Miniature Gyroscopes Research Articles

Method for measuring jugular venous pulse with a miniature gyroscope sensor patch.

The right internal jugular vein is connected to the right atrium of the heart via the superior vena cava, and consequently its pressure, known as the jugular venous pressure or the jugular venous pulse (JVP), is an important indicator of cardiac function. The JVP can be estimated visually from the neck but it is rather difficult and imprecise. In this article we propose a method to measure the JVP using a motion sensor patch attached to the neck. The JVP signal was extracted from the sensor's 3-axes gyroscope signal and aligned with simultaneously measured ECG and seismocardiogram signals.The method was tested on 20 healthy subjects. The timings of the characteristic JVP waves were compared with the ECG R peaks and seismocardiogram heart sounds S1 and S2. The JVP was reliably measured from 18 subjects with all three waves identified. The timings of the waves were also physiologically plausible when compared to the ECG R peak and the heart sounds. Importantly, the JVP was also found to modulate with respiration, further indicating that the measured signal was indeed the JVP and not the carotid pulse.The results show that the JVP can be measured with a wearable patch-like device registering the delicate motions of the right internal jugular vein. The method has potential to be developed into a clinical tool to measure cardiac health in diseases such as heart failure and chronic obstructive pulmonary disease (COPD).Clinical relevance-The developed method could enable an affordable measurement of clinically important cardiac parameter, jugular venous pulse, as a part of a routine examination.

A wearable embedded device for chronic low back patients to track lumbar spine position

In present scenario, people always work in an enclosed environment where they sit in the bend posture that causes severe damage in lumbar spine. According to the survey of World Health Organization, around the world 500,000 to 800,000 people are suffering from spinal cord injury (SCI). In that about 53% of the people who are aged between 16 and 30 suffer from chronic low back pain. A new wearable device which consists of miniature gyroscope and accelerometer are used in detecting the voluntary action of lumbar spine in the proposed system. The proposed system consists of a vibrator, Bluetooth element, a microcontroller and an android application. The vibrator motor is used to intimate the improper sitting position of the person. A Bluetooth element is used in transmitting the data from the module and the android application that runs on smart phone. It records the analyzed data of the sensor. A microcontroller is used to control the overall working of the designed system. The capability of this cost effective, simple device is capable to measure the lumbar spine position with the efficiency of 95% and provide a feedback to the user.

Study on Influence on Sensitive of Thermosensitive Element to Open Jet Gyroscope

This paper describes the effect mechansim of sensitive of thermosensitive element to open jet gyroscope. When different angular rate is applied, the distribution of airflow velocity at thermosensitive element is calculated by using fluid-solid coupling. The result shows that when angular rate about Z axis is applied, the distance between thermal resistance wires of d=0.6mm can decrease the influence of vortex inside of jet sensing cavity. Then, the temperature of thermal resistance wire is changing fast, which can increase the output voltage of Wheatstone Bridge and improve the sensitive of open jet gyroscope. The jet gyroscope can be applied in rugged environment with the virtue of supporting high overload and low cost etc. [1]. Open jet gyroscope is miniature gyroscope that the structure is simpler. Thermal resistance wire is thermosensitive element of open jet gyroscope and the detection of angular rate is carried out by Wheatstone Bridge consist of thermosensitive element. When the gyroscope has the angular rate input, the airflow velocity of two symmetrical thermal resistance wire is different. With the increasing angular rate, the difference of airflow velocity is increasing at the mean time. Accordingly, this causes the changes of current crossing two thermal resistance wire. Furthermore, the output of Wheatstone Bridge is voltage corresponding to angular rate. This paper calculates the flow field distribution of jet sensing cavity inside of open jet gyroscope when different angular are applied. Additional, It studies the difference of airflow velocity when there are different distances between two thermal resistance wires, which lays foundation for the set of thermosensitive element.

