About two thirds of stroke survivors live with impaired arm and hand functions. Therapeutic interventions leverage the brain's inherent neuroplasticity to increase adaptation to stroke by using both sensory and motor stimuli through repetitive motions.
Mirror therapy is one of the crucial therapy modalities used in stroke rehabilitation. In mirror therapy, a mirror is placed in the patient's sagittal plane so that the patient cannot see the paretic limb. The patient is then asked to move the healthy limb while observing it in the mirror. The imagery and visual feedback from the mirror create the impression in the patient's mind that their paretic limb is moving. This kind of therapy is known to activate the sensorimotor cortex and facilitate the brain neuroplasticity that aid in adaptation to stroke.
Inspired by the success of mirror therapy, a new form of therapy using assistive robotic systems has been developed to further facilitate motor recovery. This therapy is typically referred to as robotic bilateral therapy, robotic bimanual therapy, or robotic mirror therapy. With this therapy, the motion of a healthy limb is used to create the same motion of the paretic limb. Robotic mirror therapy applies mirrored motion of the healthy limb to the paretic limb, in contrast to the conventional mirror therapy where the paretic limb remains inactive during treatment. The main objective of the robotic mirror therapy is to provide proprioceptive stimulus to the sensory cortex to facilitate neuroplasticity and functional recovery. This therapy modality also addresses one of the deterministic factors, i.e., nonspontaneous or limited spontaneous use of the paretic limb that affects full recovery after stroke. Applying motion to the paretic limb also helps reduce contracture, maintain muscle tone, and lower spasticity. Furthermore, as the patient can direct the therapy by himself or herself, robotic mirror therapy addresses major limiting factors of the conventional therapist-centered rehabilitation, including rising costs and shortages of available resources, such as facilities, therapists, and funding.
While robotic mirror therapy has great potential in treating stroke victims, few have attempted to assist finger motion in hand rehabilitation. The systems that have been developed have various shortcomings, such as an inability to operate in three-dimensional space, limitations in grasping and manipulating objects in real-world scenarios, and lack of fine control of the fingers. It, therefore, can be appreciated that it would be desirable to have an effective system and method for robotic mirror therapy of the hands.
The present disclosure may be better understood with reference to the following figures. Matching reference numerals designate corresponding parts throughout the figures, which are not necessarily drawn to scale.
As described above, it would be desirable to have an effective system and method for providing robotic mirror therapy of the hands. Disclosed herein are examples of such systems and methods. In one embodiment, a robotic mirror therapy system includes a motion command glove that is worn on the healthy hand and a motion actuator glove that is worn on the impaired (e.g., paretic or injured) hand. The motion command glove is equipped with position sensors so that the motions of the hand and fingers can be tracked. In addition, the motion command glove can be equipped with force sensors so that the forces imposed upon the hand can be measured. The motion actuator glove is also equipped with position sensors and can also comprise force sensors. In addition, the motion actuator glove includes actuators so that, when the healthy hand is moved, apply the same movement to the impaired hand. Furthermore, if the healthy hand grasps or otherwise interacts with an object, the impaired hand can be made to likewise grasp or otherwise interact with a similar object with the same amount of force. With this master-slave arrangement, therapy is provided to the impaired hand by performing actions along with the healthy hand.
In the following disclosure, various specific embodiments are described. It is to be understood that those embodiments are example implementations of the disclosed inventions and that alternative embodiments are possible. Such alternative embodiments include hybrid embodiments that include features from different disclosed embodiments. All such embodiments are intended to fall within the scope of this disclosure.
Robotic mirror therapy uses a master-slave scheme in which a robotic system senses motion of a healthy limb and controls an impaired limb in a manner that “mirrors” the motion of the healthy limb. As noted above, various attempts have been made at developing such a system for the hands, but those systems have various shortcomings that limit their usefulness. By considering technology gaps and the high incidence of hand disability and injuries, a novel hand therapy robotic mirror therapy system has been developed. In one embodiment, the system comprises a motion command glove, a motion actuator glove, a control unit, and a graphical user interface. The motion command glove, which is worn on the healthy hand, can comprise embedded position and force sensors configured to acquire joint trajectories and contact forces associated for particular movement, grasping, and manipulation actions. The motion actuator glove, acting under the control of the control unit, provides fine motor control over the impaired hand based on the inputs from the motion command glove. The graphical user interface facilitates the entry of therapy inputs, therapy data visualization, and outcome data logging for therapy evaluation.
