Motor system, motor, and robot arm device comprising the same

A motor system, comprising a motor and a control unit, said motor comprising:

• a rack member provided with a periodic structure on a surface thereof, said periodic structure having a periodic arrangement of elements, wherein the rack member has a body with a substantially cylindrical shape with the periodic arrangement on a circumferential surface of said cylinder, said gear elements being distributed in a helical path around said cylindrical shape;
• a tooth member accommodating a set of multiple actuators, each of said actuators comprising an engaging element shaped for engaging a respective gear element and a drive unit for driving said engaging element to move back and forth with respect to said periodic structure, wherein each engaging element engages said respective gear element at least during part of its movement towards said respective gear element to cause a relative movement between said rack member and said tooth member, and wherein each of said actuators is positioned spaced apart to engage said periodic structure at a different wrapped phase thereof, wherein the tooth member comprises a housing provided with a circular opening for receiving at least part of said rack member, and wherein the set of actuators is arranged in a radial direction with respect to said rack member, wherein the arrangement of the engaging elements and the arrangement of the gear elements is configured to allow a simultaneous rotation and translation of the rack member relative to the housing;
• and
• wherein the control unit is configured for periodically controlling each drive unit of each actuator in the set of actuators to operate in a time-shifted manner with respect to each other to cause said simultaneous rotation and translation of the rack member.