*5.2. Experimental Results*

In order to validate the simulation results, experiments have been done using a two-coil reluctance coil gun corresponding to the optimal configuration (as explained in Section 5.1). This launcher is shown in Figure 29. It is part of our new RoboCup robot presented in Figure 30.

**Figure 29.** 2 coils optimized reluctance coil gun.

**Figure 30.** RoboCup robot for testing the optimized coil gun.

A custom four-channel coil gun driver has been designed but is not in the scope of this paper. It includes four MOSFET for capacitor commutation with a 160 A current peak under 450 V on each coil. A safety system for dissipating energy stored in the capacitors when the system is switched off or stopped has been implemented in this driver, justifying the aluminium ventilated power heat sink that can be seen on the right board of Figure 31. For triggering the coils in a very accurate time sequence

(and for controlling DC motors and low level sensors), a micro-controller board has been designed and can be seen on the left side of Figure 31. In our test corresponding to the chosen optimal case, the second coil has been triggered exactly 10 ms after the first one.

**Figure 31.** Four-channel reluctance coil gun driver (on the right).

Ball speed measurements have been done using a high speed camera on 20 successive tests. Average measured ball velocity is equal to *VBall* = 15.5 m·s−1. This is consistent with the theoretical value (16 m·s<sup>−</sup>1). Error is only 3.1% and dispersion is low (*<sup>σ</sup>* = 0.2 m·s<sup>−</sup>1). These results show that the simulation model used in this paper is accurate, despite many strongly non-linear effects, and that the structure of a reluctance coil gun can be optimized very efficiently without changing the amount of copper used and the size of the actuator.
