Baojun Chen - Academia.edu (original) (raw)
Papers by Baojun Chen
World Journal of Gastroenterology Wjg, Aug 1, 2002
AIM:To study the feasibility of panning and screening phage-displaying recombinant single-chain v... more AIM:To study the feasibility of panning and screening phage-displaying recombinant single-chain variable fragment (ScFv) of anti-tumor monoclonal antibodies for fixed whole cells as the carriers of mAb-binding antigens.
Zhonghua zhong liu za zhi [Chinese journal of oncology], 2002
To analyze the distribution and significance of occludin mRNA expression in human gastric cancer,... more To analyze the distribution and significance of occludin mRNA expression in human gastric cancer, as well as its relationship with gastric cancer pathology and multidrug resistance (MDR) in vivo. In situ hybridization (ISH) technique was used to evaluate the expression of occludin mRNA in 42 gastric carcinoma specimens obtained by surgery and 23 relatively normal gastric mucosa obtained by gastric endoscopy. All specimens had been stored in cryostatic section. Occludin mRNA was found positive in the cytoplasm of gastric glandulous epithelia as blue particles with intensive stain in 14 of 42 gastric carcinomas (33.3%), 23 of 42 paracancerous gastric tissues (54.8%), 14 of 23 relatively normal gastric tissues (60.9%), 9 of 16 well differentiated carcinomas (56.3%), 4 of 14 moderately differentiated carcinomas (28.6%), 1 of 10 poorly differentiated carcinomas (10.0%) and none of 2 mucosal carcinomas. There were significant differences in occludin mRNA positive rate between relatively n...
Ultrasound in Medicine & Biology, 2009
The cytological results of FNAB were as followed; benign (856, 54.94%), malignant (262, 16.82%), ... more The cytological results of FNAB were as followed; benign (856, 54.94%), malignant (262, 16.82%), indeterminate (238, 15.28%), and inadequate samples (202, 12.96%). In the univariate analysis, it showed statistically significant (pϭ0.02, pϭ0.05 and pϽ0.0001, respectively) for the following facts: 1) echogenicity, 2) calcification, 3) final op pathology. In sub categorized calcifications, macro-puls eggshell calcification group and eggshell calcification were more significant than others (pϭ0.02 and pϭ0.01). Among them malignant lesion on final op. pathology was the strong contributor. However, the following factors did not make significant effects (pϭ0. 06, pϭ0.70, pϭ0.65, pϭ0.74, pϭ0.97, pϭ0.18, pϭ0.41, pϭ0.65, pϭ0.12 and pϭ0.07 respectively): size, performing doctor, faculty vs. trainee group, aspiration technique, composition, margin, shape, parenchymal echogenicity, vascularity and final assessment. Conclusion: Marked hypoechogenic nodule and malignant nodule tend to make more adequate FNAB samples, compared with others. On the other hand, inadequate sampling is more common in the nodule with eggshell or macro-calcification.
Trials, 2013
Background: It is becoming increasingly necessary for community health centers to make rehabilita... more Background: It is becoming increasingly necessary for community health centers to make rehabilitation services available to patients with osteoarthritis of the knee. However, for a number of reasons, including a lack of expertise, the small size of community health centers and the availability of only simple medical equipment, conventional rehabilitation therapy has not been widely used in China. Consequently, most patients with knee osteoarthritis seek treatment in high-grade hospitals. However, many patients cannot manage the techniques that they were taught in the hospital. Methods such as acupuncture, tuina, Chinese medical herb fumigation-washing and t'ai chi are easy to do and have been reported to have curative effects in those with knee osteoarthritis. To date, there have been no randomized controlled trials validating comprehensive traditional Chinese medicine for the rehabilitation of knee osteoarthritis in a community health center. Furthermore, there is no standard rehabilitation protocol using traditional Chinese medicine for knee osteoarthritis. The aim of the current study is to develop a comprehensive rehabilitation protocol using traditional Chinese medicine for the management of knee osteoarthritis in a community health center.