As described in greater detail below, the control unit 16 is configured to receive and execute commands from the computing device 18 that control the manner in which the system 10 is operated. More particularly, the control unit 16 receives sensed data regarding movement of a healthy hand and, responsive to commands from software that are used to control manipulation of the user's impaired hand.
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Regardless of the specific nature of the position sensors 50, the sensors can be used to track manipulation of the healthy hand for the purpose of manipulating the impaired hand in the same manner. As noted above, the position sensors 50 are integrated into the MCG 12. In some embodiments, the position sensors 50 can be attached to the inner or outer surface of the glove material, or can be located between opposed layers of the glove material. Although not illustrated in
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The force sensors 52 can comprise any sensors with which the applied forces can be determined. In some embodiments, the force sensors 22 each comprise a capacitive, piezoelectric, piezoresistive, or resonant-based sensor. As with the position sensors 50, the force sensors 52 can be attached to the inner or outer surface of the glove material, or can be located between opposed layers of the glove material. Although not illustrated in
Although the MCG 12 has been described as comprising a conventional glove, it is noted that, in some embodiments, the glove 32 can instead be a partial glove that does not cover all of the surfaces of the hand and wrist. In fact, the glove may not actually be a “glove” in the strictest sense of the term. For example, the “glove” can comprise multiple independent finger sleeves or finger loops that are tethered to a wrist cuff or other component of the term “glove.” Regardless of the particular configuration, Applicant notes that the “glove” is used broadly to describe substantially any article that can be worn on the hand in a manner in which the various sensors described above are placed in positions that enable their above-described functionalities.
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Integrated with the dorsal side of the MAG 14 are multiple finger actuators 78 that are configured to actuate an associated finger of the user's impaired hand. More specifically, the finger actuators 78 can bend the fingers inward toward the palm, as when the hand is used to grasp an object, as well as extend the fingers outward away from the palm, as when the hand releases an object. In addition to finger actuators 78, the MAG 14 can include a wrist actuator 80, which is configured to flex and extend the hand at the wrist.
In some embodiments, the various actuators 78, 80 are “soft” fluidic actuators that extend and retract responsive to the pressure of a fluid present within the actuators. Such actuators may be preferred over other types of actuators as they enable soft robotic manipulation of the impaired hand as opposed to rigid control, as would be provided by an exoskeleton or other rigid mechanism. Examples of fluidic actuators include pneumatic actuators that use air as a driving fluid and hydraulic actuators that use oil as a driving fluid. In some embodiments, the actuators 78, 80 can be configured in similar manner to the actuators disclosed in commonly-assigned U.S. Patent Application No. US 2018/0303698, which is hereby incorporated by reference into the present disclosure.
The actuators 78, 80 can be attached to the inner or outer surface of the glove material, or can be located between opposed layers of the glove material, depending upon the configuration and nature of the actuators. Although not illustrated in
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While the MAG 14 has also been described as comprising a conventional glove, it is noted that, in some embodiments, the glove 60 can also be a partial glove that does not cover all of the surfaces of the hand and wrist. Regardless of the particular configuration, Applicant reiterates that the term “glove” is used broadly to describe substantially any article that can be worn on the hand in a manner in which the various actuators and sensors described above are placed in positions that enable their above-described functionalities.
When the system 10 is used to provide robotic mirror therapy, the healthy hand's movements are used as a reference for manipulation of the MAG 14. This movement is tracked by the position sensors 50 of the MCG 12. In addition, the forces encountered by the healthy hand are tracked by the force sensors 52 of the MCG 12. The data collected by the sensors 50, 52 are transmitted to the control unit 16. This data can then be analyzed to determine how to actuate the MAG 14 so as move the impaired hand in a manner in which it mirrors the movement of the healthy hand. This analysis can be performed by the robotic mirror therapy program 26 (
As discussed above, the robotic mirror therapy program 26 comprises one or more algorithms that can be used to analyze the collected data by the MCG 12 and determine how to manipulate the MAG 14. In some embodiments, a non-adaptive or an adaptive hybrid force-position control algorithm is used to determine the control actions that are needed to manipulate the MAG 14 in a manner in which mirrored movement of the impaired hand is achieved. In cases in which the MAG 14 is fluid-based, this can entail determining actuation pressures and/or fluid flows necessary for correct actuation of the finger and/or wrist actuators 78, 80. The control actions determined by the control algorithm can be provided to the control unit 16, which can then control the actuators 78, 80 as commanded.
