Pitch Feedback Research Articles

Evaluation of different feedback designs for target guidance in human controlled robotic cranes: A comparison between high and low performance groups

Labour shortages and costly operator training are driving the need for digital on-board robotic crane operator support in forestry and construction. This simulator study investigated the effects of sonification (auditory, pitch/loudness) and continuous visual (brightness/size) feedback on aiming movements with a robotic crane for low and high performers. The feedback was designed non-linear and linear. Thirty-six participants controlled a robotic crane bimanually using joysticks across 320 movements. Performance and skill indicators (movement time, accuracy, trajectory, smoothness) as well as satisfaction, and usefulness were assessed. Low-performing participants showed higher movement accuracy, particularly with non-linear pitch feedback compared to visual feedback. High performers exhibited no significant performance improvement in movement time, accuracy, or smoothness. There was no effect of linear or non-linear mapping of the feedback. Additionally, perceived satisfaction was lower with auditory than visual feedback. These results suggest that real-time auditory feedback can enhance operator accuracy whereas acceptance remains challenging.

Robust multi‐loop control of a floating wind turbine

AbstractA principal challenge facing the control of floating offshore wind turbines (FOWTs) is the problem of instability, or “negative damping,” when using blade pitch feedback to control generator speed. This closed‐loop instability can be attributed to non‐minimum phase zeros in the transfer function from blade pitch to generator speed. Standard approaches to improving stability and performance include robust tuning of control gains and introducing multiple feedback loops to respond to platform motion. Combining these approaches is nontrivial because multiple control loops complicate the impact of coupling in the system dynamics. The single‐loop approach to analyzing stability robustness neglects inter‐loop coupling, while a simplistic multi‐loop approach is highly sensitive to dimensional scaling and overestimates the robustness of the single‐loop controller. This work proposes a sensitivity representation that separates some of the natural FOWT dynamic coupling into a parallel feedback loop in the sensitivity function loop to address both of these concerns. The modified robustness measure is used with a simplified linear FOWT model to optimize scheduled multi‐loop control parameters in an automated tuning procedure. This controller is implemented for the 10‐MW Ultraflexible Smart FLoating Offshore Wind Turbine (USFLOWT) and compared against conventional single‐ and multi‐loop controllers tuned using frequency‐domain analysis and high‐fidelity OpenFAST simulations. The multi‐loop robust controller shows the highest overall performance in generator speed regulation and tower load reduction, though consideration of power quality, actuator usage, and other structural loading leads to additional trade‐offs.

P-36 Movement sonification by pitch feedback enhances context-dependent motor sequence learning

P-36 Movement sonification by pitch feedback enhances context-dependent motor sequence learning

Behavioral and ERP evidence of differences in pitch feedback control in late bilinguals’ L1 and L2 speech production

AbstractThis study compared late bilinguals’ pitch feedback control in L1 and L2 production using a frequency-altered feedback paradigm in which participants read target words while presented with unexpected pitch-shift in their voice feedback. Variables of language (L1 or L2) and perturbation magnitudes (0, 100, 200, or 400 cents) were manipulated. Behaviorally, participants produced larger magnitudes but longer latencies of vocal compensation in L2 than in L1 production, suggesting that L2 pitch feedback control has greater importance but lower efficiency. Event-related potential findings demonstrated that 400-cent shifts elicited greater N1 amplitudes than those in the 0-cent baseline condition in L1 production. This difference was non-significant in L2 production, implying different neural processing of unaltered feedback and externally-generated feedback in L1 and L2 production. Participants’ vocal compensation and P2 amplitudes were similarly modulated by pitch-shift in L1 and L2 production, implying a similar gating mechanism to correct internal and external errors.

Effects of sensorimotor voice training on event-related potentials to pitch-shifted auditory feedback.

