Powered orthotic device

• US 20040106881A1
• Filed: 11/21/2003
• Published: 06/03/2004
• Est. Priority Date: 11/21/2002
• Status: Active Grant

• Current Assignee: Massachusetts Institute of Technology
• Original Assignee: Massachusetts Institute of Technology
• Inventors: Narendran, Kailas N., McBean, John M.
• Granted Patent: US 7,396,337 B2
• Time in Patent Office: Days
• US Class Current: 601/5
• CPC Class Codes: A61B 5/389 Electromyography [EMG]
• CPC Class Codes: A61B 5/4528 Joints A61B5/4533, A61B5/4538 take precedence
• CPC Class Codes: A61F 2/72 Bioelectric control, e.g. myoelectric
• CPC Class Codes: A61H 1/0277 Elbow
• CPC Class Codes: A61H 2205/06 Arms

Abstract

A powered orthotic device, worn about a patient'"'"'s elbow or other joint, senses relatively low level signals in the vicinity of the joint generated by a patient having spinal cord or other nerve damage. In response to the relatively low level signals, the powered orthotic device moves, causing the patient'"'"'s joint to move accordingly.

Claims

1. A powered orthotic device for augmenting a person'"'"'s muscular functionality comprising:

a brace adapted to be coupled to a body pair of the person and having a length such that the brace traverses a joint of the person, said brace including at least one strap for attaching the brace to the body part of the person;

sensing means, fixed in at least one of the at least one straps such that when said strap is coupled to the body part said sensing means is coupled to at least one muscle of the person and wherein in response to the person attempting to move the body part said sensing means senses a surface electromyographic (EMG) signal of the muscles connected to the joint and determines a desired joint torque from the EMG signal and provides a sensor signal in response thereto; and

an actuator coupled to receive the sensor signal from said sensing means and in response to the sensor signal said external actuator provides a force having a magnitude which is proportional to a magnitude of the sensor signal provided by said sensing means and wherein the ratio of power delivered by said actuator to the mass of the actuator takes into account all of the elements needed to generate the force.

2. The device of claim 1 further comprising:

means for receiving the sensor signal and for scaling the sensor signal by a variable amount; and

an active feedback control loop circuit coupled to control the amount of force applied to the joint by said external actuator.

3. The device of claim 2 wherein said active feedback control loop circuit further comprises means for providing a measurement of output torque to ensure an accurate application of force.

4. The device of claim 3 further comprising:

a cable drive coupled between said actuator and said brace such that in response to movement of the actuator, said cable drive moves the brace.

5. The device of claim 4 further comprising a wheelchair wherein:

at least a portion of said cable drive system is coupled to said wheel chair; and

said actuator is disposed such that the mass of said actuator is substantially supported by said wheelchair.

6. The device of claim 1 wherein said actuator corresponds to an electric actuator.

7. The device of claim 1 wherein said actuator corresponds to a hydraulic actuator which comprises a compressor and wherein the ratio of power delivered by said actuator to the mass upon which the actuator acts is selected to be above a predetermined threshold level.

8. The device of claim 1 wherein said actuator corresponds to a pneumatic actuator which comprises a compressor and wherein the ratio of power delivered by said actuator to the mass upon which the actuator acts is selected to be above a predetermined threshold level.

9. A powered orthotic device for augmenting a person'"'"'s muscular functionality comprising:

a brace adapted to be coupled to a body part of the person and having a length such that the brace traverses a joint of the person;

sensing means coupled to at least one muscle of the person wherein in response to the person attempting to move the body part, said sensing means noninvasively senses a desired muscular force of the person and provides a sensor signal in response thereto;

an external actuator coupled to receive the sensor signal from said sensing means and in response to the sensor signal said external actuator provides a force having a magnitude which is proportional to a magnitude of the sensor signal provided by said sensing means wherein the ratio of power delivered by said actuator to the mass of the actuator takes into account all of the elements needed to generate the force;

a control means coupled to said external actuator, said control means including means for making a low impedance measurement of output torque and for providing a feedback signal to said external actuator to ensure an accurate application of the force provided by said external actuator.