This thesis presents an in-depth investigation to determine the most suitable mobile base design for a powerful and dynamic robotic manipulator. It details the design process of such a mobile platform for use in an indoor human environment that is to carry a two-arm upper-body humanoid manipulator system. Through systematic dynamics analysis, it was determined that a variable footprint holonomic wheeled mobile platform is the design of choice for such an application. Determining functional requirements and evaluating design options is performed for the platform’s general configuration, geometry, locomotion system, suspension, and propulsion, with a particularly in-depth evaluation of the problem of overcoming small steps. Other aspects such as processing, sensing and the power system are dealt with sufficiently to ensure the feasibility of the overall proposed design. The control of the platform is limited to that necessary to determine the appropriate mechanical components. Simulations are performed to investigate design problems and verify performance. A basic CAD model of the system is included for better design visualization. The research carried out in this thesis was performed in cooperation with the German Aerospace Center (Deutsches Zentrum für Luft- und Raumfahrt)’s Robotics and Mechatronics Institute (DLR RM). The DLR RM is currently utilizing the findings of this research to finish the development of the platform with a target completion date of May 2008.

Bilateral incomplete-information negotiations of multiple issues present a difficult yet common negotiation problem that is complicated to solve from a mechanism design perspective. Unlike multilateral situations, where the individual aspirations of multiple agents can potentially be used against one another to achieve socially desirable outcomes, bilateral negotiations only involve two agents; this makes the negotiations appear to be a zero-sum game pitting agent against agent. While this is essentially true, the gain of one agent is the loss of the other, with multiple issues, it is not unusual that issues are valued asymmetrically such that agents can gain on issues important to them but suffer losses on issues of less importance. Being able to make trade-offs amongst the issues to take advantage of this asymmetry allows both agents to experience overall benefit. The major complication is negotiating under the uncertainty of incomplete information, where agents do not know each other's preferences and neither agent wants to be taken advantage of by revealing its private information to the other agent, or by being too generous in its negotiating. This leaves agents stumbling in the dark trying to find appropriate trade-offs amongst issues. In this work, we introduce the Bilateral Automated Mediation (BAM) framework. The BAM framework is aimed at helping agents alleviate the difficulties of negotiating under uncertainty by formulating a negotiation environment that is suitable for creating agreements that benefit both agents jointly. Our mediator is a composition of many different negotiation ideas and methods put together in a novel third-party framework that guides agents through the agreement space of the negotiation, but instead of arbitrating a final agreement, it allows the agents themselves to ratify the final agreement.

This thesis presents an in-depth investigation to determine the most suitable mobile base design for a powerful and dynamic robotic manipulator. It details the design process of such a mobile platform for use in an indoor human environment that is to carry a two-arm upper-body humanoid manipulator system. Through systematic dynamics analysis, it was determined that a variable footprint holonomic wheeled mobile platform is the design of choice for such an application. Determining functional requirements and evaluating design options is performed for the platform’s general configuration, geometry, locomotion system, suspension, and propulsion, with a particularly in-depth evaluation of the problem of overcoming small steps. Other aspects such as processing, sensing and the power system are dealt with sufficiently to ensure the feasibility of the overall proposed design. The control of the platform is limited to that necessary to determine the appropriate mechanical components. Simulations are performed to investigate design problems and verify performance. A basic CAD model of the system is included for better design visualization. The research carried out in this thesis was performed in cooperation with the German Aerospace Center (Deutsches Zentrum für Luft- und Raumfahrt)’s Robotics and Mechatronics Institute (DLR RM). The DLR RM is currently utilizing the findings of this research to finish the development of the platform with a target completion date of May 2008.

Bilateral incomplete-information negotiations of multiple issues present a difficult yet common negotiation problem that is complicated to solve from a mechanism design perspective. Unlike multilateral situations, where the individual aspirations of multiple agents can potentially be used against one another to achieve socially desirable outcomes, bilateral negotiations only involve two agents; this makes the negotiations appear to be a zero-sum game pitting agent against agent. While this is essentially true, the gain of one agent is the loss of the other, with multiple issues, it is not unusual that issues are valued asymmetrically such that agents can gain on issues important to them but suffer losses on issues of less importance. Being able to make trade-offs amongst the issues to take advantage of this asymmetry allows both agents to experience overall benefit. The major complication is negotiating under the uncertainty of incomplete information, where agents do not know each other's preferences and neither agent wants to be taken advantage of by revealing its private information to the other agent, or by being too generous in its negotiating. This leaves agents stumbling in the dark trying to find appropriate trade-offs amongst issues. In this work, we introduce the Bilateral Automated Mediation (BAM) framework. The BAM framework is aimed at helping agents alleviate the difficulties of negotiating under uncertainty by formulating a negotiation environment that is suitable for creating agreements that benefit both agents jointly. Our mediator is a composition of many different negotiation ideas and methods put together in a novel third-party framework that guides agents through the agreement space of the negotiation, but instead of arbitrating a final agreement, it allows the agents themselves to ratify the final agreement.

