Chapter 1. Introduction 4 For this reason, a robust nonlinear H ∞ state feedback controller is used in this thesis for the quadrotors flight problem. On the other hand, improving the controlperformance optimality is another aspect. An iLQR controller is addressed based on the optimal LQR control technique to improve the controlperformance. Several control techniques have been explored in this thesis in both the simulations and the experiment. First, a robust nonlinear H ∞ state feedback controller was developed to stabilise the quadrotor attitude, track a predefined path and address the team formationcontrol problems with external disturbance consideration by solving Hamilton-Jacobi inequality. The controller stability was analysed via Lya- punov function and robustness conditions were obtained. The main advantages of applying the nonlinear H ∞ optimal control approach are various. Firstly, it is able to attenuate the disturbance energy by measuring a ratio between the energy of cost vector and the energy of disturbance signal vector . Secondly, although it is a nonlinear control approach, the performance criterion can be included in the control objective. Thirdly, robustness of stability and performance is guaranteed. Finally, solving the control action law leads to tuning parameters, which is easy to find better parameters . Due to these reasons, the nonlinear H ∞ optimal control approach was chosen in this thesis. The controller was tested in simu- lations and real work under different scenarios. On the other hand, an optimal control approach was developed based on the LQR control approach. The iLQR controller was applied for the full quadrotor nonlinear dynamic model, and the dynamic model was linearised at each time step as an equilibrium point. Third, Proportional Derivative square P D 2 , IBS and LQR controllers were applied for comparison purposes. All these controllers were tested in simulation with several scenarios.
According to , in this project, is a coordinated control strategy of multiple robots based on artificial vision to measure the relative position between them, in order to achieve and maintain the specified formation. A leader robot is given that moves about an unknown trajectory and unknown speed. In order to maintain the robots with certain distance between the leader, a controller is designed by using visual information about the position of the leader robot. At equilibrium point, the control system is proved to be stable which achievement of the navigation objective. Experimental results with a leader robot and a follower robot, are included to show the performance based on the vision control system.
Several technique have proposed to give a solution with good performance , , , , , , , , , , . However, in the robotic applica- tion, there are some uncertainties in the system, due to the sensors imprecision, inac- curate actuator and environment change every time . In terms of robot’s position and orientation, it produces the accumulation error of robot formation. The fuzzy logic control algorithm can overcome the uncertainty problems . Unfortunately, the type-1 fuzzy logic controller (T1FLC) can’t ensure the performance, because the uncertainty is crisp value. To the best our knowledge, only a few of existing results have been presented to solve the problem of leader-followerformationcontrol based on the interval type-2 fuzzy logic controller (IT2FLC) , , . This paper aims to investigate how to design the leader-followerformationcontrol based on the IT2FLC for achieving robust formation against the leader faults. The rest of paper is organized as follows: Section 2 briefly discusses the leader-follower kinematic model while Section 3 describes our proposed controller and material. To demonstrate the usefulness of the proposed control algorithm, the simulations and the result are pre- sented in Section 4, and finally, the conclusion of the study is given in Section 5.
The cooperative control of multiple vehicle systems despite its wide range of practical applications requires tackling important theoretical and practical challenges which have attracted many researchers in recent years. Formationcontrol problems for multiple vehicle systems can be categorized with applications to unmanned aerial vehicles (UAVs), autonomous underwater vehicles, cooperative transport, mobile robots, cooperative role assignment and cooperative search. In this paper, we seek to drive a control algorithm for cooperation between quadrotors that allow the robots to control their position and angles to grasp and transport a common payload in various maneuvers. The controller is designed to move the object by two or more quadrotors. To make a framework for interplay between a group of quadrotors and payload, many control schemes have been extensively used to solve the problems of creating formationcontrol for UAVs. Some of them have focused on centralized and leader-follower approach to access interaction between cooperative quadrotors and payload [1-7]. Although these methods have acceptable results on small robotic systems but suffer from several disadvantages including high computational complexity of centralized methods in large- scale systems and possibility of disappearing the group formation in leader-follower strategy due to not receiving the position of leader by the followers.
