Fault tolerance operation of cooperative manipulators

Autonomous or teleoperation of critical tasks in space applications require fault tolerant robotic manipulators. These manipulators are able to maintain their tasks even if a joint fails. If it is presumed that the manipulator is fault tolerant on its trajectory, then the next step is to provide a fault tolerant force at the end-effector of the manipulator. The problem of cooperative fault tolerant force is addressed in this paper within the operation of two manipulators. The cooperative manipulators are used to compensate the force jump which occurs on the force of the end-effector of one manipulator due to a joint failure. To achieve fault tolerant operation, the contribution of the faulty joint for the force of the end-effector of the faulty manipulator is required to be optimally mapped into the torque of the faulty and healthy manipulators. The optimal joint torque reconfigurations of both manipulators for compensating this force jump are illustrated. The proposed frameworks are deployed for two cooperative PUMA560 manipulators. The results of the case studies validate the fault tolerant cooperation strategies.

A robust adaptive hybrid force/position control scheme of two planar manipulators handling an unknown object interacting with an environment

This paper presents a robust hybrid force/position control scheme of two cooperative manipulators handling an unknown object interacting with an unknown environment. The uncertainty of the object is considered in the weight, length, and the position of centre of mass (COM). The environment is assumed to have an unknown but high stiffness. A hybrid force/position control algorithm is designed for the known system and environment case. The exponential convergence of the position and the interaction force with the environment is proved using the Lyapunov direct method. Similarly, in the unknown object and environment case, and in the presence of bounded disturbances on the robots and the object, an adaptive sliding mode hybrid force/position control scheme is designed. The asymptotic convergence of the object's position and the constraint force is guaranteed using the proposed control methodology. The internal forces and moments between the object and robots are controlled independently of the object's motion and environmental interaction forces. Simulation results confirm the performance and effectiveness of the suggested control methodologies.

4-Amino-1,8-naphthalimide-based anion receptors: employing the naphthalimide N-H moiety in the cooperative binding of dihydrogenphosphate

The 4-amino-1,8-naphthalimide-based anion receptor 3 binds dihydrogenphosphate with 1:1 stoichiometry through cooperative hydrogen bonding to a naphthalimide N–H and thiourea N–H groups. This was clearly established from ¹H NMR titration experiments in DMSO-d₆ where a substantial shift in the resonance for the naphthalimide N–H was observed concomitant with the expected thiourea N–H chemical shift migration upon successive additions of H₂PO₄⁻. However, whilst ¹H NMR titration experiments indicate that 3 was capable of binding other anions such as acetate, the naphthalimide N–H does not participate and the N–H resonance was essentially invariant during the titration. The lack of cooperative binding in this instance was justifiable on steric grounds.

The impact of teaching models, group structures and assessment modes on cooperative learning in the student design studio

As a result of ever diminishing teaching resources, an increasing number of architectural educators are setting group design projects, rather then spreading their time thinly over a large number of individual projects. This allows them to co-ordinate longer and more in-depth review sessions on a smaller number of assignment submissions. However, while the group
model may offer an authentic learning model by reflecting design in practice, the approach is not without its obvious shortcomings as a teaching archetype for the assessment of the knowledge and skill competencies of individual students. Hence, what is clear is the need for a readily adoptable andragogy for the teaching and assessment of group design projects.
The following paper describes the background, methodology and findings of a Strategic Teaching and Learning Grant funded research project carried out in the year 2005 at the School of Architecture and Building at Deakin University. The project aimed to inform a change of classroom/studio practice governing the assemblage, teaching and assessment of student design teams. The development through these changes of cooperative and student centred learning principles focused on effective design collaboration and fair assessment should, it will be argued, lead to an enhanced group-learning experience in studio, which will subsequently and ultimately enhance professional practice.

Measuring moral judgement and the implications of cooperative education and rule-based learning

The Defining Issues Test (DIT), developed by Rest (1986), measures a person's level of moral development using hypothetical social dilemmas. Although the DIT is useful for measuring moral development in social settings, it might not adequately capture an individual's moral judgement abilities in solving work-related problems (Weber, 1990; Trevino, 1992; Welton et al., 1994). In the present study, the moral judgement levels of 97 accounting students were measured over a 1 year period using two separate test instruments, the DIT and a context-specific instrument developed by Welton et al. (1994). The test scores are significantly higher on the DIT than the Welton instrument (between the instruments and over time), suggesting that accounting students use higher levels of moral reasoning in resolving hypothetical social dilemmas and lower levels of moral reasoning in resolving context-specific dilemmas. The difference in test scores was highest during cooperative education (work placement programme), implying that the environment is a significant determinant on students' test scores.