Journal of Immunotherapy, 2003
Tumor-specific cytotoxic T lymphocytes (CTLs) from patients with early-stage tumors are usually m... more Tumor-specific cytotoxic T lymphocytes (CTLs) from patients with early-stage tumors are usually more efficient at attacking tumor cells than CTLs from the progressing tumor stages. The authors investigated the antitumor activity of CTLs from gastric cancer patents and healthy donors. In this study, peripheral blood lymphocytes (PBLs) from gastric cancer patients and healthy donors were stimulated with HLA-A matched allogeneic gastric cancer cells such as KATO-3, MKN45, and SGC7901. Three different populations of lymphocyte, p5-CTL-KATO, h4-CTL-MKN45, and h4-CTL-KATO, were induced and expanded. Flow cytometry analyses showed that 85.2% to 97.8% of these cells were CD3-positive and 45.5% to 51.2% were CD8-positive. The induced CTLs efficiently kill HLA-A2 or HLA-A24 gastric cancer cells through CTL-mediated cytotoxicity. However, no effects were observed for other cancer cells or HLA-A2 negative gastric cancer cells. The specific cytotoxicity of the induced CTLs was further confirmed by cold-target inhibition and monoclonal antibody blockage. These results suggest that CTL-mediated cytotoxicity specific for tumor cells can be produced by stimulating PBLs from healthy donors using HLA-A matched tumor cells, which will lead to the development of new immunotherapeutic strategies to kill cancer cells.
Biochemistry and Cell Biology, 2006
MG7-Ag is a human gastric-carcinoma-associated antigen with a high specificity. So far it is rema... more MG7-Ag is a human gastric-carcinoma-associated antigen with a high specificity. So far it is remained unclear whether MG7-Ag is correlated with the in vivo cellular immune response of patients with gastric cancer. In this study, we detected the expression of the T cell receptor (TCR) repertoire of T cell subpopulations and cytokines in tumor-infiltrating lymphocytes (TIL), peripheral blood lymphocytes (PBL), and residue benign mucosal lymphocytes (NML) of patients with gastric cancer using semiquantitative RT-PCR. Our data showed that the expanded clones in CD8(+) NML and TIL and CD4+ NML and PBL in MG7-Ag-positive patients were significantly fewer than those of MG7-Ag-negative patients (p = 0.0360; p = 0.0026; p = 0.0065 p = 0.0109, respectively). The levels of IL-8 in CD8(+) TIL and TNF in CD4(+) TIL from the MG7-Ag-positive group were significantly higher than those from the MG7-Ag-negative group (p = 0.0302; p = 0.0177, respectively). Taken together, the results demonstrated a weaker T cell immune response and more proinflammatory cytokine secretion in MG7-Ag-positive patients with gastric cancer than in MG7-Ag-negative ones. This likely contributes to the poor prognosis in MG7-Ag-positive gastric-cancer patients.
Informatics in Control Automation and Robotics: Revised and Selected Papers from the International Conference on Informatics in Control Automation and Robotics 2009, Mar 16, 2011
Author Index Alici, Gursel 63 Azinheira, José R. 269 Birattari, Mauro 217 Bonforte, A. 317 Bouraq... more Author Index Alici, Gursel 63 Azinheira, José R. 269 Birattari, Mauro 217 Bonforte, A. 317 Bouraqadi, Noury 201 Braiek, Naceur Benhadj 113 Brutschy, Arne 217 Bujorianu, Manuela L. 337 Bujorianu, Marius C. 337 Burriss, Elise T. 63 Chai, Yi 49 Chen, Baojun 187 Chesi, Graziano 159 Chiu, David KY 49 Dahmen, Christian 243 Defoort, Michael 201 Dertimanis, Vasilis K. 301 de Paul Garcıa-Alvizu, Vicente 143 Doniec, Arnaud 201 Dorigo, Marco 217 Dragos, Claudia-Adina 99 Dymond, Patrick 229 Fanti, Maria Pia 3 Garcıa-Valdovinos, Luis G. 143 ...
IEEE/ASME Transactions on Mechatronics, 2014
Allowing amputees to volitionally control robotic prostheses can improve the adaptability to terr... more Allowing amputees to volitionally control robotic prostheses can improve the adaptability to terrain changes. In this paper, we propose a myoelectric controller for a robotic transtibial prosthesis to realize adaptive slope walking. It works together with the intrinsic controller, enabling amputee users to pay relatively less attention on myoelectric control during walking. Amputee users convey the information of ground slope to prostheses by consciously performing dorsiflexion and plantar flexion of the "phantom ankle" with different intensities at the beginning of the swing phase. Two channels of surface electromyographic signals are measured from the residual shank, and they are mapped to the inclination angle of the slope. Control parameters of the intrinsic controller are then calculated according to the estimated inclination angle. In this preliminary study, two transtibial amputee subjects were recruited. They were asked to convey six targeted inclination angles ( ± 5 • , ±10 • , and ±15 • ) to the prosthesis with the trained myoelectric controller during level-ground walking, and satisfactory control performance was achieved. This experiment was designed to simulate the scenario of transiting from level-ground walking to slope walking. Experimental results of controlling the robotic prosthesis to walk on level ground and slopes further verified that it is promising for amputees to adaptively walk on the ground with varied inclination angles in daily life.
