Speed Compensation Research Articles

Fine-Grained Power and Body-Bias Control for Near-Threshold Deep Sub-Micron CMOS Circuits

Lowering supply voltage is still the most effective technique to reduce dynamic power, and Vdd is being pushed toward the threshold voltage for ultra-low power applications. However, near-threshold circuit leakage power is comparable to switching power and performance is highly sensitive to static and dynamic threshold voltage variations. This makes designing circuits for a target performance very difficult, and post-silicon tunability is required to achieve performance targets without taking huge design margins. Post-silicon tuning of voltage supply and body bias in active mode, together with power gating for idle leakage power minimization are being investigated to tackle variability challenges in near-threshold operation. In this paper, we review and put in perspective techniques recently proposed in the literature for fine-grained post-silicon tuning and power gating. These techniques leverage the typical row-based ASIC layout style and use the row as the atomic element for circuit clustering. The results of row-based power gating on a set of benchmark circuits show that the leakage savings can be achieved are, superior to those obtained using existing power-gating solutions and with much tighter timing and area constraints. Benchmark results on row-based forward body biasing show large leakage power savings with a maximum savings of 61% in case of 18% compensation in 45 nm and 93% in case of 10% compensation in 32 nm with respect to block-level approaches. Finally, row-based dual-Vdd can provide post-silicon speed compensation in near-threshold region up-to 45% while achieving more than 50% lower power compared to single-Vdd.

A New anticipatory speed-controller for IC engines based on torque sensing loop

Some engineering applications requires constant engine speed such as power generators, production lines, etc. The current paper focuses on adding a new closed loop based on engine torque. Load cells can be used to measure the torque of load applied, the electrical signal is properly handled to manipulate a special fuel actuator to compensate for the reduction in engine speed. The speed loop still acts as the most outer closed loop. This method leads to rapid speed compensation and lead control action.

The effects of visibility conditions, traffic density, and navigational challenge on speed compensation and driving performance in older adults

Research on how older drivers react to natural challenges in the driving environment is relevant for both the research on mental workload and that on age-related compensation. Older adults ( M age = 70.8 years) were tested in a driving simulator to assess the impact of three driving challenges: a visibility challenge (clear day, fog), a traffic density challenge (low density, high density) and a navigational challenge (participants followed the road to arrive at their destination, participants had to use signs and landmarks). The three challenge manipulations induced different compensatory speed adjustments. This complicated interpretation of the other measures of driving performance. As a result, speed adjustment indices were calculated for each condition and participant and composite measures of performance were created to correct for speed compensation. (These speed adjustment indices correlated with vision test scores and subscales of the Useful Field of View ®.) When the composite measures of driving performance were analyzed, visibility × density × navigational challenge interactions emerged for hazard RT and SD of lane position. Effects were synergistic: the impact of the interaction of challenge variables was greater than the sum of independent effects. The directions of the effects varied depending on the performance measure in question though. For hazard RT, the combined effects of high-density traffic and navigational challenge were more deleterious in good visibility conditions than in fog. For or SD of lane position, the opposite pattern emerged: combined effects of high-density traffic and navigational challenge were more deleterious in fog than in clear weather. This suggests different aspects of driving performance tap different resources.

Noble Logic for Preventing Scratch on Roll-to-Roll Printed Layers in Noncontacting Transportation

