Path control method and apparatus

In a method wherein a path-controlled part is driven by a plurality of arms controlled in and defining a reference coordinate system in which points are designated by at least one angular quantity, a path control method comprising:

• providing a teach point information signal that represents teach points to define a path for the part;
• calculating through interpolation a main path point different from the teach points, from the teach point information signal, said teach points being expressed in a general purpose coordinate system different from said reference coordinate system;
• calculating a command signal representing the main path point expressed in the reference coordinate system from the main path point through a coordinate transformation;
• calculating in the reference coordinate system an order expressed in the reference coordinate system and defining a new point along the path from two of said signals that are expressed in the reference coordinate system by using only addition, subtraction, division and multiplication in the reference coordinate system through interpolation;
• sensing positional information about the arms;
• calculating differences between the order and the positional information;
• and
• driving the arms in response to signals expressive of the differences to move the path controlled part toward the new point designated by the order.

In an apparatus wherein a path-controlled part is driven by a plurality of arms controlled in and defining a reference coordinate system in which points are designated by at least one angular quantity, apparatus for driving a path-controlled part in the reference coordinate system comprising:

• means for providing a teach point information signal that represents teach points to define a path for the part;
• means for calculating a main path point different from the teach points, from the teach point information signal, said teach points being expressed in a general purpose coordinate system different from said reference coordinate system, for calculating a command signal representing the main path point expressed in the reference coordinate system from the main path point through a coordinate transformation, and for calculating in the reference coordinate system an order expressed in the reference coordinate system and defining a new point along the path from two of said signals;
• and
• means for driving the arms in response to said order.

In an apparatus wherein a path controlled part is driven by a plurality of arms controlled in and defining a reference coordinate system in which points are designated by at least one angular quantity, apparatus for driving a path-controlled part in the reference coordinate system comprising:

• means for providing a teach point information signal that represents teach points to define a path for the part;
• means for calculating through interpolation a main path point different from the teach points, from the teach point information signal, said teach points being expressed in a general purpose coordinate system different from said reference coordinate system, for calculating a command signal representing the main path point expressed in the reference coordinate system from the main path point through a coordinate transformation, and for calculating in the reference coordinate system an order expressed in the reference coordinate system and defining a new point along the path from two of said signals that are expressed in the reference coordinate system using only addition, subtraction, division and multiplication in the reference coordinate system through interpolation;
• means for sensing positional information about the arms;
• means for calculating differences between the order and the positional information;
• and
• means for driving the arms in response to signals expressive of the differences to move the path-controlled part toward the point represented by the order.