greater accuracy. Static and dynamic hystereses as well as interpolation methods of zero-crossing detection are investigated.

COMPARISON OF SITE-SPECIFIC AND CONVENTIONAL UNIFORM IRRIGATION MANAGEMENT FOR POTATOES

Site-Specific Irrigation Management (SSIM) can be defined as irrigation management (depth, timing) based on crop need to defined sub-areas of a field referred to as management zones. Implementation of SSIM will require additional irrigation system hardware, labor, and information on soil and/or plant water status in each management zone. Costs associated with these additional requirements will need to be offset by increased receipts from improved crop yield and quality in order for the technology to be adopted by producers. The potential for SSIM to increase crop yield, quality, and economic return has not been evaluated in field studies. Crops such as potatoes, for which yield and quality are highly sensitive to soil water availability, are most likely to show an economic benefit from site-specific irrigation management. A two-year field study was conducted to evaluate the potential for SSIM to increase yield and quality of potatoes relative to Conventional Uniform Irrigation Management (CUIM). Near real-time soil water content was used to schedule irrigations under both irrigation management treatments. Field average water application was nearly the same for the irrigation management treatments, 503 mm (19.8 in.) in 2001 and 445 mm (17.5 in.) in 2002. In both study years, tuber yield distributions trended 4% greater under site-specific irrigation management but were not significantly different (p < 0.05). Total tuber yield per unit of water applied from irrigation and precipitation was 4% greater in 2001 and 6% greater in 2002 under SSIM. Based on a local tuber quality adjusted potato processing contract price structure, the trend in gross income averaged across the field site was

Interactive relay controlled power system modeling

159/ha (

Using TACS functions within EMTP to teach protective relaying fundamentals

65/acre) greater with SSIM. This increase in gross income is likely about half the actual cost of commercial site-specific irrigation technology. The required 3- to 5-year crop rotation for potato disease management means that the site-specific irrigation system needs to be mobile or an economic benefit must also be realized from other crops in the rotation. The economic benefit of SSIM needs to be increased or realized for other crops in the rotation for it to be an economically viable technology in potato production systems in Idaho.

Support Platform and Communications to Manage Cooperative AUV Operations

Four fundamental algorithms that make it possible to simulate numerous types of protective relay systems are identified. The characteristics of these fundamental modules necessary for building an embedded relay model within an EMTP (electromagnetic transient program) are discussed. A directional time overcurrent relay model is used to provide a detailed demonstration of relay model development and to illustrate the utilization of the fundamental modules. The results of using this relay model in a modeled power system reveal the power of this concept to enhance power systems education, applications engineering, and relay design procedures. >

Design platform for plug-and-play IEEE 1451 traffic signal

The purpose of this discussion is to provide an educational tool for investigating relaying concepts by modeling digital relays using TACS functions within EMTP in a closed-loop manner. Various elements of digital protection systems are identified and organized to generate an systematic approach to modeling the actual hardware of relay systems. Discussion is limited to conventional relaying systems that monitor the vitality of the 60 fit voltages and/or currents. TACS functions for transport delay and pulse generators are used to model dynamics associated with analog to digital conversion and sampling systems. DSP algorithms convert a sequence of sampled data into a sequence of values for magnitude and phase components. A simple example of a time overcurrent relay is developed to demonstrate the techniques to implement relay control in EMTP with TACS and illustrates the kinds of phenomena that can be studied using these techniques.

Field testing of a variable rate sprinkler and control system for site-specific water and nutrient application

For the testing of control and communications algorithms in cooperative behavior, a fleet of autonomous underwater vehicles (AUVs) is under development by the University of Idaho. This paper discusses one piece of the puzzle in this fleet: the communications module to manage multiple agents. The communications system provides multiple modes of operation. Different communications mediums to and from the vehicle support these modes of operation. The tools supplied by the different modes of operation assist the researchers in developing communications, control algorithms, and valuable hardware systems.

Low Cost Distributed Control System for Autonomous Vehicles

A new approach for integrating traffic controllers with signals and sensors is being investigated that involves the plug and play distributed sensor technologies that conform to the IEEE 1451 standard. The components and basic architecture of the IEEE 1451 standard are described in this paper. Preliminary work has resulted in an inexpensive hardware and software development platform. Using this platform will facilitate determining operating performance and identifying development challenges involved with implementing a distributed sensor network for traffic control. Proof of concept calculations suggest that the IEEE 1451 network approach has sufficient bandwidth to manage the information requirements. A map for future development work is suggested.

A distributed smart signal architecture for traffic signal controls

Development and implementation of site-specific sprinkler irrigation management has been limited due to the lack of variable rate sprinklers. Thirty-two prototype variable rate sprinklers were constructed and field tested on a three-span linear-move irrigation system. An algorithm was developed for a distributed control network to allow each sprinkler to be individually controlled in groups of six or seven along the linear-move lateral. Water application uniformity was monitored over a 36% to 100% range in application rate. Measured application uniformity equaled or exceeded 90%. Variable rate nitrogen application was monitored over a 1.1-ha area. Measured nitrogen application rate was within 4% of the target application rate. Results indicate that the prototype variable rate sprinkler and control system allows water and chemical application to vary over a 36% to 100% range in application rate with minimal effect on water application uniformity.

Pedestrian navigation and integration with distributed smart signal traffic controls

A fleet of autonomous underwater vehicles was developed to field test control algorithms for cooperative behavior. Researchers and engineers at the University of Idaho require a low cost test platform capable of underwater communications to coordinate activities associated with multi-agent autonomous behavior. On each vehicle, a distributed approach to vehicle control uses five off-the-shelf 8-bit microprocessors that communicate together using Ethernet. This architecture provides many advantages over the traditional, centralized architecture, including ease of implementation, low cost, and reduced error rates during the design phase. This paper describes the process of distributing functional software tasks among the hardware in a way that minimizes the burden of inter-processor communications to take advantage of concurrent design concepts.