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One of the most interesting and demanding uses of the vibrissal sense in both rodents and insectivores is in predation. Etruscan shrews, for instance, prey on insects such as crickets which are themselves highly agile, exquisitely mechanosensitive, and almost as large as the shrew itself. Shrews succeed in hunting these creatures by fast and precise attacks. Previous work has demonstrated that tactile shape cues are both necessary and sufficient for evoking and controlling these attacks, whereas visual and olfactory cues are not needed. Rats are also efficient predators that can detect, track, and immobilise prey animals such as cockroaches in darkness. In this activity we will reverse-engineer the neurobiological substrates for vibrissal tracking to develop algorithms that will allow a wheeled mobile robot, equipped with an artificial active vibrissal system and a highly manoeuvrable “head”, to locate, identify, and track fast-moving targets such as smaller robots or remote-controlled toy vehicles. This work will require scientific and technological advances in the following areas:

• Biomimetic control of orienting
• Biomimetic control in tracking
• Fusing predictive tracking with object recognition

Biomimetic control of orienting

Successful predation in whiskered animals is reliant on the midbrain superior colliculus which is involved in controlling the rapid orienting movements needed to locate and keep pace with a moving target. In addition to vibrissal information the colliculus will also require vestibular and/or proprioceptive inputs in order to generate appropriate control signals. We will perform electrophysiological and behavioural studies to investigate the role of the colliculus in the control of whisking and whisker-guided head movements, and to understand the integration of vestibular and whisker information in animals that are searching for a target in space. Computational models will be developed to explain these data and to control whisking/orienting movements in simulated and actual whisking robots.

Biomimetic predictive control in tracking

The fast, ballistic movements needed for prey tracking will also require predictive rather reactive control. The cerebellum is likely to play an essential role here as cerebellar damage particularly impairs predictive aspects of motor behaviour. Studies of the role of the cerebellum in the control of primate grasp also suggest it as a likely neural substrate for relevant internal, forward models. Anatomically, the cerebellum is involved in a closed loop with the superior colliculus indicating a close synergy between these two systems. Building on models of cerebellar predictive control developed for other motor behaviours, such as eye movements, we will develop cerebellar-inspired algorithms for predictive pursuit and evaluate their effectiveness in controlling tactile tracking behaviour in our robot platform.

Fusing predictive tracking with object recognition

To complete our model of predation in whisking animals, and to generate a biomimetic system that demonstrates useful integrative functionality, we will combine the orienting/tracking competences described above with those for tactile object recognition investigated in activity 3 (Adaptive tactile coding, memory & decision-making). The resulting control systems will allow our whiskered mobile robot platform to distinguish between target objects to be tracked and distracter objects to be ignored or avoided. We believe that the demonstration of such functionality will represent a very substantial advance in artificial tactile sensing and control compared to existing technologies.