The pitch perturbation technique is a validated technique that has been used for over 30 years to understand how people control their voice. This technique involves altering a person's voice pitch in real-time while they produce a vowel (commonly, a prolonged /a/ sound). Although post-task changes in the voice have been observed in several studies (e.g., a change in mean fo across the duration of the experiment), the potential for using the pitch perturbation technique as a training tool for voice pitch regulation and/or modification has not been explored. The present study examined changes in event related potentials (ERPs) and voice pitch in three groups of subjects due to altered voice auditory feedback following a brief, four-day training period. Participants in the opposing group were trained to change their voice fo in the opposite direction of a pitch perturbation stimulus. Participants in the following group were trained to change their voice fo in the same direction as the pitch perturbation stimulus. Participants in the non-varying group did not voluntarily change their pitch, but instead were asked to hold their voice constant when they heard pitch perturbations. Results showed that all three types of training affected the ERPs and the voice pitch-shift response from pre-training to post-training (i.e., "hold your voice pitch steady" task; an indicator of voice pitch regulation). Across all training tasks, the N1 and P2 components of the ERPs occurred earlier, and the P2 component of the ERPs occurred with larger amplitude post-training. The voice responses also occurred earlier but with a smaller amplitude following training. These results demonstrate that participation in pitch-shifted auditory feedback tasks even for brief periods of time can modulate the automatic tendency to compensate for alterations in voice pitch feedback and has therapeutic potential.

Data-driven control of the coupled loads for floating wind turbine systems based on deformable trailing edge flaps

Load controller design for floating wind turbine systems (FWTS) poses unique challenges owing to the couplings of platform motions, blade loads and rotor power. Any controller based on a single objective is likely to worsen other performance metrics. This paper presented a data-driven control system to comprehensively handle that muti-objective coupling problem. The control system was realized by introducing a model free adaptive control (MFAC) based on deformable trailing edge flap (DTEF) and a feedback compensation in the blade pitch control loop. The identification error and actuator saturation were considered while designing the control law. The proposed control system was numerically tested in the modified FAST code equipped with DTEF interfaces. Numerical results showed considerable load reductions on blades and floating platforms at the cost of the added DTEF actuation and a minor increase in blade pitch rate. Moreover, the generator power fluctuations and the fatigue loading on drive train and tower were also alleviated. In addition, the synchronous aero-hydro-elastic coupling relationships in the wind-blade-wave-platform system were impaired by introducing the servo-dynamics of DTEF and blade pitch feedback compensation. Hence the total energy flowing into FWTS was dissipated.

Temporal specificity of abnormal neural oscillations during phonatory events in laryngeal dystonia.

Laryngeal dystonia is a debilitating disorder of voicing in which the laryngeal muscles are intermittently in spasm resulting in involuntary interruptions during speech. The central pathophysiology of laryngeal dystonia, underlying computational impairments in vocal motor control, remains poorly understood. Although prior imaging studies have found aberrant activity in the CNS during phonation in patients with laryngeal dystonia, it is not known at what timepoints during phonation these abnormalities emerge and what function may be impaired. To investigate this question, we recruited 22 adductor laryngeal dystonia patients (15 female, age range = 28.83–72.46 years) and 18 controls (eight female, age range = 27.40–71.34 years). We leveraged the fine temporal resolution of magnetoencephalography to monitor neural activity around glottal movement onset, subsequent voice onset and after the onset of pitch feedback perturbations. We examined event-related beta-band (12–30 Hz) and high-gamma-band (65–150 Hz) neural oscillations. Prior to glottal movement onset, we observed abnormal frontoparietal motor preparatory activity. After glottal movement onset, we observed abnormal activity in the somatosensory cortex persisting through voice onset. Prior to voice onset and continuing after, we also observed abnormal activity in the auditory cortex and the cerebellum. After pitch feedback perturbation onset, we observed no differences between controls and patients in their behavioural responses to the perturbation. But in patients, we did find abnormal activity in brain regions thought to be involved in the auditory feedback control of vocal pitch (premotor, motor, somatosensory and auditory cortices). Our study results confirm the abnormal processing of somatosensory feedback that has been seen in other studies. However, there were several remarkable findings in our study. First, patients have impaired vocal motor activity even before glottal movement onset, suggesting abnormal movement preparation. These results are significant because (i) they occur before movement onset, abnormalities in patients cannot be ascribed to deficits in vocal performance and (ii) they show that neural abnormalities in laryngeal dystonia are more than just abnormal responses to sensory feedback during phonation as has been hypothesized in some previous studies. Second, abnormal auditory cortical activity in patients begins even before voice onset, suggesting abnormalities in setting up auditory predictions before the arrival of auditory feedback at voice onset. Generally, activation abnormalities identified in key brain regions within the speech motor network around various phonation events not only provide temporal specificity to neuroimaging phenotypes in laryngeal dystonia but also may serve as potential therapeutic targets for neuromodulation.

