Having a hand that is capable of producing a suitable variety of timbres does not ensure that you will actually *get* a suitable variety of timbres, because you also have to drive the hand into the drumhead in a suitable variety of ways. Most of the percussion robots that I have seen either just have one degree of freedom to strike the drum, or sometimes an additional second degree of freedom to move that hand closer to or further away from the center of the drum. But again, if you watch how humans play you will see that they also manipulate the angle at which they strike the drum. This implies that you need a third degree of freedom at least.