Multiple robot manipulators cooperating in a common manipulation task can accomplish complex tasks that a single manipulator would be unable to complete. To achieve physical cooperation with multiple manipulators working on a common object, interaction forces need to be controlled throughout the motion. The aim of this research is to develop an inverse dynamics model-based cooperative force and position control scheme for multiple robot manipulators. An extended definition of motion is proposed to include force demands based on a constrained Lagrangian dynamics and Lagrangian multipliers formulation. This allows the direct calculation of the inverse dynamics with both motion and force demands. A feedforward controller based on the proposed method is built to realise the cooperative control of two robots sharing a common load, with both motion and force demands. Furthermore, this thesis develops a method to design an optimal excitation trajectory for robot dynamic parameter estimation utilising the Schroeder Phased Harmonic Sequence. This method yields more precise and accurate inverse dynamics models, which result in better control. The proposed controller is then tested in an experimental set-up consisting of two robot manipulators and a common load. Results show that in general the proposed controller performs noticeably better position and force tracking, especially for higher speed motions, when compared to traditional hybrid position/force controllers.

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"Fading is one of the most fundamental impairments to wireless communications. The standard approach to combating fading is by adding redundancy - or diversity - to help increase coverage and transmission speed. Motivated by the results in multiple-input multiple-output technologies, which are usually used at base stations or access points, cooperation commutation has been proposed to improve the performance of wireless networks which consist of low-cost single antenna devices. While the majority of the research in cooperative communication focuses on flat fading for its simplicity and easy analysis, in practice the underlying channels in broadband wireless communication systems such as cellular systems (UMTS/LTE) are more likely to exhibit frequency selective fading. In this dissertation, we consider a frequency selective fading channel model and explore distributed diversity techniques in broadband wireless relay networks, with consideration to practical issues such as channel estimation and complexity-performance tradeoffs. We first study a system model with one source, one destination and multiple decode-and-forward (DF) relays which share a single channel orthogonal to the source. We derive the diversity-multiplexing tradeoff (DMT) for several relaying strategies: best relay selection, random relay selection, and the case when all decoding relays participate. The best relay selection method selects the relay in the decoding set with the largest sum-squared relay-to-destination channel coefficients. This scheme can achieve the optimal DMT of the system at the expense of higher complexity, compared to the other two relaying strategies which do not always exploit the spatial diversity offered by the relays. Different from flat fading, we find special cases when the three relaying strategies have the same DMT. We further present a transceiver design and prove it can achieve the optimal DMT asymptotically. Monte Carlo simulations are presented to corroborate the theoretical analysis. We provide a detailed performance comparison of the three relaying strategies in channels encountered in practice. The work has been extended to systems with multiple amplify-and-forward relays. We propose two relay selection schemes with maximum likelihood sequential estimator and linear zero- forcing equalization at the destination respectively and both schemes can asymptotically achieve the optimal DMT. We next extend the results in the two-hop network, as previously studied, to multi-hop networks. In particular, we consider the routing problem in clustered multi-hop DF relay networks since clustered multi-hop wireless networks have attracted significant attention for their robustness to fading, hierarchical structure, and ability to exploit the broadcast nature of the wireless channel. We propose an opportunistic routing (or relay selection) algorithm for such networks. In contrast to the majority of existing approaches to routing in clustered networks, our algorithm only requires channel state information in the final hop, which is shown to be essential for reaping the diversity offered by the channel. In addition to exploiting the available diversity, our simple cross-layer algorithm has the flexibility to satisfy an additional routing objective such as maximization of network lifetime. We demonstrate through analysis and simulation that our proposed routing algorithm attains full diversity under certain conditions on the cluster sizes, and its diversity is equal to the diversity of more complicated approaches that require full channel state information. The final part of this dissertation considers channel estimation in relay networks. Channel state information is vital for exploiting diversity in cooperative networks. The existing literature on cooperative channel estimation assumes that block lengths are long and that channel estimation takes place within a fading block. However, if the forwarding delay needs to be reduced, short block lengths are preferred, and adaptive estimation through multiple blocks is required. In particular, we consider estimating the relay-to-destination channel in DF relay systems for which the presence of forwarded information is probabilistic since it is unknown whether the relay participates in the forwarding phase. A detector is used so that the update of the least mean square channel estimate is made only when the detector decides the presence of training data. We use the generalized likelihood ratio test and focus on the detector threshold for deciding whether the training sequence is present. We also propose a heuristic objective function which leads to a proper threshold to improve the convergence speed and reduce the estimation error. Extensive numerical results show the superior performance of using this threshold as opposed to fixed thresholds."

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Social behaviours have been widely studied in behavioural economics and psychology. However, the origins of these behaviours in the brain are poorly understood. In this dissertation I will discuss two main avenues of study which constituted separate projects during my PhD candidacy. The first section contains experiments in which I collaborated with Dr Raymundo Báez-Mendoza on the topic of inequity. The second part includes a study on coordination and cooperation behaviour in macaques. Inequity is a concept ubiquitous in daily life. It is the difference between one’s own reward and that of another. There have been several studies that have suggested inequity affects brain activity. However, few studies have touched upon how this parameter is incorporated in neuronal activity. In the experiments that will be described here, monkeys (Macaca mulatta) performed actions to obtain rewards for both themselves and another. The level of inequity in these rewards was manipulated by varying the magnitude of own and other’s rewards. We then proceeded to study neuronal activity by means of single neuron recordings in the striatum of two macaques. We found that inequity modulated task related activity in about 32% of recorded striatal neurons. In addition to this study on inequity we also recorded some sessions in which one of the animals made choices with varying rewards for self and other. From these results, I attempted to characterise behaviour with regards to own reward and inequity in choice situations. Inequity has been considered a contributing factor in explaining cooperation behaviour. Coordination and cooperation are important and frequently observed behaviours. To study coordination and cooperation, I designed an experiment in which the combination of two monkeys’ choices determined the rewards for both animals. In this dissertation I attempt to address how the animals perform combined choices (playing together vs. alone) as well as the nature of their behaviour (e.g. pro-social vs. self-interested). The aim of this work was to characterise what type of information the animals use to solve these tasks. This is vital if one is to study these concepts in the brain using macaques as a model. In summary, this work contributes to a better understanding of social behaviour and provides an example of how this social behaviour is computed in the brain.

