# Optimizing Parameters for an Electrical Car Employing Vehicle Dynamics Simulation Program
## 4 Description of the Optimization Methods  
The basic concepts related to optimization can be found in reference [12]. These concepts are clarified below. The race car can be described with a finite number of technical data. Data that cannot be modified during the optimization procedure, are called design parameters, while others are called design variables. Together, they unambiguously define the vehicle model. The introduction of design parameters is necessary because in most cases not all the data of the vehicle can be chosen freely. This may be due to the fact that the competition rules make restrictions (or fix the value) on certain data, or other practical or economic reasons (such as the use of an existing vehicle chassis, motor, or other vehicle components), or we may simply know the optimal value of a given technical data. The design variables are categorized as mathematically continuous or discrete. It is usually easier to work with continuous design variables (since they can take any value in a given interval), but in certain situations (for example, if we need to select a rim for our car from the available sizes), you must use discrete design variables. In the intermediate case, when we know that we are looking for the value of a design variable in a discrete set containing a large number of elements (e.g., chain gear ratio selection), we talk about pseudo-discrete design variables. In this case, we solve the problem by considering the design variable to be continuous and then finding the most suitable discrete value closest to it. The given fixed values of the design variables and parameters define a possible vehicle construction. This construction may be suitable for the designer, or it may also be possible that it does not meet the functional or other requirements. The conditions that the given construction must meet are called optimization conditions. These can be, for example, geometric optimization conditions, such as the minimum and maximum required track or wheelbase of the race car, or conditions related to the technical implementation, such as the minimum number of sprocket teeth in a chain drive, below which the chain drive cannot work. A construction that satisfies all the optimization conditions is called a permissible construction. There are usually a large or infinite number of constructions that meet the optimization conditions. To select the optimal vehicle construction, we interpret an objective function on the set of design variables, the value of which is a quantity (metric) characteristic of the vehicle (for example, the time required to cover a given distance or reach a given speed, energy consumption, or top speed), based on which metric the designer prefers, one construction will be selected over another. In most cases, we formulate the optimization problem as the minimization of the objective function. The selection of the objective function has a significant effect on the whole optimization process, and thus, on the resulting optimal construction. We have the option of simultaneously interpreting several objective functions, but we recommend this only if the interpretation of one objective function is not sufficient and the objective functions do not contradict each other. The simulation program presented in Section 3 can be used for optimization purposes in two ways: firstly, it helps to design a new vehicle. In this first case, only certain technical data (design parameters) have a given fixed value, for example, satisfying the competition rules. For the other technical data (design variables) we must find the optimal values, which are the most suitable for the given competition task (e.g., 100 m drag race). Secondly, it helps to prepare an existing vehicle for a given competition task. In this second case, we can vary or adjust only a few of the vehicle's technical data. In both cases, using the simulation program and the optimization procedure, the possibility of successful racing can be significantly increased, and a lot of time and cost can be saved.