The use of roll-to-roll (R2R) printed electronics is a relatively new method of mass producing flexible electronic devices while keeping production costs down. The geometrical qualities of a printed pattern, such as surface roughness and uniformity, could deteriorate. Moreover, the geometric qualities of a printed layer affect the functional qualities of a printed electronic device directly. Therefore, the functional qualities (conductivity and mobility) of a multilayer electronic device could deteriorate in the presence of a scratch defect on the printed layer. In general, a scratch on a printed pattern on a flexible substrate is induced by contact between the rolls and printed pattern in R2R printing systems. To prevent such contact, one of the best solutions is to use an air flotation unit. However, a scratch defect could be induced even though an air flotation process is used to minimize contact, because the flotation height of a moving web is affected by web tension. In this paper, we discuss an analytical model of an air-floated moving substrate. For the noncontacting transfer of a moving web without a scratch defect, a mathematical tension model has been developed by considering an induced strain due to aerodynamic forces and verified by numerical and experimental studies. Additionally, the correlation between the flotation height of an air-floated moving web and speed compensation used to control the tension are investigated. The analysis shows that tension fluctuations can cause the substrate to touch the air-flotation subsystem, which is installed to prevent contact, resulting in defects such as scratches on the printed layer. On the basis of the proposed model, a logic is developed to minimize scratch defects on R2R printed layers in noncontacting transportation. Through a guideline based on this logic, the scratched area density on R2R printed layers can be reduced by approximately 70%.

A Way of Stepped Frequency Velocity Compensation

This paper introduces the advantage and disadvantage of traditional motion compensation way in the stepped-frequency Pulses radar, and analyzes the motion influence on the one-dimension range profile. On the premise of understanding the current speed compensation algorithm, this paper offers an improved method, which is the new two-step approach. This method reduces the operation and enhances the Real-time performance of system. The characteristic of this method is that proposes the concept of the minimum pulse group self adaptive speed researching range. Even though, we don’t have the premise of speed prior knowledge, it also has a well applying prospect and universality. Comparing to the algorithm previously advanced, it has more extensive applications and practicability.

Chatter prevention and improved finish of workpiece for a milling process

This paper presents how real-time chatter prevention can be realized by feedback of an acoustic cutting signal. The efficacy of the proposed adaptive spindle speed tuning algorithm is verified by intensive experimental simulations. A pair of microphones, perpendicular to each other, is used to acquire the acoustic cutting signal resulting from milling chatter. A real-time feedback control loop is constructed for spindle speed compensation in such a way to ensure that the milling process is within the stability zone of the stability lobe diagram. The acoustic chatter signal index (ACSI) and the spindle speed compensation strategy (SSCS) are proposed to quantify the acoustic signal and actively to tune the spindle speed respectively. By converting the acoustic feedback signal into the ACSI, an appropriate spindle speed compensation rate (SSCR) can be determined by the SSCS based on a real-time chatter level or the ACSI. Accordingly, the compensation command, referred to as added-on voltage (AOV), is applied to increase/decrease the spindle motor speed. By employing the commercial software MATLAB/Simulink and the dSpace DS1104 interface module to implement the controller, the proposed chatter prevention algorithm is practically verified by intensive experiments. By inspection on the precision and quality of the workpiece surface after milling, the efficacy of the real-time chatter prevention strategy via acoustic signal feedback is further assured.

롤투롤 시스템에서의 비 접촉 이송 시스템을 위한 수학적 장력 모델에 관한 연구

In a post printing section of roll to roll printing systems, scratch problem is the major defects. The functional qualities such as conductivity, mobility could deteriorate because of the scratch defect. In general, the scratch of the printed pattern on the flexible substrate was induced from a contact between rolls and printed pattern in the post printing section. In this paper, for non-contacting transfer of a moving web, a mathematical tension model has been developed considering strain due to air floatation and the proposed mode has been validated by numerical simulation. Additionally, the correlation between floatation height and speed compensation to control the tension and register are investigated. On the basis of the proposed model, a guide line of speed control in R2R printing system is presented to guarantee the non-contact between rolls and R2R printed pattern on the flexible substrate.

