Matsushita Electric Industrial Co., Ltd.

Kenji Sogawa

Mikio Hasegawa

Makoto Doi

Akiyoshi Nakada

Toshitsugu Inoue

Yoichi Sugitomo

Toshihiro Ide

A robot control apparatus includes a sine wave signal-outputting device, an operating device, a command device for outputting a current value, a substracting device, an electric power amplifying device, and a programmable filter. The outputting device outputs sine wave signals of first and second phases having a phase difference of approximate 90.degree. generated by a position shift of a movable portion of a motor for driving an arm of a robot. The operating device determines the difference between a product of a value corresponding to the first phase signal and a value obtained by first-order differentiating a value corresponding to the second phase signal and a product of a value corresponding to the second phase signal and a value obtained by first-order differentiating the value corresponding to the first phase signal. The subtracting device subtracts the current value from the value outputted from the operating device based on the current value, and outputs a signal corresponding to a result the subtraction. The amplifying device outputs a signal to supply electric power to the motor in response to the signal outputted from the subtracting device. A filter operates as one of a high-pass and a band-pass filters according to the difference outputted from the command device, and is provided between the outputting device and the operating device and operates as a high-pass filter when the arm starts moving and the band-pass filter operates when the arm stops in contact with an object, and outputs a signal to the operating device.

Robot control apparatus

A direct-drive robot is controlled by a process in which a digital positional deviation value (between a command value and a value delivered from an encoder for detecting the motion of a movable part to be controlled in the robot) is increased or decreased in accordance with a result of comparison of the digital positional deviation value with a threshold value before the digital positional deviation value is converted to an analog value, and the analog value is then amplified by a gain depending upon the result of the comparison of the digital positional deviation with the threshold value. This enhances the servo rigidity, restrains slight vibrations during a stopping operation of the robot, and achieves smooth operation during a moving operation of the robot.

Robot control process

In an industrial robot including a control apparatus capable of executing control of the robot in a position control mode, a velocity control mode and a current control mode. The control apparatus includes a changeover section (20) for executing changeover between the position control mode and the current control mode. The position of an object is sensed by driving a set of arms of the robot in a force control mode which is a combination of the velocity control mode and the current control mode, and detecting the position at which the arms contact an object and are halted. Detection of the halted condition is performed based on a condition of an output signal produced from a position sensor (13), and by repetitively performing such detection for a plurality of different points on the body surface, a plurality of position values are derived which are compared with reference position data. Any change of the position of the object from a reference position is thereby computed by a computation section (24), whereby the robot itself is capable of sensing the position or attitude of an object, in 2 dimensions or 3 dimensions.

Industrial robot

An industrial robot includes a movable arm and an electric motor driving the arm. A current flowing through the motor is controlled so that the arm is moved into predetermined positions and is balanced in the predetermined positions sequentially. A device memorizes values of the motor current at which the arm is balanced in the respective predetermined positions. A target value of the motor current is calculated on the basis of the memorized motor current values. The target motor current value allows the arm to be balanced in a given position.

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Osaka, Japan

Kenji Sogawa