Model-based design of a wave-feedforward control strategy in floating wind turbines

Abstract. Floating wind turbines rely on feedback-only control strategies to mitigate the negative effects of wave excitation. Improved power generation and lower fatigue loads can be achieved by including information about incoming waves in the turbine controller. In this paper, a wave-feedforward control strategy is developed and implemented in a 10 MW floating wind turbine. A linear model of the floating wind turbine is established and utilized to understand how wave excitation affects rotor speed and so power, as well as to show that collective pitch is suitable for reducing the effects of wave excitation. A feedforward controller is designed based on the inversion of the linear model, and a gain-scheduling algorithm is proposed to adapt the feedforward action as wind speed changes. The performance of the novel wave-feedforward controller is examined first by means of linear analysis and then with non-linear time-domain simulations in FAST. This paper proves that including some information about incoming waves in the turbine controller can play a crucial role in improving power quality and the turbine fatigue life. In particular, the proposed wave-feedforward control strategy achieves this goal complementing the industry-standard feedback pitch controller. Together with the wave-feedforward control strategy, this paper provides some insights about the response of floating wind turbines to collective-pitch control and waves, which could be useful in future control-design studies.

Effector-independent brain network for auditory-motor integration: fMRI evidence from singing and cello playing

Many everyday tasks share high-level sensory goals but differ in the movements used to accomplish them. One example of this is musical pitch regulation, where the same notes can be produced using the vocal system or a musical instrument controlled by the hands. Cello playing has previously been shown to rely on brain structures within the singing network for performance of single notes, except in areas related to primary motor control, suggesting that the brain networks for auditory feedback processing and sensorimotor integration may be shared (Segado et al. 2018). However, research has shown that singers and cellists alike can continue singing/playing in tune even in the absence of auditory feedback (Chen et al. 2013, Kleber et al. 2013), so different paradigms are required to test feedback monitoring and control mechanisms. In singing, auditory pitch feedback perturbation paradigms have been used to show that singers engage a network of brain regions including anterior cingulate cortex (ACC), anterior insula (aINS), and intraparietal sulcus (IPS) when compensating for altered pitch feedback, and posterior superior temporal gyrus (pSTG) and supramarginal gyrus (SMG) when ignoring it (Zarate et al. 2005, 2008). To determine whether the brain networks for cello playing and singing directly overlap in these sensory-motor integration areas, in the present study expert cellists were asked to compensate for or ignore introduced pitch perturbations when singing/playing during fMRI scanning. We found that cellists were able to sing/play target tones, and compensate for and ignore introduced feedback perturbations equally well. Brain activity overlapped for singing and playing in IPS and SMG when compensating, and pSTG and dPMC when ignoring; differences between singing/playing across all three conditions were most prominent in M1, centered on the relevant motor effectors (hand, larynx). These findings support the hypothesis that pitch regulation during cello playing relies on structures within the singing network and suggests that differences arise primarily at the level of forward motor control.

Instrumental Transformations in Heinrich Biber’s Mystery Sonatas

Each of Heinrich Biber’s Mystery Sonatas features a distinct violin tuning. How do these scordatura relate to standard tuning? How might they affect the sonatas’ musical organization and players’ experience? Transformational voice-leading theory helps to reveal overlapping categories here. Quintal scordatura include adjacent-string fifths, creating zones where notated and sounding intervals match. Chordal scordatura, in which the strings realize a triad, involve more displacement. Psychological research on altered pitch feedback suggests that scordatura are most unsettling for players when they preserve aspects of standard tuning. Analyzing scordatura, then, shows how instruments function as spaces for musical action.

