DENSO WAVE INCORPORATED

A three dimensional measurement system has a measurement unit that images the measuring object and that has a light projecting device projecting projected light onto the measuring object and a light receiving device receiving the reflected light. The system has a specular reflection member that forms a mounting surface for mounting the measuring object and reflects projected light at a specific angle. The system has a data acquisition unit that acquires imaging data and a coordinate calculation unit that calculates three dimensional coordinates for the part of the imaging data whose brightness is higher than the lower limit brightness and does not calculate three dimensional coordinates for the part whose brightness is lower than the lower limit brightness. The light receiving device is arranged at a position where the brightness of the part where the specular reflection member is imaged is lower than the lower limit brightness.

There is provided a method and an apparatus for controlling a robot arm. In this control scheme, a position error indicating a deviation between a command position, which is a control target position, and a current position, which is a position where the arm of the robot is currently located, is acquired. When the acquired position error exceeds a threshold, a new corrected command position between the current position and the command position is set. After the arm of the robot is moved to the corrected command position, a new corrected command position reset between the corrected command position serving as a new current position and the command position. Reconfiguration of a corrected command position is iterated until a current position of the robot arm becomes equal to the command position so that movement of the robot arm is achieved from the current position to the command position.

An speed detection apparatus of a rotational shaft in a robot arm that is applied to a drive mechanism is provided. The speed detection apparatus includes: first and second rotation sensors that are disposed on a side of a rotational shaft of the robot arm and outputs first and second rotational position signals with a phase difference of 90 degrees; first and second differentiators that differentiate the first and second rotational position signals; and a speed calculator that obtains a rotational speed of the robot arm by calculating a sum of squares of a first differential signal and a second differential signal.

A position of gravity of center of a load loaded to an industrial load is estimated. The robot has a robot arm driven horizontally. The robot arm includes first to fourth axis. Acceleration generated at the second axis during accelerated and decelerated intervals of each of three operation periods. In each operation period, the second axis is driven to move the robot arm from one initial position to one first estimating position and returns it from the estimating position to the initial position. During each operation period, the load is given a known mass, the fourth axis is positioned at a preset angle, and the first, third and fourth axes are the same in positions between the initial and estimating positions. The fourth-axis position is changed to different angles for every operation period. Based on calculated acceleration and known factors of the robot and load, the position is estimated.

In an eccentricity error correction method for an angle detector, an output shaft angle is determined in at least three measurement positions. A difference between an arm angle value at each measurement position and the output shaft angle detected at each measurement position is determined as an eccentricity error. An error curve indicates a relationship between the arm angle value and the eccentricity error, and is determined as a function of the arm angle value by approximating the eccentricity error at each measurement position with a sine wave of which a single cycle is a single rotation of the arm. A correction formula that associates the output shaft angle and the arm angle value is determined using the error curve. A correction value corresponds to the detected output shaft angle, and is determined based on the correction formula and correcting the eccentricity error when the arm is rotated.