Self sufficient wireless transmitter powered by foot-pumped urine operating wearable MFC.

The first self-sufficient system, powered by a wearable energy generator based on microbial fuel cell (MFC) technology is introduced. MFCs made from compliant material were developed in the frame of a pair of socks, which was fed by urine via a manual gaiting pump. The simple and single loop cardiovascular fish circulatory system was used as the inspiration for the design of the manual pump. A wireless programmable communication module, engineered to operate within the range of the generated electricity, was employed, which opens a new avenue for research in the utilisation of waste products for powering portable as well as wearable electronics.

Improved single- and multi-contact life-time testing of dental restorative materials using key characteristics of the human masticatory system and a force/position-controlled robotic dental wear simulator.

This paper presents a new in vitro wear simulator based on spatial parallel kinematics and a biologically inspired implicit force/position hybrid controller to replicate chewing movements and dental wear formations on dental components, such as crowns, bridges or a full set of teeth. The human mandible, guided by passive structures such as posterior teeth and the two temporomandibular joints, moves with up to 6 degrees of freedom (DOF) in Cartesian space. The currently available wear simulators lack the ability to perform these chewing movements. In many cases, their lack of sufficient DOF enables them only to replicate the sliding motion of a single occlusal contact point by neglecting rotational movements and the motion along one Cartesian axis. The motion and forces of more than one occlusal contact points cannot accurately be replicated by these instruments. Furthermore, the majority of wear simulators are unable to control simultaneously the main wear-affecting parameters, considering abrasive mechanical wear, which are the occlusal sliding motion and bite forces in the constraint contact phase of the human chewing cycle. It has been shown that such discrepancies between the true in vivo and the simulated in vitro condition influence the outcome and the quality of wear studies. This can be improved by implementing biological features of the human masticatory system such as tooth compliance realized through the passive action of the periodontal ligament and active bite force control realized though the central nervous system using feedback from periodontal preceptors. The simulator described in this paper can be used for single- and multi-occlusal contact testing due to its kinematics and ability to exactly replicate human translational and rotational mandibular movements with up to 6 DOF without neglecting movements along or around the three Cartesian axes. Recorded human mandibular motion and occlusal force data are the reference inputs of the simulator. Experimental studies of wear using this simulator demonstrate that integrating the biological feature of combined force/position hybrid control in dental material testing improves the linearity and reduces the variability of results. In addition, it has been shown that present biaxially operated dental wear simulators are likely to provide misleading results in comparative in vitro/in vivo one-contact studies due to neglecting the occlusal sliding motion in one plane which could introduce an error of up to 49% since occlusal sliding motion D and volumetric wear loss V(loss) are proportional.

Development of a parametric kinematic model of the human hand and a novel robotic exoskeleton.

This paper reports the integration of a kinematic model of the human hand during cylindrical grasping, with specific focus on the accurate mapping of thumb movement during grasping motions, and a novel, multi-degree-of-freedom assistive exoskeleton mechanism based on this model. The model includes thumb maximum hyper-extension for grasping large objects (~> 50 mm). The exoskeleton includes a novel four-bar mechanism designed to reproduce natural thumb opposition and a novel synchro-motion pulley mechanism for coordinated finger motion. A computer aided design environment is used to allow the exoskeleton to be rapidly customized to the hand dimensions of a specific patient. Trials comparing the kinematic model to observed data of hand movement show the model to be capable of mapping thumb and finger joint flexion angles during grasping motions. Simulations show the exoskeleton to be capable of reproducing the complex motion of the thumb to oppose the fingers during cylindrical and pinch grip motions.

Improved energy output levels from small-scale Microbial Fuel Cells.

This study reports on the findings from the investigation into small-scale (6.25 mL) MFCs, connected together as a network of multiple units. The MFCs contained unmodified (no catalyst) carbon fibre electrodes and for initial and later experiments, a standard ion-exchange membrane for the proton transfer from the anode to the cathode. The anode microbial culture was of the type commonly found in domestic wastewater fed with 5 mM acetate as the carbon-energy (C/E) source. The cultures were mature and acclimatised in the MFC environment for approximately 2 months before being re-inoculated in the experimental MFC units. The cathode was of the O(2) diffusion open-to-air type, but for the purposes of the polarization experiments, the cathodic electrodes were moistened with ferricyanide. The main aim of this study was to investigate the effects of connecting multiples of MFC units together as a method of scale up by using stacks and comparison of the effects of different PEM and MFC structural materials on the performance. Impedance matching (maximum-power-transfer) was achieved through calculation of total internal impedance. Three different PEM materials were compared in otherwise identical MFCs in sets of three. For individual isolated MFCs, Hyflon E87-03 was shown to produce twice, whilst E87-10 produced approximately 1.5 times the power output of the control (standard) PEM. However, when MFCs containing the E87-03 and E87-10 membranes were connected in a stack, the system suffered from severe instability and cell reversal. To study the effects of the various polymeric MFC structural materials, four small-scale units were manufactured from three different types of RP material; acrylo-butadiene-styrene coated (ABS), ABS coated (ABS-MEK) and polycarbonate (polyC). The stack of four (4) units prototyped out of polyC produced the highest power density values in polarisation experiments (80 mW/m(2)).

