- Email: [email protected]
3D ANALYSIS OF UPPER BODY MOVEMENTS IN BILATERAL AMPUTEE GAIT USING INERTIAL SENSORS
Poster Session 1/Gait Analysis. 14:45-15:45, Room 103 & Alley Area,
Poster 32
S509
3D ANALYSIS OF UPPER BODY MOVEMENTS IN BILATERAL AMPUTEE GAIT USING INERTIAL SENSORS J.M.AVisser1,2, A.M. Willon1,2and R.C. Payne1 Structure and Motion Laboratory, The Royal Veterinary College London, 2 Institute of Orthopeadics and Musculoskeletal Science, University College London; email: [email protected] 1
INTRODUCTION Every year about 275 bilateral lower limb amputees are referred for prosthetic rehabilitation in the UK [1]. After rehabilitation many amputees have problems with prosthetic walking and performing daily tasks. Hardly any research has been done to asses these problems.
contacts were determined from the vertical position of the heel marker.
In bilateral amputees, lower limb joints are missing and replaced by passive prosthetic joints, or not replaced at all. This means that the mechanical work of locomotion must be generated elsewhere in the body. Previous research [2] showed that, for many bilateral amputees, less than 50% of the total work done at the centre of mass was generated at the remaining leg and hip joints. It is therefore assumed that the upper body movements make an important contribution to bilateral amputee gait. The purpose of this pilot study is to investigate the usability of a six degree-of-freedom inertial sensor system for upper body movement analysis in healthy and bilateral amputee gait. The inertial sensor motion analysis system will facilitate upper body movement monitoring in and outside the laboratory environment. This can make it a useful instrument in rehabilitation. METHODS Six healthy male subjects (aged between 20 and 36 years) and one male bilateral amputee walking with short non-articulated pylon prosthesis (age 40 years) were studied. A six degree-of-freedom inertial sensor system (Xbus Kit, Xsens Technologies B.V., Enschede, the Netherlands, www.xsens.com ) was used. These inertial sensors are based on accelerometers, gyroscopes, and magnetometers. A six camera 3D motion analysis system (Qualisys AB, Gothenburg, Sweden) was used to collect the reference motion analysis data. For each subject one MTx sensor was attached to the sacrum and one to the sternum. Reflective markers were attached to the subject’s skin to define body segments of the legs and upper body. For the amputee an extra sensor was attached to the left leg for stride parameter detection. The subjects walked at self selected comfortable speed. Motion analysis camera data and inertial sensor data were collected for each trial.
Figure 1: Orientation of Thorax relative to Pelvis. Six strides of bilateral amputee walking at 0.8 m/s. RESULTS AND DISCUSSION The segmental angles obtained from the inertial sensors were similar to those obtained from the camera system. Initial leg contact could be detected from the accelerometer data of the inertial sensor attached to the amputee’s leg. For each subject a cyclical pattern in the upper body movements in gait was observed. The range of motion from thorax relative to pelvis in healthy gait was 10 to 16 degrees for both twist and lateral flexion, and 5 degrees for flexion-extension. The thorax stayed relatively still while the pelvis showed a greater range of movement. In the bilateral amputee a greater range of upper body movements was observed. The flexion-extension and lateral flexion range were both 15 to 20 degrees and twist had a range of 25 to 30 degrees (Figure 1). The graph shows a similar pattern as was observed in the healthy subjects. However an asymmetry between the first and second half of the stride can be observed in the bilateral amputee segment angles. This asymmetry was probably caused by a length difference between left and right prosthesis. The results of this pilot study show that the upper body movements in bilateral amputee gait are significantly larger than in normal gait. Research in larger numbers of amputees must show if this is consistent for all bilateral amputee gait.
Three dimensional segment angles of the thorax relative to the pelvis were calculated from both the 3D marker position data and the inertial sensor data. The segment angles are represented as twist (rotation round vertical), lateral flexion (sideward bending) and flexion-extension (forward bending).
The inertial sensor system is found to be a useful instrument for upper body motion analysis in healthy and bilateral amputee gait. The use of additional sensors in further research will improve the possibilities of the system.