Chatter prevention for milling process by acoustic signal feedback

This paper presents how real-time chatter prevention can be realized by feedback of acoustic cutting signal, and the efficacy of the proposed adaptive spindle speed tuning algorithm is verified as well. The conventional approach to avoid chatter is to select a few appropriate operating points according to the stability lobes by experiments and then always use these preset cutting conditions. For most cases, the tremble measurement, obtained by accelerometers or dynamometers, is merely to monitor spindle vibration or detect the cutting force, respectively. In fact, these on-line measures can be more useful, instead of always being passive. Furthermore, most of these old-fashioned methodologies are invasive, expensive, and cumbersome at the milling stations. On the contrary, the acoustic cutting signal, which is fed into the data acquisition interface, Module DS1104 by dSPACE, so that an active feedback loop for spindle speed compensation can be easily established in this research, is non-invasive, inexpensive, and convenient to facilitate. In this research, both the acoustic chatter signal index (ACSI) and spindle-speed compensation strategy (SSCS) are proposed to quantify the acoustic signal and compensate the spindle speed, respectively. By converting the acoustic feedback signal into ACSI, an appropriate spindle speed compensation rate (SSCR) can be determined by SSCS based on real-time chatter level. Accordingly, the compensation command, referred to as added-on voltage (AOV), is applied to actively tune the spindle motor speed. By employing commercial software MATLAB/Simulink and DS1104 interface module to implement the intelligent controller, the proposed chatter prevention algorithm is practically verified by intensive experiments. By inspection on the precision and quality of the workpiece surface after milling, the efficacy of the real-time chatter prevention strategy via acoustic signal feedback is further examined and definitely assured.

Position Control of an Object Coupled with Motor via Elastic Joint

The control method enabling compensating of influence of certain mismatch between estimated and real parameters of elastic coupling and transported object on dynamical quality of positioning is presented and investigated. An additional speed regulation contour ensuring object speed compensation in accordance of signal generated by reference model is applied for this purpose. The two types of speed correction controllers are investigated. The system modeling results are presented. Ill. 7, bibl. 3 (in English; summaries in English, Russian and Lithuanian).

Translation Speed Compensation in the Dorsal Aspect of the Medial Superior Temporal Area

The dorsal aspect of the medial superior temporal area (MSTd) is involved in the computation of heading direction from the focus of expansion (FOE) of the visual image. Our laboratory previously found that MSTd neurons adjust their focus tuning curves to compensate for shifts in the FOE produced by eye rotation (Bradley et al., 1996) as well as for changes in pursuit speed (Shenoy et al., 2002). The translation speed of an observer also affects the shift of the FOE. To investigate whether MSTd neurons can adjust their focus tuning curves to compensate for varying translation speeds, we recorded extracellular responses from 93 focus-tuned MSTd neurons in two rhesus monkeys (Macaca mulatta) performing pursuit eye movements across displays of varying translation speeds. We found that MSTd neurons had larger shifts in their tuning curves for slow translation speeds and smaller shifts for fast translation speeds. These shifts aligned the focus tuning curves with the true heading direction and not with the retinal position of the FOE. Because the eye was pursuing at the same rate for varying translation speeds, these results indicate that retinal cues related both to translation speed and extraretinal signals from pursuit eye movements are used by MSTd neurons to compute heading direction.

An approach to minimize build errors in direct metal laser sintering

This paper discusses the effect of geometric shape on the accuracy of direct metal laser sintering (DMLS) prototypes. The percentage shrinkages due to different shapes are investigated and their empirical relationship is determined. A new speed-compensation (SC) method is proposed to reduce uneven shrinkage affected by the two-dimensional geometric shape at each layer. From case studies conducted, the optimized SC method is found to be efficient in improving the accuracy of prototypes fabricated. Note to Practitioners-This paper aims to address the problem of dimensional errors of parts built by the direct metal laser sintering (DMLS) process. Existing compensation approaches are normally based on a general relationship between the nominal dimensions and the errors after sintering. However, the effect arising from different geometric shapes is not considered. A new approach is proposed using different scan speed settings to compensate for the effect of geometric shapes to improve the dimensional accuracy of the entire part. During processing, the laser sinters along the trajectory are guided by the hatch vectors or dexel. An appropriate experimental method is used to establish the relationship for different scan speeds with the dexel length to the final accuracy. When building the part, the laser scan speed is adjusted dynamically according to the dexel length which varies with the geometric shape of the part. The case study demonstrates that the proposed method can generate correct speed settings to effectively increase the dimensional accuracy of the final part. Although this method has been developed based on the DMLS process, it is also applicable to other laser sintering processes. In future research, other process parameters, such as laser power, will be considered independently, or together with the scan speed, for possible further improvement on the dimensional accuracy.

