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DAMPING. (1) The absorption of energy, as in viscous damping of mechanical energy and resistive damping of electrical energy. (2) A property of a dynamic system which causes oscillations to die out and makes the response of the system approach a constant value.

DATA COLLECTION. The act of bringing data from one or more points to a central point.

DATA ENTRY. The process of coding or reading a single data device - such as a card or badge reader, numeric keyboard or rotary switch - for storage and later use.

DATA HIERARCHY. A data structure consisting of sets and subsets such that every subset of a set is of lower rank than the data of the set.

DATA LOGGING. Recording of data about events that occur in time sequence.

DEAD BAND. A range within which a nonzero input causes no output.

DECOUPLER. An element in a manufacturing cell that assists the flow of material in the cell or performs other functions to assist the operators or robots.

DEGREE OF FREEDOM. One of a limited number of ways in which a point or a body may move or in which a dynamic system may change, each way being expressed by an independent variable and all required to be specified if the physical state of the body or system is to be completely defined

DELIVERY CYCLE. The time from the receipt of the customer order to the time of the shipment of the product or of the supplying of the service, also called order cycle.

DERIVATIVE CONTROL. Control scheme whereby the actuator drive signal is proportional to the time derivative of the difference between the input, desired output, and the measured actual output.

DESIGN. The process of developing a detailed description that allows a product or process to be built or repro duced.

DIGITAL. The representation of numerical quantities by means of discrete numbers. It is possible to express in binary digital form all information stored, transferred, or processed by dual-state conditions, e.g., onloff openlclosed, octal and BCD values. 

DIGITAL-TO-ANALOG CONVERTER (D/A, DAC). A device which transforms digital data into analog data.

DIRECT COST. Cost factors that are assignable to individual units of production, such as labor in assembly or materials in a product.

DIRECT DIGITAL CONTROL (DDC). Use of a computer to provide the computations for the control functions of one or multiple control loops used in process control operations.

DIRECT NUMERICAL CONTROL (DNC). The use of an external shared computer for distribution of part program data via data lines to more than one remote machine tool.

DISASSEMBLY. Operation in which a single unit is separated into two or more parts or subassemblies.

DISCRETE. Pertaining to distinct elements or to representation by means of distinct elements, such as characters.

DISCRETE PARTS MANUFACTURING. A process that produces distinct items.

DISPATCHING. (1) Selecting and sequencing of available jobs to be run at individual work stations and the assignment of these jobs. (2) The act of scheduling a task for execution.

DISTAL. Away from the base, toward the end effector of the arm.

DISTRIBUTED NUMERICAL CONTROL. A computer numerical control system in which a microprocessor used as a resident controller for a robot or machine tool also interacts with a host computer or other controllers.

DOWNLOAD. Transfer of files andlor programs from a computer to a local computerlcontroller.

DOWNTIME. The time interval during which a device is inoperative.

DRAGGING. In computer graphics, the translation of a selected display item along a path defined by a graphic input device.

DRIFT. The tendency of a system's response to move gradually away from the desired response.

DUE DATE. The latest calendar date at which an operation, or part, or order is to be completed.

DUPLEX. Data transmission in two directions. Full duplex describes two data paths which allow simultaneous data transmission in both directions. Half-duplex describes one data path which allows data transmission in either of two directions, but only one direction at a time.

DUTY CYCLE. The fraction of time during which a device or system will be active or at full power.

DYNAMIC ACCURACY. (1) Deviation from true value when relevant variables are changing with time. (2) Difference between actual position response and position desired or commanded of an automatic control system as measured during motion.

DYNAMIC MODEL. A representation that deals with changing factors over time

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