Pitch Trajectories Research Articles

Quadrupedal galloping control for a wide range of speed via vertical impulse scaling

This paper presents a bio-inspired quadruped controller that allows variable-speed galloping. The controller design is inspired by observations from biological runners. Quadrupedal animals increase the vertical impulse that is generated by ground reaction forces at each stride as running speed increases and the duration of each stance phase reduces, whereas the swing phase stays relatively constant. Inspired by this observation, the presented controller estimates the required vertical impulse at each stride by applying the linear momentum conservation principle in the vertical direction and prescribes the ground reaction forces at each stride. The design process begins with deriving a planar model from the MIT Cheetah 2 robot. A baseline periodic limit cycle is obtained by optimizing ground reaction force profiles and the temporal gait pattern (timing and duration of gait phases). To stabilize the optimized limit cycle, the obtained limit cycle is converted to a state feedback controller by representing the obtained ground reaction force profiles as functions of the state variable, which is monotonically increasing throughout the gait, adding impedance control around the height and pitch trajectories of the obtained limit cycle and introducing a finite state machine and a pattern stabilizer to enforce the optimized gait pattern. The controller that achieves a stable 3 m s−1 gallop successfully adapts the speed change by scaling the vertical ground reaction force to match the momentum lost by gravity and adding a simple speed controller that controls horizontal speed. Without requiring additional gait optimization processes, the controller achieves galloping at speeds ranging from 3 m s−1 to 14.9 m s−1 while respecting the torque limit of the motor used in the MIT Cheetah 2 robot. The robustness of the controller is verified by demonstrating stable running during various disturbances, including 1.49 m step down and 0.18 m step up, as well as random ground height and model parameter variations.

Cross-language identification of non-native lexical tone

We extend to lexical-tone systems a model of second-language perception, the Perceptual Assimilation Model (PAM) (Best & Tyler, 2007), to examine whether native-language lexical-tone experience influences identification of novel tone. Native listeners of Cantonese, Thai, Mandarin, and Yoruba hear six CV syllables, each produced with the three phonemic Yoruba tones (High-level/H, Mid-level/M, Low-level/L), presented randomly three times. In a 3-AFC task, participants indicate a syllable’s tone by selecting from a set of arrows the one that illustrates its pitch trajectory. Accuracy scores (proportion correct) were submitted to a two-way rANOVA with L1-Group (x4) as the between-subjects factor and Tone (x3) as the within-subjects factor. There was no main effect of Tone or Group. The Tone-by-Group interaction was significant (p = 0.031) but driven by one group: Thai listeners identified H and M more accurately than L (both p < 0.05), though L accuracy was above chance (59%; chance = 33.33%). Tone-error patterns indicate that Thai listeners primarily confused L with M (two-way L1-Group x Response-pattern rANOVA p < 0.05). Overall, despite their different tonal-L1 backgrounds, listeners performed comparably. As predicted by the PAM, listeners attended to gradient phonetic detail and acoustic cues relevant to L1 phoneme distinctions (F0 height/direction) in order to classify non-native contrasts. [NSF grant #0965227.]

Categorization of natural dynamic audiovisual scenes.

This work analyzed the perceptual attributes of natural dynamic audiovisual scenes. We presented thirty participants with 19 natural scenes in a similarity categorization task, followed by a semi-structured interview. The scenes were reproduced with an immersive audiovisual display. Natural scene perception has been studied mainly with unimodal settings, which have identified motion as one of the most salient attributes related to visual scenes, and sound intensity along with pitch trajectories related to auditory scenes. However, controlled laboratory experiments with natural multimodal stimuli are still scarce. Our results show that humans pay attention to similar perceptual attributes in natural scenes, and a two-dimensional perceptual map of the stimulus scenes and perceptual attributes was obtained in this work. The exploratory results show the amount of movement, perceived noisiness, and eventfulness of the scene to be the most important perceptual attributes in naturalistically reproduced real-world urban environments. We found the scene gist properties openness and expansion to remain as important factors in scenes with no salient auditory or visual events. We propose that the study of scene perception should move forward to understand better the processes behind multimodal scene processing in real-world environments. We publish our stimulus scenes as spherical video recordings and sound field recordings in a publicly available database.