Total hip arthroplasty using a cementless dual-mobility cup provides increased stability and favorable gait parameters at five years follow-up

BackgroundRates of dislocation following primary total hip arthroplasty (THA) vary from 0.5 to 10%. Dual-mobility cups in THA demonstrate increased stability. Clinical outcomes following THA with dual-mobility cups have been reported, but gait has not been assessed. Therefore we performed a retrospective case control study to answer: (1) is gait better in patients following THA with a dual-mobility cup than in frail, elderly patients of the same age? (2) Are clinical outcomes better in patients following THA with a dual-mobility cup than in frail, elderly patients? (3) What is the dislocation rate following THA with a dual-mobility cup? HypothesisWe hypothesized that patients who underwent THA with a dual-mobility cup have a better gait compared to frail, elderly patients of the same age. Patients and methodsTwenty patients (22 hips), mean age 79.9±7.7 (range, 62.3–88.3) years were assessed in this retrospective case-control series 5.6±1.4 (range: 4.1–8.8) years following dual-mobility cup THA. A reference group consisted of 72 “frail elderly” patients in a rehabilitation hospital for health problems unrelated to the lower limb, with no lower limb surgery or neurological conditions. Temporal and spatial gait performance were measured with four miniature gyroscopes, mounted on each thigh and calf, while patients walked freely along a 30m corridor. Harris Hip Score, WOMAC, radiological outcomes, and dislocation rate were determined. ResultsAll gait parameters were better in the dual-mobility group compared to the frail elderly group. The dual-mobility group had a higher cadence (100.3 steps/minute versus 75.6 steps/minute), shorter (relative to gait cycle time) stance (61.6% versus 67.8%), shorter (relative to gait cycle time) double stance (23.3% versus 36.0%), longer stride (1.13m versus 0.80m), and faster walking speed (0.96m/s versus 0.52m/s). Range of motion of the shank, thigh and knee were better in the dual-mobility group. Harris Hip Score was 87.6±13.9 (range 51–100) and WOMAC score was 11.3±12.1 (range 0–34) in the THA group. We observed no dislocations. DiscussionGait patterns five years following THA with the dual-mobility cup were better or comparable to published study populations. Level of evidenceIII, retrospective case-control series.

Optimised geometry model for liquid‐suspended miniature gyroscope

The levitation of the rotor eliminates mechanical friction and obtains high sensitivity for miniature gyroscopes. However, it is difficult to control the rotor stability because of the rotor's small size. A novel liquid-suspended rotor miniature gyroscope is proposed, whose stability is improved by liquid suspension. The magnetic and flow field models of the miniature gyroscope are established. Based on models, the driving torque and viscous torque were analysed to optimise the structures of the driving stator and the rotor. The optimised stator structure is 6-phase-12-coil, the optimised rotor radius is 7.44 mm, and the maximum rotational speed of the rotor of 11 210 rpm.

Emulated Analysis of the Preview-LQG Controller for Micromachined Tunneling Gyroscope

Only when the tunneling gap is maintained near 10Å can the micromachined tunneling gyroscope operate regularly to generate tunneling current which is so weak that it would be submerged by the thermal-mechanical noise, 1/f tunneling noise and so on. At the meantime, the dynamic range of the device will be reduced drastically by the nonlinearity of the tunneling effect. So a controller must be designed for the miniature tunneling gyroscope to realize a 10 Å tunneling gap to decrease the nonlinearity and so as to enlarge the band-width of the device. At the other hand, the signal-to-noise ratio can be raised by the controller. Because of the anti-interference and robusticity of the LQG control theory and the time-varying characteristic of Coriolis acceleration, the preview-LQG control strategy is selected to design the closed-loop system. The simulation results suggest that the tunneling gap can be controlled near its nominal value and the measured input angular rate can be estimated accurately by the preview-LQG controller even if the input angular rate is a slowly time-varying random signal.

Application of wavelet neural network in signal processing of MEMS accelerometers

A new method with wavelet neural network is described to optimize MEMS accelerometers for temperature independent sensitivity. Linear accelerations are measured and compensated by a thermocouple the fast algorithm which is used to deal with the nonlinearity error. The simulation results show that MEMS accelerometers with compensation is characterized by an excellent temperature stability of the sensitivity with less than 0.1% variation for a temperature range −40–100°C, while the variation of acceleration without compensation is 8%. The proposed algorithm can be useful for realization of high accuracy miniature gyroscope systems based on MEMS technology.