Extracting textural features from tactile sensors.

This paper describes an experiment to quantify texture using an artificial finger equipped with a microphone to detect frictional sound. Using a microphone to record tribological data is a biologically inspired approach that emulates the Pacinian corpuscle. Artificial surfaces were created to constrain the subsequent analysis to specific textures. Recordings of the artificial surfaces were made to create a library of frictional sounds for data analysis. These recordings were mapped to the frequency domain using fast Fourier transforms for direct comparison, manipulation and quantifiable analysis. Numerical features such as modal frequency and average value were calculated to analyze the data and compared with attributes generated from principal component analysis (PCA). It was found that numerical features work well for highly constrained data but cannot classify multiple textural elements. PCA groups textures according to a natural similarity. Classification of the recordings using k nearest neighbors shows a high accuracy for PCA data. Clustering of the PCA data shows that similar discs are grouped together with few classification errors. In contrast, clustering of numerical features produces erroneous classification by splitting discs between clusters. The temperature of the finger is shown to have a direct relation to some of the features and subsequent data in PCA.

An adaptive gaze stabilization controller inspired by the vestibulo-ocular reflex.

The vestibulo-ocular reflex stabilizes vision in many vertebrates. It integrates inertial and visual information to drive the eyes in the opposite direction to head movement and thereby stabilizes the image on the retina. Its adaptive nature guarantees stable vision even when the biological system undergoes dynamic changes (due to disease, growth or fatigue etc), a characteristic especially desirable in autonomous robotic systems. Based on novel, biologically plausible neurological models, we have developed a robotic testbed to qualitatively evaluate the performance of these algorithms. We show how the adaptive controller can adapt to a time varying plant and elaborate how this biologically inspired control architecture can be employed in general engineering applications where sensory feedback is very noisy and/or delayed.

Implementing spiking neural networks for real-time signal-processing and control applications: a model-validated FPGA approach.

In this paper, we present two versions of a hardware processing architecture for modeling large networks of leaky-integrate-and-fire (LIF) neurons; the second version provides performance enhancing features relative to the first. Both versions of the architecture use fixed-point arithmetic and have been implemented using a single field-programmable gate array (FPGA). They have successfully simulated networks of over 1000 neurons configured using biologically plausible models of mammalian neural systems. The neuroprocessor has been designed to be employed primarily for use on mobile robotic vehicles, allowing bio-inspired neural processing models to be integrated directly into real-world control environments. When a neuroprocessor has been designed to act as part of the closed-loop system of a feedback controller, it is imperative to maintain strict real-time performance at all times, in order to maintain integrity of the control system. This resulted in the reevaluation of some of the architectural features of existing hardware for biologically plausible neural networks (NNs). In addition, we describe a development system for rapidly porting an underlying model (based on floating-point arithmetic) to the fixed-point representation of the FPGA-based neuroprocessor, thereby allowing validation of the hardware architecture. The developmental system environment facilitates the cooperation of computational neuroscientists and engineers working on embodied (robotic) systems with neural controllers, as demonstrated by our own experience on the Whiskerbot project, in which we developed models of the rodent whisker sensory system.

Stigmergy, self-organization, and sorting in collective robotics.

Many structures built by social insects are the outcome of a process of self-organization, in which the repeated actions of the insects interact over time with the changing physical environment to produce a characteristic end state. A major mediating factor is stigmergy, the elicitation of specific environment-changing behaviors by the sensory effects of local environmental changes produced by previous behavior. A typical task involving stigmergic self-organization is brood sorting: Many ant species sort their brood so that items at similar stages of development are grouped together and separated from items at different stages of development. This article examines the operation of stigmergy and self-organization in a homogeneous group of physical robots, in the context of the task of clustering and sorting Frisbees of two different types. Using a behavioral rule set simpler than any yet proposed for ant sorting, and having no capacity for spatial orientation or memory, the robots are able to achieve effective clustering and sorting showing all the signs of self-organization. It is argued that the success of this demonstration is crucially dependent on the exploitation of real-world physics, and that the use of simulation alone to investigate stigmergy may fail to reveal its power as an evolutionary option for collective life forms.