A Method to Monitor Eye and Head Tracking Movements in College Baseball Players

This study had two purposes. The first was to develop a method to measure horizontal gaze tracking errors (based on synchronized eye and head tracking recordings) as subjects viewed many pitched balls. The second was to assess horizontal eye, head, and gaze tracking strategies of a group of Division 1 college baseball players. Subjects viewed, but did not swing a bat at, tennis balls projected by a pneumatic pitching machine. Subjects were to call out numbers and the color of these numbers (black or red) on the balls. The trajectory of each pitch was very predictable. Eye and head movements were monitored with a video eye tracker and an inertial sensor, respectively, and these movements were synchronized with ball position using an analog recording device. Data were analyzed for 15 subjects. Eye rotation, head rotation, gaze errors (GEs), and unsigned gaze errors (UGEs) were calculated at various elapsed times. On average, subjects tracked the pitched ball with the head throughout the pitch trajectory, while the eye was moved very little until late in the pitch trajectory. On average, gaze position matched the target position throughout the pitch trajectory. There was some variability in the mean amplitudes of head and eye movement between subjects. However, the eye and head were related by a common rule (partial rotational vestibulo-ocular reflex suppression) for all subjects. Although the mean amplitudes of the GE and UGE varied between subjects, these means were not consistent with anticipatory saccades for any subject. On average, Division 1 college players tracked the pitched ball primarily with the head and maintained gaze close to the ball throughout much of the pitch trajectory. There was variability between subjects regarding the head and eye movement amplitudes and GEs, but, overall, all subjects maintained gaze close to the ball throughout the pitch trajectory despite the fact that these individuals were not batting.

Multi-pitch Streaming of Harmonic Sound Mixtures

Multi-pitch analysis of concurrent sound sources is an important but challenging problem. It requires estimating pitch values of all harmonic sources in individual frames and streaming the pitch estimates into trajectories, each of which corresponds to a source. We address the streaming problem for monophonic sound sources. We take the original audio, plus frame-level pitch estimates from any multi-pitch estimation algorithm as inputs, and output a pitch trajectory for each source. Our approach does not require pre-training of source models from isolated recordings. Instead, it casts the problem as a constrained clustering problem, where each cluster corresponds to a source. The clustering objective is to minimize the timbre inconsistency within each cluster. We explore different timbre features for music and speech. For music, harmonic structure and a newly proposed feature called uniform discrete cepstrum (UDC) are found effective; while for speech, MFCC and UDC works well. We also show that timbre-consistency is insufficient for effective streaming. Constraints are imposed on pairs of pitch estimates according to their time-frequency relationships. We propose a new constrained clustering algorithm that satisfies as many constraints as possible while optimizing the clustering objective. We compare the proposed approach with other state-of-the-art supervised and unsupervised multi-pitch streaming approaches that are specifically designed for music or speech. Better or comparable results are shown.

Comparative Analysis between Two Trajectory Models of Sinusoidal Maneuvering Missiles

For the sinusoidal maneuvering missile, its important but difficulty to distinguish the Base Course with Constant Velocity Model and the Tangential Arcs Model as the trajectory model. Their similarities and differences are studied to find out the selection method firstly, and their mathematical models are set up in the base-course coordinate system based on the existing references. Using the kinematical equations, the control complexities are derived. Then with the premise of same amplify, same max tangential velocity, same base-course pitch, their overloads and plane trajectories are compared, and drawn out some useful conclusions, such as TA model should be the prior selection for route planning, while BCCV model could be its approximate solution under certain conditions.

A Quantitative Comparison of Chrysanthine Theory and Performance Practice of Scale Tuning, Steps, and Prominence of the Octoechos in Byzantine Chant

Byzantine Chant performance practice is computationally compared to the Chrysanthine theory of the eight Byzantine Tones (octoechos). Intonation, steps, and prominence of scale degrees are quantified, based on pitch class profiles. The novel procedure introduced here comprises the following analysis steps: (1) the pitch trajectory is extracted and post processed with music-specific filters. (2) Pitch class histograms are calculated by kernel smoothing. (3) Histogram peaks are detected. (4) Phrase ending analysis aids the finding of the tonic to align pitch histograms. (5) The theoretical scale degrees are mapped to the empirical ones. (6) A schema of statistical tests detects significant deviations of theoretical scale tuning and steps from the estimated ones in performance practice. (7) The ranked histogram peak amplitudes are compared to the theoretic prominence of particular scale degrees. The analysis of 94 Byzantine Chants performed by four singers shows a tendency of the singers to level theoretic particularities of the echos that stand out of the general norm in the octoechos: theoretically extremely large steps are diminished in performance. The empirical intonation of the IV. scale degree as the frame of the first tetrachord is more consistent with the theory than the VI. and the VII. scale degree. In practice, smaller scale degree steps (67–133 cents) appear to be increased and the highest scale step of 333 cents appears to be decreased compared to theory. In practice, the first four scale degrees in decreasing order of prominence I, III, II, IV are more prominent than the V., VI., and the VII..

