Abstract: An automated order fulfillment system and mobile robot are disclosed, where the mobile robot includes a compliant drive for moving between levels of a multilevel storage structure. In one example, the compliant drive comprises a drive shaft having splines configured to provide rotational play that prevents jamming of a vertical drive gear on the end of the shaft with a rack in a vertical track.

Abstract: A tie tack for flexibly securing a four-in-hand neck tie to the shirt of the wearer. The tie tack has a cross-bar member for inserting into the button hole of a shirt for securing the tack thereto. A flexible thread extends between the cross-bar and a releasable fastener. A second releasable fastener is adhesively attached to the back surface of the tie adjacent the wearer. The fasteners are of the hook and loop variety with one being a hook type and the other the loop type. When the tie includes a loop, label or such that allows the small back portion of the tie to pass therethrough for securing the two portions together, the fastener is attached to the back surface thereof.