In some embodiments, the data collected from both the MCG 12 and the MAG 14, the data generated by the algorithm (e.g., control data), as well as the results of data analysis can be presented to the user and/or a medical professional (e.g., physical therapist) in a graphical user interface shown in a display device of the control unit 16 or the computing device 18. In addition, the data/results can be stored within one or more of the files 30 in the memory 22. The collected and generated data can include finger trajectories, the degree and manner of assistance provided by the MAG 14, as well as force and/or pressure data. The data that is collected/generated during each rehabilitation session can be provided as feedback to the user and/or medical professional and the user's progress can be tracked over time. In addition, retrospective analyses of the therapy's effectiveness can be performed using the stored data.
The pneumatic components drive pressurized air into and out of the actuators 78, 80 to provide the necessary hand movements, such as finger flexion and/or extension and wrist flexion and/or extension. The capability of applying both pressure and vacuum enables bidirectional motion regardless of joint stiffness of the hand. In some embodiments, the air pressure is controlled using proportional valves by varying their orifice size using pulse width modulation (PWM). The pressure and vacuum in the actuators 78, 80 can be monitored using pressure and vacuum sensors, respectively. Data from these sensors provides feedback to the control unit 16, which executes controlled actions by controlling airflow using the proportional and solenoid valves.
The adaptive force-position control scheme is based on hybrid force-position techniques with an integrated adaptive controller to generate the required motion and force for the user's impaired hand by following desired trajectories and contact forces received from the healthy hand for rehabilitation-based grasping tasks and hand gestures.
The joint space position control enables the impaired digits to follow desired (healthy hand) joint trajectories, including angular position (θd) and angular velocity (ωd). These desired joint trajectory inputs are compared against the MCG 12 feedback and then the error is used in a closed-loop proportional-integral-derivative (PID) position control algorithm to determine a control action. Concurrently, the force control loop ensures that a desired contact force measured between the fingers or the fingers and another object is met by considering motion and dynamic coupling between the MAG 14 and the user's hand along with interaction with objects. The contact forces between the robotic digit and the finger (f) is compared against the desired input force (fd), and then the error is input into a proportional force control law in order to determine another control action. The contact force can be calculated in a feedback loop using an inverse dynamic model that receives the angular position feedback from the IMU sensors and the soft actuation torque (τ) from an actuator dynamic model.
In order to calculate the applied torque at each joint, the combination of joint angles (θ) measured by the IMU sensors and the actuation pressure measured by the pressure sensors are used through a theoretical model, such as the model described in aforementioned U.S. Patent Application No. US 2018/0303698. These loops control the angular motion of the finger joints and the force exerted from the robotic digit and human finger onto an object. The final control action (an air pressure, Pa) is then determined by a combination of actuation pressure or vacuum associated with the position (Pθ), force (Pf), and current internal pressure (P) of actuators measured by in-line pressure sensors. In order to ensure safe operation of the actuators interacting with the hand, a set of safety check conditions can be implemented in the control algorithms that avoid the occurrence of unwanted physiological reactions.
Since tuning the control gains for achieving a desired performance according to each user's biomechanical characteristics is not an intuitive task, an adaptive control algorithm can be integrated into the force-position controller, as shown in
As mentioned above, various information can be conveyed to the user and/or a medical professional using a graphical user interface (GUI).
A Force Data Display of the GUI 90 presents the data received by the GUI and can use a color scheme to indicate the closeness of the force applied by the hand with MAG 12 to the force captured from the MCG 14. For example, red can be used to depict when the force is much lower than the required force, yellow can be used to depict when the force has increased but is still lower than the required force, and green can be used to depict when the force required to perform the desired motion equals that required for the manipulation task.
The User Options section of the GUI 90 includes a record button for data recording, a connect button that connects the GUI to the MAG 12 and the MCG 14, and a select button for selecting one of various operation modes, including gesture, single-hand manipulation, and two-hand manipulation. In addition, the User Options section contains a calibrate button that can be used to calibrate the system before the activity begins. In addition, there is a print button for printing desired data and an exit button for terminating the therapy session. A Current Activity Descriptor section of the GUI 90 provides information as to what activity is taking place at the time, whether it is simple flexion/extension, grasping, or manipulation.
This application claims priority to co-pending U.S. Provisional Application Ser. No. 62/833,892, filed Apr. 15, 2019, which is hereby incorporated by reference herein in its entirety.
Number | Date | Country | |
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62833892 | Apr 2019 | US |