The chronometric mechanism of the sun compass in homing pigeons is independent of the length of the light phase

Sandhoppers are reported to rely on the length of the light phase to calculate a mean variation of azimuth speed. We conducted some experiments to test the influence of the length of the light phase on the computation of the azimuthal speed variation of the sun during the day by homing pigeons. We performed releases with birds which had been subjected to a reduction of the light phase. The results indicated that shortening the light phase does not affect the orientation performance of the homing pigeons, showing that the azimuth speed compensation mechanism in these birds is independent of the duration of the light phase.

Precise Position Control of the Ultrasonic Motor Using the Speed Compensation Type NN Controller

We propose the speed compensation type Neural Network (NN) controller for position control of Ultrasonic Motor (USM). The USM has dead-zone which rotor doesn't rotate or rotates very low speed when control input is small. It is because the USM uses frictional drive as driving principle. The fixed gain type PID controller cannot carry out precise position control by influence of dead-zone. This proposed control method uses the NN controller such that relation between control error and rotation speed become linear. To realize this relationship, we introduce the weighting factor so that control error correspons to rotation speed. If the wieghting factor is chosen appropriate value, this controller realizes very small overshoot and precise position control. The effectiveness of proposed design method is confirmed by experiments using the existent USM.

Pursuit speed compensation in cortical area MSTd.

When we move forward the visual images on our retinas expand. Humans rely on the focus, or center, of this expansion to estimate their direction of self-motion or heading and, as long as the eyes are still, the retinal focus corresponds to the heading. However, smooth pursuit eye movements add visual motion to the expanding retinal image and displace the focus of expansion. In spite of this, humans accurately judge their heading during pursuit eye movements even though the retinal focus no longer corresponds to the heading. Recent studies in macaque suggest that correction for pursuit may occur in the dorsal aspect of the medial superior temporal area (MSTd); neurons in this area are tuned to the retinal position of the focus and they modify their tuning to partially compensate for the focus shift caused by pursuit. However, the question remains whether these neurons shift focus tuning more at faster pursuit speeds, to compensate for the larger focus shifts created by faster pursuit. To investigate this question, we recorded from 40 MSTd neurons while monkeys made pursuit eye movements at a range of speeds across simulated self- or object motion displays. We found that most MSTd neurons modify their focus tuning more at faster pursuit speeds, consistent with the idea that they encode heading and other motion parameters regardless of pursuit speed. Across the population, the median rate of compensation increase with pursuit speed was 51% as great as required for perfect compensation. We recorded from the same neurons in a simulated pursuit condition, in which gaze was fixed but the entire display counter-rotated to produce the same retinal image as during real pursuit. This condition yielded the result that retinal cues contribute to pursuit compensation; the rate of compensation increase was 30% of that required for accurate encoding of heading. The difference between these two conditions was significant (P < 0.05), indicating that extraretinal cues also contribute significantly. We found a systematic antialignment between preferred pursuit and preferred visual motion directions. Neurons may use this antialignment to combine retinal and extraretinal compensatory cues. These results indicate that many MSTd neurons compensate for pursuit velocity, pursuit direction as previously reported and pursuit speed, and further implicate MSTd as a critical stage in the computation of egomotion.

Performance of integrated engine-CVT control considering powertrain loss and CVT response lag

In this paper, an integrated engine-continuously variable transmission (CVT) control algorithm is suggested by considering the powertrain loss and the inertia torque due to the CVT ratio change. In addition, compensation algorithms to reduce the effect of the CVT ratio response lag on the drive torque are presented. Experimental results show that the optimal engine speed compensation algorithm gives better engine operation around the optimal operation line compared with the optimal torque compensation while showing nearly the same acceleration response. The performance of the proposed integrated engine-CVT control algorithms is compared with that of conventional CVT control, and it is found that better engine operation on the optimal operation line can be achieved by using integrated control during acceleration.