The angular data were cut into strides, using the initial ground contact of the right leg as zero, and plotted. The
REFERENCES 1. NASDAB, The Amputee Statistical Database for the United Kingdom: 2004/05 report, 2005 2. Wright DA, PhD Thesis Brunel University, Brunel 2005
XXI ISB Congress, Poster Sessions, Wednesday 4 July 2007
Journal of Biomechanics 40(S2)
Poster 32
S509
3D ANALYSIS OF UPPER BODY MOVEMENTS IN BILATERAL AMPUTEE GAIT USING INERTIAL SENSORS J.M.AVisser1,2, A.M. Willon1,2and R.C. Payne1 Structure and Motion Laboratory, The Royal Veterinary College London, 2 Institute of Orthopeadics and Musculoskeletal Science, University College London; email: [email protected] 1
INTRODUCTION Every year about 275 bilateral lower limb amputees are referred for prosthetic rehabilitation in the UK [1]. After rehabilitation many amputees have problems with prosthetic walking and performing daily tasks. Hardly any research has been done to asses these problems.
contacts were determined from the vertical position of the heel marker.
In bilateral amputees, lower limb joints are missing and replaced by passive prosthetic joints, or not replaced at all. This means that the mechanical work of locomotion must be generated elsewhere in the body. Previous research [2] showed that, for many bilateral amputees, less than 50% of the total work done at the centre of mass was generated at the remaining leg and hip joints. It is therefore assumed that the upper body movements make an important contribution to bilateral amputee gait. The purpose of this pilot study is to investigate the usability of a six degree-of-freedom inertial sensor system for upper body movement analysis in healthy and bilateral amputee gait. The inertial sensor motion analysis system will facilitate upper body movement monitoring in and outside the laboratory environment. This can make it a useful instrument in rehabilitation. METHODS Six healthy male subjects (aged between 20 and 36 years) and one male bilateral amputee walking with short non-articulated pylon prosthesis (age 40 years) were studied. A six degree-of-freedom inertial sensor system (Xbus Kit, Xsens Technologies B.V., Enschede, the Netherlands, www.xsens.com ) was used. These inertial sensors are based on accelerometers, gyroscopes, and magnetometers. A six camera 3D motion analysis system (Qualisys AB, Gothenburg, Sweden) was used to collect the reference motion analysis data. For each subject one MTx sensor was attached to the sacrum and one to the sternum. Reflective markers were attached to the subject’s skin to define body segments of the legs and upper body. For the amputee an extra sensor was attached to the left leg for stride parameter detection. The subjects walked at self selected comfortable speed. Motion analysis camera data and inertial sensor data were collected for each trial.
Figure 1: Orientation of Thorax relative to Pelvis. Six strides of bilateral amputee walking at 0.8 m/s. RESULTS AND DISCUSSION The segmental angles obtained from the inertial sensors were similar to those obtained from the camera system. Initial leg contact could be detected from the accelerometer data of the inertial sensor attached to the amputee’s leg. For each subject a cyclical pattern in the upper body movements in gait was observed. The range of motion from thorax relative to pelvis in healthy gait was 10 to 16 degrees for both twist and lateral flexion, and 5 degrees for flexion-extension. The thorax stayed relatively still while the pelvis showed a greater range of movement. In the bilateral amputee a greater range of upper body movements was observed. The flexion-extension and lateral flexion range were both 15 to 20 degrees and twist had a range of 25 to 30 degrees (Figure 1). The graph shows a similar pattern as was observed in the healthy subjects. However an asymmetry between the first and second half of the stride can be observed in the bilateral amputee segment angles. This asymmetry was probably caused by a length difference between left and right prosthesis. The results of this pilot study show that the upper body movements in bilateral amputee gait are significantly larger than in normal gait. Research in larger numbers of amputees must show if this is consistent for all bilateral amputee gait.
Three dimensional segment angles of the thorax relative to the pelvis were calculated from both the 3D marker position data and the inertial sensor data. The segment angles are represented as twist (rotation round vertical), lateral flexion (sideward bending) and flexion-extension (forward bending).
The inertial sensor system is found to be a useful instrument for upper body motion analysis in healthy and bilateral amputee gait. The use of additional sensors in further research will improve the possibilities of the system.
The angular data were cut into strides, using the initial ground contact of the right leg as zero, and plotted. The
REFERENCES 1. NASDAB, The Amputee Statistical Database for the United Kingdom: 2004/05 report, 2005 2. Wright DA, PhD Thesis Brunel University, Brunel 2005
XXI ISB Congress, Poster Sessions, Wednesday 4 July 2007
Journal of Biomechanics 40(S2)