Arc Linear Motors for Direct Drive Robots: Galileo Sphere

This paper presents the design of an arc linear motor for a new type of robot, named Galileo Sphere, based on direct drive technology for pick and place operations. Pick and place robots require high dynamics and position accuracy and repeatability. A classical implementation is based on rotating electric machines with reduction gearboxes and kinematic mechanisms that convert the rotating motion to linear where necessary. The direct drive technology reduce mechanical losses, backlash, MTBF and a number of components. This technology also achieves higher dynamic and accuracy. The robot has a polar-like configuration with 5 degree of freedom. A dynamical simulator was used to assess motors, that satisfies a typical pick and place trajectory with the different payload. The proposed solution resulted feasible, even at high working frequencies and with payloads up to 4 kg. The precision and repeatability remained high, within 100 mum. The working is a spherical sector with 1870 mm maximum diameter, and 450 mm vertical reach.