An Embedded Foundation for HIL-Based Load Emulation and Automatic Door Validation

Title:  An Embedded Foundation for HIL-Based Load Emulation and Automatic Door Validation
Author: Felix Bille
Date & Time: June 15th, 15:30-16:30
Location: Seminar Room M 3170-73 in the M-building, LTH
Supervisor: Björn Olofsson, Eric Schyllert (ASSA ABLOY Entrance Systems)
Examiner:  Karl-Erik Årzén


Abstract:

This thesis presents the development and evaluation of an embedded hardware and software platform for future Hardware-in-the-Loop (HIL) based motor testing at ASSA ABLOY Entrance Systems. The motivation for the work is to reduce the number of physical door setups required for motor testing by complementing them with a configurable HIL rig capable of simulating different door types and configurations. Rather than delivering a complete HIL system, the thesis focuses on the embedded platform required for reliable real-time current control, current sensing and controller evaluation, as a foundation for future HIL development.

A custom four-layer printed circuit board (PCB) was designed and evaluated together with a dual-core STM32H745XI microcontroller. Two current sensing solutions were compared and the INA240 current sense amplifier was found to perform better than the TMCS1108 Hall-effect sensor, with a standard deviation that was roughly an order of magnitude lower for the usable ADC configurations. The ADC configuration was required to take controller timings into account, as measurement accuracy and real-time control signal calculations were constrained by the controller frequency.

Three controller structures were implemented and evaluated: a PI controller tuned with the Ziegler-Nichols frequency method combined with manual tuning, a state-feedback controller designed through pole placement and a state-feedback controller with integral action. Both controllers with integral action performed well for the locked motor case. A significant system nonlinearity was identified during the evaluation of the observer. The results suggest that both controllers compensated for this nonlinearity by relying heavily on the integral action. The nonlinearity caused the Luenberger observer to fail across all tested pole placements, as the underlying linear model assumption was not satisfied.

The platform satisfies the core requirements for a first HIL prototype, including bidirectional torque control, data logging and reference tracking using prerecorded door current data. The most critical remaining step is to investigate and resolve the system nonlinearity, likely originating from the motor driver configuration. Once this has been resolved, the platform can be used for accurate load emulation.