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• Saccade Generation for Active Vision
  Ahmed Sheik Deeb
  Friday 10th February 2012 at 01:00 PM

    Cotton Club, Cotton 350

  An active visual attention system is presented for use in robots. This system requires a method of directing the robotâ€^TMs camera at targets of interest. Directing the robotâ€^TMs camera is similar to a mechanism done by the human eye known as the saccadic eye movements. The saccadic eye movements rapidly shifts eyesâ€^TM position and redirect the line of sight toward different objects so that they can be seen more clearly.

  There are two approaches for implementing visual systems: a bottom-up approach which directs the camera at elements of the visual field that have high salience, or a top-down approach which directs the vision under deliberative control. A system inspired by the biological architecture of the behaviour in the human eye is presented by combining both bottom-up and top-down techniques. An artificial analogue of the superior colliculus is used to combine a set of data-driven feature maps. The relative weighting of the various maps are dependent on the task being performed by the robot.

  A discussion of the architecture of the gaze control system and simulations illustrating the operation of the artificial superior colliculus are discussed. These simulations are for two main maps: saliency and threshold maps. The superior colliculus is believed to contain these maps and to play the multisensory control role in the execution of saccadic eye movements.

  In this thesis proposal, a prototype implementation of the superior colliculus maps modeling the visual sensing is presented as a space based neural model of visual attention. It is important to note that the system is not attempting to mimic the human neurobiological equivalent function. On the contrary, the anatomical knowledge is used as a motivation for the proposed model architecture.

• FEEDBACK CONTROL OF VIBRATION IN AIRCRAFT AND IN THE EAR
  Professor Steve Elliott
  Monday 13th February 2012 at 01:10 PM

    Cotton Club, Cotton 350

  The low frequency sound and vibration inside aircraft is now attenuated using commercial active control systems. These typically operate using many shakers acting on the structure to modify its vibration and hence reduce excitation of the sound field.

  As the structure becomes larger, the number of actuators and sensors required for effective control rises significantly. Conventional, fully coupled, control systems then become costly in terms of weight and sensitivity to individual failures. An alternative strategy is to distributing the control over multiple local controllers, which has been shown to be effective in a number of cases. Recent work will be presented on tuning these local control loops to maximise the power they absorb from the structure, which may allow the mass production of generic active control modules that include an actuator, sensor and self-tuning controller.

  The workings of the inner ear also provide a remarkable natural example of distributed active vibration control, whose objective is to enhance the motion within the cochlea. A simple model for this cochlear amplifier, in which each of the outer hair cells act as local control loops, will be described and its use illustrated in predicting the otoacoustic emissions generated by the ear. These emissions are used clinically to screen the hearing of young children and so it is important to understand how they are generated within the cochlea.

• PERSONAL AUDIO AND ACTIVE CONTROL OF SOUND IN THE ENVIRONMENT
  Professor Steve Elliott
  Tuesday 14th February 2012 at 09:00 AM

    Cotton Club, Cotton 350

  As well as being able to reproduce sound in one region of space, it would be useful in many applications to be able to control the level of reproduced sound in other spatial regions. This is motivated by issues of privacy for the user and the need to reduce annoyance for other people nearby. The techniques for implementing this kind of "personal audio" using array of loudspeakers have much in common with systems for the active control of sound, where the traditional objective has been only to reduce the sound level in environments such as cars and aircraft, for example.

  Several practical examples of personal audio systems will be described, including using an array of loudspeakers in headrests to reproduce separate audio channels in adjacent seats, a system to reduce radiated sound from hands-free mobile devices and zonal amplification of TV audio. These systems often have a fundamental trade-off between performance and array effort, where the latter affects both the electrical power requirements of the array and its robustness to variations in driver response. Signal processing strategies will be described that allow a good compromise to be drawn between these competing requirements.

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