Towards dynamically-favourable quad-rotor aerial robots

This paper outlines progress towards realising practical quad-rotor robot helicopters and, in particular, the Australian National University’s ‘X-4 Flyer’ platform. Two challenges facing the X-4 are generating sufficient thrust and managing unstable dynamic behaviour. We address these issues with a rotor design technique for maximising thrust and the application of a novel rotor mast configuration. An aero-elastic blade design is described and its performance results are presented. A sprung teetering rotor hub that allows adjustment of the blade flapping characteristics and a quad-rotor dynamic model with blade flapping are introduced. The use of inverted rotors is shown to produce favorable stability properties for the Mark II X-4 Flyer.

Nonlinear control of the Reaction Wheel Pendulum

In this paper we introduce the Reaction Wheel Pendulum, a novel mechanical system consisting of a physical pendulum with a rotating bob. This system has several attractive features both from a pedagogical standpoint and from a research standpoint. From a pedagogical standpoint, the dynamics are the simplest among the various pendulum experiments available so that the system can be introduced to students earlier in their education. At the same time, the system is nonlinear and underactuated so that it can be used as a benchmark experiment to study recent advanced methodologies in nonlinear control, such as feedback linearization, passivity methods, backstepping and hybrid control. In this paper we discuss two control approaches for the problems of swingup and balance, namely, feedback linearization and passivity based control. We first show that the system is locally feedback linearizable by a local diffeomorphism in state space and nonlinear feedback. We compare the feedback linearization control with a linear pole-placement control for the problem of balancing the pendulum about the inverted position. For the swingup problem we discuss an energy approach based on collocated partial feedback linearization, and passivity of the resulting zero dynamics. A hybrid/switching control strategy is used to switch between the swingup and the balance control. Experimental results are presented.

PIPP #1 - Pedestrian Interaction Patch Project

The Pedestrian Interaction Patch Project (PIPP) seeks to exert influence over and encourage abnormal pedestrian behavior. By placing an unadvertised (and non recording) interactive video manipulation system and projection source in a high traffic public area, the PIPP allows pedestrians to privately (and publically) re-engage with a previously inactive physical environment, like a commonly used walkway or corridor. This system, the results of which are projected in real time on the architectural surface, inadvertently provides pedestrians with questions around preconceived notions of self and space. In an attempt to re-activate our relationship with the physical surrounds we occupy each day the PIPP creates a new set of memories to be recalled as we re-enter known environments once PIPP has moved on and as such re-enlivens our relationship with the everyday architecture we stroll past everyday. The PIPP environment is controlled using the software program Isadora, devised by Mark Coniglio at Troika Ranch, and contains a series of video manipulation patches that are designed to not only grab the pedestrians attention but to also encourage a sense of play and interaction between the architecture, the digital environment, the initially unsuspecting participant(s) and the pedestrian audience. The PIPP was included as part of the planned walking tour for the “Playing in Urban Spaces” seminar day, and was an installation that ran for the length of the symposium in a reclaimed pedestrian space that was encountered by both the participants and general public during the course of the day long event. Ideally once discovered PIPP encouraged pedestrians to return through the course of the seminar day to see if the environmental patches had changed or altered, and changed their standard route to include the PIPP installation or to avoid it, either way, encouraging an active response to the pathways normally traveled or newly discovered each day.

Generic one round group key exchange in the standard model

Minimizing complexity of group key exchange (GKE) protocols is an important milestone towards their practical deployment. An interesting approach to achieve this goal is to simplify the design of GKE protocols by using generic building blocks. In this paper we investigate the possibility of founding GKE protocols based on a primitive called multi key encapsulation mechanism (mKEM) and describe advantages and limitations of this approach. In particular, we show how to design a one-round GKE protocol which satisfies the classical requirement of authenticated key exchange (AKE) security, yet without forward secrecy. As a result, we obtain the first one-round GKE protocol secure in the standard model. We also conduct our analysis using recent formal models that take into account both outsider and insider attacks as well as the notion of key compromise impersonation resilience (KCIR). In contrast to previous models we show how to model both outsider and insider KCIR within the definition of mutual authentication. Our analysis additionally implies that the insider security compiler by Katz and Shin from ACM CCS 2005 can be used to achieve more than what is shown in the original work, namely both outsider and insider KCIR.

The effect of flocculants on the filtration of bagasse pulp pads

This study examined the effect of flocculants on the filtration parameters of bagasse pulp. In the first phase, flocculants were effective for improving the fiber retention of three different bagasse pulp slurries, based on flocculant system studies using a dynamic drainage jar. In the second phase, pulp pads were formed using these flocculants and the steady-state permeability and compressibility parameters were measured. The results showed that the flocculant system that was effective for a pulp slurry was entirely ineffective in improving pulp pad permeability or compressibility during the second experimental phase for two of the bagasse pulp samples.