Robot apparatus, and measuring method of rotation driving apparatus

1. A robot apparatus which drives a joint by a controlling apparatus, wherein:

the joint comprises:

a rotation driving source,

a transmission configured to change driving of the rotation driving source,

a first angle sensor configured to detect a rotation angle of a rotation shaft of the rotation driving source, and

a second angle sensor configured to detect a rotation angle of an output shaft of the transmission; and

the controlling apparatus is configured to obtain output values of the first and second angle sensors by driving the rotation driving source and driving the joint via the transmission in an orientation of the robot apparatus by which a gravity moment acting on the joint is smaller than driving resistance of the joint, and to calculate an angular difference between a predetermined angle and the rotation angle of the output shaft of the transmission based on the obtained output values of the first and second angle sensors.

2. The robot apparatus according to claim 1 , wherein the controlling apparatus is further configured to, before driving the rotation driving source and driving the joint via the transmission in the orientation of the robot apparatus by which the gravity moment acting on the joint is smaller than the driving resistance of the joint, drive the joint in a direction opposite to a driving direction of the joint and move gears of the transmission to one side.

3. The robot apparatus according to claim 1 , wherein the controlling apparatus is further configured to, when driving the rotation driving source and driving the joint via the transmission in the orientation of the robot apparatus by which the gravity moment acting on the joint is smaller than the driving resistance of the joint, drive the joint by a rotation angle larger than a past-calculated angular difference of the transmission.

4. The robot apparatus according to claim 1 , wherein the predetermined angle is an ideal value of the rotation angle of the output shaft of the transmission, which is calculated based on the output value of the first angle sensor and a transmission ratio of the transmission.

5. The robot apparatus according to claim 1 , wherein the controlling apparatus is further configured to stop the joint at an arbitrary position, and, when the output values of the first and second angle sensors do not change before and after the stop, to decide the orientation at the joint stop position as the orientation of the robot apparatus by which the gravity moment acting on the joins is smaller than the driving resistance of the joint.

6. The robot apparatus according to claim 5 , wherein the controlling apparatus is further configured to control the orientation by controlling the robot apparatus such that the gravity moment acting on the joint becomes approximately constant.

7. The robot apparatus according to claim 5 , wherein the controlling apparatus is further configured to control the orientation by controlling the robot apparatus such that a gravity center of the robot apparatus to be driven approximately coincides with a vertical axis passing through a joint axis of the joint.

8. The robot apparatus according to claim 7 , wherein

the controlling apparatus is further configured to detect, by using a gravity sensor arranged on a base of the robot apparatus, an orientation of the base to a vertical axis, and

the controlling apparatus is further configured to control a position of a link such that the gravity center of the link approximately coincides with the vertical axis passing through the joint axis of the joint, based on the detected orientation of the base to the vertical axis.

9. The robot apparatus according to claim 1 , wherein

the controlling apparatus is further configured to control a driving direction of the rotation driving source so as to generate an overshoot section in which, by mass of a link driven by the joint, the joint operates by a certain angle in an opposite direction of the gravity moment acting on the joint, and

the controlling apparatus is further configured to obtain the output values of the first and second angle sensors in the overshoot section.

10. The robot apparatus according to claim 1 , wherein the controlling apparatus is further configured to detect a state of the transmission from the calculated angular difference and to notify a user of the detected state.

11. The robot apparatus according to claim 1 , wherein

the robot apparatus is configured to have an inspection mode, and

the controlling apparatus is configured to operate in the inspection mode.

12. The robot apparatus according to claim 1 , wherein the controlling apparatus is configured to operate the robot apparatus based on a robot program in which a joint driving period has been set previously, and obtain the output values of the first and second angle sensors in the joint driving period.

13. The robot apparatus according to claim 1 , wherein the controlling apparatus is further configured to calculate the magnitude of the angular difference from the obtained output values, compare the angular difference with a predetermined threshold, and diagnose a lifetime of the transmission based on a result of the comparison.

14. The robot apparatus according to claim 1 , wherein

the controlling apparatus is further configured to calculate the magnitude of the angular difference of the transmission from the obtained output values,

the controlling apparatus further comprises a storing unit configured to store the angular difference, and

the controlling apparatus is further configured to predict a life expectancy of the robot apparatus based on the angular difference stored in the storing unit.

15. A controlling method of a robot apparatus which comprises a joint having a rotation driving source, a transmission configured to change driving of the rotation driving source, a first angle sensor configured to detect a rotation angle of a rotation shaft of the rotation driving source, and a second angle sensor configured to detect a rotation angle of an output shaft of the transmission, the controlling method comprising:

obtaining, by a controlling apparatus, output values of the first and second angle sensors by driving the rotation driving source and driving the joint via the transmission in an orientation of the robot apparatus by which a gravity moment acting on the joint is smaller than driving resistance of the joint; and

calculating, by the controlling apparatus, an angular difference between a predetermined angle and the rotation angle of the output shaft of the transmission based on the obtained output values of the first and second angle sensors.

16. A non-transitory computer-readable storage medium which stores a control program for performing a controlling method of a robot apparatus which comprises a joint having a rotation driving source, a transmission configured to change driving of the rotation driving source, a first angle sensor configured to detect a rotation angle of a rotation shaft of the rotation driving source, and a second angle sensor configured to detect a rotation angle of an output shaft of the transmission, the controlling program comprising:

code for obtaining, by a controlling apparatus, output values of the first and second angle sensors by driving the rotation driving source and driving the joint via the transmission in an orientation of the robot apparatus by which a gravity moment acting on the joint is smaller than driving resistance of the joint; and

code for calculating, by the controlling apparatus, an angular difference between a predetermined angle and the rotation angle of the output shaft of the transmission based on the obtained output values of the first and second angle sensors.

17. A controlling apparatus which controls a robot apparatus which comprises a joint having a rotation driving source, a transmission configured to change driving of the rotation driving source, a first angle sensor configured to detect a rotation angle of a rotation shaft of the rotation driving source, and a second angle sensor configured to detect a rotation angle of an output shaft of the transmission, wherein

the controlling apparatus is configured to obtain output values of the first and second angle sensors by driving the rotation driving source and driving the joint via the transmission in an orientation of the robot apparatus by which a gravity moment acting on the joint is smaller than driving resistance of the joint, and

the controlling apparatus is configured to calculate an angular difference between a predetermined angle and the rotation angle of the output shaft of the transmission based on the obtained output values of the first and second angle sensors.