###### Abstract  
In this paper, an integrated model of a semi-active seat suspension with a human model over a quarter is presented. The proposed eight-degrees of freedom (8-DOF) integrated model consists of 2-DOF for the quarter car model, 2-DOF for the semi-active seat suspension and 4-DOF for the human model. A magneto-rheological (MR) damper is implemented for the seat suspension. The fuzzy logic-based self-tuning (FLST) proportional-integral-derivative (PID) controller allows to regulate the controlled force on the basis of sprung mass velocity error and its derivative as input. The controlled force is tracked by the Heaviside step function which determines the supply voltage for the MR damper. The performance of the proposed integrated model is analysed, in-terms of human head accelerations, for several road profiles and at different speeds. The performance of the semi-active seat suspension is compared with the traditional passive seat suspension to validate the effectiveness of the proposed integrated model with a semi-active seat suspension. The simulation results show that the semi-active seat suspension improves the ride comfort significantly by reducing the head acceleration effectively compared to the passive seat suspension. semi-active seat suspension; integrated model; control; fuzzy logic-based self-tuning; PID 2020 10 3185 24 March 202  
design of parameter-bound work within a limited frequency range [3]. The active and semi-active seat suspension outperforms the passive suspension and overcomes the inadequacies of the passive seat suspension. The active seat suspension is comprised of an actuator which generates the force regulated by using the control law driven by signals measured with the help of the sensors. The controller controls the actuators to generate an adequate amount of force or dissipate the energy from the system. In spite of the great accuracy and the performance of the active seat suspension, disadvantages such as a high capital and running costs, a complicated design and the power requirements make it less popular and redundant for commercial vehicle application [4]. The semi-active seat suspension was used widely because of its characteristics such as the semi-active suspension that does not require high power, while varying the damping force is one of the key features. Another crucial feature of the semi-active suspension is that it can even work as the passive suspension when the controller fails [5]. Therefore, the semi-active seat suspension has the features of both the active and passive seat suspensions. The entirely new segment of the smart dampers provides wide applications in the industries owing to their versatility and promising performance as compared to the conventional oil-filled dampers. The magneto-rheological (MR) and electro-rheological (ER) dampers belong to the segment of smart dampers, as they can give a quick response and can change the damping in just a few milliseconds, as per real-time requirements [6; 7]. MR dampers are highly reliable and can easily be maintained [8]. Due to these reasons, semi-active seat suspension is considered in this work. The performance of semi-active seat suspension has been studied by many researchers in the past. [PERSON] and [PERSON] [9] showed the performance of a robust sliding mode control on the electrorheological seat suspension with the human model. [PERSON] et al. [10] implemented the integrated semi-active seat suspension with the MR damper. One of the authors of this study has previously investigated the performance of semi-active suspension systems with different control strategies such as skyhook, groundhook and hybrid and reported the suitability of the control strategies for the desired application [11]. Advanced and intelligent controls, e.g., fuzzy logic control (FLC), artificial neural networks (ANN), adaptive neuro-fuzzy inference system (ANFIS), evolving radial basis function networks and so forth have attracted the minds of researchers to controlled suspensions, owing to their better control performance [12].