Current and Future Management of Bilateral Loss of Vestibular Sensation — An Update on the Johns Hopkins Multichannel Vestibular Prosthesis Project

Bilateral loss of vestibular sensation can disable individuals whose vestibular hair cells are injured by ototoxic medications, infection, Ménière's disease or other insults to the labyrinth including surgical trauma during cochlear implantation. Without input to vestibulo-ocular and vestibulo-spinal reflexes that normally stabilize the eyes and body, affected patients suffer blurred vision during head movement, postural instability, and chronic disequilibrium. While individuals with some residual sensation often compensate for their loss through rehabilitation exercises, those who fail to do so are left with no adequate treatment options. An implantable neuroelectronic vestibular prosthesis that emulates the normal labyrinth by sensing head movement and modulating activity on appropriate branches of the vestibular nerve could significantly improve quality of life for these otherwise chronically dizzy patients.This brief review describes the impact and current management of bilateral loss of vestibular sensation, animal studies supporting the feasibility of prosthetic vestibular stimulation, and a vestibular prosthesis designed to restore sensation of head rotation in all directions. Similar to a cochlear implant in concept and size, the Johns Hopkins Multichannel Vestibular Prosthesis (MVP) includes miniature gyroscopes to sense head rotation, a microcontroller to process inputs and control stimulus timing, and current sources switched between pairs of electrodes implanted within the vestibular labyrinth. In rodents and rhesus monkeys rendered bilaterally vestibulardeficient via treatment with gentamicin and/or plugging of semicircular canals, the MVP partially restores the vestibulo-ocular reflex for head rotations about any axis of rotation in 3-dimensional space. Our efforts now focus on addressing issues prerequisite to human implantation, including refinement of electrode designs and surgical technique to enhance stimulus selectivity and preserve cochlear function, optimization of stimulus protocols, and reduction of device size and power consumption.

Quantification of Tremor and Bradykinesia in Parkinson's Disease Using a Novel Ambulatory Monitoring System

An ambulatory system for quantification of tremor and bradykinesia in patients with Parkinson's disease (PD) is presented. To record movements of the upper extremities, a sensing units which included miniature gyroscopes, has been fixed to each of the forearms. An algorithm to detect and quantify tremor and another algorithm to quantify bradykinesia have been proposed and validated. Two clinical studies have been performed. In the first study, 10 PD patients and 10 control subjects participated in a 45-min protocol of 17 typical daily activities. The algorithm for tremor detection showed an overall sensitivity of 99.5% and a specificity of 94.2% in comparison to a video reference. The estimated tremor amplitude showed a high correlation to the Unified Parkinson's Disease Rating Scale (UPDRS) tremor subscore (e.g., r = 0.87, p < 0.001 for the roll axis). There was a high and significant correlation between the estimated bradykinesia related parameters estimated for the whole period of measurement and respective UPDRS subscore (e.g., r = -0.83, p < 0.001 for the roll axis). In the second study, movements of upper extremities of 11 PD patients were recorded for periods of 3-5 hr. The patients were moving freely during the measurements. The effects of selection of window size used to calculate tremor and bradykinesia related parameters on the correlation between UPDRS and these parameters were studied. By selecting a window similar to the period of the first study, similar correlations were obtained. Moreover, one of the bradykinesia related parameters showed significant correlation (r = -0.74, p < 0.01) to UPDRS with window sizes as short as 5 min. Our study provides evidence that objective, accurate and simultaneous assessment of tremor and bradykinesia can be achieved in free moving PD patients during their daily activities.