Fair division is the problem of dividing one or several goods among a set of agents in a way that satisfies a suitable fairness criterion. Traditionally studied in economics, philosophy, and political science, fair division has drawn a lot of attention from the multiagent systems community, since this field is strongly concerned about how a surplus (or a cost) should be divided among a group of agents. Arguably, the Shapley value is the single most important contribution to the problem of fair division. It assigns to each agent a share of the resource equal to the expected marginal contribution of that agent. Thus, it is implicitly assumed that individual marginal contributions can be objectively computed. In this thesis, we propose a game-theoretic model for sharing a joint reward when the quality of individual contributions is subjective. In detail, we consider scenarios where a group has been formed and has accomplished a task for which it is granted a reward, which must be shared among the group members. After observing the contribution of the peers in accomplishing the task, each agent is asked to provide evaluations for the others. Mainly to facilitate the sharing process, agents can also be requested to provide predictions about how their peers are evaluated. These subjective opinions are elicited and aggregated by a central, trusted entity, called the mechanism, which is also responsible for sharing the reward based exclusively on the received opinions. Besides the formal game-theoretic model for sharing rewards based on subjective opinions, we propose three different mechanisms in this thesis. Our first mechanism, the peer-evaluation mechanism, divides the reward proportionally to the evaluations received by the agents. We show that this mechanism is fair, budget-balanced, individually rational, and strategy-proof, but that it can be collusion-prone. Our second mechanism, the peer-prediction mechanism, shares the reward by considering two aspects: the evaluations received by the agents and their truth-telling scores. To compute these scores, this mechanism uses a strictly proper scoring rule. Under the assumption that agents are Bayesian decision-makers, we show that this mechanism is weakly budget-balanced, individually rational, and incentive-compatible. Further, we present approaches that guarantee the mechanism to be collusion-resistant and fair. Our last mechanism, the BTS mechanism, is the only one to elicit both evaluations and predictions from the agents. It considers the evaluations received by the agents and their truth-telling scores when sharing the reward. For computing the scores, it uses the Bayesian truth serum method, a powerful scoring method based on the surprisingly common criterion. Under the assumptions that agents are Bayesian decision-makers, and that the population of agents is sufficiently large so that a single evaluation cannot significantly affect the empirical distribution of evaluations, we show that this mechanism is incentive-compatible, budget-balanced, individually rational, and fair.

<p>This dissertation uses game theoretic models to examine the effects of agent anonymity on markets for goods and for information. In open, anonymous settings, such as the Internet, anonymity is relatively easy to obtain --- oftentimes another email address is sufficient. By becoming anonymous, agents can participate in various mechanisms (such as elections, opinion polls, auctions, etc.) multiple times. The first chapter (joint work with Vincent Conitzer) studies elections that disincentivize voters from voting multiple times. A voting rule is false-name-proof if no agent ever benefits from casting additional votes. In elections with two alternatives, it is shown that there is a unique false-name-proof voting rule that is most responsive to votes. The probability that this rule selects the majority winner converges to 1 as the population grows large. Methods to design analogous rules for elections with 3 or more alternatives are proposed. The second chapter (also joint work with Vincent Conitzer) extends the analysis in the first chapter to broader mechanism design settings, where the goal is to disincentivize agents from participating multiple times. The cost model from the first chapter is generalized and revelation principles are proven. The third chapter studies a setting where firms are able to recognize their previous customers, and may use information about consumers' purchase histories to price discriminate (which may incentivize consumers to be anonymous). The formal model considers a monopolist and a continuum of heterogeneous consumers, where consumers are able to maintain their anonymity at some cost. It is shown that when consumers can costlessly maintain their anonymity, they all individually choose to do so, which paradoxically results in the highest profit for the monopolist. Increasing the cost of anonymity can benefit consumers, but only up to a point; at that point, the effect is reversed. Some of the results are extended to a setting with two competing firms selling differentiated products. Finally, the cost of maintaining anonymity is endogenized by considering a third party that can make consumers anonymous for a fee of its choosing. It is shown that this third party would prefer to be paid by the firm for allowing consumers to costlessly maintain their anonymity.</p> / Dissertation

