Design of a Clutch–Spring Knee Exoskeleton for Running

2014 ◽  
Vol 8 (3) ◽  
Author(s):  
Grant Elliott ◽  
Andrew Marecki ◽  
Hugh Herr
Keyword(s):  
Control Strategy ◽  
Stance Phase ◽  
Planetary Gear ◽  
Knee Extension ◽  
Swing Phase ◽  
Gear Transmission ◽  
Sensory Inputs ◽  
Peak Knee ◽  
Low Mass ◽  
And Control

Because the leg is known to exhibit springlike behavior during the stance phase of running, several exoskeletons have attempted to place external springs in parallel with some or all of the leg during stance, but these designs have failed to permit natural kinematics during swing. To this end, a parallel-elastic exoskeleton is presented that introduces a clutch to disengage the parallel leg-spring and thereby not constrain swing-phase movements of the biological leg. A custom interference clutch with integrated planetary gear transmission, made necessary by the requirement for high holding torque but low mass, is presented and shown to withstand up to 190 N·m at 1.8 deg resolution with a mass of only 710 g. A suitable control strategy for locking the clutch at peak knee extension is also presented, where only an onboard rate gyroscope and exoskeletal joint encoder are employed as sensory inputs. Exoskeletal electromechanics, sensing, and control are shown to achieve design critieria necessary to emulate biological knee stiffness behaviors in running.

scholarly journals ROLE OF HAMSTRING MUSCLES IN KNEE JOINT STABILITY PROVIDING AND INJURY PREVENTION

2016 ◽  
Vol 3 ◽  
pp. 522
Author(s):  
Inese Pontaga
Keyword(s):  
Stance Phase ◽  
Knee Extension ◽  
Swing Phase ◽  
Joint Stability ◽  
Distance Runners ◽  
Leg Extension ◽  
Hamstring Muscles ◽  
Extreme Extension ◽  
Torque Values

The aim of our investigation was to determine the ratio of maximal torque values and the torques in the certain positions of range of movements (ROM) between hamstring (H) and quadriceps femoris (Q) muscles at medium and high velocity of movement in concentric (CC) and eccentric (ECC) action of hamstring muscles. The knee muscles of 15 amateur female short and middle distance runners were tested by the dynamometer system in the isokinetic movements with the angular velocity of 90º/s and 240º/s in CC and at the velocity of 90º/s in ECC H/ CC Q muscles contractions. The torque values produced by the muscles are detected at the different angular positions of the ROM with the step of 10º. The ratios of H/ Q muscles torques are calculated. The H/Q muscles maximal torques ratio is 0.51 ± 0.13 at the velocity of 90º/s in CC and 0.60 ± 0.09 in ECC H/ CC Q muscles contractions, and 0.59 ± 0.09 CC at the velocity of 240º/s. The H/Q maximal torques ratio and this ratio in the knee extreme extension and flexion at the ECC contraction of H is higher due to greater torques produced by the H in comparison with Q muscle. The H must be stronger to decelerate the thigh and lower leg extension in the late swing phase of running and to extend the hip in early stance phase to provide powerful sprint running and prevent the knee and H injury. The H/Q muscles torques ratio in extended knee positions are similar in medium (90º/s) and fast (240º/s) velocity of motions because CC action of H muscles cannot prevent extreme knee extension.

scholarly journals Validation of a Novel Device for the Knee Monitoring of Orthopaedic Patients

Sensors ◽  
2019 ◽  
Vol 19 (23) ◽  
pp. 5193 ◽  
Author(s):  
Mahmut Enes Kayaalp ◽  
Alison N. Agres ◽  
Jan Reichmann ◽  
Maxim Bashkuev ◽  
Georg N. Duda ◽  
...  
Keyword(s):  
Motion Capture ◽  
Stance Phase ◽  
Swing Phase ◽  
Flexion Angle ◽  
Sensor System ◽  
Measurement Unit ◽  
Data Set ◽  
Orthopaedic Patients ◽  
Peak Knee ◽  
Good For

Fast-track surgery is becoming increasingly popular, whereas the monitoring of postoperative rehabilitation remains a matter of considerable debate. The aim of this study was to validate a newly developed wearable system intended to monitor knee function and mobility. A sensor system with a nine-degree-of-freedom (DOF) inertial measurement unit (IMU) was developed. Thirteen healthy volunteers performed five 10-meter walking trials with simultaneous sensor and motion capture data collection. The obtained kinematic waveforms were analysed using root mean square error (RMSE) and correlation coefficient (CC) calculations. The Bland–Altman method was used for the agreement of discrete parameters consisting of peak knee angles between systems. To test the reliability, 10 other subjects with sensors walked a track of 10 metres on two consecutive days. The Pearson CC was excellent for the walking data set between both systems (r = 0.96) and very good (r = 0.95) within the sensor system. The RMSE during walking was 5.17° between systems and 6.82° within sensor measurements. No significant differences were detected between the mean values observed, except for the extension angle during the stance phase (E1). Similar results were obtained for the repeatability test. Intra-class correlation coefficients (ICCs) between systems were excellent for the flexion angle during the swing phase (F1); good for the flexion angle during the stance phase (F2) and the re-extension angle, which was calculated by subtracting the extension angle at swing phase (E2) from F2; and moderate for the extension angle during the stance phase (E1), E2 and the range of motion (ROM). ICCs within the sensor measurements were good for the ROM, F2 and re-extension, and moderate for F1, E1 and E2. The study shows that the novel sensor system can record sagittal knee kinematics during walking in healthy subjects comparable to those of a motion capture system.

