## 4 Discussion  
The purpose of this paper was to test the theoretical performances of the hydraulic interconnected suspension system by comparing the simulated results against the ones obtained from a traditional passive suspension system with front and rear ARBs. Two performance parameters were chosen as essential for increasing the dynamic performance of the car based on the study of the performance envelope: the ability of the wheel to follow the road profile (which can be correlated with mechanical grip) and pitch stability (which is beneficial to downforce generation). However, giving the fact that the chosen vehicle for the simulation runs only in Formulas Student competitions, the mechanical grip improvement is more valuable. The primary advantage of the system proposed by [PERSON] and [PERSON] for the hydraulically interconnected suspension system is the increase of mechanical grip as a result of the fact that the stiffness of the wrap mode can be eliminated [2]. Judging by the results in this paper, this hypothesis seems to be correct: in both the steady state and dynamic simulations, the wheels of the interconnected suspension systems have much lower relative displacements relative to the road. Another advantage of the proposed system is the ability to choose the pitch stiffness of the vehicle independently of all the other elastic elements of the suspension system. Due to this advantage, the pitch stability of the car was improved, when compared with the traditional passive suspension, with beneficial effects on downforce generation. Judging the two systems described in this paper by only these two performance factors, it is clear that the hydraulically interconnected suspension system is the superior choice when compared with the traditional passive suspension system. However, it is important to note that certain simplifications were done to decrease the computational time necessary to solve the EOMs of both models. The most notable simplification made was using ideal conduits and fittings. Giving this simplification, the pressure loss that is present in any hydraulic systems due to diameters and lengths, the shape and construction of the fittings, and their overall effects of the type of flow of the hydraulic fluid is not considered in this model. As a result, the performances of a real-life hydraulically interconnected suspension can present some differences from the presented mathematical model due to the architecture of the hydraulic system itself. Another important simplification made to the system is the idealization of the hydraulic fluid. In the current model, the hydraulic fluid was considered incompressible and therefore acted as an ideal lever. However, any material is compressible to some degree [20]. This property of the hydraulic fluid can create some problems since in a double-acting cylinder, like the ones used for the construction of a hydraulically interconnected suspension system, the compressibility of the fluid can act as two springs, acting in parallel, pushing  
Figure 29: Chassis pitch root mean square for a realistic road profile and external accelerations. against the piston [20]. This means that for simulations done at higher frequencies, the resonance of the hydraulic fluid itself can affect the simulation results. This problem is further compounded by the fact that if the air is dissolved in the hydraulic fluid or water contamination occurs, the bulk modulus of the fluid will decrease therefore decreasing the resonance frequency of the fluid. These problems, along with various environmental factors that might affect the flow of the hydraulic fluid (such as temperature), can be considered logically as the next necessary step in simulating and constructing such a system for either racing or industrial or general transport purposes. Conceptualization, all authors; methodology, A.-C.P. ; software, all authors; validation, C.A. ; writing--original draft preparation, A.-C.P. ; writing--review and editing all authors; supervision, C.A.