Robot calibration method and robot calibration device

1. A robot calibration method in which a position of an arm tip of an articulated robot comprising an arm having a plurality of links and a plurality of joint axes and a base which supports the arm via another joint axis is calibrated, the method comprising:

measuring a relative positional relationship between a first link and a second link on opposite ends of at least three links which are separated from the base and which are connected to each other so as to execute collective calibration for at least two joint axes between the at least three links;

measuring a relative positional relationship between the base and a link connected to the base to execute independent calibration for a joint axis between the base and the link, or measuring a relative positional relationship between the first link and another link connected to the at least three links so as to execute independent calibration for a joint axis between the first link and the other link; and

calibrating the position of the arm tip based on the collective calibration and the independent calibration.

2. The robot calibration method according to claim 1 , wherein the at least two joint axes for which the collective calibration is executed include a linear motion axis.

3. The robot calibration method according to claim 1 , wherein the collective calibration is executed by contact-measuring, with a gauge, relative positions and relative postures between a first reference surface defined on the first link and a second reference surface defined on the second link.

4. A robot calibration device which calibrates a position of an arm tip of an articulated robot comprising an arm having a plurality of links and a plurality of joint axes and a base which supports the arm via another joint axis, the device comprising:

a first reference surface and a second reference surface which are provided on a first link and a second link, respectively, on opposite ends of at least three links which are separated from the base and which are connected to each other;

a gauge which contact-measures relative positions and relative postures between the first reference surface and the second reference surface;

a measuring instrument which measures a relative positional relationship between the base and a link connected to the base, or a measuring instrument which measures a relative positional relationship between the first link and another link connected to the at least three links; and

a processor which calibrates the position of the arm tip based on measurement results of the gauge and measurement results of the measuring instrument.

5. The robot calibration device according to claim 4 , wherein at least two joint axes between the at least three links include a linear motion axis.

6. The robot calibration device according to claim 4 , further comprising a first member attached to the first reference surface and a second member attached to the second reference surface, wherein the gauge is attached to the first member and measures a position and posture of the second member relative to the first member.

7. The robot calibration device according to claim 6 , wherein the first member includes a pair of gauge attachment surfaces which are orthogonal to each other, and the second member includes a pair of gauge measurement surfaces which are orthogonal to each other and which respectively face the pair of gauge attachment surfaces.