Mobile Ad hoc networks (MANETs) are flexible networks that transmit packets node-by-node along a route connecting a given source and destination. Frequent link breaks (due to node mobility) and quick exhaustion of energy (due to limited battery capacity) are two major problems impacting on the flexibility of MANETs. Cooperative communication is a key concept for improving the system lifetime and robustness and has attracted considerable attention. As a result, there is much published research concerning how to utilize cooperative communication in a MANET context. In the past few years, most cooperative technologies have focused on lower layer enhancements, such as with the Physical Layer and MAC Layer, and have become very mature. At the Network Layer, although some research has been proposed, issues still remain such as the lack of a systematically designed cooperative routing scheme (including route discovery, route reply, route enhancement and cooperative data forwarding), the use of cooperative communication for mobility resilience, and route selection (jointly considering the energy consumption, energy harvesting potential and link break probability). Driven by the above concerns, a novel Constructive Relay based CooPerative Routing (CRCPR) protocol based on a cross-layer design is proposed in this thesis. In CRCPR, we fi rst modify the traditional hello message format to carry some additional neighbour information. Based on this information, a key aspect of this protocol is to construct one or more small rhombus topologies within the MANET structure, which are stored and maintained in a COoPerative (COP) Table and Relay Table. Next, the route request procedure is re-designed to improve resilience to node mobility with a scheme called Last hop Replacement. Finally, assuming nodes are mostly battery-powered, destination node based route-decision criteria are explored that can consider energy consumption, energy harvesting and link break probability to determine an appropriate route across the MANET. As the hello message format is modi ed to carry additional information, the control overhead is increased. However, in order to improve the control message eficiency, a new generalised hello message broadcasting scheme entitled Adjust Classi ed Hello Scheme is developed, which can be deployed onto every routing protocol employing a hello mechanism. As well as designing a new routing protocol for MANETs, including route discovery, route selection, route reply, route maintenance, route enhancement and cooperative data forwarding, the proposed scheme is implemented within an Opnetbased simulation environment and evaluated under a variety of realistic conditions. The results con rm that CRCPR improves mobility resilience, saves energy via cooperative communication and reduces the control overhead associated with the hello message mechanism.

Clustering and cooperative transmission are the key enablers in power-constrained Internet of Things (IoT) networks. The challenges for power-constrained devices in IoT networks are to reduce the energy consumption and to guarantee the Quality of Service (QoS) provision. In this thesis, optimal node selection algorithms based on clustering and cooperative communication are proposed for different network scenarios, in particular: • The QoS-aware energy efficient cluster heads (CHs) selection algorithm in one-hop capillary networks. This algorithm selects the optimum set of CHs and construct clusters accordingly based on the location and residual energy of devices. • Cooperative nodes selection algorithms for cluster-based capillary networks. By utilising the spacial diversity of cooperative communication, these algorithms select the optimum set of cooperative nodes to assist the CHs for the long-haul transmission. In addition, with the regard of evenly energy distribution in one-hop cluster-based capillary networks, the CH selection is taken into consideration when developing cooperative devices selection algorithms. The performance of proposed selection algorithms are evaluated via comprehensive simulations. Simulation results show that the proposed algorithms can achieve up to 20% network lifetime longevity and up to 50% overall packet error rate (PER) decrement. Furthermore, the simulation results also prove that the optimal tradeoff between energy efficiency and QoS provision can be achieved in one-hop and multi-hop cluster-based scenarios.

Thesis (M.C.P.)--Massachusetts Institute of Technology, Dept. of Urban Studies and Planning; and, (M. Arch.)-- Massachusetts Institute of Technology, Dept. of Architecture, 1979. / MICROFICHE COPY AVAILABLE IN ARCHIVES AND ROTCH. / Bibliography: leaves [182]-[183]. / by Abraham Ford Jr. / M.C.P. / M.Arch.

Thesis (M.Arch.)--Massachusetts Institute of Technology, Dept. of Architecture, 1982. / MICROFICHE COPY AVAILABLE IN ARCHIVES AND ROTCH. / Bibliography: p. 236-239. / by Carol Jean Boemer. / M.Arch.

It has been widely accepted that profit maximisation the cornerstone of economic analysis. The prevalence of non profit maximising firms such as cooperatives, partnership and the increasing importance in stakeholders' interest has raised my interest in this topic. My thesis looks into the reasons that drive the prevalence of non-profit firms, such as the perception bias of managers, the special law and regulation in certain countries and the emphasis on the stakeholders' interests. I base my analysis mainly on the oligopoly model and provided analysis on how the market is like in non-profit maximising environment compared to profit maximsing environment. I find out that non-profit firm is not necessary less profitable under certain circumstance. First chapter introduces the related literature; second chapter focuses on the influence of managers' perception bias on firms' decision; chapter three applied a two stage model to see how for-profit firms and non-profit firms react under uncertainty and last chapter focus on the governance of cooperative/partnership.