Abstract: A motor control method is disclosed in which a drive motor is connected to an adjustable frequency power supply in which the frequency of the power supplied to the motor can be selectively varied. While the motor is running at a constant speed as determined by the frequency of the power supplied to the motor, the value of the current being supplied to the motor by the power supply is sensed and an actual current signal representative of said actual current value is produced. A reference current signal which is representative of a selected maximum current value and thereby a maximum load at which the motor speed may be increased is also provided. The actual current signal is compared with the reference current signal and if the former is less than or equal to the latter, an output signal is provided. In response to the output signal resulting from the comparison, the value of the actual frequency of the power supplied to the motor is increased to a preselected value so that the motor speed also increases.

Abstract: An adjustable frequency motor drive system for a hoist is disclosed in which the frequency of the power supply to the motor can be selectively varied and the speed of the motor will follow the varying frequency at a slip speed relative to the frequency. The slip speed of the motor may not exceed a value beyond which the motor can control the hoist load. Accordingly, a frequency value based on the frequency of the power supply to the motor is selected as the frequency which is not to be exceeded by the motor speed expressed as a frequency. Signals representative of the actual motor speed and the selected frequency value are compared and, if the signal representative of the motor speed exceeds the signal representative of the frequency value which is not to be exceeded, an output signal is produced which may be used to apply a brake which stops and holds the motor and hoist and thereby maintains the load suspended.

Abstract: A hoist for raising and lowering objects with an apparatus for detecting mechanical overload of the hoist. The system provides a hoist having an alternating current motor connected to an alternating current power supply. The level of current of the power supplied to the motor is compared to a level of power indicative of a mechanical overload condition. If the current signal representative of the actual motor current level equals or exceeds the mechanical overload reference current then an overload output signal is provided.

Abstract: Hitherto, in the tension control for a reel, it is impossible to exceed the tension controlling range of about 1:10 which is determined by the tension controlling range of a single DC motor, so that for the reel which requires a tension controlling range over 1:10, a plurality of DC motors have been combined and used or a gear ratio between the reel and the DC motor has been changed for many years so far.In this invention an attention is paid to the fact such that the unpreferable phenomena such as a change in characteristic due to an armature reaction, and deterioration of rectification or the like which are caused by setting the field system to a low level can be fairly suppressed by limiting the setting and controlling range to a low region of an armature current.

Abstract: There is provided a thread cutting control method in an NC apparatus having a CPU in an arithmetic unit whereby real time clocks which are generated for every constant time are received as an interruption signal and a sampling operation is performed in response to the interruption signal, thereby controlling the feed system of a machine tool having a thread cutting function.

Abstract: A method of detecting and controlling a work start point of a robot of the teaching playback control type is disclosed. The robot has an interpolating function and responds to a position sensor, and a work tool is attached to the robot wrist to be accurately positioned to a work start point of a work object. A shadow of the work tool is produced by an illumination source. The work line of the object, the work tool, and the shadow thereof are image-recognized by a visual sensor. The visual sensor generates position correcting signals along the first and second correcting directions on the basis of the image recognized. The edge of the work tool is moved along the first correcting direction in response to a position correcting signal so as to reduce the distance between the work line and an edge of the work tool on the image recognized.

Abstract: The speed of a motor or a moving body driven by a motor is detected by interpolating by an estimated speed, the speed between pulse signals generated by a pulse generator. The estimated speed is obtained by updating a variable representing the torque disturbance obtained by compensating for a variable representing a motor torque by a variable representing a torque disturbance synchronously with a clock pulse of a predetermined interval, and the initial value of the estimated speed and a compensatory amount of the torque disturbance is updated each time the pulse generator generates a pulse. In the prior art, the mean speed of the present pulse signal section was regarded as the initial value in the immediately following pulse signal section, while in the present invention, the real (spontaneous) speed is obtained when the pulse generator generates a pulse signal, and this real speed is regarded as the initial value of the estimated speed of the immediately following pulse signal section.

Abstract: A servo motor control apparatus for a cutting machine comprises a position feedback loop, a speed feedback loop and a current feedback loop. A current command for the machine is preset to a voltage corresponding to a frictional torque when the motor starts rotation or changes rotating direction, in order to compensate for response lag of motor resulting from frictional torque. The response lag is improved and machining error is reduced by setting a value of a pertinent integral element in the controller comprising an integral element to zero. The sign of such value can be reversed at the moment that the motor operation start command or direction inversion command has changed to positive or negative from zero.

Abstract: Hitherto, in the tension control for a reel, it has been impossible to exceed the tension controlling range of about 1:10 which is determined by the tension controlling range of a single DC motor, so that for the reel which requires a tension controlling range over 1:10, a plurality of DC motors have been combined and used or the gear ratio between the reel and the DC motor has been changed to date.In this invention, attention is paid to the fact that undesirable phenomena such as a change in characteristic due to an armature reaction, and deterioration of rectification which are caused by setting the field system to a low level can be sufficiently suppressed by limiting the setting and controlling range to the low region of an armature current.

