This rotational motion is treated as a separate axis for one of the gantry configurations described here. Alternatively, it may be set to zero within the gantry algorithm for linear motion. Frequently, gantries also incorporate a transverse axis, which allows X-Y placement of the supported payload. Consequently, a transverse axis may result in a dynamic center of mass for the gantry axis. In this situation, the gantry axis motion at high acceleration rates induces significant moments (twisting) about the yaw axis. These moments depend on the linear acceleration rate and the transverse position of the crossaxis mass. A gantry configuration with 2 motors and a minimum of 2 encoders has the inherent advantage of providing 2 control loops which can actively resist moments (twisting) about the yaw axis.