Abstract: A non-cutting tool or stylus (32), mounted in a position where a tool normally resides on a turret (26) of a numerically controlled machining system, rubs against the workpiece (41) as it rotates. The rubbing vibrations emanating from the workpiece (41) are picked up as a touch signal by an accelerometer (62) whose output signal is conditioned and fed to the numerical control (46). Diameter measurements, for example, are made directly by touching two opposing points on the workpiece (41) on opposite sides of the machine centerline (14) whereupon a difference calculation is made to provide the required diameter measurement.

Abstract: A reference post assembly (50) directly mounted on a numerically controlled machining system such as a lathe obviates the need for a datum ring including reference datum surfaces (42,44) and being conventionally provided on the external cylindrical surface and face of a chuck (36) which holds the workpiece (41) being machined. The reference post assembly (50) is comprised of an elongated reference post member (52) of selected cross section, i.e., square or round, which is resiliently mounted on the lathe in a known calibrated position with respect to the workpiece (41). The post (52) is ultrasonically vibrated in a longitudinal mode by one or more piezoelectric elements (54) coupled to an electrical signal oscillator (56).

Abstract: The invention disclosed provides a control system for an electric vehicle which automatically slows the vehicle during a turn and causes it to be increasingly slowed as the sharpness of the turn increases. The invention includes means for regulating the field excitation in accordance with a field regulating signal; means providing an armature current indicative signal; means providing a turning angle signal which is indicative of the turning angle of the vehicle; and a field excitation selector which receives the armature current indicative signal and the turning angle signal and then selects one or the other or a minimum reference value as the field regulating signal. The signal which produces the maximum field excitation is thus automatically selected. If a turning maneuver is being carried out, the turning angle signal increases until, at some point, the field excitation becomes a function of the steering angle and the vehicle is then automatically slowed as a function of the sharpness of the turn.

Abstract: A two-stage electrical braking system for a variable speed alternating current induction motor powered from a variable frequency, variable voltage power source utilizes capacitance connected across a primary winding of the motor in a first stage of braking and short-circuits the primary winding in a second braking stage. The system is arranged such that the control of the two braking stages is independent of the motor terminal voltage and braking can be initiated by either a braking command or automatically upon interruption of power to the system. The control system uses a fixed time delay to initiate the second stage of braking a predetermined time interval after the first stage is initiated.

Abstract: A method for operating a computer controlled industrial machine in which a plurality of axes of motion are independently controlled. The method utilizes programmable data processors to enable the production of motion command signals to the servo drives of the machine. In one embodiment, coordinated motion of several axes is attained by programmably grouping axes into motion groups. Each motion group has an assigned master processor which coordinates the operation of all axis processors in that group. The axis processors can be re-assigned to any other motion group while a programmed motion is being performed.

Abstract: A bidirectional communications link, termed a customization window, comprises a series of routines including functions, procedures and status flags implemented in software, interfaced between a machine control logic (MCL) operating to control the auxiliary functions of a computerized numerical control (CNC) system and a numerical control (NC) operating to control the multi-axis motions of the system whereby the MCL, implemented in software, can access the NC, also implemented in software, and control the system but only under conditions dictated by the NC and enforced by the routines of the customization window so that, for example, the integrity of the NC software will not be compromised by any of the MCL software which is of a user programmable type. Additionally, machine setup data and the availability of optional system control features are routed from the NC to the MCL through the customization window.

Abstract: A method for operating a computer controlled industrial machine, such as a lathe, in which a machining operation can be interrupted, a tool displaced from a workpiece and the operation subsequently resumed at the point of interruption. The method includes provision for interrupting canned cycles, such as threadcutting cycles on a lathe, in a manner to prevent damage to any previously cut threads. In one embodiment, the method provides for retrace of prior machining operations before resuming the interrupted operation.

Abstract: The invention disclosed is a control system for controlling a pair of separately excited motors arranged such that each motor of the pair drives a separate wheel on a common axle of an electrically powered vehicle. The control system continuously and individually adjusts the field excitation of the drive motors so that torque and speed of the separate wheels are apportioned to the wheels as a function of the steering angle of the vehicle.

Abstract: A method and apparatus are disclosed for providing very precise incremental motion of a numerically controlled machine tool, or other similarly controlled object, along a circularly arced path. For a mutually perpendicular X and Y coordinate system, X and Y indices are determined based on certain prescribed input information related to the parameters of the circular path and the relative rate of motion between the machine tool and the workpiece, and on immediate, continuously recomputed, coordinates of the tool or object. The indices are each scaled by a modulus related to the radius of the arc to generate incremental distances .DELTA.X and .DELTA.Y according to which the next move is to be made. The process is reiterated until the desired circular path is complete. In both method and apparatus, only integer values of .DELTA.X and .DELTA.Y are used for implementing each increment of motion. Non-integer values are carried forward to the next iteration of the process to prevent error accumulation.

Abstract: A method for preventing interference between relatively moveable components of a computer controlled industrial machine in which the position of the moveable machine elements are controlled by a computer program. For each movement, the computer first determines a predicted path for the movement and thereafter determines whether the path will intersect a safe zone, a safe zone being defined as a zone containing an element which is to be protected from contact with the moveable element. If a predicted path intersects a safe zone, the machine operation is halted. Provision is made for manual moves, i.e., movements not directed by the computer up to the nearest intersection point with a safe zone.