Ultrasound speed compensation in an ultrasonic robot tracking system

This paper presents a novel method for ultrasound speed compensation in ultrasonic robot tracking. It employs optimization algorithms to estimate the best value of the ultrasound speed for every computation of the robot end-effector position. Compared with the other existing method for ultrasound speed compensation, this method has the advantage that no extra equipment is required to monitor the environment conditions (temperature etc.). The simulation, which is described at the end of this paper, shows that the real trajectory is extracted with very good precision from a set of distorted data caused by serious ultrasound speed drifting.

Integrated engine-CVT control considering powertrain response lag in acceleration

In this paper, an engine-CVT integrated control algorithm is suggested by considering the inertia torque and the CVT ratio change response lag in acceleration. In order to compensate for drive torque time delay due to CVT response lag, two algorithms are presented: (1) an optimal engine torque compensation algorithm, and (2) an optimal engine speed compensation algorithm. Simulation results show that the optimal engine speed compensation algorithm gives better engine operation around the optimal operation point compared to the optimal torque compensation while showing nearly the same acceleration response. The performance of the proposed engine-CVT integrated control algorithms are compared with those of conventional CVT control, and It is found that optimal engine operation can be achieved by using integrated control during acceleration, and improved fuel economy can be expected while also satisfying the driver’s demands.

A simple speed sensorless control for variable frequency induction motor drives

This paper presents a method for speed control of an AC drive with variable frequency PWM inverter without a speed sensor. The proposed control algorithm is based on speed compensation as a function of the load torque. The load torque estimate is obtained with a single current sensor in the DC link of the inverter. Most of the problems that are the consequence of cross-coupling and numerous nonlinearities in the system, are solved with the use of pre-formed look-up table, that gives the stator frequency as a function of the reference speed and the load. The control system is implemented using digital techniques, and the steady state error is less than half of the stator frequency resolution. Theoretical analyses and experimental verification supports the validity of the proposed control concept, and its usefulness to practical application.

Nonlinear Control of Underactuated Ships with Forward Speed Compensation

In this paper a nonlinear control law for an underactuated ship is derived by using a nonlinear ship model which includes the hydrodynamic effects due to time-varying speed and wave frequency. The nonlinear ship model does not have the structural properties of symmetric inertia and positive damping at high speed, which have been a common assumption when designing nonlinear ship tracking control systems. Backstepping control designs are used to circumvent the problem of a non-symmetrical inertia matrix. In this paper we have considered a ship with one propeller and one bow thruster. This is actually an underactuated system since only two actuators are used to control three degrees of freedom. The application of speed and wave dependent models for ship control is a first step towards the design of a new generation of nonlinear ship control systems that can operate under time-varying speed and wave frequency conditions. Previous work has often relied on the assumption of constant speed, and practical solutions have been based on switching between different control schemes at different speeds. Compensation of slowly-varying environmental disturbances, such as ocean currents, 2nd-order wave drift and wind forces are done by using adaptive backstepping. For tracking applications, global convergence is proven by using Barbalat's lemma. Computer simulations illustrate the performance of the control law.

A Highly-Integrated Intelligent Sensor for Gas-Liquid-Chromatography

The hardware design and ASIC realisation of a multichannel interfacing unit is described. This unit is used in a PC-based chromatography system for the acquisition of data from a number of analytic instruments. The attached analogue signals are partially integrated, digitised, buffered in a FIFO memory for speed compensation purposes and, finally, provided to the PC via a serial asynchronous RS-232-C connection. Based on the acquired integrals, the evaluation software employs a novel numerical method for extracting the parameters of the chromatographic peaks. A standard graphical user interface is employed for the visualisation of the chromatograms being processed.