Simultaneous EEG/fMRI Reveals Spatiotemporal Correlates of Baseball Pitch Recognition

pitch trajectories (Fastball, Curveball, and Slider), while we simultaneously recorded BOLD fMRI at 3x3x3 mm, using a 3T scanner, and scalp EEG, using our custom-built 43channel EEG system [6]. Each trial consisted of a letter cue (“F”-Fastball, “C”-Curveball, “S”-Slider) and countdown bar, the simulated pitch, and then a (+/-) feedback sign to indicate if the subject was correct on the trial (Fig. 1) . Subjects were instructed to respond when the pitch matched the cue and before the pitch ended. There were a total 450 trials over 5 scans with a 60/40 split between Go/NoGo. We performed standard preprocessing on all data [6]. We used logistic regression with a sliding window [7] on stimulus-locked epochs to discriminate between combinations of Correct Go,Correct NoGo, and Incorrect NoGo trials using the EEG data. We first analyzed the BOLD signal using a traditional event related analysis. For the single-trial variability analysis, we analyzed the BOLD signal by correlating the trial-to-trial variability of the EEG classifiers within each class with the BOLD data, similar to the approach of Goldman et al. (see [6] for details). Results are presented at the group level.

You Can't Think and Hit at the Same Time: Neural Correlates of Baseball Pitch Classification.

Hitting a baseball is often described as the most difficult thing to do in sports. A key aptitude of a good hitter is the ability to determine which pitch is coming. This rapid decision requires the batter to make a judgment in a fraction of a second based largely on the trajectory and spin of the ball. When does this decision occur relative to the ball’s trajectory and is it possible to identify neural correlates that represent how the decision evolves over a split second? Using single-trial analysis of electroencephalography (EEG) we address this question within the context of subjects discriminating three types of pitches (fastball, curveball, slider) based on pitch trajectories. We find clear neural signatures of pitch classification and, using signal detection theory, we identify the times of discrimination on a trial-to-trial basis. Based on these neural signatures we estimate neural discrimination distributions as a function of the distance the ball is from the plate. We find all three pitches yield unique distributions, namely the timing of the discriminating neural signatures relative to the position of the ball in its trajectory. For instance, fastballs are discriminated at the earliest points in their trajectory, relative to the two other pitches, which is consistent with the need for some constant time to generate and execute the motor plan for the swing (or inhibition of the swing). We also find incorrect discrimination of a pitch (errors) yields neural sources in Brodmann Area 10, which has been implicated in prospective memory, recall, and task difficulty. In summary, we show that single-trial analysis of EEG yields informative distributions of the relative point in a baseball’s trajectory when the batter makes a decision on which pitch is coming.

A disturbance observer design for backlash compensation

Electromechanical systems usually have an innate backlash in their gear trains which is normally nonlinear and limits the performance of the system. In this paper, a disturbance observer is designed in order to estimate the properties of the backlash. Generally, such disturbance observers are designed with the inverse model of the nominal plant but since the backlash is an internal factor of the plant, its effect cannot be separated from the system output. In the proposed model, the plant is reconfigured to separate the effects of the backlash from the output, and a new type of disturbance observer is proposed to detect and compensate for the backlash in the remodelled plant. The suggested disturbance observer is applied to the knee joint of a humanoid robot. Using the proposed disturbance observer, it is shown that the backlash can be compensated for, and that the tracking error decreases in the knee pitch trajectory. Also, an error analysis of the input trajectory is carried out to verify the performance of the proposed disturbance observer and the validity of the proposed control scheme is discussed.

A Probabilistic Interaction Model for Multipitch Tracking With Factorial Hidden Markov Models

We present a simple and efficient feature modeling approach for tracking the pitch of two simultaneously active speakers. We model the spectrogram features of single speakers using Gaussian mixture models in combination with the minimum description length model selection criterion. To obtain a probabilistic representation for the speech mixture spectrogram features of both speakers, we employ the mixture maximization model (MIXMAX) and, as an alternative, a linear interaction model. A factorial hidden Markov model is applied for tracking pitch over time. This statistical model can be used for applications beyond speech, whenever the interaction between individual sources can be represented as MIXMAX or linear model. For tracking, we use the loopy max-sum algorithm, and provide empirical comparisons to exact methods. Furthermore, we discuss a scheduling mechanism of loopy belief propagation for online tracking. We demonstrate experimental results using Mocha-TIMIT as well as data from the speech separation challenge provided by Cooke We show the excellent performance of the proposed method in comparison to a well known multipitch tracking algorithm based on correlogram features. Using speaker-dependent models, the proposed method improves the accuracy of correct speaker assignment, which is important for single-channel speech separation. In particular, we are able to reduce the overall tracking error by 51% relative for the speaker-dependent case. Moreover, we use the estimated pitch trajectories to perform single-channel source separation, and demonstrate the beneficial effect of correct speaker assignment on speech separation performance.