Teaching practices for effective cooperative learning in an online learning environment (OLE)

As a teaching practice the application of cooperative learning in tertiary education can present unique challenges for both the practitioner and her students. Mastering this teaching approach requires careful planning, design and implementation for effective deployment in a face-to-face setting. In this setting the success of the cooperative learning approach has been demonstrated. The complexity is significantly increased by additional variables such as the selection and application of technological teaching tools and the change in nature of existing variables including awareness of students' social and communication skills when applying this practice in an Online Learning Environment (OLE). In addition student acceptance of this e-learning approach to learning also needs to be carefully considered. The practitioner must be aware of these factors and have suitable methods in place to support collaboration and interaction between student groups to ensure the ultimate goal with regard to students' learning is achieved. This paper considers how cooperative learning can be combined effectively with these variables and factors of an OLE, and begins with the presentation of a conceptual framework to represent this relationship as a constructive teaching practice. It is anticipated that the conceptual framework would be applied by other practitioners to facilitate cooperative teaching within their OLE. To demonstrate the validity of the framework a case scenario is provided using an Information Technology (IT) undergraduate unit named 'IT Practice'. This is a wholly online unit where extensive participation by the students within small groups is a core requirement. The paper demonstrates the themes of designing curriculum and assessment, as well as flexible teaching strategies for learner diversity but primarily concentrates on managing an effective OLE; that is managing small groups in an online teaching environment.

Conceptualising best practices in cooperative industry-based learning in information systems and information technology: an inter-institutional investigation in Australian higher education

The professional fields of information systems and information technology are drivers and enablers of the global economy. Moreover, their theoretical scope and practices are global in focus. University graduates need to develop a range of leadership, conceptual and technical capacities to work effectively in, and contribute to, the shaping of companies, business models and systems which operate in globalised settings. This paper reports a study of the operation of industry-based learning (IBL) at three Australian universities, which employ different models and approaches, as part of a series of investigations of the needs, circumstances and perspectives of various stakeholders (program coordinator, faculty teaching staff, the students, industry mentors, and the professional body which has supported the most recent stage of this study). The focus of this paper is a discussion of salient pragmatic considerations as we attempt to conceptualise what constitutes best practice in offering industry-based learning for higher education students in the disciplines of information systems and information technology.

Geographic routing with cooperative relaying and leapfrogging in wireless sensor networks

A novel geographic routing protocol for multi-hop wireless sensor networks is presented. It exploits the broadcast nature of the wireless channel to enable on-demand cooperative relaying and leapfrogging for circumventing weak radio links. In order to achieve energy efficiency, a metric is introduced for next-hop selection that takes into account information on the residual battery energy, the geographical position of the sensor nodes, and the channel quality of the involved radio links when available. Performance results show that the completely decentralized protocol offers significant benefits by reducing the number of (re)transmissions required to reach the destination. This translates into network-wide energy savings that extend the network lifetime.

The rise and decline of the New South Wales cooperative housing societies

In the past, New South Wales cooperative housing societies made an important contribution to the financing of housing construction. In this paper the expansion and later contraction of the societies is explained. It is shown that, in recent times, not only have they suffered from a drying up of loan funding, but also a great number have operated at far below their possible level of efficiency.

Dynamic output feedback control of single-link flexible manipulators

This paper presents an efficient technique to design dynamic feedback control scheme for single-link flexible manipulators.  A linear model can be derived for the robotic system using the assumed-mode method.  Conventional techniques such as pole-placement or LQR require physical measurements of all systme states,  posing a stringent requirement for its implementation.  To overcome this problem, a low-order state functional observer is proposed here for reconstruction of the state feedback control action.  The observer design involves solving an optimisation problem with the objective to generate a feedback gain that is as close as possible to that of the required feedback controller.  A condition for robust stability of the closed-loop system under the observer-based control scheme is given.  The attractive features of the propsed technique are the resulted functional state observer is of a very low order and it requires only sensor measurements of only the output- the tip position of the arm.