A system comprises a controller for a vehicle. The controller comprises a processor and a memory. The controller is configured to make readings of an infrared sensor positioned to sense objects and motion in a rear passenger foot well. The controller determines if there is an object present in the foot well using the readings. The controller then determines if there is motion in the foot well using the readings. The controller then activates a knee bolster when motion is determined, and deactivates a knee bolster when motion is not determined.