scholarly journals Human muscle activity and lower limb biomechanics of overground walking at varying levels of simulated reduced gravity and gait speeds

PLoS ONE ◽  
2021 ◽  
Vol 16 (7) ◽  
pp. e0253467
Author(s):  
Mhairi K. MacLean ◽  
Daniel P. Ferris
Keyword(s):  
Lower Limb ◽  
Muscle Activity ◽  
Muscle Activation ◽  
Stance Phase ◽  
Knee Extension ◽  
Medial Gastrocnemius ◽  
Gravity Level ◽  
Reduced Gravity ◽  
Overground Walking ◽  
Peak Knee

Reducing the mechanical load on the human body through simulated reduced gravity can reveal important insight into locomotion biomechanics. The purpose of this study was to quantify the effects of simulated reduced gravity on muscle activation levels and lower limb biomechanics across a range of overground walking speeds. Our overall hypothesis was that muscle activation amplitudes would not decrease proportionally to gravity level. We recruited 12 participants (6 female, 6 male) to walk overground at 1.0, 0.76, 0.55, and 0.31 G for four speeds: 0.4, 0.8, 1.2, and 1.6 ms-1. We found that peak ground reaction forces, peak knee extension moment in early stance, peak hip flexion moment, and peak ankle extension moment all decreased substantially with reduced gravity. The peak knee extension moment at late stance/early swing did not change with gravity. The effect of gravity on muscle activity amplitude varied considerably with muscle and speed, often varying nonlinearly with gravity level. Quadriceps (rectus femoris, vastus lateralis, & vastus medialis) and medial gastrocnemius activity decreased in stance phase with reduced gravity. Soleus and lateral gastrocnemius activity had no statistical differences with gravity level. Tibialis anterior and biceps femoris increased with simulated reduced gravity in swing and stance phase, respectively. The uncoupled relationship between simulated gravity level and muscle activity have important implications for understanding biomechanical muscle functions during human walking and for the use of bodyweight support for gait rehabilitation after injury.

A New Stance Control Knee Orthosis Using a Self-Locking Mechanism Based on a Planetary Gear Train

2019 ◽  
Vol 141 (6) ◽  
Author(s):  
Gaspar Rodríguez Jiménez ◽  
David Rodríguez Salgado ◽  
Francisco Javier Alonso Sanchez ◽  
Jose María del Castillo Granados
Keyword(s):  
Stance Phase ◽  
Planetary Gear ◽  
Swing Phase ◽  
Gear Train ◽  
Planetary Gear Train ◽  
External Agent ◽  
Locking Mechanism ◽  
Control Knee ◽  
And Performance ◽  
Knee Orthosis

The objective of this work was to design and build a fully mechanical knee orthosis. A knee orthosis should both allow control of the angle of flexion of the knee during the stance phase of the gait cycle and leave the joint free during the swing phase. Knee orthoses are normally used to assist the walking of people suffering from muscle weaknesses or gait pathologies in order to avoid excessive knee flexion during the stance phase. The design of the orthosis proposed in the present work is characterized by allowing the knee to be locked at any angle of flexion during the stance phase, and because the orthosis can be unlocked to allow the joint to be released in the swing phase without the action of any external agent, i.e., without requiring external electrical or electronic systems for the control and performance of the orthosis. These characteristics mean that the design can be adapted to the gait of any user. The proposed design consists of a set of three rods, one attached to the user's thigh, another to the calf, and the other to the foot, connected to each other by a self-locking planetary gear train (PGT).

scholarly journals Spatiotemporal Activation of Lumbosacral Motoneurons in the Locomotor Step Cycle

2002 ◽  
Vol 87 (3) ◽  
pp. 1542-1553 ◽  
Author(s):  
Sergiy Yakovenko ◽  
Vivian Mushahwar ◽  
Veronique VanderHorst ◽  
Gert Holstege ◽  
Arthur Prochazka
Keyword(s):  
Spinal Cord ◽  
Stance Phase ◽  
Three Dimensional ◽  
Swing Phase ◽  
Caudal Part ◽  
Step Cycle ◽  
Lumbosacral Spinal Cord ◽  
Sensory Inputs ◽  
Hindlimb Muscles ◽  
Rostral Part

