1 Functional Specification Smart Irrigation System Version Number: 97 Revision Date‐Time: 04/14/2014 12:20:00 PM Development Project Lead: Valerie McManus Peer Reviewer: Robert Strand Assigned: SQA Engineer TBD Business Analyst: TBD Engineering Manager: Xu Han Version Status Date Edited By Description of Change 1 Draft 04/14/2014 Jon Bebeau Compile individual works Company Confidential This document contains confidential and proprietary information of EEL4901.901S14 – Smart Irrigation System Group. Any reproduction, disclosure, or use in whole or in part is expressly prohibited, except as may be specifically authorized by prior written agreement or permission.
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Functional Specification Smart Irrigation System
Version Number: 97
Revision Date‐Time: 04/14/2014 12:20:00 PM
Development Project Lead: Valerie McManus
Peer Reviewer: Robert Strand
Assigned: SQA Engineer TBD
Business Analyst: TBD
Engineering Manager: Xu Han
Version Status Date Edited By Description of Change
1 Draft 04/14/2014 Jon Bebeau Compile individual works
Company Confidential This document contains confidential and proprietary information of EEL4901.901S14 – Smart Irrigation System Group. Any reproduction, disclosure, or use in whole or in part is expressly prohibited, except as may be specifically authorized by prior written agreement or permission.
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Table of Contents
1 OVERVIEW
1.1 Description
1.2 Scope
1.2.1 Objectives
1.2.2 Non-Objectives
1.3 References
2 FUNCTIONALITY
2.1 Existing Functionality Details
2.2 Proposed Design
2.2.1 Description of Functionality
2.2.2 User Interface Changes
2.2.3 External Interfaces
2.2.4 Process Flow
2.3 Alternate Design Options Considered
2.4 Design Decision Summary
3 CONSIDERATIONS
3.1 Dependencies and Assumptions
3.2 Risks
3.3 Managed Issues
4 SIGN-OFF
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1. Overview
The Smart Irrigation System (SIS) provides a complete water distribution, monitoring, and
control, and management system to optimize the effective use of water resources to irrigate
vegetation in a residential setting. Given the increasing environmental impact of water use for
irrigation coupled with the increasing expense of water resources and regulation, the Smart
Irrigation System leverages technology to effectively and efficiently provide the needed water
resources to the intended growth areas while providing accountability to the stakeholders. This
document outlines the specific components that embody the System, outlines how these
components interoperate and describes the functions, features and benefits of the Smart
Irrigation System.
1.1 Description
The Smart Irrigation System is positioned for the residential consumer market. The system can
be installed where an existing traditional irrigation systems exists, replacing several components
but utilizing many of existing components. The Smart Irrigation System can be the initial
installed watering system, or installed in combination with most existing systems providing a
modular growth path.
The Smart Irrigation System consists of several separate but cooperating components. A
network of in-ground, solar powered, wirelessly connected moisture sensors for a grid of the
property to measure soil moisture content and water (rain) fall. The density and distribution of
the moisture sensors vary according to the vegetation requirement. For example, grass may
need only a few sensors per irrigation zone. Flowering plants or vegetable gardens benefit from
a higher density of sensors to meet the irrigation plan of water distribution.
Periodically, each moisture sensor reports monitoring samples to a central hub, the Control
Point. The Control Point, not unlike traditional irrigation control units, is hub to receive wireless
sensor data and aggregate data. In addition, the Control Point contains the necessary circuitry,
power supplies, and switches to control and monitor solenoid valves for water distribution.
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Unlike traditional water control units, there are no displays, buttons, dials, switches (manual),
no user interaction occurs at the Control Point. Instead, a second wireless 802.11, compatible
with typical home wireless infrastructures, provides the link for user interaction. The Control
Point interfaces with the user over a hosted web server utilizing a web GUI for all Control Point
interaction.
The Control Point directs the operation of solenoid valves to direct water flow, monitors water
flow rates with fluid rate monitors, pressure sensors and provides external contacts to devices
such as well pumps, water retention pumps, and water level sensors where water cisterns are
employed.
The integration of moisture sensors network, water source selection control, and sensing with
an intuitive GUI interface provides for granular watering goals, cost effective resource
utilization, and scheduling as well as fault sensing, such as obstruction in the downstream
watering heads, high or low water pressures and alert messaging to report problems to the
system manager.
The benefit to the stakeholder is control of a scarce, increasingly expensive resource,
monitoring for system faults, like water line breaks, maintaining compliance with local
restriction and getting the most for the investment, not to mention a superior landscape.
