Scheduling Skip Function Overview

Pasha

Created: ; updated: .

Observant irrigation customers could be divided into two main groups - pressurised irrigation customers and surface irrigation customers. In pressurised irrigation systems, water is pressurised using a pump and applied to the plants under pressure through a system of pipes. In surface irrigation, the system relies on movement of water to the crops due to the force of gravity.

Most of Observant’s irrigation customers use pressurised irrigation systems, and the Observant Irrigation Scheduling solution was designed with mainly these customers in mind.

The Skip Functionality

There are two types of skip operations in Observant Global - manual skip and auto skip.

Manual Skip

Manual skip is normally used by customers when they have identified that the bay that is currently being watered has had enough water, and they would like to progress the irrigation schedule to the next bay earlier than originally planned.

Implementation

  • The current bay is closed
  • The next bay is opened
  • Subsequent bays receive a program update to open sooner

Auto Skip

Auto skip is triggered when the system identifies a bay failure and is trying to skip to the next bay. The motivation for auto skip in pressurised irrigation systems is to avoid pump shutdown or a burst pipe. The motivation for auto skip in surface irrigation systems is to avoid a channel blowing out.

Implementation

  • The current bay is left untouched (it has already ‘failed’)
  • The next bay is opened
  • Subsequent bays receive a program update to open sooner

Scheduling Failures

A schedule may fail for a number of reasons. These reasons can be roughly divided into the following groups:

  • Communications - the field unit (or gateway) dropped off the 3G or radio network
  • Battery - the field unit (or gateway) has shutdown due to low battery level
  • Cabling - the device is unreachable due to faulty cabling
  • Device - pump, actuator or valve report a failure (i.e actuator jammed or pump stopped on high pressure)
  • Congestion - the cloud platform can’t reach the relevant field unit in time
  • Timeout - the cloud platform couldn’t confirm that the bay moved to the desired state within the given timeframe

These failures will usually occur in one of the two critical stages of the schedule execution - opening or closing time.

Auto Skip Effectiveness

Whether auto skip will help to keep a pump running or prevent a channel from blowing out depends on the type of failure that has occurred. In some instances, auto skip may not help, and might even make things worse. These include the following:

  • If the failure occurs at closing time there would be no use to auto skip since the next bay should already be opening.
  • If there is a network congestion, it would mean that no field unit in that network can be reached, so auto skip would not help unless the congestion improves.
  • If a unit is experiencing intermittent comms problems, but ends up opening, we might attempt to auto skip to the next unit, which may result in multiple bays open at the same time.

How did I end up with two bays open at the same time?

The following errors might result in multiple bays being open at the same time in a single scheduling sequence:

  • A bay being marked as failed to open due to communications failure, congestion or timeout failures, but eventually opening
  • A bay failing to close due to battery, cabling or device failures

In both cases the system might be aware after a time that there are multiple open bays in the scheduling sequence, but will require user intervention (through the software or in the field) to resolve the issue.

Multiple Failures in a Row

In some cases the auto skip function will be triggered multiple times in a row, marking multiple bays as failed, and sometimes having multiple bays open at the same time. This is normally caused by one of the following reasons:

  • Gateway failure - when a gateway goes offline or its battery runs flat, multiple bays will be affected, resulting in multiple consecutive skips (and failures)
  • Congestion - in some cases, where there are large radio network deployed, or some communications reliability issues within a radio network, the auto skip functionality may cause congestion in the radio network, which in turn may result in bays reporting a failure to open (after a timeout) when in fact they open in the field.



Have more questions? Submit a request
Powered by Zendesk