A novel real-time feedback pitch angle control system for vertical-axis wind turbines

Modern horizontal-axis wind turbines improve their performance by controlling the blade pitch, which is a well-developed technique in practical use. However, the application of this method in vertical-axis wind turbines (VAWTs) is restricted, due to continuous changes in both the relative wind velocity and angle of attack of the blade. In the study, through an in-depth aerodynamic analysis between the blade pitch and performance of VAWTs, a real-time feedback blade pitch control system is developed, which is based on the real-time flow velocity around the blade. Subsequently, a computational fluid dynamics method with FLUENT is constructed to evaluate the performance of the pitch control system on improving VAWT performance. The calculation method is verified via wind tunnel experimental data. Results indicate that real-time feedback control of the pitch angle increases the average power coefficient in a wide range of tip speed ratios (TSRs). At low TSRs, it significantly improves the starting performance by decreasing the occurrence of vortex shedding and flow separation on the blade surface. At high TSRs, it effectively increases the power coefficient of VAWTs. Additionally, at high TSRs, the power coefficient generally exceeds 0.3 and the maximal power coefficients of the VAWTs corresponds to 0.441. At high TSRs, when compared to the zero pitch, the power coefficient relatively increases by at least 12.7%.

Abnormally increased vocal responses to pitch feedback perturbations in patients with cerebellar degeneration.

Cerebellar degeneration (CD) has deleterious effects on speech motor behavior. Recently, a dissociation between feedback and feedforward control of speaking was observed in CD: Whereas CD patients exhibited reduced adaptation across trials to consistent formant feedback alterations, they showed enhanced within-trial compensation for unpredictable formant feedback perturbations. In this study, it was found that CD patients exhibit abnormally increased within-trial vocal compensation responses to unpredictable pitch feedback perturbations. Taken together with recent findings, the results indicate that CD is associated with a general hypersensitivity to auditory feedback during speaking.

The Influence of Pitch-by-Pitch Feedback on Neural Activity and Pitch Perception in Baseball.

This study was designed to examine the influence of performance feedback on task performance and neural activity in expert and novice baseball players. Participants completed a video task to determine whether thrown pitches were balls or strikes while their neural activity was recorded. After each pitch, participants were given feedback on the accuracy of their choice. Results indicated that college players exhibited larger frontocentral positivity amplitudes compared with novices, regardless of feedback type. Furthermore, results showed that the feedback-related negativity was related to response accuracy following incorrect feedback for college players, with larger feedback-related negativity amplitude associated with greater response accuracy. This relationship is independent of any relations between overall task accuracy and either feedback-related negativity amplitude or response accuracy following incorrect feedback. These results indicate that the nature of neural activity during pitch feedback for college baseball players can inform and influence participants' subsequent pitch-location performance.

Electrical Brain Responses Reveal Sequential Constraints on Planning during Music Performance.

Elements in speech and music unfold sequentially over time. To produce sentences and melodies quickly and accurately, individuals must plan upcoming sequence events, as well as monitor outcomes via auditory feedback. We investigated the neural correlates of sequential planning and monitoring processes by manipulating auditory feedback during music performance. Pianists performed isochronous melodies from memory at an initially cued rate while their electroencephalogram was recorded. Pitch feedback was occasionally altered to match either an immediately upcoming Near-Future pitch (next sequence event) or a more distant Far-Future pitch (two events ahead of the current event). Near-Future, but not Far-Future altered feedback perturbed the timing of pianists’ performances, suggesting greater interference of Near-Future sequential events with current planning processes. Near-Future feedback triggered a greater reduction in auditory sensory suppression (enhanced response) than Far-Future feedback, reflected in the P2 component elicited by the pitch event following the unexpected pitch change. Greater timing perturbations were associated with enhanced cortical sensory processing of the pitch event following the Near-Future altered feedback. Both types of feedback alterations elicited feedback-related negativity (FRN) and P3a potentials and amplified spectral power in the theta frequency range. These findings suggest similar constraints on producers’ sequential planning to those reported in speech production.

