This paper presents a piezoelectric rotational energy harvester based on the frequency up-conversion principle and building on the findings from a previously introduced device. The prototype is capable of converting the low frequency and random motion from the human body into a much higher transducer frequency, which increases conversion effectiveness. Design changes, such as using longer and thinner piezoelectric bending beams, have lead to a vast improvement in the achieved output voltage. The beams now experience a clean ring-down after an initial deflection. Furthermore, a custom made linear shaking system for reproducing human motion in a laboratory environment is shown. The results obtained prove successful frequency up-conversion and electrical damping. A maximum power output of 28 micro watts was achieved when the internal rotor went into continuous rotation.