TS. Schedule Logic Overview

Owned by iarmstrong
Last updated: Nov 01, 2023
4 min read

 

Introduction

Keep these relationships in mind when making changes to the schedule logic and calendar values. 

Item

Description

Item

Description

Agent

Picks the blocks and executes schedule logic on them.

Dependencies

Only some blocks are available to mine at each moment.

Incentives

With the available blocks, prefer to mine some over others.

Destination Logic

With the selected block, find a destination.

Steps Logic

With the selected source and destination, 

  1. Optionally break the route into multiple legs (such as production and rehandle),

  2. Select a fleet for each leg.

Fleets

With each selected fleet, find a truck and loader combination with remaining hours.

Loader Types

With the selected loader, consume loader hours at the loader production rate.

Truck Types

With the selected truck, consume truck hours at the truck production rate.

Once the sum of movement between a source and destination hits a Constraint, then no more material may be moved between those points. 

In Optimise Products mode, once all constraints have been hit, the Product Specifications are used to recalculate the ore destinations for optimum crusher feed. 

Once the destinations have been chosen, the following warnings may appear:

  • "Overflow" indicates that the optimised destinations use more truck hours than are available in the fleet.

  • "Optimisation Failure" indicates that the sum of mined ore is greater than the sum of capacities/constraints.

If either of these two warnings are encountered, the solution is to (a) mine less tonnes, or (b) travel shorter hauls, by changing the Constraints on mining and dumping in the Calendar.

Agents

An Agent executes the scheduling logic as individual schedule transactions, where a transaction is defined as moving an amount of material between a source and destination with a specific truck and loader. 

Users may at times set up multiple agents to execute different, concurrent scheduling logic (such as ore/waste incentives, deposit1/deposit2 destination logic, AHS/Manual step logic, etc).

Dependencies and Incentives

In each Period, each Agent filters the blocks by their dependencies, sorts them by their incentives, and selects the highest ranked available block.

Agents, Dependencies and Incentives

Destinations and Constraints

The Agent selects the highest ranked block and checks for available Destinations. If a block fails, it is removed from that Agent's ranked block list (another Agent may still try to mine it though).

Destinations and Constraints

In the Optimise Products mode, ore destinations are only assigned at the end of the period. If the assignment exceeds the destination capacity constraint, then it returns an Infeasible Solution. 

Steps Logic and Fleets

Once an Agent knows the Source, Material and Destination, then it uses the Step Logic to look up the waypoints and fleet(s) for the transaction.

It may be a single step (such as pit ⇒ crusher) or multi-step (such as pit ⇒ stockpile ⇒ crusher).

Successive steps may utilise different fleets. 

Equipment Matching

Once an Agent knows the Fleet, then it picks the first loader/truck pairing with available hours remaining. 

In the Optimised Products mode, ore destinations are only assigned at the end of the period. If the assignment exceeds the equipment available hours, then the hours continue into Overflow. 

Haulage

The Agent queries Haul Infinity for a cycle time for the given source, material, destination, truck, and loader. 

In the Optimise Products mode, ore destinations are only assigned at the end of the period. If the assignment fails due to no route found, then the scheduler will show an error message.

Possible Issues

Summary of issues that may be returned by the schedule logic:

Scheduling Mode

Issue Type

Cause

Solution

Scheduling Mode

Issue Type

Cause

Solution

Optimise Products

 

Infeasible Solution

The optimiser could not find a destination for a material, either due to constraints or to product specifications.

Either reduce the ore mined or relax the capacities/constraints/grade limits that are constricting the movement

Invalid Cycle Time

Haul Infinity could not find a route.

Either there is no route in Haul Infinity, or the route contains steep segments/dynamic haulage

Overflow

The optimised destinations use more equipment hours than available.

Either reduce tonnage targets or reallocate equipment to shorter hauls

Constrain on Trucks

 

Constrained by Steps Logic

If a step rule uses multiple fleets, both fleets must have available hours.

Either reduce tonnage targets or reallocate equipment to shorter hauls

Stockpiles reclaim defaults to zero

Calendar > Stockpiles > Reclaim Target = 0

Manually set rehandle targets for each stockpile in each period

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