This study presents a cost-efficient Hardware-in-the-Loop platform for liquid-level process control education, designed to bridge the gap between theoretical learning and real-world industrial practice. The proposed system integrates NI myRIO and NI myDAQ hardware with LabVIEW-based real-time simulation and controller implementation, enabling flexible experimentation across a range of linear and nonlinear tank models. Through real-time controllers, students can design, tune, and validate classical digital controllers while gaining hands-on experience with real-time process dynamics. Experimental results from Model-in-the-Loop and Hardware-in-the-Loop configurations confirm the high accuracy between simulated and hardware responses, with low normalized root mean square error (NRMSE < 0.07) and high normalized cross-correlation (NCC > 0.99) between MIL and HIL responses. Additionally, learning outcomes were assessed using rubrics and student perception surveys aligned with ABET criteria. The platform successfully satisfies ABET student outcomes (SO1, SO2, SO7) by promoting modeling, system identification, and real-time implementation skills. Student surveys reveal high satisfaction mean = 5.44 and a Cronbach’s α of 0.91367, highlighting enhanced engagement, flexibility, and confidence in control system design. This work demonstrates an adaptable, scalable educational solution that strengthens engineering competencies while keeping implementation costs low.

Liquid level control plays a crucial role in process industries, where accurate and stable regulation is required to ensure operational safety and process efficiency. In practice, nonlinear tank dynamics and wide operating ranges often degrade the performance of conventional proportional-integral-derivative (PID)-based control strategies, leading to excessive overshoot, oscillations, and prolonged settling times. Although various advanced control techniques have been proposed, many of them rely on complex tuning procedures or heuristic design, which limits their practical applicability. This paper proposes a mass-balance-based liquid level control strategy that directly exploits the physical relationship between inflow, outflow, and liquid level. The proposed method introduces a mode-switching mechanism that distinguishes between transient and steady-state operating conditions. During transient operation, the control valve is driven to its saturation limits to accelerate level correction, while steadystate regulation is achieved by balancing inflow and outflow to maintain mass equilibrium. Unlike conventional PID controllers, the proposed approach does not require parameter tuning, system identification, or optimization procedures. Simulation studies are conducted on nonlinear tank systems to evaluate the effectiveness of the proposed strategy. The results demonstrate that the proposed method achieves fast setpoint tracking with zero overshoot and reduced settling time compared with conventional proportional (P), proportional-integral (PI), and PID, and cascade control schemes. Quantitative performance comparisons further confirm the robustness and practical advantages of the proposed control strategy for nonlinear liquid level control applications.