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Variable Assembly Language (VAL) is a computer-based control system and language designed specifically for use with Unimation Inc. industrial robots.
The VAL robot language is permanently stored as a part of the VAL system. This includes the programming language used to direct the system for individual applications. The VAL language has an easy to understand syntax. It uses a clear, concise, and generally self-explanatory instruction set. All commands and communications with the robot consist of easy to understand word and number sequences. Control programs are written on the same computer that controls the robot. As a real-time system, VAL's continuous trajectory computation permits complex motions to be executed quickly, with efficient use of system memory and reduction in overall system complexity. The VAL system continuously generates robot control commands, and can simultaneously interact with a human operator, permitting on-line program generation and modification.
A convenient feature or VAL is the ability to use libraries or manipulation routines. Thus, complex operations may be easily and quickly programmed by combining predefined subtasks.
The VAL language consists of monitor commands and program instructions.The monitor commands are used to prepare the system for execution of user-written programs. Program instructions provide the repertoire necessary to create VAL programs for controlling robot actions.
- 1Terminology
- 3The VAL system
Terminology[edit]
The following terms are frequently used in VAL related operations.
Monitor[edit]
The VAL monitor is an administrative computer program that oversees operation of a system. It accepts user input and initiates the appropriate response; follows instructions from user-written programs to direct the robot; and performs the computations necessary to control the robot.
Editor[edit]
The VAL editor is an aid for entering information into a computer system, and modifying existing text. It is used to enter and modify robot control programs. It has a list of instructions telling a computer how to do something. VAL programs are written by system users to describe tasks the robot is to perform.
Location[edit]
Location is a position of an object in space, and the orientation of theobject. Locations are used to define the positions and orientations the robot tool is to assume during program execution.
VAL programming[edit]
Several conventions apply to numerical values to be supplied to VAL commands and instructions. Preceding each monitor-command description are two symbols indicating when the command can be typed by the user. A dot (.) signifies the command can be performed when VAL is in its top-level monitor mode and no user program being executed (that is, when the system prompt is a dot). An asterisk (*) indicates the command can be performed at the same time VAL is executing the program (that is, when the system prompt is an asterisk). If both symbols are present the command can be executed in either case. Most monitor commands and program instructions can be abbreviated. When entering any monitor command or program instruction, the function name can be abbreviated to as many characters as are necessary to make the name unique.
For commands and instructions, angle brackets, < >, are used to enclose an item which describes the actual argument to appear. Thus the programmer can supply the appropriate item in that position when entering the command or instruction. Note that these brackets used here are for clarification, and are never to be included as part of a command or instruction.
Many VAL commands and instructions have optional arguments. For notations, optional arguments are enclosed in square brackets, [ ]. If there is a comma following such an argument, the comma must be retained if the argument is omitted, unless nothing follows. For example, the monitor BASE command has the form:
To specify only a 300-millimeter change in the Z direction, the commandcould be entered in any of the following ways:
- BASE 0,0,300,0
- BASE ,300,
- BASE ,300
Note that the commas preceding the number 300 must be present to correctly to relate the number with a Z-direction change. Like angle brackets, square brackets are never entered as part of a command or instruction.
Several types of numerical arguments can appear in commands and instructions. For each type there are restrictions on the values that are accepted by VAL. The following rules should be observed:
- Distances are entered to define locations to which the robot is to move. The unit of measure for distances is millimeter, although units are never explicitly entered for any value. Values entered for distances can be positive or negative, with their magnitudes limited by a number representative of the maximum reach of the robot (for example, 1024 mm and 700 mm for the PUMA 500 and PUMA 250 robots, respectively). Within the resultant range, distance values can be specified in increments of 0.01 mm. Note, however, that some values cannot be represented internally, and are stored as the nearest representable value.
- Angles in degrees are entered to define and modify orientations the robot is to assume at named locations, and to describe angular positions of robot joints. Angle values can be positive or negative, with their magnitudes limited by 1800 or 3600 depending on the usage. Within the range, angle values can be specified in increments of 0.01°. Values cannot be represented internally, however they are stored as
nearest representable value.
The VAL system[edit]
The function of VAL is to regulate and control a robot system by following user commands or instructions. In addition to being a compact stand-alone system, VAL has been designed to be highly interactive to minimize programing time, and to provide as many programming aids as possible.
External communication[edit]
The standard VAL system uses an operator's console terminal and manual control box to input commands and data from the user. The operator console serves as the primary communication device and can be either a direct play terminal or a printing terminal. Interaction with other devices in an automated cell is typically handled by monitoring input channels and switching outputs. By this means the robot can control a modest cell without the need for other programmable devices.
VAL Operating System[edit]
The controller has two levels or operation:
- the top level is called the VAL operating system, or monitor, because it administers operations of the system, including interaction with the user;
- the second level is used for diagnostic work on the controller hardware. The system monitor is a computer program stored VAL programmable read-only memory (PROM) in the Computer/Controller.
PROM memory retains its contents finitely, and thus VAL is immediately available when the controller is switched on. The monitor is responsible for control of the robot, and its commands come from the manual control unit, the system terminal, or from programs. To increase its versatility and flexibility, the VAL monitor can perform of its commands even while a user program is being executed. Commands that can be processed in this way include those for controlling the status the system, defining robot locations, storing and retrieving information the floppy disk, and creating and editing robot control programs.
