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L10: Interacting Control Loops

Prerequisites: L06-L09 | Effort: 60 min | Seborg: Chapter 16

Learning Objectives

  1. ✅ Understand MIMO (Multi-Input Multi-Output) systems
  2. ✅ Implement two-tank system with interaction
  3. ✅ Simulate coupled loops (one affects the other)
  4. ✅ Observe loop interaction effects
  5. ✅ Understand when decoupling or advanced control needed

Theory Recap: Interacting Loops (Seborg Ch. 16)

Loop Interaction: When one controller's output affects another loop's PV.

Example: Two-tank system - Tank 1 valve affects Tank 1 level (direct) - Tank 1 valve also affects Tank 2 level (interaction) - Controllers "fight" each other

Solution approaches: 1. Detune one or both controllers 2. Cascade control 3. Decoupling control 4. Model Predictive Control (MPC)

Odibi Hands-On

Example 1: Two-Tank Interaction

# two_tank_interaction.yaml
# Tank 1 feeds Tank 2
# Independent level controllers on each tank
# Observe interaction and oscillations

Working example: /examples/cheme_course/L10_interacting_loops/two_tank_interaction.yaml

Summary

  • ✅ Interaction occurs when loops share actuators or flows
  • ✅ Can cause oscillations and poor performance
  • ✅ Odibi simulates multi-entity interactions

Next: L11: Cascade Control