Patent Application
20090043357
Functional Electrical Stimulation (FES) is a technique for applying electrical currents to neural tissue for the purpose of restoring a degree of control over abnormal or absent body-functions via the generation of muscle contraction. However, accurate and stable control of limbs by FES is difficult because electrically stimulated musculoskeletal systems have strong nonlinearity, time variability, large latency, and fatigue in their response. Moreover, over-stimulated muscles will easily cause fatigue. Optimal control of FES is necessary for extended time use.
For the reasons stated above, as well as other deficiencies in the prior art, a new control system and methods of stimulations have been developed to achieve optimal control of stimulation with a goal of lightening the degree of muscle fatigue.
It is an object of the present system to overcome the disadvantages and problems in the prior art.
The present inventions proposes a new method of providing electrostimulation to alleviate foot drop and/or initiate arm swing, such method being suitable for optimally controlling stimulation to avoid fatigue over extended time use.
The present invention also proposes new systems for providing electrostimulation, such new system including two separated modules, wherein the modules communicate with one another via wireless means.
The present invention proposes the optimization of electrical stimulation by incorporating the method unto the system of the present invention, as well as by positioning components of the system in strategic places on the user's body.
The present invention proposes the method and system to produce artificial arm swing through the stimulation of triceps to generate the elbow extension for body balancing to improve gait quality. Further, the method will address foot drop to make walking easier and more “normal”-like.
These and other features, aspects, and advantages of the apparatus and methods of the present invention will become better understood from the following description, appended claims, and accompanying drawings where:
The following description of certain exemplary embodiment(s) is merely exemplary in nature and is in no way intended to limit the invention, its application, or uses. Throughout this description, the term “gait” refers to a particular way or manner of moving on foot.
Now, specifically to
Firstly, in the pre-swing phase 100 the system delivering the method is initialized 101. Initialization can include turning on the instrument, allowing the system to perform a systems check, having the system establish remote contacts, and the like.
The system can then define required values necessary to successfully provide the method 103. Values can refer to angular values, timing values, etc. As the system will rely on on-board instrumentation for determining when the user is in a particular phase of the gait, the instruments should be “zeroed” to offset the initial values to avoid false positives or missed periods of needed stimulation for the user. The instrumentation may also be modified to provide training and conditioning, for example decreasing or increasing the sensitivity of the instrumentation to provide a less stringent or more stringent exercise.
The algorithmic function of detecting whether the user's heel is “off” will then be determined 105. As is well known in the art, the pre-swing phase initiates when the heel of a foot is lifted off of the surface while the toes remain in contact with the surface (see
If the heel is detected “off”, a determination of the degree of the foot segment flexion is made 107. As is known in the art, in the period between heel off and toe off, the ankle moves from dorsiflexion to plantarflexion. Generally, from the time of heel-off, the foot measures at an angle of from about 20 to about 35 degree from the surface. The increase in ankle degree occurs as the swing progresses, and measurement is continually made.
As the swing progresses to the toe-off, an algorithm is enacted to determine whether swing is detected 109. A swing can be detected by noting the increase in angle change of the foot to the surface. In another embodiment, a detection of swing can be determined by noting the changes in the hips, knees, ankle, or upper body. Changes that can be noted include angle change, pressure, weight, flexion and/or extension. If swing is not detected, the algorithm is looped for determination of the foot segment flexion degree.
If the swing is detected, a determination is made when the swing has ended 111. As is well known in the art, a swing is generally terminated at the heel strike of the swinging foot. Determining the end of the swing can be based on decrease angle between the foot and the contact surface. In another embodiment, determination of the end of the swing can be based on change of pressure, angle, weight, flexion and/or extension as exhibited by the hips, knees, ankle, or upper body.
As is well known, an end of a swing on one foot will initiate the beginning of the swing phase on the alternate foot.
An algorithm is then made as to whether the alternate foot is being swung 113. If “yes”, stimulating paralyzed muscles can occur 114. Stimulation of paralyzed muscles is electrical-stimulation, and can occur by positioning electrical conducting devices on or around the paralyzed muscles of the user. The electrical conducting devices can be pads, wrap around implements, wires, or embedded devices into the body of the user. Stimulation preferably occurs at the proper moment in order to improve the walking pattern to be appeared more “normal”, i.e. similar to a non-paralyzed person's walk.