References[edit]
- PUMA 560 VAL Manual
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Language, a system of conventional spoken, manual, or written symbols by means of which human beings, as members of a social group and participants in its culture, express themselves. The functions of language include communication, the expression of identity, play, imaginative expression, and emotional release.
human nervous system: Language
The language area of the brain surrounds the Sylvian fissure in the dominant hemisphere and is divided into two major components named after…
Characteristics of language
Definitions of language
Many definitions of language have been proposed. Henry Sweet, an English phonetician and language scholar, stated: “Language is the expression of ideas by means of speech-sounds combined into words. Words are combined into sentences, this combination answering to that of ideas into thoughts.” The American linguists Bernard Bloch and George L. Trager formulated the following definition: “A language is a system of arbitrary vocal symbols by means of which a social group cooperates.” Any succinctdefinition of language makes a number of presuppositions and begs a number of questions. The first, for example, puts excessive weight on “thought,” and the second uses “arbitrary” in a specialized, though legitimate, way.
A number of considerations (marked in italics below) enter into a proper understanding of language as a subject:
Every physiologically and mentally typical person acquires in childhood the ability to make use, as both sender and receiver, of a system of communication that comprises a circumscribed set of symbols (e.g., sounds, gestures, or written or typed characters). In spoken language, this symbolset consists of noises resulting from movements of certain organs within the throat and mouth. In signed languages, these symbols may be hand or body movements, gestures, or facial expressions. By means of these symbols, people are able to impart information, to express feelings and emotions, to influence the activities of others, and to comport themselves with varying degrees of friendliness or hostility toward persons who make use of substantially the same set of symbols.
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Different systems of communication constitute different languages; the degree of difference needed to establish a different language cannot be stated exactly. No two people speak exactly alike; hence, one is able to recognize the voices of friends over the telephone and to keep distinct a number of unseen speakers in a radio broadcast. Yet, clearly, no one would say that they speak different languages. Generally, systems of communication are recognized as different languages if they cannot be understood without specific learning by both parties, though the precise limits of mutual intelligibility are hard to draw and belong on a scale rather than on either side of a definite dividing line. Substantially different systems of communication that may impede but do not prevent mutual comprehension are called dialects of a language. In order to describe in detail the actual different language patterns of individuals, the term idiolect, meaning the habits of expression of a single person, has been coined.
Typically, people acquire a single language initially—their first language, or native tongue, the language used by those with whom, or by whom, they are brought up from infancy. Subsequent “second” languages are learned to different degrees of competence under various conditions. Complete mastery of two languages is designated as bilingualism; in many cases—such as upbringing by parents using different languages at home or being raised within a multilingual community—children grow up as bilinguals. In traditionally monolingual cultures, the learning, to any extent, of a second or other language is an activity superimposed on the prior mastery of one’s first language and is a different process intellectually.
Language, as described above, is species-specific to human beings. Other members of the animal kingdom have the ability to communicate, through vocal noises or by other means, but the most important single feature characterizing human language (that is, every individual language), against every known mode of animal communication, is its infinite productivity and creativity. Human beings are unrestricted in what they can communicate; no area of experience is accepted as necessarily incommunicable, though it may be necessary to adapt one’s language in order to cope with new discoveries or new modes of thought. Animal communication systems are by contrast very tightly circumscribed in what may be communicated. Indeed, displaced reference, the ability to communicate about things outside immediate temporal and spatial contiguity, which is fundamental to speech, is found elsewhere only in the so-called language of bees. Bees are able, by carrying out various conventionalized movements (referred to as bee dances) in or near the hive, to indicate to others the locations and strengths of food sources. But food sources are the only known theme of this communication system. Surprisingly, however, this system, nearest to human language in function, belongs to a species remote from humanity in the animal kingdom. On the other hand, the animal performance superficially most like human speech, the mimicry of parrots and of some other birds that have been kept in the company of humans, is wholly derivative and serves no independent communicative function. Humankind’s nearest relatives among the primates, though possessing a vocal physiology similar to that of humans, have not developed anything like a spoken language. Attempts to teach sign language to chimpanzees and other apes through imitation have achieved limited success, though the interpretation of the significance of ape signing ability remains controversial.
In most accounts, the primary purpose of language is to facilitate communication, in the sense of transmission of information from one person to another. However, sociolinguistic and psycholinguistic studies have drawn attention to a range of other functions for language. Among these is the use of language to express a national or local identity (a common source of conflict in situations of multiethnicity around the world, such as in Belgium, India, and Quebec). Also important are the “ludic” (playful) function of language—encountered in such phenomena as puns, riddles, and crossword puzzles—and the range of functions seen in imaginative or symbolic contexts, such as poetry, drama, and religious expression.
Language interacts with every aspect of human life in society, and it can be understood only if it is considered in relation to society. This article attempts to survey language in this light and to consider its various functions and the purposes it can and has been made to serve. Because each language is both a working system of communication in the period and in the community wherein it is used and also the product of its history and the source of its future development, any account of language must consider it from both these points of view.
The science of language is known as linguistics. It includes what are generally distinguished as descriptive linguistics and historical linguistics. Linguistics is now a highly technical subject; it embraces, both descriptively and historically, such major divisions as phonetics, grammar (including syntax and morphology), semantics, and pragmatics, dealing in detail with these various aspects of language.
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