Cortical networks for speech motor control in unilateral vocal fold paralysis.

To evaluate brain networks for motor control of voice production in patients with treated unilateral vocal fold paralysis (UVFP). Cross-sectional comparison. Nine UVFP patients treated by type I thyroplasty, and 11 control subjects were compared using magnetoencephalographic imaging to measure beta band (12-30 Hz) neural oscillations during voice production with perturbation of pitch feedback. Differences in beta band power relative to baseline were analyzed to identify cortical areas with abnormal activity within the 400 ms perturbation period and 125 ms beyond, for a total of 525 ms. Whole-brain task-induced beta band activation patterns were qualitatively similar in both treated UVFP patients and healthy controls. Central vocal motor control plasticity in UVFP was expressed within constitutive components of central human communication networks identified in healthy controls. Treated UVFP patients exhibited statistically significant enhancement (P < 0.05) in beta band activity following pitch perturbation onset in left auditory cortex to 525 ms, left premotor cortex to 225 ms, and left and right frontal cortex to 525 ms. This study further corroborates that a peripheral motor impairment of the larynx can affect central cortical networks engaged in auditory feedback processing, vocal motor control, and judgment of voice-as-self. Future research to dissect functional relationships among constitutive cortical networks could reveal neurophysiological bases of central contributions to voice production impairment in UVFP. Those novel insights would motivate innovative treatments to improve voice production and reduce misalignment of voice-quality judgment between clinicians and patients. 3b Laryngoscope, 129:2125-2130, 2019.

Different musical experiences differentially modulate the auditory-motor processing of feedback errors during vocal production

The present study investigated the effects of musical experiences on auditory-motor control of pitch feedback errors during vocal production. Thirty-four female musicians who were assigned to a group of professional signers (n = 17) and a group of instrument players (n = 17) and seventeen female non-musicians aged 18–29 years participated in the present study. All participants vocalized a vowel sound /u/ for about 5-6 seconds while hearing their vocal pitch unexpectedly shifted -50 or -200 cents, and their vocal compensations for pitch perturbations were measured and compared. The results showed significantly larger compensatory vocal responses produced by non-musicians when compared to professional singers (p&amp;lt;0.001) and instrument players (p&amp;lt;0.008). Moreover, instrument players produced significantly larger vocal compensations than professional singers (p = 0.026). The observed effects of musical experiences were independent of the size of pitch perturbation. These findings provide the first behavioral evidence for the differential modulation of vocal compensations for pitch perturbations by different musical experiences, which may be related to the difference between singers and players in extensive vocal training.

Adaptive State Feedback Pitch Angle Control of Wind Turbines for Speed Regulation and Blades Loadings Alleviation

This research article presents an adaptive state feedback blades pitch control of wind turbines for speed regulation and structural blades loadings mitigation in high wind speeds. The proposed control is a combination of a state feedback control and an integrator. It enables to improve the generator speed tracking, as well as to reduce the flap-wise bending moment at the root of the blades. The motivation principal of the proposed controller is that its structure allows surpassing the trade-off between the control objectives. The control scheme is tested on the NREL’s FAST 5 MW baseline wind turbine model in MATLAB/Simulink under different wind speed profiles and its performances are compared with those of the baseline gain scheduling proportional integral (GSPI) control and the disturbance accommodation control (DAC). The simulation results enable to conclude that the proposed controller has good performances in term of generator speed tracking as well as blade root flap-wise bending moment fluctuations reduction. Moreover, the controller is tested to be robust under system uncertainties.

