**6. Trajectory Variation**

*6.1. Specificity of the Free-Piston Engine*

The free-piston engine allows the piston stroke to be adjusted in a highly dynamic manner so that different trajectories can be followed. For practical implementation, care must be taken that there are no discontinuities in the acceleration, as this on the one hand cannot be implemented and on the other hand represents a high load on the drive train. Furthermore, it is advantageous for the trajectory variation if it can be described analytically. Here, various parameters can be set that can specifically adapt the shape of the trajectory. In the following sections, various functions will be presented which allow the piston stroke course to be adjusted.