The aim of this study was to produce a dynamic model of the spatiotemporal activation of ensembles of alpha motoneurons (MNs) in the cat lumbosacral spinal cord during the locomotor step cycle. The coordinates of MNs of 27 hindlimb muscles of the cat were digitized from transverse sections of spinal cord spanning the entire lumbosacral enlargement from the caudal part of L4 to the rostral part of S1 segments. Outlines of the spinal cord gray matter were also digitized. Models of the spinal cord were generated from these digitized data and displayed on a computer screen as three-dimensional (3-D) images. We compiled a chart of electromyographic (EMG) profiles of the same 27 muscles during the cat step cycle from previous studies and used these to modulate the number of active MNs in the 3-D images. The step cycle was divided into 100 equal intervals corresponding to about 7 ms each for gait of moderate speed. For each of these 100 intervals, the level of EMG of each muscle was used to scale the number of dots displayed randomly within the volume of the corresponding MN pool in the digital model. One hundred images of the spinal cord were thereby generated, and these could be played in sequence as a continuous-loop movie representing rhythmical stepping. A rostrocaudal oscillation of activity in hindlimb MN pools emerged. This was confirmed by computing the locus of the center of activation of the MNs in the 100 consecutive frames of the movie. The caudal third of the lumbosacral enlargement showed intense MN activity during the stance phase of locomotion. During the swing phase, the focus of activation shifted abruptly to the rostral part of the enlargement. At the stance-swing transition, a transient focus of activity formed in the most caudal part of the lumbosacral enlargement. This was associated with activation of gracilis, posterior biceps, posterior semimembranosus, and semitendinosus muscles. These muscles move the foot back and up to clear the ground during locomotion, a role that could be described as retraction. The spatiotemporal distribution of neuronal activity in the spinal cord during normal locomotion with descending control and sensory inputs intact has not been visualized before. The model can be used in the future to characterize spatiotemporal activity of spinal MNs in the absence of descending and sensory inputs and to compare these to spatiotemporal patterns in spinal MNs in normal locomotion.

The AMP-Foot 2.1 : actuator design, control and experiments with an amputee

Robotica ◽  
2014 ◽  
Vol 32 (8) ◽  
pp. 1347-1361 ◽  
Author(s):  
Pierre Cherelle ◽  
Karen Junius ◽  
Victor Grosu ◽  
Heidi Cuypers ◽  
Bram Vanderborght ◽  
...  
Keyword(s):  
Control Strategy ◽  
Energy Efficient ◽  
Experimental Validation ◽  
Stance Phase ◽  
State Of The Art ◽  
New Energy ◽  
Full Power ◽  
And Control ◽  
Future Work ◽  
Actuator Design

SUMMARYThe Ankle Mimicking Prosthetic (AMP-) Foot 2 is a new energy efficient, powered transtibial prosthesis mimicking intact ankle behavior. The author's research is focused on the use of a low power actuator which stores energy in springs during the complete stance phase. At push-off, this energy can be released hereby providing propulsion forces and torques to the amputee. With the use of the so-called catapult actuator, the size and weight of the drive can be decreased compared to state-of-the-art powered prostheses, while still providing the full power necessary for walking.In this article, the authors present a detailed description of the catapult actuator followed by a comparison with existing actuator technology in powered prosthetic feet with regard to torque and power requirements. The implication on the actuator's design will then be outlined. Further, a description of the control strategy behind the AMP-Foot 2 and 2.1 will be given. In the last section of the article, the actuation principle and control are illustrated by experimental validation with a transfemoral amputee. Conclusions and future work complete the paper.

Dry chip feedrate control using online chip moisture

TAPPI Journal ◽  
2018 ◽  
Vol 17 (05) ◽  
pp. 295-305
Author(s):  
Wesley Gilbert ◽  
Ivan Trush ◽  
Bruce Allison ◽  
Randy Reimer ◽  
Howard Mason
Keyword(s):  
Production Rate ◽  
Control Strategy ◽  
Rate Control ◽  
Near Infrared ◽  
Dry Mass ◽  
The Other ◽  
Process Variability ◽  
Moisture Sensor ◽  
Feedback Control Strategy ◽  
And Control

Normal practice in continuous digester operation is to set the production rate through the chip meter speed. This speed is seldom, if ever, adjusted except to change production, and most of the other digester inputs are ratioed to it. The inherent assumption is that constant chip meter speed equates to constant dry mass flow of chips. This is seldom, if ever, true. As a result, the actual production rate, effective alkali (EA)-to-wood and liquor-to-wood ratios may vary substantially from assumed values. This increases process variability and decreases profits. In this report, a new continuous digester production rate control strategy is developed that addresses this shortcoming. A new noncontacting near infrared–based chip moisture sensor is combined with the existing weightometer signal to estimate the actual dry chip mass feedrate entering the digester. The estimated feedrate is then used to implement a novel feedback control strategy that adjusts the chip meter speed to maintain the dry chip feedrate at the target value. The report details the results of applying the new measurements and control strategy to a dual vessel continuous digester.

A power management and control strategy with grid-ancillary services for a microgrid based on DC Bus

2014 ◽  
Vol 9 (4) ◽  
pp. 792 ◽  
Author(s):  
Anna Pinnarelli ◽  
Giuseppe Barone ◽  
Giovanni Brusco ◽  
Alessandro Burgio ◽  
Daniele Menniti ◽  
...  
Keyword(s):  
Power Management ◽  
Control Strategy ◽  
Ancillary Services ◽  
Dc Bus ◽  
And Control
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