Whisking with robots from rat vibrissae to biomimetic technology for active touch

This article summarizes some of the key features of the rat vibrissal system, including the actively controlled sweeping movements of the vibrissae known as whisking, and reviews the past and ongoing research aimed at replicating some of this functionality in biomimetic robots

Cohort profile: the Siyakhula cohort, rural South Africa

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Comparing innovation systems for solar photovoltaics in the United Kingdom and in China

Innovation in renewable energy sources (RES), such as solar photovoltaics (PV), can play an important part in CO2 reductions for climate change mitigation, as well as contributing to economic development. With a production capacity growing by more than 70% per year over the last 7 years, China is rapidly emerging as an important player in the global PV market, with significant levels of exports to Western European countries. The country's low labour cost combined with the potentially huge internal market should enable it to contribute to technology learning processes, driving down costs and increasing market diffusion. By comparison, though the UK aims to show global leadership in climate change policy, e.g. by setting a legally binding target to reduce CO2 emissions by 60% by 2050, it has been slow in developing either production capacity or markets for PV technology. By adopting a national innovation systems framework of analysis, the paper identifies the different technological and institutional actors and relations of the innovation systems for PV in the UK and in China, and assesses the extent to which these are likely to encourage or constrain the technological development and the market diffusion of this technology in the two countries. This novel effort to compare and contrast the innovation systems in the two countries combines information collected in both the UK and China and interviews with a sample of key actors in the PV sector. The comparison of the two countries’ innovation systems both unveils striking differences from which valuable policy lessons can be derived for the management of innovation in the energy sector and helps understanding of how such innovation could contribute to economic development

Empirically inspired simulated electro-mechanical model of the rat mystacial follicle-sinus complex

In whiskered animals, activity is evoked in the primary sensory afferent cells (trigeminal nerve) by mechanical stimulation of the whiskers. In some cell populations this activity is correlated well with continuous stimulus parameters such as whisker deflection magnitude, but in others it is observed to represent events such as whisker-stimulator contact or detachment. The transduction process is mediated by the mechanics of the whisker shaft and follicle-sinus complex (FSC), and the mechanics and electro-chemistry of mechanoreceptors within the FSC. An understanding of this transduction process and the nature of the primary neural codes generated is crucial for understanding more central sensory processing in the thalamus and cortex. However, the details of the peripheral processing are currently poorly understood. To overcome this deficiency in our knowledge, we constructed a simulated electro-mechanical model of the whisker-FSC-mechanoreceptor system in the rat and tested it against a variety of data drawn from the literature. The agreement was good enough to suggest that the model captures many of the key features of the peripheral whisker system in the rat

The Emergence of Action Sequences from Spatial Attention: Insight from Rodent-Like Robots

Animal behaviour is rich, varied, and smoothly integrated. One plausible model of its generation is that behavioural sub-systems compete to command effectors. In small terrestrial mammals, many behaviours are underpinned by foveation, since important effectors (teeth, tongue) are co-located with foveal sensors (microvibrissae, lips, nose), suggesting a central role for foveal selection and foveation in generating behaviour. This, along with research on primate visual attention, inspires an alternative hypothesis, that integrated behaviour can be understood as sequences of foveations with selection being amongst foveation targets based on their salience. Here, we investigate control architectures for a biomimetic robot equipped with a rodent-like vibrissal tactile sensing system, explicitly comparing a salience map model for action guidance with an earlier model implementing behaviour selection. Both architectures generate life-like action sequences, but in the salience map version higher-level behaviours are an emergent consequence of following a shifting focus of attention

Whisker-object contact speed affects radial distance estimation

Whiskered mammals such as rats are experts in tactile perception. By actively palpating surfaces with their whiskers, rats and mice are capable of acute texture discrimination and shape perception. We present a novel system for investigating whisker-object contacts repeatably and reliably. Using an XY positioning robot and a biomimetic artificial whisker we can generate signals for different whisker-object contacts under a wide range of conditions. Our system is also capable of dynamically altering the velocity and direction of the contact based on sensory signals. This provides a means for investigating sensory motor interaction in the tactile domain. Here we implement active contact control, and investigate the effect that speed has on radial distance estimation when using different features for classification. In the case of a moving object contacting a whisker, magnitude of deflection can be ambiguous in distinguishing a nearby object moving slowly from a more distant object moving rapidly. This ambiguity can be resolved by finding robust features for contact speed, which then informs classification of radial distance. Our results are verified on a dataset from SCRATCHbot, a whiskered mobile robot. Building whiskered robots and modelling these tactile perception capabilities would allow exploration and navigation in environments where other sensory modalities are impaired, for example in dark, dusty or loud environments such as disaster areas. © 2010 IEEE

Perception of simple stimuli using sparse data from a tactile whisker array

We introduce a new multi-element sensory array built from tactile whiskers and modelled on the mammalian whisker sensory system. The new array adds, over previous designs, an actuated degree of freedom corresponding approximately to the mobility of the mystacial pad of the animal. We also report on its performance in a preliminary test of simultaneous identification and localisation of simple stimuli (spheres and a plane). The sensory processing system uses prior knowledge of the set of possible stimuli to generate percepts of the form and location of extensive stimuli from sparse and highly localised sensory data. Our results suggest that the additional degree of freedom has the potential to offer a benefit to perception accuracy for this type of sensor. © 2013 Springer-Verlag Berlin Heidelberg

Whiskered texture classification with uncertain contact pose geometry

Tactile sensing can be an important source of information for robots, and texture discrimination in particular is useful in object recognition and terrain identification. Whisker based tactile sensing has recently been shown to be a promising approach for mobile robots, using simple sensors and many classification approaches. However these approaches have often been tested in limited environments, and have not been compared against one another in a controlled way. A wide range of whisker-object contact poses are possible on a mobile robot, and the effect such contact variability has on sensing has not been properly investigated. We present a novel, carefully controlled study of simple surface texture classifiers on a large set of varied pose conditions that mimic those encountered by mobile robots. Namely, single brief whisker contacts with textured surfaces at a range of surface orientations and contact speeds. Results show that different classifiers are appropriate for different settings, with spectral template and feature based approaches performing best in surface texture, and contact speed estimation, respectively. The results may be used to inform selection of classifiers in tasks such as tactile SLAM

Brain-inspired Bayesian perception for biomimetic robot touch

Studies of decision making in animals suggest a neural mechanism of evidence accumulation for competing percepts according to Bayesian sequential analysis. This model of perception is embodied here in a biomimetic tactile sensing robot based on the rodent whisker system. We implement simultaneous perception of object shape and location using two psychological test paradigms: first, a free-response paradigm in which the agent decides when to respond, implemented with Bayesian sequential analysis; and second an interrogative paradigm in which the agent responds after a fixed interval, implemented with maximum likelihood estimation. A benefit of free-response Bayesian perception is that it allows tuning of reaction speed against accuracy. In addition, we find that large gains in decision performance are achieved with unforced responses that allow null decisions on ambiguous data. Therefore free-response Bayesian perception offers benefits for artificial systems that make them more animal-like in behavior