An intelligent robotic aid system for human services

The long term goal of our research at the Intelligent Robotic Laboratory at Vanderbilt University is to develop advanced intelligent robotic aid systems for human services. As a first step toward our goal, the current thrusts of our R&D are centered on the development of an intelligent robotic aid called the ISAC (Intelligent Soft Arm Control). In this paper, we describe the overall system architecture and current activities in intelligent control, adaptive/interactive control and task learning

Numerical simulation of the influence of the orifice aperture on the flow around a teeth-shaped obstacle

The sound generated during the production of the sibilant [s] results from the impact of a turbulent jet on the incisors. Several geometric characteristics of the oral tract can affect the properties of the flow-induced noise so that the characterization of the influence of different geometric parameters on the acoustic sources properties allows determining control factors of the noise production. In this study, a simplified vocal tract/teeth geometric model is used to numerically investigate the flow around a teeth-shaped obstacle placed in a channel and to analyze the influence of the aperture at the teeth on the spectral properties of the fluctuating pressure force exerted on the surface of the obstacle, which is at the origin of the dipole sound source. The results obtained for Re = 4000 suggest that the aperture of the constriction formed by the teeth modifies the characteristics of the turbulent jet downstream of the teeth. Thus, the variations of the flow due to the modification of the constriction aperture lead to variations of the spectral properties of the sound source even if the levels predicted are lower than during the production of real sibilant fricative

A Method of co-registering multiple magnetic resonance imaged vocal tract volumes for fricatives

In a study of fricative production, Magnetic Resonance Imaging was used to investigate three-dimensional tract geometries of fricatives produced in different vowel contexts. Scan sequences were designed to minimize the number of elicitations required, to reduce acquisition times, and to constrain the imaging of a given phone to a single session. A new method of assembling vocal tract volumes was developed to consolidate the data obtained using this approach. Sagittal, axial and oblique-coronal imaging orientations were chosen to best resolve the tract in the midsagittal plane, the pharynx, and around the fricative constriction. Each fricative token was acquired using a 36 second imaging sequence. Three corresponding point clouds were created by sampling air-tissue boundaries in each image stack, and aligned using anatomical landmarks on the face and spinal column, creating a single, multiplysampled volume. A composite tract model was developed, using the most suitable data source at each region of the tract. Vocal tract models of eight English fricatives, produced in three vowel contexts, were constructed in this manner. The models have provided important insights into the articulation of the constriction and tongue grooving, as well as differences in the production of voiced/voiceless fricatives.6 page(s

An MRI study of the effect of vowel context on english fricatives

To gain a better understanding of the long-observed effects of vocalic context, the articulation of fricatives was investigated using Magnetic Resonance Imaging. Five speakers of American English were imaged while producing eight fricatives in the contexts /i-a-u-?/. Sagittal, axial and oblique-coronal volumes were acquired for each vowel-fricative combination. Acoustic recordings were made during scans and separately in an anechoic chamber. Vocal tract models were generated by aligning and superimposing all three stack orientations. The models reveal that a variety of articulatory strategies are employed in the production of English fricatives, and that vocalic context is significant. For some subjects, tongue shape differs little with vowel context; other subjects show highly varied tongue shape differences but little difference in lip rounding. Two subjects show significant variation with vowel context for every fricative, including [?]. Two show very little difference, even for [f]. The sublingual cavity in [?] is extensive for two subjects, but only slightly bigger than in [s] for two other subjects. Tongue grooving in and behind the constriction also varies, and is especially evident in the oblique scans. Overall, more variation and effect of vowel context was observed than expected from the literature.6 page(s

Intelligent User Interface for a Rehabilitation Robot

this paper are all designed to make ISAC an intelligent system, as its name suggests. One important pre-requisite for intelligence is the ability to sense. We have relied on vision sensors for the most part, mainly due to their general purpose nature. The same camera that locates objects on the table can also tell if the hand is grasping a fork, or if the fork has picked up some food. The fusion of information from various sensors is also important. For example, we are implementing an ultrasonic ranging sensor that will compliment the camera based face-tracking module. The modules described here are currently under implementation. Future work involves testing these features and receiving feedback from users. After all, a user friendly interface is successful only if the users find it to be so. Reference

Articulatory–acoustic kinematics: The production of American English ∕s∕

Due to its aerodynamic, articulatory, and acoustic complexities, the fricative ∕‐∕ is known to require high precision in its control, and to be highly resistant to coarticulation. This study documents in detail how jaw, tongue front, tongue back, lips, and the first spectral moment covary during the production of ∕‐∕, to establish how coarticulation affects this segment. Data were obtained from 24 speakers in the Wisconsin x-ray microbeam database producing ∕‐∕ in prevocalic and pre-obstruent sequences. Analysis of the data showed that certain aspects of jaw and tongue motion had specific kinematic trajectories, regardless of context, and the first spectral moment trajectory corresponded to these in some aspects. In particular contexts, variability due to jaw motion is compensated for by tongue-tip motion and bracing against the palate, to maintain an invariant articulatory–aerodynamic goal, constriction degree. The change in the first spectral moment, which rises to a peak at the midpoint of the fricative, primarily reflects the motion of the jaw. Implications of the results for theories of speech motor control and acoustic–articulatory relations are discussed