Patent ID: 6301522
Filing Date: 2001-10-09
Classification: B65H,G07B

Abstract:
A method for creating a motion profile used in controlling motion of an axis of a motor in a mailing machine, the motion profile expressing the motion of the axis in terms of a motion variable having a value depending on time, the motion profile consisting of a finite number of segments, the motion repeating after the motion prescribed in the finite number of segments is performed, the motion prescribed only at predetermined values of time separated by a loop closure period and measured from a starting time corresponding to a trigger event, the method comprising the steps of:a) if absolute mechanical positional synchronism with respect to motion of another axis is not required and a quick step move is not needed, determining position and velocity after each loop closure period by forward integrating over time from starting values of jerk, acceleration, velocity and position of the axis to be controlled;b) if absolute mechanical positional synchronism with respect to another axis is required and a quick step move is not needed, determining position after each loop closure period by performing a displacement mapping having an input selected from the group consisting of actual position of a reference axis and commanded position of a reference axis, wherein the displacement mapping is a non-parabolic function of the commanded or actual position of the reference axis;c) if a quick step is needed and absolute mechanical positional synchronism with respect to motion of another motor is not required, determining position of the axis to be controlled after each loop closure period based on a parabolic velocity equation, having as inputs a step time and a step value, wherein in performing a quick step without regard for absolute mechanical positional synchronism with respect to motion of another axis, the predetermined parabolic equation in time is:V.sub.i =6S(t.sub.s -t)/t.sub.s.sup.3,where i is a counter restarting from some starting value at the beginning of each segment, where t.sub.s is the step time, and where S is the step value, and further wherein the velocity so calculated is used to determine the position of the axis to be controlled according to the equation:P.sub.i =P.sub.i-1 +V.sub.i,where V.sub.i is the velocity of the axis to be controlled at the time indicated by the counter i; andd) if a quick step is needed and absolute mechanical positional synchronism with respect to motion of another motor is required, determining position of the axis to be controlled after each loop closure period by a displacement mapping having an input selected from the group consisting of actual position of a reference axis and commanded position of a reference axis, wherein the displacement mapping is a parabolic function of the commanded or actual position of the reference axis.