Abstract: A method of controlling a welding robot substantially comprises (i) teaching three points in the neighborhood of a teaching line to define a weaving pattern, and (ii) controlling three basic axes of a welding robot so that a welding torch tip of the robot moves on one of the surfaces of a triangular pillar formed by shifting a triangular plane defined by the above three points along the teaching line, while executing a weaving operation which is determined by a weaving amplitude, a weaving frequency, and a welding velocity. After continuing the above movement until the torch tip arrives at the end point of the teaching line, the weaving operation along the next teaching line is effected utilizing a new triangular plane which is formed by rotating the former triangular plane on an axis defined by the former teaching line and the next teaching line.

Abstract: A welding robot controlling method for controlling a welding robot having a welding torch which has a tip thereof directed toward a teaching direction and sensor which intermittently generates a locus correction signal for the tip of the welding torch, comprising, (1) giving the locus correction signal as a resultant vector of an arbitrary number of two-dimensional vectors on a plane which intersects a welding line direction, (2) correcting a locus by controlling the three basic axes of the robot in a direction of a resultant vector which is composed of a predetermined length vector of which direction is parallel to a line connecting two teaching points and which passes through a tip of the welding torch and the locus correction vector, when the locus correction signal is generated, (3) controlling the three basic axes of the robot such that the tip of welding torch moves on a line which is parallel to the line connecting the two teaching points, until a subsequent locus correction signal is again given after

Abstract: The present invention discloses a cable support which can assure smooth operation of an industrial robot. The cable support is substantially characterized by having a movable support on one end of an operating arm and an auxiliary support on the wrist-side end of the arm respectively, wherein the movable support consists of a first rotary shaft rotatably mounted on the operating arm, a slanted resilient support arm having the proximal end thereof rotatably mounted on the first rotary shaft, and a cable holder tiltably mounted on a second rotary shaft mounted on the slanted resilient support arm and the auxiliary support consists of a third rotary shaft mounted on the operating arm and a cable clamp rotatably mounted on the second rotary shaft.

Abstract: The present invention discloses a cable support which can assure smooth operation of an industrial robot. The cable support is substantially characterized by having a movable support on one end of an operating arm and an auxiliary support on the wrist-side end of the arm respectively, wherein the movable support consists of a first rotary shaft rotatably mounted on the operating arm and a cable holder tiltably mounted on the first rotary shaft and the auxiliary support consists of a second rotary shaft mounted on the operating arm and a cable clamp rotatably mounted on the second rotary shaft.

Abstract: This invention discloses an electric motor comprising a stator, a rotor disposed concentrically within the stator, a drive shaft rotatably supporting the rotor with a circular gap between the stator and rotor and an output shaft connected to the drive shaft and sharing the same rotating axis with the drive shaft, wherein the improvement is characterized in that the electric motor further includes a resilient connecting member which connects the drive shaft and the output shaft and means which detects the torsion of the resilient connecting member produced during the transmission of the torque from the rotor to the output shaft and measures the transmission torque from the detected torsion.

Abstract: A gas-filled switch with an improved arc extinguishing characteristics. Such gas-filled switch comprises a gas-filled casing, a pair of electrodes disposed in the casing, a conductive retaining ring which encircles at least one of the electrodes, a permanent magnet of a cylindrical configuration mounted in the retaining ring, a conductive cylindrical body disposed in one end opening of the retaining ring, and an arc-drive coil encircling the conductive cylindrical body and having one end connected to the conductive cylindrical body and other end connected to the electrode. Due to such construction, one root of an arc generated between the electrodes is moved from one electrode to the conductive cylindrical body so that the other root of the arc is subjected to the magnetic flux of the permamemt magnet while the previous one root of the arc is subjected to the magnetic flux of the arc-drive coil so as to extinguish the arc during the rotation of the arc.

Abstract: This invention discloses a contact sensing device for detecting the contact of a moving element such as a welding torch attached to a robot arm with a fixed body. The contact sensing device substantially comprises a support-side member, a work-side member, a spherical bearing mounted on either the support-side member or work-side member, a slide shaft slidably mounted on the spherical bearing, the slide shaft being slidable in an axial direction, an elastic member mounted on the slide shaft for making the work-side member biasingly come into contact with the support-side member, at least three rollers mounted on a first surface of either the support-side member or the work-side member, the rollers capable of coming into contact with a second surface of either the support-side member or the work-side member which opposes the first surface, at least one roller engaging member mounted on the second surface on which one of the rollers runs, and a limit switch actuated by the displacement of the slide shaft.

Abstract: An apparatus for controlling a DC motor driven screw feed which moves the table of a machine tool into prescribed positions including a plurality of limit switches which detect the position of the table, a rate change control circuit which receives signals from the limit switches and changes the rate of revolution of the DC motor when the table has reached prescribed rate change positions and a current limiting circuit which supplies the DC motor with a prescribed constant current and keeps the output torque of the DC motor at a prescribed level when the table has reached a prescribed dwell position.