Multivariable Hydraulic System – 4-Tank Process Lab
Description
This laboratory system is a multivariable hydraulic process composed of four interconnected tanks. The tanks are connected through a configurable network of electrovalves, allowing multiple flow paths and dynamic interaction between the tanks. This flexibility enables the implementation of various operating scenarios and experimental setups, making it ideal for advanced control studies. The system is designed to illustrate complex control challenges typical of MIMO (Multiple-Input, Multiple-Output) processes, including strong coupling between variables. Users can remotely interact with the system to test and compare different control strategies. Basic control can be implemented using classic PID controllers for each loop, while more advanced scenarios involve decoupling techniques to mitigate the cross-effects between control loops. This setup provides a realistic platform to understand the limitations of single-loop control and the benefits of multivariable approaches. The system is well-suited for teaching, research, and remote experimentation in the fields of automatic control, process dynamics, and control system design.
Objective
To provide a remote-accessible, hands-on platform for analyzing and controlling a multivariable hydraulic process, highlighting key challenges in MIMO systems and enabling students and researchers to test various control strategies, including PID and decoupling techniques.
Method
The system operates through four water tanks connected by a configurable network of electrovalves. By opening or closing specific valves, users can create different interconnection scenarios, simulating various hydraulic processes. Each tank's water level is controlled via variable-speed pumps, while sensors continuously measure system states in real time. Users interact with the system remotely by designing control algorithms (e.g., PID, decoupling), which are then applied directly to the physical setup. This approach enables both open-loop and closed-loop experiments under realistic operating conditions.
Practical Applications
- Industrial process control - Water distribution networks - Coupled tank systems in chemical engineering - Design and testing of MIMO controllers - Validation of control algorithms in real time
Key Features
- Four interconnected tanks with dynamic configuration via electrovalves - Real-time remote access and control - Support for PID control and decoupling strategies - Multiple experiment scenarios based on valve configuration - Educational and research-oriented design
Learning Outcomes
- Understand the behavior of multivariable dynamic systems - Identify and manage interactions between coupled subsystems - Design and implement PID and decoupling-based controllers - Analyze system response and controller performance - Gain experience in real-time control system implementation Develop skills in remote experimentation and monitoring
Functional In/Out Diagram
The functional diagram above illustrates the main components of the system and their interactions:
Input: - Control signals sent to pumps via PWM (Pulse Width Modulation) - Valve configuration (electrovalves opened or closed) - Controller parameters (e.g., PID gains or decoupling matrix) - Setpoints for desired tank levels
Process: - Water is pumped into the tanks based on PWM control signals. - Electrovalves control the interconnection between tanks, allowing different flow configurations. - Flowmeters measure the flow rate at each inlet and between tanks. - Water levels are measured using distance sensors.
Output: - Real-time distance sensor data used to compute tank water levels. - System behavior visualizations (levels, flow rates, control responses).