1.2 Scope
For the purpose of this project, we elected to limit the development of several function and
features primarily to accommodate available time and resources. Yet, many features either
differentiate SIS from competition or provide benefits intrinsic to a new generation of irrigation
management. Features like multiple water sources, for instance, cistern storage or potable and
recycled water selection shall be deferred for future development. Still, references, where
appropriate, remain with the overall documentation to provide a point of departure for future
versions. Without scope restrictions, scope creep is likely endangering the timely completion of
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this project. The set of in-scope function and features are enumerated below along with
commentary explaining the decisions.
1. Target market simplification.
a. Residential properties under two acres. This area restriction relates to the
wireless portion of the moisture sensors, specifically to need to propagate RF
signals emanating from the moisture sensor at near ground level to a receive
(Control Point) mounted in a central location. The concern is available RF power,
antenna gain and most importantly obstruction to line-of-site.
b. The concept of in-ground, controlled, residential irrigation is well known and
understood as common knowledge. This reduces the barrier to entry.
2. Wireless range of 150 meters. The least understood technology is low power RF
communication of practical digital communication. Correspondingly, the wireless
communication between the moisture sensor and Control Point is likely the most
challenging design component. Limiting the range provides the best opportunity for
success.
3. Up to 8 zones. A zone is a collection of watering discharge heads (Heads) (sprinklers,
drip lines) connected and controlled by a single valve. All Heads are active when their
zone is activated.
4. Up to 32 wireless moisture sensors.
5. Installation into an existing in-ground, traditional irrigation system.
a. The initial prototype shall be installed overlaying an existing, traditional in-
ground irrigation system. This restriction is simply to minimize the cost and time
requires to install and demonstrate the SIS.
b. Only the in-ground system, not potted plants or above ground utility will be
supported.
6. Control Point requires 120V 2A utility power.
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7. Compatible off the shelf components. To minimize the need for newly created
components, we plan to leverage the existing body of readily complementary plumbing
and irrigation components:
a. Common facilities, ¾ PCV piping, valves, utility water supplies, both potable and
recycled water, availability or complementary components, valves, solenoid
valves, PVC pipe and fittings, various sprinkler heads, drip lines, spray nozzles,
tools, supplies.
b. Importantly, a body of common knowledge and readily available tutorials for the
common homeowner.
8. Web Based GUI to configure, monitor and control the SIS.
a. Create watering schedules.
b. Create allowable watering dates/times.
c. Design watering budgets and watering goals.
d. Prioritize resource consumption budget.
e. Generate alert messages.
Other features or stubs to support future development, exist and documented in Section 1.2.2,
Non-Objectives.
1.2.1 Objectives
Background
The goal is an environmentally sensitive optimization of water allocation, while recognizing the
need for irrigation both for esthetic and commercial values while nurturing the landscape
investment.
Many inventions are born from experience. The Smart Irrigation System also has its roots in
personal experience. Several of the features embodied in the design resulted from failures with
an existing residential irrigation systems. This traditionally employs a controller, solenoid water
valves and electronic control unit, all quality components for leading manufacture.
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Aside from the normal, annoying clogged sprinkler heads, occasional broken water control
valves and arcane control unit “programming” method, a $1,200 water bill for one month
forced the issue of system supervision.
In the instant case, the lawn service uses a commercial riding lawn mower. Due to wet
conditions the ground became unusually soft. The weight of the equipment cracked the city's
main water feed pipe to the irrigation system. Later the pipe burst. The obscured location of
the burst and heavy foliage cover prevented observation of running water. The runoff drained
to a stormwater system and remained unnoticed for over a month.
A series of obvious needs arose. How could it have been prevented? Or, more to the point, how
could it have been detected and remedied quickly. After researching my options, additional
shortcomings of the prototypical residential irrigation systems emerged. At present there is not
an existing residential system that meets these needs; hence a suitable Professional Design
Project emerged. Necessity is, aptly, the mother of invention. Additional functions and features
not part of the project but none the less important, have been summarized in next section.
Here, we prioritize and outline the specific features and functions addressed by the SIS system.
Monitoring
Existing commercial offerings provide little to no monitoring or supervision. From the
background, the feature to detect and report a critical issue like broken water main is
paramount in the design. Monitoring is divided into two areas; (1) fault detection and alert
notification and (2) monitoring of normal daily usage and comparison to expected or defined
irrigation goals.
