Methods of and system for swing damping movement of suspended objects

An apparatus for damping initial or residual swing of a load suspended by a flexible cable from a horizontally moving trolley controlled by a controller in which forces exerted on the trolley by the motion of the suspended load are used to provide a position error signal, the apparatus comprising:

• means for sensing forces on point of suspension of the load and providing an output indicative of the sensed forces;
• means for subtracting the sensed forces from desired forces to generate a force error;
• means for multiplying the force-error by a damping factor to create a force-position error;
• means for maintaining the accumulation deviations of position from a desired position;
• means for multiplying the accumulation deviation of position by a damping factor;
• means for summing the force-position error with the damped accumulated position error;
• and
• means for transmitting the summed-damped errors to the controller of the trolley.

A method of swing damping the movement of an object suspended from a horizontally movable trolley, wherein the trolley moves the object from a first position to a second position, the method comprising the steps of:

• accelerating the trolley with non-uniform acceleration until the trolley reaches preplanned velocity and then decelerating the trolley at a non-uniform deceleration until the trolley stops at the second position;
• damping the motion of the load if the load is not initially at rest by sensing forces exerted by the load on the hoist with a force sensor;
• summing the output of the force sensor with a desired force and multiplying the result by force following gains to obtain a force following component of robot movement;
• and
• summing the programmable component of robot movement with position updates and passing the result through a line tracker which updates the input from the force sensor while providing output from the force control computer to a trajectory generator, the output of which operates the robot position controller according to a selected acceleration profile which includes empirical inputs from the force sensor.

A method of swing damping movement of a load suspended from a gantry which translates in a horizontal direction, wherein the gantry is controlled by a robot position controller which sums the actual position of the gantry with the desired position of the gantry to produce a position error signal, which position error signal is summed with a negative velocity until the output is zero which causes the gantry to stop, the method comprising:

• sensing dynamic forces on the load due to initial swinging of the load and providing an output indicative of the sensed forces;
• subtracting the output from the force sensor from a desired force of input to generate a force error expressed as a force position error;
• subtracting the force position error from an actual position update input from which a running total of position increments has been subtracted to produce the position increments;
• feeding the position increment signals through a line tracker, which line tracker periodically updates the aforerecited steps, and
• applying the output of the line tracker to trajectory generator in the robot position controller which trajectory generator subtracts the line tracker signal from a desired position signal so as to provide a position error signal which includes a component indicative of the sensed dynamic forces.

A system for swing damping movement of a load suspended from a gantry which translates in horizontal directions, wherein the gantry is controlled by a robot position controller which sums the actual position of the gantry with the desired position of the qantry to produce a position error signal, which position error signal is modified by the output of a trajectory generator which has as an input a desired position signal, the position error signal being summed with a negative velocity signal until the output is zero which causes the gantry to stop, the system comprising:

• force sensing means for sensing dynamic forces on the load due to initial swinging of the load and providing an output indicative of the sensed forces;
• means for subtracting the output from the force sensing means from a desired input force to generate a force error expressed as a force position error;
• means for feeding an actual position signal to a position update summer;
• means for totalizing a running total of position increments;
• means for subtracting the force position error from an actual position update input from which the running total of position increments has been subtracted to produce the position increment signals;
• a line tracker for periodically updating the position of the load;
• means for feeding the position increment signals through the line tracker, and
• means for applying the output of the line tracker to the trajectory generator in the robot position controller which trajectory generator subtracts the line tracker signal from a desired position signal so as to provide a position error signal which includes a component indicative of the sensed dynamic forces.