ORTHOGONAL CONTROL DEVICE

PURPOSE:To operate an arm until its becoming horizontal and in a line by discriminating a joint control range by calculating the arm tip position of an arm structure and respectively calculating an orthogonal control calculation outside the range and a joint control calculation within the range, in the title device for the arm position of a crane, etc. CONSTITUTION:A tip position calculation device 5 calculates the present value of the joint angle theta2 of a 2nd arm 2, the tip part 4 of the 2nd arm from the lengths of 1st and 2nd arms and the present distance l of the joint part 3 of the 1st arm 1. A joint control range discrimination device 6 then decides whether performing a joint control or orthogonal control from the calculation distance land a reference value. At the time when the present distance l is at more than the reference value the joint control is performed by a joint control calculation device 7 and in case of less than the reference value the orthogonal control is performed by an orthogonal control calculation device 8. With this structure the arm can be operated until becoming horizontal and in a line.