The experiments were conducted throughout 2014, in two consecutive periods (Exp 1: January–July and Exp 2: October–December), with the use of two famous characters in the role of trustee as a main difference. Specifically, the main experiment (Exp 1) used Silvio Berlusconi, former Prime Minister of Italy and leader of the centre-right parties’ coalition, while the control experiment (Exp 2) used Piero Angela, a famous TV host. We conducted our main experiment over the course of one semester, for the purpose of avoiding unexpected political developments which could affect the public image and result in fluctuations in the public trust index towards Berlusconi. In order to control for a potential seasonal confound, we also consulted public electoral and political polls (managed by the Presidency of Ministers and the Italian Department of Information and Publishing 1 ). Only one agency (IPR Marketing) provided reports throughout the whole year (December 2013, May 2014 and December 2014). According to these reports, trust index towards Berlusconi proved to be fairly consistent for the investigated period (25%, 23% and 20%, respectively). The obtained results confirmed that Berlusconi carried potential to arouse, sensitize and polarize the audience, and as such was suitable to be chosen as experimental stimulus. [4,28,29]. In order to choose a control stimulus who would be a better fit in terms of political neutrality and high popularity, we conducted a pilot online survey on an independent sample of 42 students, assessing two acclaimed national television hosts, Piero Angela (86 years) and Gerry Scotti (59 years). Both stimuli were selected for their high popularity and relatively close age to Berlusconi. Neither of the stimuli was an acclaimed politician or has been publicly associated with Italian politics. Participants were asked to decide if each of the TV hosts is taking a political side (i.e. to quantify the political orientation of the stimulus) and if so, which
In this chapter, we have studied a leader-follower stochastic differential game with asymmetric information. This kind of game problem possesses several attractive features. First, the game problem has the Stackelberg feature, which means the two players play as different roles during the game. Thus the usual approach to deal with game problems, such as [6–8, 10], where the two players act as equivalent roles, does not apply. Second, the game problem has the asymmetric information between the two players, which was not considered in [3, 13, 14]. In detail, the information available to the follower is based on some sub-σ-algebra of that available to the leader. Stochastic filtering technique is introduced to compute the optimal filtering estimates for the corresponding adjoint processes, which act as the solution to some FBSDFE. Third, the Stackelberg equilibrium is represented in its state feedback form for the LQ problem under some appropriate assumptions. Some new conditional mean-field FBSDEs and system of Riccati equations are introduced to deal with the leader’s LQ problem.
In this paper we introduce a novel construct, Leader-Member Exchange (LMX) importance, which we position as a meta-perception indicating whether followers view their LMX relationship as personally important or valuable to them. Based on social exchange theory, we examine the extent to which the obligation followers feel towards their leader depends jointly on the quality and the importance of the LMX relationship. We examine how LMX importance influences the process through which LMX quality affects employees’ level of organizational citizenship behaviour (OCB) by focusing on felt obligation (a measure of followers’ reciprocity obligation in the social exchange process) as a mediating variable. Across two studies, we found that high levels of both LMX quality and LMX importance interacted to engender a greater feeling of obligation in followers to repay the perceived favourable exchanges with their leader. Felt obligation predicted leader-rated OCB, demonstrating support for our hypothesised moderated mediation model. However, psychological empowerment, when included alongside felt obligation (in Study 2) did not mediate the LMX-OCB relationship. Overall, our findings extend the focus of LMX theory beyond the confines of LMX quality to incorporate the importance of the LMX relationship.
relationships between follower behaviour and leader reactions, this concern may exist with regard to other relationships. For instance, in Study 2, leaders’ self-esteem did not moderate the relationship between leader identity threat and follower behaviours. However, the extensive literature on self-esteem indicates that self-esteem and threat have a significant correlation (Campbell & Sedikides, 1999). However, participants can inflate their ratings due to various biases, ranging from leniency, appearing to be socially desirable, or participants demonstrate to have consistency in ratings (Podsakoff et al., 2003). This could be a limitation in the three studies of this thesis. One of the possible limitations of the studies was the social desirability bias. Social desirability refers to the fact that items may be written in such a way as to reflect more socially desirable attitudes, behaviours, or perceptions (Podsakoff et al., 2003). For instance, the attribution items of Study 2 which attempted to investigate the cause of follower behaviours a personal or environmental attribute may have been influenced by the respondents’ desire to appear as being socially acceptable. Second, followers’ gender did have any significance with regards to leader identity threat. This could be due to the respondents desire to appear as not being biased or prejudiced. Podsakoff et al. (2003) recommends that such issues can be avoided by providing clear concepts keeping questions simple, specific, and concise; avoid double-barrelled questions and reducing the questions relating to more focused questions; and avoiding complicated language. In this thesis, the vignettes were simple as well as the questions asked to the participants were focussed (e.g., would you recommend Pat for –Bonus). Furthermore, the findings of the studies indicate that leader’s ratings for many of the measures were significantly different for the proactive and proficient condition, suggesting that social desirability may not have significantly affected participants ratings. In addition, the question order was randomised in each block and the answer scales varied in the blocks for instance ILT scale range was from 1-9 and the competency, performance potential scale range was from were from 1-5. These methods helped reduce social desirability biases (Podsakoff et al., 2003).
