The purpose of this thesis is to develop a seat control system that can provide constant support to the seated passenger’s back. While providing support, it is important to ensure that the pressure exerted on the passenger’s back is not excessive. In addition, as the backrest reclines, the static seat-pan would cause the passenger to slide, leading to uncomfortable sitting posture.

To address these issues, three subsystems have been developed in this thesis research including:​ i) following control system, ii) pressure control system and iii) synchro-tilt control system. The following control system controls the backrest to follow the movement of the passenger. The pressure control system senses and controls the contact pressure between passenger’s back and seat cushion. The synchro-tilt control system synchronizes the rotation of seat-pan with the reclination of the seat backrest to avoid passenger’s sliding.

Then the three subsystems are integrated into a combined control system. Two cases are studied. The first one is for passenger to lean forward. In this case, when the passenger leans forward, the backrest will rotate forward to follow the passenger’s motion under the following control. When the passenger stops motion, the control system switches to the pressure control to provide comfortable support. In the course of seat motion, the synchro-tilt control system is always on to rotate the seat-pan.

The second case is for passenger to lean back. Initially the pressure control system is on as the passenger sits in the seat. When the passenger wants to lean back, he/she would push back against the backrest hard enough to build up a pressure beyond a threshold. This serves a trigger signal to switch the control system to the following control to recline the seat backrest. When the passenger stops motion, the system will switch back to the pressure control again. Similarly, in the course of seat motion, the synchro-tilt control system is always on to rotate the seat-pan.

This thesis describes the control methods, sensors and controllers used for experiment, and discusses various implementation issues. At the end, the test results have shown the effectiveness of the proposed methods.