PROPULSION SYSTEM WITH PNEUMATIC ARTIFICIAL MUSCLES FOR POWERING ANKLE-FOOT ORTHOSIS

2013 ◽  
Vol 43 (4) ◽  
pp. 3-16 ◽  
Author(s):  
Ivanka Veneva ◽  
Bram Vanderborght ◽  
Dirk Lefeber ◽  
Pierre Cherelle
Keyword(s):  
Ankle Joint ◽  
Position Control ◽  
Human Motion ◽  
Propulsion System ◽  
Joint Torque ◽  
Joint Control ◽  
Artificial Muscles ◽  
Ankle Foot Orthosis ◽  
Pneumatic Artificial Muscles ◽  
Foot Orthosis

Abstract The aim of this paper is to present the design of device for control of new propulsion system with pneumatic artificial muscles. The propulsion system can be used for ankle joint articulation, for assisting and rehabilitation in cases of injured ankle-foot complex, stroke patients or elderly with functional weakness. Proposed device for control is composed by microcontroller, generator for muscles contractions and sensor system. The microcontroller receives the control signals from sensors and modulates ankle joint flex- ion and extension during human motion. The local joint control with a PID (Proportional-Integral Derivative) position feedback directly calculates desired pressure levels and dictates the necessary contractions. The main goal is to achieve an adaptation of the system and provide the necessary joint torque using position control with feedback.

Nonlinear Modeling of Human Quiet Standing

2012 ◽  
Vol 523-524 ◽  
pp. 717-721
Author(s):  
Hiroyuki Takagi ◽  
Takuya Tabata ◽  
Ken Sasaki
Keyword(s):  
Nonlinear Control ◽  
Ankle Joint ◽  
Center Of Pressure ◽  
Control Model ◽  
Joint Torque ◽  
Quiet Standing ◽  
Upper Body ◽  
Joint Control ◽  
Maximum Deviation ◽  
Evaluation Indexes

Fluctuation during quiet standing of a person is one of the evaluation indexes of aging. Usually, fluctuation is measured by the center of the subject’s weight distribution on the floor, which is called center-of-pressure (COP), or the two dimensional trajectory of the top of the head taken from above the subject. In both cases, common evaluation indexes are standard deviation or maximum deviation. Control models of human quiet standing have been proposed and studied, and now it is widely accepted that human quiet standing is a nonlinear control system. However, there is no established nonlinear control model that expresses the characteristics of human quiet standing accurately. If we could express the nonlinear control dynamics of human quiet standing, the parameters of the control model can be utilized to evaluate subject’s motor control ability in more detail. In this study, we modeled the human body as a two link inverted pendulum. Leaning angle of the lower body and the upper body, and COP were measured in the experiment. Analysis of the data has revealed an asymmetry in the ankle joint torque in the anterior-posterior postural control. This asymmetry was modeled by asymmetric feedback gains of the feedback loop of ankle joint control. The proposed nonlinear model was verified by comparing the simulation results and the experimental data.

Preliminary Design and Engineering Evaluation of a Hydraulic Ankle–Foot Orthosis

2016 ◽  
Vol 10 (4) ◽  
Author(s):  
Brett Neubauer ◽  
William Durfee
Keyword(s):  
Steady State ◽  
Electric Motor ◽  
Position Control ◽  
Power Transmission ◽  
Fluid Power ◽  
Hydraulic Pump ◽  
Motor Impairments ◽  
Power Circuit ◽  
Ankle Foot Orthosis ◽  
Foot Orthosis

Ankle foot orthoses (AFOs) are used to correct motor impairments of the ankle. While current AFOs are passive, advances in technology and wearable robotics have opened the opportunity for a powered AFO. The hydraulic ankle foot orthosis (HAFO) is a device that takes advantage of the exceptional power-to-weight and force-to-weight of hydraulic fluid power. The device is untethered, and the power transmission chain is battery–electric motor–hydraulic pump–hose–cylinder, with the power supply worn at the waist and the cylinder actuators at the ankle. The fluid power circuit is configured as an electrohydraulic actuator (EHA) that is controlled by controlling the electric motor. The first prototype weighs 3.3 kg of which 0.97 kg is worn at the ankle. Steady-state torque–velocity performance showed that the prototype can provide 65 N·m of assistance torque and a no-load velocity of 105 deg/s. Closed-loop position control showed low steady-state error but a slow response. The current prototype demonstrates the potential of hydraulics for providing large torques in a compact, lightweight device. The speed performance of the prototype is inadequate for normal walking but can be improved by switching to servo valve control or by developing a custom hydraulic pump.

