Abstract: An adaptive control scheme for the tip position control of a single-link flexible manipulator handling unknown changing loads and its experimental verification are presented. The scheme essentially comprises a least-squares identification algorithm and a self-tuning pole-placement controller. The controller uses a novel recursive algorithm which constrains the control signal not to respond immediately to any sudden changes in the control gains due to changes in the parameter estimate vector. Another salient feature of the present work is the observation of a 'ringing effect' transient during payload release and its resolution. This was achieved by a resetting of the parameter estimate vector to its no-load value, prior to payload release. A performance comparison of the new adaptive control with a constant-gain pole placement controller as well as a standard self-tuning pole placement controller clearly demonstrates its superior ability in handling unknown changing loads. >

Abstract: To suppress the amount of data frames passing through a public network and to provide advantages for both the telephone company and subscribers, a traffic control system is provided for controlling traffic in data frames transmitted between a public network and a subscriber through channels. Each data frame consists of a header and a payload. The header includes a predetermined bit indicating whether or not the payload includes traffic data. The system comprises, between the public network and the subscriber, a traffic control unit that includes channel filters each for receiving data frames from the subscriber through the corresponding channel, and for transmitting each data frame to the public network only when the predetermined bit in the header of the data frame indicates that the payload includes traffic data, and a channel reproducing unit for receiving data frames from the public network, and for reproducing an omitted data frame that has been discarded, to transmit the received data frames and the reproduced data frame to the subscriber.

Abstract: The invention pertains to a switching method for a common memory based switching field and to the switching field. In the method (1) a plurality of input gates (a₁...a n ) receive cells (10), each comprising a header (11) and a payload portion (12); (ii) the header (11) and the payload portion (12) of a cell (10) arriving at the switching field are separated from each other, whereby header conversion operations required for the next link are performed in respect of the header (11), and the payload portion (12) is written to a common memory (24); (iii) and each cell (10) is transmitted via one or more output gates (c₁...c n ) to one or more output lines. In order to optimise practical apparatus for obtaining a faster switching time and, as a result, a larger number of gates for each switching block, packets consisting of a new header obtained from the header conversion and a common memory address of the payload are switched to a time-shared bus (22) which routes each packet to output buffers (b₁... b n) in a manner known per se; and when each cell is to be transmitted, a corresponding payload portion (12) is read from the common memory (24), said payload portion (12) and said new header are combined into a new cell, and the new cell is transmitted to said one or more output lines.

Abstract: In a telecommunications system where a node has to send a message through a packet switched network which is of a length greater than the maximum packet size, the message is divided into smaller packets which are sent individually through the network. The packets may be sent by what is known as a connectionless service where each packet is treated independently. It is proposed that the packets are sent by a method of transmitting variable length messages on a telecommunications network from a source to a destination via an ATM or DQDB switch in fixed length cells or slots which include a header field and a payload field wherein the method includes providing a segment type field, a sequence number field and a message indentifier field in the payload field and wherein the routing information is obtained without use of the Virtual Path or Circuit Identifiers.

Abstract: In a telecommunications system where a node has to send a message through a packet switched network which is of a length greater than the maximum packet size, the message is divided into smaller packets which are sent individually through the network. The packets may be sent by what is known as a connectionless service where each packet is treated independently. It is proposed that the packets are sent by a method of transmitting variable length messages on a telecommunications network from a source to a destination via an ATM or DQDB switch in fixed length cells or slots which include a header field and a payload field wherein the method includes providing a segment type field, a sequence number field and a message indentifier field in the payload field and wherein the routing information is obtained without use of the Virtual Path or Circuit Identifiers.

Abstract: A gripping unit includes a generally U-shaped frame fixed to a shaft which is rotatably connected to a manipulator arm. The actuator frame has a pair of spaced apart actuator arms. A generally U-shaped payload frame has a bracket member for attaching to a payload and a pair of payload arms extending from opposite ends of the bracket member. Each payload arm is pivotally coupled to a corresponding one of the actuator arms so that the payload frame is pivotal with respect to the actuator frame about an axis which is perpendicular to the axis of the shaft. A cam mechanism is operable to releasably hold the payload frame in certain orientations. A brake device prevents rotation of the actuator frame about the axis of the shaft.

Abstract: PURPOSE: To test and evaluate a functional operation of a packet exchange communication network in real time. CONSTITUTION: A test packet formed by inserting various test information to a payload part of the packet consisting of a control block, including output addresses and the payload part is stored in a memory of a transmission unit 24, prior to the start of a test run. The test packet is sent to a specific reception unit 25 at a high speed from a transmission unit 24, via a packet exchange network (PSS) under the control of a transputer 28. The reception unit analyzes information of the test packet, received under the control of a transputer 29 in real time to discriminate whether or not an undesired outcome has been produced. Since the test information is inserted to the payload part of the packet, an enormous amount of test information is transmitted, by which many kinds of errors are discriminated. Further since the test packet is transmitted at a high speed by the hardware of the transmission unit test can the made in real time, up to a fault with a low occurrence rate.

Abstract: This paper presents a novel algorithm for implementing Orthogonally Multiplexed QAM (OQAM) modulation schemes. The approach is based on an odd frequency stacking of frequency carriers in a critically sampled modem configuration. The novelty of the method is the use of Discrete FFT processors able to work at one baud rate in OQAM systems. The paper establishes the computational payload of the algorithms, and compares them with different implementation methods. Also, a new Maximum Likelihood synchronization procedure for phase recovery is developed, which accomplishes a direct estimation of phase deviation.

Abstract: A D'Alembert-Lagrangian approach is developed for the dynamics of a chain of flexible links. The governing equations and boundary conditions for each link are derived. While the approach is developed for chains with any numbers of links, the dynamic equations are written explicitly for a chain with two flexible links and a payload. © 1992 John Wiley & Sons, Inc.

Abstract: Abstract Thus far, rockets have depended almost exclusively on chemical fuel, in either solid or liquid form. Its function is to produce an upward thrust strong enough to take the payload far away from the gravitational force of the Earth, which decreases in inverse proportion to the square of the distance from the Earth. As has already been said, Newton’s third law of motion teaches us that the rocket motor’s thrust produces a reaction in the opposite, in this case upwards, direction. In a chemical rocket the reaction between a fuel and an oxidizing agent in a combustion chamber produces hot exhaust gases. The hotter these gases are, the faster they travel and the greater the lifting capability of the rocket. The search has therefore obviously been for techniques of producing the hottest possible reactions, but there are natural physical limits beyond which one cannot go. This in turn imposes a limit on the upward velocity attainable with a simple single-stage rocket-around 3 km/s-far short of the 8 km/s needed to put a satellite into orbit.