*5.3. Test Bench*

A low-impact velocity pendulum test bench is designed to test the sensors as it offers flexibility to change the parameters (Figure 8). It consists of a 2.03 m swinging arm and a human head-form of diameter 150 mm. The standard head mass of 4.5 kg is scaled in this work to 6.81 kg to increase the force. A 5 mm thick rubber sheet is glued to the head to damp the vibrations. Further, a thin aluminum sheet is attached to make the head conductive. The airbag is mounted rigidly and kept inflated. The measurement system (Table 1) includes a standard rotary encoder, an airbag pressure sensor and two high-speed cameras.

A conducting thread provides electrical contact between the pendulum head and the human body to simulate actual human body capacitance, which is kept constant throughout the calibration and testing.

**Figure 8.** Low-impact velocity pendulum test bench.


**Table 1.** Instrumentation.

*<sup>a</sup>* Frames per second.