Internet technology (IT) has changed the way information is disseminated, which has led to changes in transaction-making and the creation of new electronic markets. This has also led to the emer-gence of new types of online intermediaries, and new selling mechanisms. Since most online selling involves commodity goods and the discovery of low prices, the design of selling mechanism primarily focuses on the disclosure of price information. Low-price discovery selling mechanisms, however, have caused buyers to shift from one mechanism to another to get the best deals. Online sellers are facing profit pressures as a result. Price information only addresses a portion of consumer needs though. They need information to identify uncertainties that may harm them during transactions. Consumers also search for products and services that fit their individual preferences and are willing to pay a price premium for such offerings. Sellers have to offer additional information and to do decommoditization, or consumers will abandon selling mechanisms that do not match their needs. This dissertation examines these issues in three essays. It explores two online selling mechanisms: online group-buying auctions and a la carte pricing schemes in airline industry. The a la carte pricing is to offer flexible pricing to consumers. The research employs an Internet-based experimental test bed, a single-firm empirical case study, and an econometric model to test the relevant theories. I evaluate the design of online group-buying auctions, where consumers are more uncertain about group-buying as a mechanism for organizing economic exchange. I also evaluate the design of online selling mechanisms in the air travel services industry, where digitally-intermediation has created problems with suppliers¡¦ ownership of their customers and increasing channel conflicts. The results indicate that the dominance of price in consumer purchase decisions can be mitigated by complementary information, as well as value-added product and service information that an online selling mechanism provides. Consumer information requirements are dynamic and inconsistent though. So an effective selling mechanism must identify how to disclose an adequate amount of information to consumer. Some of the new mechanism designs that have emerged have produced a means for sellers to be more effective. My findings suggest that, in addition to price transparency, online selling mechanisms also affect transaction completion uncertainty, and support the expression of personal preferences.

This work is initiated from an observation of the rolling-sliding kinematic behavior observed in the motion of the knee joint. We use the slip ratio as a parameter to analyze the rolling-sliding properties of a mechanism, and also propose a method to design new mechanisms with specific slip ratio. In this research, we first verify the many definitions of the slip ratio, then modify a best definition to suit various rolling-sliding motions. Most importantly, we propose two types of rolling-sliding mechanism design. By changing the parameters of the mechanism, we can adjust its slip ratio curve to be close to a desired curve. In addition, when the idea of adjustable link length is used in the design of the mechanism, exact slip ratio curve as specified can be generated by the use of some cams.

ABSTRACT DESIGN OF A DEMOLITION BOOM &Ccedil / etin, Bet&uuml / l M.S, Department of Mechanical Engineering Supervisor : Prof. Dr. Eres S&Ouml / YLEMEZ August 2007, 96 pages Excavators are used for many purposes. Some of these are digging, drilling, breaking and demolition. A demolition excavator boom consists of 3-piece boom which is different in form and construction from a 2-piece boom used in standard excavator. The aim of this thesis is to design a demolition boom for hydraulic excavator with operation weight of 30 ton. With this construction a higher reach is gained. Design of the demolition boom consists of three stages. Firstly the mechanism design is performed to determine the basic link dimensions. In the second step the structural shape of the boom is estimated to perform static stress analysis. The EXCEL program is chosen due to the ease of repetative calculations and applying the changes in structure parameters. The demolition boom is modeled by PRO-ENGINEER, and consequently the model is analyzed by using a Finite Element Analysis (FEA) in MSC.Marc-Mentat. According to the FEA results the model is revised. Keywords: Demolition Excavator, Mechanism Design, Structural design

A scenario where multiple entities interact with a common environment to achieve individual and common goals either co-operatively or competitively can be classified as a Multi-Agent System. In this thesis, we concentrate on the situations where the agents exhibit selfish, competitive and strategic behaviour, giving rise to interesting game theoretic and optimization problems. From a computational point of view, the presence of multiple agents introduces strategic and temporal issues, apart from enhancing the difficulty of optimization. We study the following natural mathematical models of such multi-agent problems faced in practice: a) combinatorial optimization problems with multi-agent submodular cost functions, b) combinatorial auctions with partially public valuations and c) online vertex-weighted bipartite matching and single bid budgeted allocations. We provide approximation algorithms, online algorithms and hardness of approximation results for these problems.