Path planning and maneuvering command are critical steps in autonomous driving vehicle systems. Robotics tracking has undergone noticeable advancements and can be achieved in many ways. In this paper, we will present a smooth path planning (SPP) that is found with Lyapunov stability and back- stepping control background.
However, given the increasing use of work teams on projects within the workplace (Chen, Kirkman, Kanfer, Allen & Rosen, 2007; Day, Gronn, & Salas, 2006; Morgeson, DeRue, & Karam, 2010), it is important for organizations to have insight into how leaders can be successful while not always being congruent with a diverse set of team members or followers. For example, a high level of ILT congruence indicates a leader may be a perfect match for what a given follower sees as an ideal leader which may result in that leader being seen by the follower as worthy of influence (Kenney et al., 1996). However, there is a paucity of research examining how leaders may operate successfully when they experience low congruence with their followers. Research is needed in this area given the influence personality and parental traits have on the development of ILTs (Keller, 2000) and the increasing diversity of backgrounds and experiences within work teams (Jackson, Joshi, & Erhardt, 2003; Phillips, Northcraft, & Neale, 2006). While ILT congruence remains an important method of gaining a contextualized look at leadership given unique follower perceptions, it is equally important to understand the influence of leader’s ability to be socially adaptive.
material resources (e.g. pay and promotions; Woolridge & Floys, 2002), as well as intangible ones like knowledge (Nonaka & Takeuchi, 1995). The higher the quality of the leadership relationship, the greater the access to resources (Graham & Uhl-Bien, 1995; Uhl-Bien et al. 2014); that is to say that an intermediate leader needs to balance the demand for resources with both other constituents of the triad. In this sense he/she is in the delicate situation to having to develop a high quality relationship with his or her own boss (as a follower), to ensure access to resources for him/herself and their teams; and (as a leader) to distribute these resources according to demands and relationship quality with his/her follower. An individual hence finds him/herself to balance the conflicting needs of groups situated in the different hierarchical layers (Denison, Hooijberg, Quinn, 1995; Smith & Lewis, 2011), and this is precisely what causes material paradoxical tensions. For example, managers in these positions have been found to perform a constant trade off between behaviours and actions aligned to adaptation to change, and resistance to change (Aherne, et al., 2014). Further, they have been found to promise upper echelons not to waste resources, whilst allowing their team secretly to scavenge the same resources; these games of compliance and deviance are at the root of corporate venturing and innovation, (Mainemelis, 2010). In this sense, intermediate leaders have to perform materially different actions to:
Unmanned Aerial Vehicles (UAV) have widely at- tracted engineers and scientists in the past decade. These platforms can be used in military operations, search and rescue operations, urbanization, etc. To extend capabilities of UAVs, they should be capable of transporting payloads individually or cooperatively. Therefore, scientists have investigated the load trans- port problem by UAVs in many research articles. Studies in this eld can be divided into two general categories: studies about cable-suspended loads [1-19] and researches about gripped loads [11,20-25]. Further- more, in some of these studies, load is transported by an individual quadrotor [1-8,10,12-17,19,23,24], while, in some other researches [9,11,18,20-22,25], coopera- tive transport of payloads by UAV teams has been investigated. Dierent control techniques have been implemented to control UAVs and payloads in these
The Stackelberg game, also called the single-leader-follower game, arises from the oligopolis- tic competition. In a Stackelberg game, there is a distinctive player, called the leader, who op- timizes the upper-level problem and a number of remaining players, called the followers, who optimize the lower-level problems jointly. In particular, the leader can anticipate the response of the followers, and then use this ability to select his optimal strategy. At the same time, each follower selects her optimal strategy according to the strategies of the leader and the followers. When dealing with more complex practical problems, such as a deregulated electricity mar- ket, we have to consider the competition among several firms and a different type of agents. The corresponding problem is called the multi-leader-follower game, which has several lead- ers and followers. Each leader can also anticipate the response of the followers, and uses this ability to select his strategy to compete with the other leaders. At the same time, each follower selects his optimal strategy according to the strategies of all leaders as well as the other follow- ers. We are particularly interested in the situation, where no player can improve his status by changing his strategy unilaterally, which we call a leader-follower Nash equilibrium, or simply a L/F Nash equilibrium.