An Automated Testing Assembly for Characterizing Stiffness of an Ankle Foot Orthosis

2011 ◽  
Author(s):  
Minal Y. Bhadane ◽  
Charles Armstrong ◽  
Mohamed Samir Hefzy ◽  
Mohammad H. Elahinia
Keyword(s):  
Ankle Joint ◽  
Automated Testing ◽  
Time Data ◽  
Angle Sensor ◽  
Ankle Foot Orthosis ◽  
Ankle Stiffness ◽  
Stiffness Variation ◽  
Stiffness Characteristics ◽  
Foot Orthosis ◽  
Testing Assembly

An ankle foot orthosis (AFO) is a device that provides a controlled force to compensate for the muscle deficiencies in the ankle and helps normalize the gait of the patient. Evidence has indicated that there exists an optimal match correlating the patient’s gait related problems and the AFO stiffness. AFO ankle stiffness is measured by the moment around the ankle joint exerted by the AFO per degree of ankle joint rotation. To date, several testing devices and procedures have been developed to assess the stiffness characteristics of AFOs. Most of the devices are manually driven and may not exactly replicate human leg motion. Objective of developing an automated testing assembly is to identify stiffness characteristics of passive AFOs so as to develop an active AFO with shape memory alloy. We have developed an assembly using aluminum T-slotted profiles, single flange linear bearings, and living hinges from 80/20 Inc. Angle measurement was done by mounting Digital Protractor on the shank segment. The whole assembly was mounted on BOSE ElectroForce 3330 test instrument. dSPACE hardware-in-the-loop solution was used for real time data capture of force and angle sensor output. After assessing the characteristics of passive AFO we incorporated SMA wire in the AFO. Similar tests were conducted to evaluate effect of SMA wires on the overall stiffness of an AFO. The results confirm that SMA wires provide stiffness variation such a way that AAFO can be developed to achieve stiffness variation close to normal ankle stiffness.

scholarly journals A Model to Predict the Effect of Ankle Joint Misalignment on Calf Band Movement in Ankle-Foot Orthoses

2007 ◽  
Vol 31 (1) ◽  
pp. 76-87 ◽  
Author(s):  
Stefania Fatone ◽  
Andrew H. Hansen
Keyword(s):  
Ankle Joint ◽  
Walking Speed ◽  
Sagittal Plane ◽  
Plantar Flexion ◽  
Dimensional Model ◽  
Ankle Foot Orthosis ◽  
Ankle Joints ◽  
Ankle Foot Orthoses ◽  
Foot Orthosis ◽  
Anterior Posterior

Accurate alignment of anatomical and mechanical joint axes is one of the major biomechanical principles pertaining to articulated orthoses, yet knowledge of the potential effects of axis misalignment is limited. The purpose of this project was to model the effects of systematic linear (proximal-distal and anterior-posterior) misalignments of single axis mechanical ankle joints in an ankle-foot orthosis (AFO) in order to determine the degree and direction of calf band travel that would occur over a functional range of motion. Sagittal plane misalignments of the ankle joint centres of an AFO were simulated using a simple two-dimensional model for both a range of ankle angles and a typical able-bodied ankle kinematic curve for self-selected normal walking speed. The model assumed that no movement occurred between the foot and the foot-plate of the AFO. The model predicted that for anterior (positive horizontal) misalignments, dorsiflexion movements would cause the calf band to travel proximally (i.e., up the leg) and plantar flexion movements would cause the calf band to travel distally (i.e., down the leg). The opposite was predicted for posterior (negative horizontal) misalignments. Proximal (positive vertical) misalignments would cause only distal movements of the calf band while distal (negative vertical) misalignments would cause only proximal movements of the calf band. Anterior-posterior misalignments were found to have a much larger effect on the amount of calf band travel than proximal-distal misalignments.

scholarly journals Ankle-foot Orthosis With an Oil Damper Versus Nonarticulated Ankle-foot Orthosis in the Gait of Patients With Subacute Stroke: A Randomized Controlled Trial

2021 ◽  
Author(s):  
Sumiko Yamamoto ◽  
Naoyuki Motojima ◽  
Yosuke Kobayashi ◽  
Yuji Osada ◽  
Souji Tanaka ◽  
...  
Keyword(s):  
Power Generation ◽  
Randomized Controlled Trial ◽  
Ankle Joint ◽  
Controlled Trial ◽  
Plantar Flexion ◽  
Vertical Angle ◽  
Power Absorption ◽  
Ankle Foot Orthosis ◽  
Randomized Controlled ◽  
Foot Orthosis

