Control System Design

Control Philosophy

CDI offers a broad spectrum of control design and consulting services related to the materials handling industry, for both mechanical design and control system design.

This combined experience has given CDI experience and understanding of both the mechanical and control aspects of transportation systems, allowing it to take a comprehensive approach to control system design. This approach proceeds from the operator’s point of view and emphasizes reliability, simplicity of control, flexibility and expandability. It draws on extensive field experience and builds on an integrated approach to system design.

CDI’s design and control consulting is built to develop advanced algorithms for the control of modern brake and actuation systems for large transport systems. Including many fields associated with material handling, including special conveyor controls (head / tail conveyors, regenerative downhill conveyors), crusher controls, feed controls, washing plant controls, dust suppression system controls, sampling plant controls and centralized controls. In addition, CDI has developed new approaches to control systems for the materials handling industry and has designed specialized instrumentation for conveyor applications and forensic engineering. CDI has published several articles that describe its control philosophy and its approach to the design of control systems.

The Objectives
  • System security
  • Maximum availability
  • Simple operator controls
  • Quick diagnostics
  • Smooth commissioning
  • Flexibility and upgradeability


  • Full system approach
  • Integrated PLC, graphics, and communication
  • Robust and modular PLC programming
  • Graphical operator interface
  • Structured programming
  • Special programming techniques
  • Detailed documentation
  • Program and process simulation
  • Comprehensive commissioning
  • Field test of installed system

Control systems

CDI’s extensive experience in control system design for the material handling industry includes concept studies, control system design, specification, bid evaluation, unbiased hardware selection, definition of control logic, very robust programming techniques , PLC and computer networks, soft start and soft stop drive controls, centralized graphical operator interfaces, specialized communication programming, field testing and system commissioning. CDI uses modern programming techniques and has experience with cross-platform systems, most types of PLCs and operator interfaces, most operator interface software packages, copper and fiber optic networks, and forensic engineering techniques.

Control systems engineering
  • Control system design
  • PLC programming
  • Operator charts
  • Centralized control and diagnosis
  • Networks and communication
  • Specialized steering and brake controls
  • Simulation
  • Field engineering
  • Instrumentation
Special techniques

CDI uses a number of special programming techniques, including digital and analog signal filtering, alarm latching, structured programming, and full program simulation prior to delivery to the site. These special techniques, combined with their global focus, have always resulted in fast commissioning time and a very high level of equipment availability.

Structured programming

  • Separation into independent components.
  • Each block of logic is simpler
  • Allows easy testing and modifications
  • Provides natural diagnostic tree

Linked Alarms

  • Only latched alarms cause shutdown
  • Eliminate ghost closures
  • Provides easy diagnostics

Systematic I/O filtering

  • Timer Filtered Digital I/O
  • Analog I/O filtered by moving average
  • Eliminates electrical noise problems.
  • Reduces contact bounce problems
  • Increase system reliability.

Program and process simulation

  • Complete simulation program in the office
  • Allows early detection of logical flaws
  • Reduces the risk of testing the live system
  • Reduces start-up time
  • Experts in belt starts and stops

Experts on Soft Start / Stop

CDI has a long history of developing, implementing, and commissioning large-scale control systems for major crushing and transportation facilities. CDI is responsible for the design and execution of the longest transporter control system in the world (Curragh project, 2,500 tph and 20.0 km in length in a single section, Australia), for several of the largest transport systems in the world (Palabora IPCC Project , 6500 tph, 9000 hp tunnel belt, South Africa), (Morenci IPCC Project, 8000 tph, 6000 hp descent belt), and for the world’s largest descent transport system (Los Pelambres Project, descent system 12.7 km, 8,700 tons per hour, 25 MW of regenerated power).


  • DC drives
  • Frequency inverters (VFD’s)
  • Wound rotor motors with resistance steps
  • Fluid Couplings – Drive Type
  • Fluid Couplings – Bucket Tube Type
  • Fluid couplings – drain type
  • Wet Clutches (Dodge CST)


  • Low speed hydraulic disc brakes
  • High speed hydraulic disc brakes
  • Air brakes

Control algorithms

  • Adaptive controls (PID)
  • Self-tuning loops
  • Preventive controls
  • Predictive-corrective controls

Through numerous successful projects, CDI has acquired a reputation for capable and resourceful engineering, combining advanced technology with a strong emphasis on safety, reliability, and productivity.

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