the transcripts several times, made a note of words and themes that appeared to be recurrent in the text and thereby searched for ‘patterns and connections between signifiers’ that differentiated them from each other. As such we applied ‘the idea of multiplicity’ (Frosh, 2014: 23) where we sought to open up the text by disrupting what appears to be a linear account of subjects’ representation of themselves within the organisational structure and their assigned roles and relationships. By paying attention to what is prominent and what is absent from the text – stands outside language as the ‘radical other’ (Frosh, 2014: 23) – we seek to show through our discussion of extracts from the transcripts the multiplicity and variability in the accounts reflective of how any attempt to put ‘something into language changes it’ (Frosh, 2014: 23). Lacan (2006: 247) saw the function of language in speech to be the evocation of the response of the Other. Meaning is not given but taken and the subject loses itself as an object in the attempt to identify itself in language. We hence approached our reading of imaginary self constructions not as a way of uncovering concrete moments of the subject’s being recognised as who he/she is or recognising others as a leader or follower but as a process of becoming (Harding, 2007) where, by trying to put something about the self into language, it shifts and is being transformed.
According to Crane & Crane (2010), non verbal behavior accounts for 65% to 93% of the human interaction to convey meaning through clues. So in a work environment, where interactions between managers, subordinates and business partners make up the major factor of conducting business, non verbal behavior is a too important field of study to neglect. When looking at a definition of leadership by Yukl (2010) it says that leadership is the process of influencing or controlling the behavior of others in order to reach a shared (business) goal. It is suggested that non verbal behavior and communication are as important, if not more, than verbal communication when it comes to leading people. Burgoon, Birk and Pfau (1990) say that leaders use NVB to influence and persuade their followers by using greater facial expressiveness and greater fluency and pitch variety. The effectiveness of leaders, such as the (positive) impact on followers' motivation, satisfaction and performance, is proven in a number of studies (Yukl, 2010, Kaiser, Hogan & Craig, 2008). Countless of definitions for non-verbal behavior are used in the scientific literature. For this paper, the following definition of non-verbal behavior will be used: every behavior and communication other than the content of the spoken word (Darioly & Schmid Mast, 2014) . Although the categorization between verbal- and non verbal is relatively clear, there can be some confusion as there is some speech related non verbal behavior. Non-verbal communication includes speech related aspects such as tone of voice, speed, and length of the speaking. However, for the scope of this research, speech-related aspects will be left out.
We consider a Stackelberg type dynamic two-players zero-sum game. One of two players is the leader and the other player is the follower. The game is a two-stages game. In the first stage the leader determines the value of its strategic variable. In the second stage the follower determines the value of its strategic variable given the value of the leader’s strategic variable. On the other hand, in the static game two players simultaneously determine the values of their strategic variable. We will show that Sion’s minimax theorem (Sion(1958)) implies that at the sub-game perfect equilibrium of the Stackelberg type dynamic zero-sum game with a leader and a follower the roles of leader and follower are irrelevant to the payoffs of players, and that the Stackelberg equilbria of the dynamic game are equivalent to the equilibrium of the static game.
The aim of the study was to contribute to the research gap on follower communication to their leaders and to explore differences in specific language use between followers of effective leaders and followers of less effective leaders, as well as to examine the language use of effective and less effective leaders. More specifically, this study focused on relation word pronouns such as ‘we’ and ‘us’ and first-person singular pronouns such as ‘I’ and ‘me’, as the literature reveals the importance of these pronouns and how they can influence people (Steffens & Haslam, 2013). The quantitative text mining method helped to investigate these communication differences, which are not interpreted, but rather derived from a real life setting.
The estimation results suggest a leader and follower relationship among banks on most of the grouped observations, although with some variations in magnitude. Generally, competition between followers is insignificant on credit market, but is significant on deposit market. Leader and follower competition result can be viewed on Table 3 below. Control variables, such as: GDP, inflation rate, interbank rate, exchange rate, HHI, credit diversification, credit to PDB ratio, and operational bank ratios are generally show consistent parameters as expected. All-sample estimates also suggesting similar results, and hence confirming the robustness of selected- sample regressions. For estimates using dynamic panel regressions, all estimations fulfill dynamic stability and well represent the data variations. Moreover, the estimations met the exogeneity assumptions for instrumental variables.
In this paper, the Extended Kalman Filter (EKF) is proposed to reduce the accumulation error in the actuator. The information gathered by relative and absolute manners will be fused to suppress the error, resulting in leader-follower mobile robot could localize itself . EKF is selected due to it produces an optimal algorithm based-on recursive filter. It is an estimator widely used in a nonlinear system. EKF will be used to fuse the measurement information from odometer and landmark in order mobile robot could localize itself accurately  . The result of this research will be presented as a performance graph consists of x, y, θ coordinates and the error graph. The rest of the paper is organized as follows. Section II will cover method used in this research. Section III will provide the experimental results and analysis, and finally, the conclusion will be presented in section IV.