Stimulation may occur to the lower limb of the user, such as leg, or an upper limb such as the arm. For example, stimulation is focused on the arm of the user to mimic the arm swing of a “normal” person. In one embodiment, more than one body part of a person is stimulated, for example both arm and leg are stimulated. In such an embodiment, stimulation of a lower limb and upper limb may alternate to simulate a “normal person” and better effective walking. As will be discussed later, stimulation will occur via wireless means.
Stimulation may be adjusted as need be to better effectuate a particular gait 115. For example, if a gait is at a higher rate of speed than normal speed of walking, strong stimulation may be required to be delivered to the user to provide faster muscle contraction and wider range of movement on the paralyzed muscle. In another example, the stimulation may be decreased if a slower gait is being exhibited. Adjustment of the stimulation will be based on the actual variable compared against a projected variable 117. For example the actual speed of the user can be compared against a projected, or programmed, speed. If necessary, stimulation can be decreased 119. In other embodiments, stimulation may be increased.
Module A 202 can include a memory device for storing gait history 201, a device for storing predefined data 203, a gait phase detector 205, a controller 207, a feedback controller 209, and a device for estimating the position of the user 211. Module A 202 also includes sensors for passing data via wireless means 210.
Module B 212 can include a plant device 213 for attachment to a muscle location on the user, and a sensor module 215 for detecting a wireless signal sent from Module A 202.
Module A 202 and Module B 212 can be configured to operate in 3 modes. Mode 1 is a foot drop stimulator with real-time feedback control. In this mode, Module A is attached to a foot segment to act as an electro-stimulation trigger and foot flexion monitoring device. Data captured by the sensors are transmitted via wireless means, such as radio-frequency, to Module B. Module B processes the received data with the gait phase detection algorithm of the present invention and applies a different control strategy to adjust stimulation parameters at different gait phases.
Mode 2 is a combination mode, combining Modules A and B into a single device to act as a foot drop stimulator. The single device is attached to the shank and electro-stimulation is trigger by the movement of the device.
Mode 3 is a combination of modes 1 and 2, i.e., a foot drop stimulator combined with an arm swing stimulator. In this mode, Module A monitors the gait phase of the user and transmits gait data to module B of the foot drop stimulator and arm swing stimulator. The arm swing stimulator produces stimulation at appropriate gait phase, and the shank stimulator addresses the foot drop problem.
The transmission of data between Module A and Module B occurs by wireless means, for example RF, WIFI, satellites, BLUETOOTH®, and other wireless technologies. Preferably, a wireless transmitter is installed in Module A and a receiver is installed in Module B.
Module A 501 is preferably attached adjacent to the foot of the user. In one embodiment, the Module A 501 can be attached to the shoe of the user, in one embodiment on the top side of the shoe. The gait phase detector 505 may be incorporated into the inside sole 503 of the shoe. As previously mentioned, the gait phase detector 505 is used to determine whether the foot is in the swing phase of the gait cycle and, if so, what section of the swing phase.
In use, the Module A 501 transmits signals 507 to the modules B 511/509, pertaining to whether electro-stimulation by the Module B should be provided. The Module A 501 may also send a signal to a remote location 513, such as a computer system, for recording information about the user's gait, swing phase, and the like. In a preferred embodiment, if mode 3 is enacted, i.e. a Module B is utilized for arm swing and foot drop stimulation the modules should either be positioned in an alternating manner (left leg/right arm, or right leg/left arm) or stimulation should be provided in an alternating manner, i.e., left leg stimulation, no right arm stimulation/no left leg stimulation, right arm stimulation. In this way, the gait cycle of a “normal” person can better be mimiced by the muscle-paralyzed user.
The system will operate according to the previously mentioned method (
Having described embodiments of the present system with reference to the accompanying drawings, it is to be understood that the present system is not limited to the precise embodiments, and that various changes and modifications may be effected therein by one having ordinary skill in the art without departing from the scope or spirit as defined in the appended claims.
In interpreting the appended claims, it should be understood that:
a) the word “comprising” does not exclude the presence of other elements or acts than those listed in the given claim;
b) the word “a” or “an” preceding an element does not exclude the presence of a plurality of such elements;
c) any reference signs in the claims do not limit their scope;
d) any of the disclosed devices or portions thereof may be combined together or separated into further portions unless specifically stated otherwise; and
e) no specific sequence of acts or steps is intended to be required unless specifically indicated.