Abstract BackgroundGait improvement in patients with stroke using ankle-foot orthosis (AFO) has been compared to the effects of non-AFO use in previous studies, but the effect of different kinds of AFOs has not been clear. When considering the effect of different kinds of AFOs on gait, the dorsiflexion and plantar flexion moment of resistance is considered a key determinant of functional effect. In this study, the effect on gait of using an AFO with an oil damper (AFO-OD), which has plantar flexion resistance but no dorsiflexion resistance, and a nonarticulated AFO, which has both dorsiflexion and plantar flexion resistance, were compared in a randomized controlled trial. MethodsForty-one patients (31 men, 10 women; mean age 58.4 ± 11.3 years) in the subacute phase of stroke were randomly allocated to two groups to undergo 2 weeks of gait training by physiotherapists while wearing an AFO-OD or a nonarticulated AFO. A motion capture system was utilized to measure shod gait without orthosis at baseline and after training with the allocated AFO. Data analysis was performed focused on the spatial and temporal parameters, ground reaction force, shank-to-vertical angle, and ankle joint kinematics and kinetics. Two-way mixed ANOVA was performed to clarify the effect of AFO use and the difference between the two AFOs. ResultsThirty-six patients completed the study (17 in the AFO-OD group and 19 in the nonarticulated AFO group). Spatial and temporal parameters and ankle joint kinematics were improved after 2 weeks in both AFO groups. Interactions were found for the range of shank-to-vertical angles in paretic single stance and ankle peak power absorption. In the AFO-OD group, both parameters improved when the participants walked with the AFO compared to the shod gait, but there was no change in the nonarticulated AFO group. Power generation was not increased in either AFO group. ConclusionsThe results of this study showed that AFO with plantar flexion resistance but without dorsiflexion resistance improved the range of the shank-to-vertical angle and ankle power absorption but not power generation in a paretic stance. (336/350 words)Trial registration: UMIN000028126 Registered 1 August 2017,https://upload.umin.ac.jp/cgi-bin/icdr/ctr_menu_form_reg.cgi?recptno=R000032197

KINETIC EFFECTS OF A LOCKED ANKLE JOINT VIA AN ANKLE-FOOT ORTHOSIS DURING WALKING

1999 ◽  
Vol 31 (Supplement) ◽  
pp. S130
Author(s):  
S. M. Clark-Donovan ◽  
J. A. Crussemeyer ◽  
J. S. Dufek ◽  
B. T. Bates
Keyword(s):  
Ankle Joint ◽  
Ankle Foot Orthosis ◽  
Kinetic Effects ◽  
Foot Orthosis

Operating Modes of Pneumatic Artificial Muscle Actuator

2013 ◽  
Vol 308 ◽  
pp. 39-44 ◽  
Author(s):  
Mária Tóthová ◽  
Ján Piteľ ◽  
Jana Boržíková
Keyword(s):  
Position Control ◽  
Artificial Muscle ◽  
Pneumatic Actuator ◽  
Variable Pressure ◽  
Artificial Muscles ◽  
Pneumatic Artificial Muscle ◽  
Operating Modes ◽  
Main Requirement ◽  
Pneumatic Artificial Muscles ◽  
Operation Characteristics

The paper describes operating modes of the PAM based actuator consisting of two pneumatic artificial muscles (PAMs) in antagonistic connection. The artificial muscles are acting against themselves and resultant position of the actuator is given by equilibrium of their forces according to different pressures in muscles. The main requirement for operation of such pneumatic actuator is uniform movement and accurate arm position control according to input desired variable. There are described in paper operation characteristics of the pneumatic artificial muscle in variable pressure and then operation characteristics of the pneumatic artificial muscle actuator consisting of two muscles in antagonistic connection.

scholarly journals Effect of Ankle Torque on the Ankle–Foot Orthosis Joint Design Sustainability

Materials ◽  
2021 ◽  
Vol 14 (11) ◽  
pp. 2975
Author(s):  
Pruthvi Serrao ◽  
Vivek Kumar Dhimole ◽  
Chongdu Cho
Keyword(s):  
Ankle Joint ◽  
Material Selection ◽  
Functional Requirements ◽  
Element Analysis ◽  
Ankle Foot Orthosis ◽  
Prominent Component ◽  
Transfer Capability ◽  
Gear Mechanism ◽  
Dynamic Loading Conditions ◽  
Foot Orthosis

The ankle joint of a powered ankle–foot orthosis (PAFO) is a prominent component, as it must withstand the dynamic loading conditions during its service time, while delivering all the functional requirements such as reducing the metabolic effort during walking, minimizing the stress on the user’s joint, and improving the gait stability of the impaired subjects. More often, the life of an AFO is limited by the performance of its joint; hence, a careful design consideration and material selection are required to increase the AFO’s service life. In the present work, a compact AFO joint was designed based on a worm gear mechanism with steel and brass counterparts due to the fact of its large torque transfer capability in a single stage, enabling a compact joint. Further, it provided an added advantage of self-locking due to the large friction that prevents backdrive, which is beneficial for drop-foot recovery. The design was verified using nonlinear finite element analysis for maximum torque situations at the ankle joint during normal walking. The results indicate stress levels within its design performance; however, it is recommended to select high-grade structural steel for the ankle shaft as the highest stresses in AFO were located on it.

Sign in / Sign up

Export Citation Format

Share Document