Method Article

Engineering Platform and Experimental Protocol for Design and Evaluation of a Neurally-controlled Powered Transfemoral Prosthesis

DOI:

10.3791/51059

July 22nd, 2014

In This Article

Summary

Loading...
$$\rightleftharpoonup{xx}$$ $$\longleftharp{xx}$$, $$\longrightharp{xx}$$,

Neural-machine interfaces (NMI) have been developed to identify the user's locomotion mode. These NMIs are potentially useful for neural control of powered artificial legs, but have not been fully demonstrated. This paper presented (1) our designed engineering platform for easy implementation and development of neural control for powered lower limb prostheses and (2) an experimental setup and protocol in a laboratory environment to evaluate neurally-controlled artificial legs on patients with lower limb amputations safely and efficiently.

Abstract

Loading...
$$\rightleftharpoonup{xx}$$ $$\longleftharp{xx}$$, $$\longrightharp{xx}$$,

To enable intuitive operation of powered artificial legs, an interface between user and prosthesis that can recognize the user's movement intent is desired. A novel neural-machine interface (NMI) based on neuromuscular-mechanical fusion developed in our previous study has demonstrated a great potential to accurately identify the intended movement of transfemoral amputees. However, this interface has not yet been integrated with a powered prosthetic leg for true neural control. This study aimed to report (1) a flexible platform to implement and optimize neural control of powered lower limb prosthesis and (2) an experimental setup and protocol to evaluate neural prosthesis control on patients with lower limb amputations. First a platform based on a PC and a visual programming environment were developed to implement the prosthesis control algorithms, including NMI training algorithm, NMI online testing algorithm, and intrinsic control algorithm. To demonstrate the function of this platform, in this study the NMI based on neuromuscular-mechanical fusion was hierarchically integrated with intrinsic control of a prototypical transfemoral prosthesis. One patient with a unilateral transfemoral amputation was recruited to evaluate our implemented neural controller when performing activities, such as standing, level-ground walking, ramp ascent, and ramp descent continuously in the laboratory. A novel experimental setup and protocol were developed in order to test the new prosthesis control safely and efficiently. The presented proof-of-concept platform and experimental setup and protocol could aid the future development and application of neurally-controlled powered artificial legs.

Introduction

Loading...
$$\rightleftharpoonup{xx}$$ $$\longleftharp{xx}$$, $$\longrightharp{xx}$$,

Powered lower limb prostheses have gained increasing attention in both commercial market1,2 and research community3-5. Compared to traditional passive prosthetic legs, motorized prosthetic joints have the advantage of allowing lower limb amputees to more efficiently perform activities that are difficult or impossible when wearing passive devices. However, currently, smooth and seamless activity transition (e.g., from level-ground walking to stair ascent) is still a challenging issue for powered prosthetic leg users. This difficulty is mainly due to the lack of a user-machine interface that can “read” the user’s movement....

Access restricted. Please log in or start a trial to view this content.

Protocol

Loading...
$$\rightleftharpoonup{xx}$$ $$\longleftharp{xx}$$, $$\longrightharp{xx}$$,

1. Platform for Implementation of Neural Control of Powered Transfemoral Prostheses

An engineering platform was developed in this study to implement and evaluate neural control of powered artificial legs. The hardware included a desktop PC with 2.8 GHz CPU and 4 GB RAM, a multi-functional data acquisition board with both analog-to-digital converters (ADCs) and digital-to-analog converters (DACs), a motor controller, digital I/Os, and a prototypical powered transfemoral prosthesis designed in our group12. The analog sensor inputs were first digitized by the ADCs and streamed into the desktop PC for signal processing. The DAC was use....

Access restricted. Please log in or start a trial to view this content.

Results

Loading...
$$\rightleftharpoonup{xx}$$ $$\longleftharp{xx}$$, $$\longrightharp{xx}$$,

Figure 4a shows seven channels of surface EMG signals measured from the thigh muscles of the subject’s residual limb when he performed hip flexion/extension, as described in Protocol 3.2.6. Figure 4b shows six gait cycles of EMG signals recorded when the subject walked on a level-ground walking path, during Protocol 3.3.4. From this figure, it can be seen that the new designed EMG electrode-socket interface can provide good quality of surface EMG signal measurements.

Access restricted. Please log in or start a trial to view this content.

Discussion

Loading...
$$\rightleftharpoonup{xx}$$ $$\longleftharp{xx}$$, $$\longrightharp{xx}$$,

An engineering platform was developed in this study to easily implement, optimize, and develop true neural control of powered prostheses. The whole platform was programmed in a virtual instrumentation based development environment and implemented on a desktop PC. The control software was composed of several independent and interchangeable modules, in each of which a specific functionality was executed (i.e. NMI intent recognition, and intrinsic control). The advantage of this modular design is that each function.......

Access restricted. Please log in or start a trial to view this content.

Disclosures

Loading...
$$\rightleftharpoonup{xx}$$ $$\longleftharp{xx}$$, $$\longrightharp{xx}$$,

No conflicts of interest declared.

Acknowledgements

Loading...
$$\rightleftharpoonup{xx}$$ $$\longleftharp{xx}$$, $$\longrightharp{xx}$$,

This work was supported in part by the National Institutes of Health under Grant RHD064968A, in part by the National Science Foundation under Grant 0931820, Grant 1149385, and Grant 1361549, and in part by the National Institute on Disability and Rehabilitation Research under Grant H133G120165. The authors thank Lin Du, Ding Wang and Gerald Hefferman at the University of Rhode Island, and Michael J. Nunnery at the Nunnery Orthotic and Prosthetic Technology, LLC, for their great suggestion and assistance in this study.

....

Access restricted. Please log in or start a trial to view this content.

Materials

List of materials used in this article
NameCompanyCatalog NumberComments
Trigno Wireless EMG SensorsDelsys, Inc.7
Trigno Wireless EMG Base StationDelsys, Inc.1
Multi-functional DAQ card (PCI-6259)National Instruments, Inc.1
Potentiometer (RDC503013A)ALPS Electric CO., LTD1
Encoder (MR series)Maxon Precision Motors, Inc.1
Motor controller (ADS50/10) Maxon Precision Motors, Inc.1
24 V Power Supply (DPP480)TDK-Lambda Americas, Inc.1
6 DOF Load Cell (Mini58)ATI Industrial Automation1
Ceiling Rail SystemRoMedic, Inc.1
NI LabView 2011National Instruments, Inc.1

References

Loading...
$$\rightleftharpoonup{xx}$$ $$\longleftharp{xx}$$, $$\longrightharp{xx}$$,
  1. The POWER KNEE. , http://www.ossur.com/prosthetic-solutions/products/knees-and-legs/bionic-knees/power-knee (2014).
  2. Walk. BiOM Ankle System. , http://www.biom.com (2014).
  3. Martinez-Villalpando, E. C., Herr, H. Agonist-antagonist active knee prosthesis: a preliminary stu....

Access restricted. Please log in or start a trial to view this content.

Reprints and Permissions

Request permission to reuse the text or figures of this JoVE article

Request Permission

Tags

Neural Machine InterfacePowered Prosthetic LegSurface EMG MeasurementProsthesis Alignment CalibrationTraining Data CollectionClassifier TrainingNeural Control TestingActivity Mode TransitionsExperimental Setup ProtocolLower Limb Amputation

Related Articles