Fault detection
Obviously, a broken water main is an emergency, both in terms of cost and wasted resources.
During the analysis, additional fault detection features presented themselves.
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● Detect changes in water volume to each zone. Characterizing normal operation of each
zone provided the basis for analysis of variance to a norm. Here, unpressurized (zone)
pipe breaks can be detected.
● Using the same method, clogged or faulty sprinkler heads are identified.
● Electrical faults of the solenoid (valves) can be detected and reported.
● Pressures, or deviation from expected pressures for both operation and standby indicate
a fault
Optimization and Cost Containment
Water budgets and goal oriented zone management is not available in the residential market.
Here SIS matches the owner defined moisture goals with financial implication to obtain the
goals and where conflict exists, how allocation will be brokered. During a drought and when a
monthly water cost is established, when water budget is over allocated, SIS will defer or reduce
irrigating some zones in favor of higher priority zones. For example, reduce watering grass in
favor of vegetables.
Utilization
Everyone has witnessed active irrigation during a downpour. Many municipalities require a
“rain sensor” to inhibit sprinkling during or immediately after rain. Commercial rain sensors are
in wanting. When operable, the amount of rain is uncorrelated to the desired moisture goals.
The SIS architects Goal-Based Active Monitoring. Here, the owner specifies the target moisture
per zone and the criteria to meet that ground moisture goal.
Set and Forget
The SIS is configured using a web-based GUI with contemporary 3D view of the property,
location of sensors, mapping of ground areas by moisture goal and procedures to insure
watering where need and when need. All accounting for local restrictions, watering cycles and
water cost budget.
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The Set and Forget objective also provided feedback. The user can receive notices of goal
failure. Perhaps the target ground moisture is not obtainable given the configured constraints.
A warning can be generated.
Target Market
The target customer is residential homeowners with existing in-ground central irrigation
systems. This leverages the sunk cost of installed piping, heads and control valve. Utilizing
portions of the existing infrastructure provides new features with minimally invasive to existing
infrastructure.
1.2.2 Non-Objectives During the design sessions, many features were discussed. For scope feasibility reasons, several
meritorious features or option became relegated as not essential for an initial offering and
removed from scope.
1. Support multiple water sources. The SIS implement one water source, public utility
water. However many water sources may be available. Supporting each or more
importantly, supporting several concurrent sources provide a robust and cost effective
gradient. Other sources include:
a. Well water
b. Recycled water
c. Cistern or collected “rain” water.
d. Natural reservoir, like pond, lake, storm water reclamation.
Each provide additional sources and each has unique implementation and equipment needs.
For example, well water requires operating well pump control and pressure monitoring sensor.
Reclaimed water provide lower cost source but may not be suitable for irrigating human
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consumable products like fruit and vegetables. There may be the need to purge lines between
types of water source utilization.
2. Commercial Use. Golf courses, apartment complexes, public areas, all are candidates for
SIS, however the scale and complexity are beyond the scope. Additionally, high water users
often have installed sophisticated irrigations systems and dedicated grounds staff. Golf
courses often implement satellite communication to monitor and control irrigation.
3. Geographic limitation. A novel feature of SIS is multiple in-ground sensors. Each reports
sensor information to the central Control Point. Each transmits only “in the blind” with
receiving responses. This primarily for cost containment. The ability to reliably
communicate with the Control Point with low power, from in-ground or near to the ground
antenna proves challenging. By limit the distance between transmitter (in-ground sensor)
and receiver (Control Point), we limit the design risk.
4. Standard protocol. The design calls for sensor payloads unrelated to any standard.
Providing or adopting a standard would provide interoperability, not currently a priority.
The Control Point to user LAN over 802.11 (Wi-Fi) will necessarily follow the standard.
5. Fixed and minimal number of sensor control. Initially, the prototype is limited to 8 valve
control switches. The design contemplated an initial fixed set of 8 with optional modules up
to 24 zones. For simplicity and proof of concept, supporting 8 zones appears sufficient.
1.3 References
● Controller Homeowner’s Guide by Smart Modular ● http://www.rainbird.com/documents/turf/man_ESP-SMTe_EN.pdf
● Quick-Start Installation and Setup Guide by Smart Modular ● http://www.rainbird.com/documents/turf/man_ESP-SMTe_QuickStart_EN.pdf
● Soil Sensor Basic Manual by Precision ● http://media.toro.com/CatalogDocuments/Manual/pss_basicmanual.pdf