B24 ジャイロセンサによる下肢三軸まわり角速度計測による歩行分析(歩行)

B24 ジャイロセンサによる下肢三軸まわり角速度計測による歩行分析(歩行)

Stair climbing detection during daily physical activity using a miniature gyroscope

A new method of monitoring physical activity that is able to detect walking upstairs using a miniature gyroscope attached to the shank is presented. Wavelet transformation, in conjunction with a simple kinematics model, was used to detect toe-off, heel-strike and foot-flat, as well cycles corresponding to stair ascent. To evaluate the system, three studies were performed. The method was first tested on 10 healthy young volunteer subjects in a gait laboratory where an ultrasonic motion system was used as a reference system. In the second study, the system was tested on three hospitalized elderly people to classify walking upstairs from walking downstairs and flat walking. In the third study, monitoring was performed on seven patients with peripheral vascular disease for 60min during their daily physical activity. The first study revealed a close relationship between the ambulatory and the reference systems. Compared to the reference system, the ambulatory system had an overall sensitivity and specificity of 98% and 97%, respectively. In the second study, the ambulatory system also showed a very high sensitivity (>94%) in identifying a 50 stairs ascent from walking on the flat and walking downstairs. Finally, compared with visual surveillance, we observed a relatively high accuracy in identifying 196 walking upstairs cycles through daily physical activity in the third study. Our results demonstrated a reliable technique of measuring walking upstairs during physical activity.

A Reliable Gyroscope-Based Gait-Phase Detection Sensor Embedded in a Shoe Insole

This paper presents results of patient experiments using a new gait-phase detection sensor (GPDS) together with a programmable functional electrical stimulation (FES) system for subjects with a dropped-foot walking dysfunction. The GPDS (sensors and processing unit) is entirely embedded in a shoe insole and detects in real time four phases (events) during the gait cycle: stance, heel off, swing, and heel strike. The instrumented GPDS insole consists of a miniature gyroscope that measures the angular velocity of the foot and three force sensitive resistors that measure the force load on the shoe insole at the heel and the metatarsal bones. The extracted gait-phase signal is transmitted from the embedded microcontroller to the electrical stimulator and used in a finite state control scheme to time the electrical stimulation sequences. The electrical stimulations induce muscle contractions in the paralyzed muscles leading to a more physiological motion of the affected leg. The experimental results of the quantitative motion analysis during walking of the affected and nonaffected sides showed that the use of the combined insole and FES system led to a significant improvement in the gait-kinematics of the affected leg. This combined sensor and stimulation system has the potential to serve as a walking aid for rehabilitation training or permanent use in a wide range of gait disabilities after brain stroke, spinal-cord injury, or neurological diseases.

The mechanics of an oscillatory rate gyroscope with piezoelectric film actuation and sensing

Many applications exist for low-cost, miniature rate gyroscopes. These are primarily in the automotive field, and relate to safety systems or vehicle navigation. This paper presents an analysis of the mechanics of an oscillatory rate gyroscope that is actuated and sensed using thin-film lead-zirconate-titanate (PZT), and is suitable for manufacture using recently developed micromachining techniques. An analytical model of the device, combining the electromechanical behaviour of PZT and the dynamic behaviour of the mechanical structure, has been developed. This model is used to investigate the basic performance of a gyro of realistic dimensions, thus demonstrating the potential feasibility of such a device.

Estimating orientation with gyroscopes and accelerometers

Many systems for recording human movement need some reference from beacons near the subject, such as video cameras. Our goal is to measure human kinematics with sensors that are placed on the segments of interest. This way, experiments in which human movement is recorded are not restricted to a lab. Our inertial sensor-unit consists of a little box with three miniature gyroscopes (Murata ENC05E) and three linear accelerometers (AD xl05) that measure 3D angular velocity and linear acceleration, respectively. Both the gyroscope and accelerometer signals contain information about the orientation of the sensor. The sensor orientation can be obtained by integration of the angular velocity signals obtained from the gyroscopes [1]. This operation introduces drift in the estimated orientation. Accelerometers do not only measure the acceleration of the sensor, but also the gravitational vector. This gravitational component not only has a bigger magnitude for many human movements but also always points downwards. This knowledge can be used to make an estimation of the tilt. The tilt is the angle between the sensor axes and the vertical. This tilt estimation is not very precise but does not suffer from drift. The abstract describes a way to fuse both sensors (gyroscopes and accelerometers) to obtain an estimate of the orientation that is both accurate and is limited in integration drift.