Mobile, dexterous, social robots for mobile manipulation and human-robot interaction

A tractor 10 is disclosed for engaging and advancing a web of paper 20 by engaging a series of holes 21 along an edge of the paper 20. The tractor 10 includes a pair of parallel side plates 12, 14 and an elongated guide member 32 defining a continuous guide track 34. The guide member 32 is positioned between the side plates 12, 14 so as to define a continuous guide channel 36 in cooperation with the guide plates 12, 14. The tractor 10 also includes a drive belt assembly 22 comprising a continuous belt 62 carrying a plurality of spaced drive members 38 adapted to engage the holes 21 along the edge of the paper 20. A drive sprocket 33 located at one end of the guide channel 36 engages the drive members 38. Each guide member 38 has a hemicylindrically shaped base 64 with a notch 66 therein, thereby defining two parallel edges 67 which ride along the guide track 34. Additionally, each drive member 38 includes a drive pin 80, the profile of the surface of the drive pin 80 has the shape of a segment of an involute.