Basics
To efficiently control the fleet performance we need to:
1. Know our objectives
a. max. production? Minimize fleet size? Other?
2. Know the status of the equipment
a. what is it doing at any given moment
3. Know the location of the equipment
a. where is it in any given moment?
4. Have the ability to process this information to define equipment assignments
Note: all this in real time!!!
“Need to know”
1. Current operating status;
a. Truck operational: haul, dump, return, queue, etc.
b. Truck down: refuel, m-ce, stand-by, waiting parts, etc.
2. Current location
3. Information which can be derived:
a. detailed cycle time, operating & down times, production by product and quantity, availability and utilization, production by source or destination
Monitoring The Status
1. Electronic & electromechanical sensors
speed, payload, brake application, tray position, engine status, transmission selection, etc
2. Mobile data terminals
terminals located in shovels, trucks, other equipment
Position Monitoring
1. Local positioning systems
a. beacon transmitters / beacon receivers
b. simple, cost efficient, owned & configurable
c. zones max 75 m, set-up & maintenance req’d
2. Global positioning systems
a. infinite monitoring, no set-up or m-ce
b. dependence on US military, deep pit problems
Truck Dispatch Systems
From:
manual input, report generation only
Through automated data acquisition & simple dispatch calculations
To:
Fully automated data acquisition and assignment calculation
Truck Dispatch: the Concept
Is it that simple?
Simple dispatch
Tt - Tc = W
Tt + Hw = C
Tt - travel time to the loading point (LP)
Tc - time committed at LP
Hw - hauler wait at LP
W - wait time
C - dispatch control factor
Dispatch Logic
1. Sort out all possible hauls and select the most efficient truck assignments
2. Assign trucks and start operation
3. Collect data: production rates, cycle times, etc for all haulers, loaders, dumps, crushers, etc.
4. Compare the collected data with the original ones and re-run assignment calculation if discrepancies exist
5. Rerun the calculation if non-scheduled events occur
6. Reassign trucks based on results of reruns
7. Continue data collection, checking for discrepancies and recalculating assignments (when needed)
Assignment Recalculation Events
1. Equipment status change; eg. ready to down
2. Addition/closure of a road segment
3. Change in measured travel time by a pre-set value
4. Change of blending requirements
5. Change of crushing/dumping rates
6. Change in shovel/dump priorities
7. Change in required/available truck ratio
8. At user predetermined interval
9. Other
Algorithm Management:Biasing
1. By loading site or a specific pit; eg room needed for subsequent operation
2. By stripping ratio; eg tie in stripping to ore excavation rate
3. By hauler - haul match; eg specific haulers working specific hauls
4. By dump area; eg restrict the dumping rate at specific dumps
5. By loading rate; eg. meet the pit advance targets
6. Other
Dispatch Strategies
1. Fixed dispatching: a truck (T) assigned to a specific shovel
2. Earliest loading: T assigned to assure its earliest loading
3. Minimum truck wait: T assigned to a shovel where it will have the shortest wait time
4. Maximum shovel utilization: T assigned to the longest waiting shovel
5. Minimum route saturation: T assigned to the route with lowest truck saturation
6. Minimum saturation & T cycle time: T assigned as above with consideration to its estimated cycle time
Modular Mining’s “Dispatch”
Sample Dispatch Objectives1. Maximize truck utilization (fleet undertrucked)
2. Maximize loading equipment utilization (overtrucked mine)
3. Minimize rehandle
4. Maximize compliance with blending requirements
Fleet Dispatch: Supplemental Outcomes
1. All equipment monitored 24 h/d: no distortion from unscheduled time, idle time, opportune maintenance, etc
2. Status changes & event codes: clearly defined and consistently used across all shifts and crews
3. Performance ratios & indicators accurately defined
4. The above linked to the job functions
After Carter, 1995 APCOM
Implementation Issues
1. Well planned briefings for all employees
on operation of the system, information collected, way of collecting it and its use
2. Structured training programs in the operation and use of the system for all employees
3. Analysis of the impact
on each job role when the system is implemented
4. Identification of the information that each employee needs to effectively perform the job: “which” employees make “what” decisions & what logic should they use
Source: P. Carter, 1995 APCOM
SIMULATION
1. Building a simulation model
2. Model inputs
3. Model validation
4. Use of simulation for optimization of mine performance
What Model Do We Need?
1. FPC type models: OEM/dealers, TALPAC of Runge, other
a. depend heavily on accuracy of inputs (15%?)
b. correction factors applied for existing mines
2. Simulation language based model
a. reflect probabilistic character of inputs
b. data acquisition and validation v. important
c. good for what-if scenarios
3. Dispatch based simulations
Data Collection / Model Validation
1. Data collection accounts for 70% expenditure and time
2. How to assure reliability of data?
a. sample field data: use summer students?
4. Model validation
a. a formal process
b. may require model adjustments/modifications