Subcortical Plasticity Following Perceptual Learning in a Pitch Discrimination Task

Practice can lead to dramatic improvements in the discrimination of auditory stimuli. In this study, we investigated changes of the frequency-following response (FFR), a subcortical component of the auditory evoked potentials, after a period of pitch discrimination training. Twenty-seven adult listeners were trained for 10 h on a pitch discrimination task using one of three different complex tone stimuli. One had a static pitch contour, one had a rising pitch contour, and one had a falling pitch contour. Behavioral measures of pitch discrimination and FFRs for all the stimuli were measured before and after the training phase for these participants, as well as for an untrained control group (n = 12). Trained participants showed significant improvements in pitch discrimination compared to the control group for all three trained stimuli. These improvements were partly specific for stimuli with the same pitch modulation (dynamic vs. static) and with the same pitch trajectory (rising vs. falling) as the trained stimulus. Also, the robustness of FFR neural phase locking to the sound envelope increased significantly more in trained participants compared to the control group for the static and rising contour, but not for the falling contour. Changes in FFR strength were partly specific for stimuli with the same pitch modulation (dynamic vs. static) of the trained stimulus. Changes in FFR strength, however, were not specific for stimuli with the same pitch trajectory (rising vs. falling) as the trained stimulus. These findings indicate that even relatively low-level processes in the mature auditory system are subject to experience-related change.

Non-certainty-equivalent adaptive satellite attitude control using solar radiation pressure

The article presents a new adaptive controller for attitude control of satellites using solar radiation pressure (SRP). The satellite has two identical solar flaps for pitch angle control. The model includes gravity gradient torque and the torque due to SRP. Unlike adaptive control design published in the literature for this model, here an adaptive law for large pitch angle trajectory control based on the non-certainty-equivalence principle is derived. The control system has a modular structure consisting of an estimator and a control module designed based on a backstepping method. Using Lyapunov analysis, it is shown that the closed-loop system is stable and the pitch angle trajectory asymptotically follows the reference trajectory. The control system designed here has some special features. In the closed-loop system, the trajectory is ultimately confined to a manifold in the space of state variables and parameter errors. Interestingly, once the estimated parameter values coincide with their true values during the adaptation process, these remain frozen and the estimation error remains zero thereafter, and the system recovers the performance of the deterministic controller. Simulation results are presented for a set of uncertain parameters of the model. These results show that in the closed-loop system, precise large pitch angle control is accomplished despite large uncertainties in the system parameters.

Kalman tracking of linear predictor and harmonic noise models for noisy speech enhancement

This paper presents a speech enhancement method based on the tracking and denoising of the formants of a linear prediction (LP) model of the spectral envelope of speech and the parameters of a harmonic noise model (HNM) of its excitation. The main advantages of tracking and denoising the prominent energy contours of speech are the efficient use of the spectral and temporal structures of successive speech frames and a mitigation of processing artefact known as the ‘musical noise’ or ‘musical tones’. The formant-tracking linear prediction (FTLP) model estimation consists of three stages: (a) speech pre-cleaning based on a spectral amplitude estimation, (b) formant-tracking across successive speech frames using the Viterbi method, and (c) Kalman filtering of the formant trajectories across successive speech frames. The HNM parameters for the excitation signal comprise; voiced/unvoiced decision, the fundamental frequency, the harmonics’ amplitudes and the variance of the noise component of excitation. A frequency-domain pitch extraction method is proposed that searches for the peak signal to noise ratios (SNRs) at the harmonics. For each speech frame several pitch candidates are calculated. An estimate of the pitch trajectory across successive frames is obtained using a Viterbi decoder. The trajectories of the noisy excitation harmonics across successive speech frames are modeled and denoised using Kalman filters. The proposed method is used to deconstruct noisy speech, de-noise its model parameters and then reconstitute speech from its cleaned parts. Experimental evaluations show the performance gains of the formant tracking, pitch extraction and noise reduction stages.