Abstract: An electrical braking control circuit for use in a control system for a direct current traction motor which may be employed, for example, to propel an electrically driven vehicle. The electrical braking controller of the invention initiates electrical braking in a plug mode of braking and then, when conditions are suitable for regenerative braking, causes a transition to regenerative braking, followed by return to a plug mode of braking whenever regenerative braking can no longer be efficiently achieved, all of which is carried out smoothly and efficiently without unduly wasting regenerative power.

Abstract: A method and apparatus by which the output value of a resolver position detection system is compensated for systematic phase shift errors produced by signal conditioning circuitry through which the signal passes.

Abstract: A plug current regulator for a dc electric traction motor propelled vehicle, implemented using a microcomputer for controlling a time-ratio switching regulator, provides a substantially smooth electrical braking function by applying relatively short time duration current pulses to build up braking current, followed by a relatively long time duration in which current pulses are inhibited. Current regulation is provided by comparing motor current to a desired braking current and generating an update signal when actual current drops below desired current. Filtering is minimized by sampling motor current at a time interval occurring relatively long after a current pulse is supplied to the motor.

Abstract: A transistor fault indicator circuit monitors the conduction state of a transistor and compares that state to a commanded state. Differences in states are treated as faults and actuate an alarm or shut down the system including the transistor. In systems in which the transistor may be operated in a continuous conduction mode for long time periods, a control circuit is provided to periodically short circuit the base-emitter bias of the transistor to force a momentary period of nonconduction during which time the proper operation of the transistor can be verified.

Abstract: Overcurrent protection is obtained in a push-pull network by circuitry repeatedly comparing signals indicative of the instantaneous current flow through the push-pull switching elements with a synchronized reference signal whose value is preferably made to decline during the ON periods of the current switches. Thus, the reference signal may initially be set relatively high to accommodate a moderately high in-rush transient and then to decline to lower levels over the remainder of the time the switching elements are on. At any time that the current signals exceed the compared to reference value, the corresponding current switch is deactivated as a protective measure.

Abstract: An electromagnetic contactor is provided with a flux sensing device, preferably a Hall effect sensor, mounted in its magnetic circuit. The magnetic circuit includes an air gap within which the flux sensing device is mounted. The air gap can be adjusted to control the percent of magnetic flux impinging on the flux sensing device whereby a signal can be taken from the device indicative of the magnitude of flux in the magnetic circuit. The signal can be used to control electrical excitation of the contactor at a predetermined flux level.

Abstract: A fault detection and inhibit circuit for a power control unit in an electric traction motor propelled vehicle of the type wherein the power control unit includes a chopper circuit and a bypass contactor for shunting the chopper circuit when its percent conduction exceeds a relatively high value and a main contactor for connecting the chopper circuit and motor to a power source. The circuit assures that neither the main contactor, the bypass contactor nor the chopper circuit are in a shorted condition before permitting the application of power to the system. In the event of a running failure, the circuit prevents restarting until the failed condition has recovered.

Abstract: A load commutated inverter synchronous motor drive system wherein a thyristor firing control of the inverter is determined by the amplitude of pesudo flux waveforms which are derived from the integral of the line voltages coupling the inverter to the motor being driven. A firing strategy is provided based on the premise that optimum thyristor firing in a load commutated inverter operating at a leading power factor occurs at a point just below the peak of the forthcoming pseudo flux waveform which point comprises an amount of volt-seconds necessary to effect current commutation plus a nominal safety margin. The determination and control is implemented, preferably, in a software phase lock loop but can, when desirable, be implemented in hardware.

Abstract: A control system for a load commutated inverter AC synchronous motor drive provides an operational shift in the event of an increase in motor terminal voltage V.sub.TERM above a preselected reference level. Under such an increase in terminal voltage, control is transferred from a condition where torque is controlled by current and the terminal voltage is uncontrolled to a condition where the load current, e.g., the DC link current I.sub.L flowing between a source side thyristor converter (AC to DC) 12 and a load side thyristor inverter (DC to AC) 14 is utilized to control the motor terminal voltage while the firing angle of the thyristor inverter 14 is used to control the motor torque. This involves increasing the minimum load or motor drive current for a desired torque while adjusting the inverter firing angle from a previous value, so that the desired torque is provided at a higher current I.sub.L and lower terminal voltage V.sub.TERM than before.

Abstract: For protection against commutation failures in a motor control circuit, there is provided a method and apparatus by which the charge on a commutating capacitor is made to track the armature current of a separately excited motor regardless of the operating mode of the motor. In preferred form, a commutating network is provided having a commutating capacitor, a charge reversal thyristor, and a commutating thyristor configured to cause commutation of a main, control thyristor upon sequentially gating the charge reversal thyristor and the commutating thyristor with charge of sufficient magnitude stored on the capacitor. The thyristors of the commutating network are gated according to the operating mode of the motor; thus, there is included a means, or step, for sensing the motor operating mode.