Robot apparatus and robot controlling method

A robot controlling method for drive-controlling a multi-articulated robot including a plurality of rotational joints, based on an input motion command, the method comprising:

• computing, by a controlling unit, a joint angle command of each of the plurality of rotational joints, wherein the joint angle command is used for driving the multi-articulated robot based on the motion command;
• moving, by the controlling unit, the multi-articulated robot by rotationally driving each of the plurality of rotational joints based on the joint angle command;
• calculating, by the controlling unit, one of a singular point angle and a singular point distance of each of the plurality of rotational joints to a singular point of the multi-articulated robot;
• and
• limiting, by the controlling unit, a rotation speed of a rotational joint specified in advance based on a type of the singular point when the one of the singular point angle and the singular point distance becomes smaller than a predetermined value,
• wherein computing the joint angle command includes:
• calculating a position command based on the motion command;
• calculating a correction rate that is a rate of correction according to the one of the singular point angle and the singular point distance;
• correcting the position command by adding a product of a previous correction amount and the correction rate;
• performing inverse kinematics calculation by transforming the position command into a tentative joint angle command;
• calculating a next joint angle command by calculating a joint angle deviation from the tentative joint angle command and a previous joint angle command, and making the tentative joint angle command smaller such that the joint angle deviation does not exceed the rotation speed;
• performing a forward kinematics calculation by calculating a next position from the next joint angle command;
• and
• calculating a next correction amount by adding the previous correction amount to a difference between the next position and the position command.

A robot apparatus comprising:

• a multi-articulated robot including a plurality of rotational joints;
• and
• a controlling apparatus that drive-controls the multi-articulated robot based on an input motion command,
• wherein the controlling apparatus includes:
• a joint angle computing unit that computes a joint angle command of each of the plurality of rotational joints for driving the multi-articulated robot based on the motion command;
• wherein the joint angle computing unit includes:
• a position command calculating unit that calculates a position and a deviation obtained from a position command based on the joint angle command;
• a position command correcting unit that corrects the position command by a correction value obtained from an angle of a particular rotational joint to the one of a singular point or a distance to the singular point;
• and
• a joint angle correction unit that obtains a next joint angle command from the corrected position command.

An article manufacturing method characterized by manufacturing articles using a robot apparatus comprising:

• a multi-articulated robot including a plurality of rotational joints;
• and
• a controlling apparatus that drive-controls the multi-articulated robot based on an input motion command,
• wherein the controlling apparatus includes:
• a joint angle computing unit that computes a joint angle command of each of the plurality of rotational joints for driving the multi-articulated robot based on the motion command;
• wherein the joint angle computing unit includes:
• a position command calculating unit that calculates a position and a deviation obtained from a position command based on the joint angle command;
• a position command correcting unit that corrects the position command by a correction value obtained from an angle of a particular rotational joint to the one of a singular point or a distance to the singular point;
• and
• a joint angle correction unit that obtains a next joint angle command from the corrected position command.

A robot controlling method for drive-controlling a multi-articulated robot including a plurality of rotational joints, based on an input motion command, the method comprising:

• computing, by a controlling unit, a joint angle command of each of the plurality of rotational joints, wherein the joint angle command is used for driving the multi-articulated robot based on the motion command;
• wherein computing the joint angle command includes:
• calculating a position and a deviation obtained from a position command based on the joint angle command;
• correcting the position command by a correction value obtained from an angle of a particular rotational joint to the one of a singular point or a distance to the singular point;
• and
• obtaining a next joint angle command from the corrected position command.

A non-transitory computer-readable recording medium on which is recorded a next joint angle command obtained by using a robot controlling method for drive-controlling a multi-articulated robot including a plurality of rotational joints, based on an input motion command, the method comprising:

• computing, by a controlling unit, a joint angle command of each of the plurality of rotational joints, wherein the joint angle command is used for driving the multi-articulated robot based on the motion command;
• wherein computing the joint angle command includes:
• calculating a position and a deviation obtained from a position command based on the joint angle command;
• correcting the position command by a correction value obtained from an angle of a particular rotational joint to the one of a singular point or a distance to the singular point;
• and
• obtaining the next joint angle command from the corrected position command.