A21 投球コースの違いがバットスイングに及ぼす影響(野球)

The present study investigated the effects of pitch trajectory on batting swing. Balls of various trajectories were pitched to a professional baseball player and his batting motion was analyzed by the three-dimensional direct linear transformation (DLT) method. Acceleration applied to the bat during the swing was measured by installed accelerometers. Results were as follows: 1) Pitched balls with an inside trajectory had an impact point closer to the pitcher, while balls pitched with an outside trajectory had an impact point closer to the catcher. 2) Although the position of the bat at the point of impact changed for different pitch trajectories, there were no significant differences in the position of the waist or shoulder. The motion of the body during the batting swing, excepting the arms, was not affected by differences in pitch trajectory. 3) Ball pitched to waist height were hit with a higher bat head speed, resulting in a greater post-impact flight distance. 4) Batters appeared to adjust their batting swing to the pitch trajectory just prior to impact.

Timing and Communicative Functions of Pitch Contours

A new research paradigm is applied to F0 synchronization with articulation, inpeak and valley contours, under four principles: (a) Timing of F0 contours enters thedefinitions of the pitch categories. (b) These phonetic exponents are linked to com-municativefunctions. (c) The listener plays a pivotal role. (d) Contextualization oftest stimuli is essential for pitch data collection. Data are presented and interpretedfrom an experimental investigation of the substance-function relationship in theperception of peak and valley shift series by German listeners, using the semanticdifferential technique. The findings of the substance-function relationship areexplained with reference to the frequency codeand to auditory enhancement,i.e.syntagmatic contrast of high-low or low-high pitch trajectories in synchronizationwith articulatory landmarks of accented syllables.

The Perceptual Integration of Auditory Stimulus Edges: An Illusory Short Tone in Stimulus Patterns Consisting of Two Partly Overlapping Glides.

Two partly overlapping frequency glides can be perceived as consisting of a long pitch trajectory accompanied by a short tone in the temporal middle. It was found that the appearance of this middle tone could not be related to peripheral processes concerned with spectral splatter or combination tones that could have emerged during the overlap of the glides. Furthermore, it was found that the middle tone was perceived even when components of the 2 glides were separated by more than an equivalent rectangular bandwidth at any time during the overlap. The appearance of the middle tone indicates that auditory events can result from the perceptual integration of component parts-that is, stimulus edges-of acoustically different sounds.

Tracking pitches for broadcast television

During a baseball game, dramatic changes in lighting conditions and the movement of objects and players can result in a shifting pattern of light and color that makes it especially difficult to track a pitched ball. Further, several ballparks have a net in place behind home plate, which contributes further to the visual clutter that the image processing system must filter out when tracking the baseball. Meeting these challenges required developing a complex system that fuses high-end computer graphics with a sophisticated algorithm for calculating flight trajectories. The paper considers the ESPN K Zone system which uses computer-generated graphics to create a shaded, translucent box that outlines the strike zone boundaries for viewers. Behind the flashy graphics, K Zone-named after a synonym for the strike zone is a sophisticated computing system that monitors each pitch's trajectory.

Synthesis of nonperiodic features of pathological voices

The question has been raised as to how successfully measures of nonperiodic vocal energy such as spectrally shaped aspiration noise, jitter, and shimmer can be used in modeling pathological voices, and how well listeners distinguish between these quantities. This work studies how two such quantities, spectrally shaped aspiration noise and jitter, can be used to synthesize pathological voices. Automatic algorithms for analyzing and modeling these measures are described. Tokens of the vowel [a] were inverse filtered and analyzed using a cepstral-domain comb filter algorithm to extract the aperiodic component of the vocal source. The pitch trajectory was established with an interpolating tracker and was high-pass filtered and analyzed to measure jitter. Synthetic tokens were then computed using the calculated levels of source noise alone, jitter alone, and a ratio of both, and the results compared with the original token in listening experiments. The success of each method at modeling the original token across a variety of voice samples will be described, as will implications for speech synthesis and voice perception. [Work supported by NIH/NIDCD.]

Pitch control of the space shuttle training aircraft

A set of shuttle training aircrafts (STAs) are used by NASA to train astronaut pilots to land the space shuttle after returning from orbit. The STA simulates the dynamics of the much larger and heavier space shuttle with the help of some hardware and software modifications. We present a STA controller that tracks the shuttle pitch trajectory. Our control system includes a feedforward controller based on zero phase error tracking control and a fuzzy proportional derivative (PD) feedback controller. Test results on a ground hardware simulator used at the Ellington Field of NASA Johnson Space Center show that the new controller significantly reduces pitch following errors between the shuttle and the STA, when compared to the existing controller.