Feedforward Feedback Pitch Control for Wind Turbine Based on Feedback Linearization with Sliding Mode and Fuzzy PID Algorithm

After exceeding rated power, variable speed variable pitch wind turbines need to keep output powers at rated value by adopting pitch angles. With the typical nonlinear characteristics of the wind turbines, it is difficult to control accurately by conventional linear controller. Though feedback control can realize the stability of the system, it is effective only when deviations are produced. As such, feedforward control can be applied to compensate the time-delay produced by feedback control. Accordingly, we propose a compound control strategy that combines feedback controller with feedforward controller in this paper. In feedback loop, we adopt fuzzy algorithm to adjust the parameters of PID controller. Furthermore, to overcome large variation of input wind speed, variable universe theory is proposed to optimize fuzzy algorithm. In feedforward loop, we propose feedback linearization to address nonlinear problem. Furthermore, sliding mode algorithm is supplied to improve the robustness of feedback linearization. Therefore, feedforward loop can efficiently compensate time-delay deficiency of wind turbine systems. Simulation results show that the proposed controller can enhance the control accuracy and robustness of the system.

Auditory-Motor Control of Vocal Production during Divided Attention: Behavioral and ERP Correlates.

When people hear unexpected perturbations in auditory feedback, they produce rapid compensatory adjustments of their vocal behavior. Recent evidence has shown enhanced vocal compensations and cortical event-related potentials (ERPs) in response to attended pitch feedback perturbations, suggesting that this reflex-like behavior is influenced by selective attention. Less is known, however, about auditory-motor integration for voice control during divided attention. The present cross-modal study investigated the behavioral and ERP correlates of auditory feedback control of vocal pitch production during divided attention. During the production of sustained vowels, 32 young adults were instructed to simultaneously attend to both pitch feedback perturbations they heard and flashing red lights they saw. The presentation rate of the visual stimuli was varied to produce a low, intermediate, and high attentional load. The behavioral results showed that the low-load condition elicited significantly smaller vocal compensations for pitch perturbations than the intermediate-load and high-load conditions. As well, the cortical processing of vocal pitch feedback was also modulated as a function of divided attention. When compared to the low-load and intermediate-load conditions, the high-load condition elicited significantly larger N1 responses and smaller P2 responses to pitch perturbations. These findings provide the first neurobehavioral evidence that divided attention can modulate auditory feedback control of vocal pitch production.

Top-Down Modulation of Auditory-Motor Integration during Speech Production: The Role of Working Memory.

Although working memory (WM) is considered as an emergent property of the speech perception and production systems, the role of WM in sensorimotor integration during speech processing is largely unknown. We conducted two event-related potential experiments with female and male young adults to investigate the contribution of WM to the neurobehavioural processing of altered auditory feedback during vocal production. A delayed match-to-sample task that required participants to indicate whether the pitch feedback perturbations they heard during vocalizations in test and sample sequences matched, elicited significantly larger vocal compensations, larger N1 responses in the left middle and superior temporal gyrus, and smaller P2 responses in the left middle and superior temporal gyrus, inferior parietal lobule, somatosensory cortex, right inferior frontal gyrus, and insula compared with a control task that did not require memory retention of the sequence of pitch perturbations. On the other hand, participants who underwent extensive auditory WM training produced suppressed vocal compensations that were correlated with improved auditory WM capacity, and enhanced P2 responses in the left middle frontal gyrus, inferior parietal lobule, right inferior frontal gyrus, and insula that were predicted by pretraining auditory WM capacity. These findings indicate that WM can enhance the perception of voice auditory feedback errors while inhibiting compensatory vocal behavior to prevent voice control from being excessively influenced by auditory feedback. This study provides the first evidence that auditory-motor integration for voice control can be modulated by top-down influences arising from WM, rather than modulated exclusively by bottom-up and automatic processes.SIGNIFICANCE STATEMENT One outstanding question that remains unsolved in speech motor control is how the mismatch between predicted and actual voice auditory feedback is detected and corrected. The present study provides two lines of converging evidence, for the first time, that working memory cannot only enhance the perception of vocal feedback errors but also exert inhibitory control over vocal motor behavior. These findings represent a major advance in our understanding of the top-down modulatory mechanisms that support the detection and correction of prediction-feedback mismatches during sensorimotor control of speech production driven by working memory. Rather than being an exclusively bottom-up and automatic process, auditory-motor integration for voice control can be modulated by top-down influences arising from working memory.