Emerging Trends in Mobile Robotics - Proceedings of the 13th International Conference on Climbing and Walking Robots and the Support Technologies for Mobile Machines, 2010
Advances in Intelligent Systems and Computing, 2014
2010 IEEE/RSJ International Conference on Intelligent Robots and Systems, 2010
This paper presents a seven-link dynamic walking model that is more close to human beings. We add... more This paper presents a seven-link dynamic walking model that is more close to human beings. We add hip actuation, upper body, flat feet and compliant ankle joints to the model. Walking sequence of the flat-foot walker has several sub-streams that form bipedal walking with dynamic series of phases, which is different with the motion of roundfoot and point-foot models. We investigate the characteristics of three different walking gaits with different step lengths. Comparison of these walking gaits in walking velocity, efficiency and stability reveals the relation between step length and walking performance. Experimental results indicate that the gait which is more close to human normal walking achieves higher stability and energetic efficiency.
2010 IEEE/ASME International Conference on Advanced Intelligent Mechatronics, 2010
This paper presents a passive dynamic walking model with segmented feet. The model extends the Si... more This paper presents a passive dynamic walking model with segmented feet. The model extends the Simplest Walking Model with the addition of flat feet and torsional springs based compliance on ankle joints and toe joints, to achieve stable walking on a slope driven by gravity. The pushoff phase includes foot rotations around toe joint and around toe tip, which shows a great resemblance to human normal walking. The segmented foot model is compared with single rigid foot model in simulations to study the advantages of adding toe joints to passive dynamic walkers. We investigate the effects of segmented foot structure on dynamic bipedal walking. Experimental results show that the model achieves efficient and stable walking on even or uneven slope.
Conference proceedings : ... Annual International Conference of the IEEE Engineering in Medicine and Biology Society. IEEE Engineering in Medicine and Biology Society. Annual Conference, 2014
Improving the intuitiveness of the interaction between human and machine is an important issue fo... more Improving the intuitiveness of the interaction between human and machine is an important issue for powered lower-limb prosthesis control. In this research, we aimed to evaluate the potential of using surface electromyography (EMG) signals measured from transtibial amputees' residual muscles to directly control the position of prosthetic ankle. In this research, one transtibial amputee subject and five able-bodied subjects were recruited. They were asked to control a virtual ankle to reach different target positions. The amputee subject finished these tasks in an average time of 1.29 seconds for different target positions with the residual limb, which was comparable with that using the amputee's sound limb and those with able-bodied subjects' dominant legs. Due to human's strong adaptability, the amputee subject was able to adapt to the control model trained one day before or trained in a posture which was different from that during performing control tasks. These res...
IEEE ... International Conference on Rehabilitation Robotics : [proceedings], 2011
This paper investigates the effects of ankle joint stiffness on gait selection of dynamic bipedal... more This paper investigates the effects of ankle joint stiffness on gait selection of dynamic bipedal walking with flat feet. We present a dynamic bipedal walking model with upper body, flat feet and compliant joints. The model can generate the three common gaits of dynamic bipedal walking. Simulation experiments are carried out to verify the analytical results and provide further results on gait comparison and selection.
Lecture Notes in Electrical Engineering, 2011
In this paper, we present an approach for passivity-based bipedal robots to achieve stable dynami... more In this paper, we present an approach for passivity-based bipedal robots to achieve stable dynamic walking on uneven terrain. A powered two-dimensional seven-link walking model with flat feet and compliant ankles has been proposed to analyze and simulate the walking dynamics. We further describe a Particle Swarm Optimization based method, which uses optimized hip actuation and ankle compliance as control parameters of bipedal walking. Satisfactory results of simulations and real robot experiments show that the passivity-based walker can achieve stable bipedal walking with larger ground disturbance by the proposed method in view of stability and efficiency.
Neurocomputing, 2015
Phase-dependent recognition strategy is an effective approach for lower-limb locomotion mode reco... more Phase-dependent recognition strategy is an effective approach for lower-limb locomotion mode recognition. However, in previous studies, classifiers, feature sets and other parameters for the classification are the same for all the phases. The potential of this method could therefore be limited, as movement characteristics of different phases are not the same. In this paper, we aim to further improve phase-dependent recognition by proposing a new parameter optimization strategy which optimizes classifier, feature set and window size individually for each phase. Seven able-bodied subjects and one transtibial amputee subject are recruited in this research and they are required to perform six kinds of locomotion tasks. Signals recorded from two inertial measurement units and one pressure insole of the measured side are used for feature set calculation. And phase-dependent recognition method with four phases defined is applied for locomotion mode identification. The proposed strategy for parameter optimization is proved to be more efficient than the conventional optimization strategy by providing better overall recognition performance and lower computation burden.
2012 4th IEEE RAS & EMBS International Conference on Biomedical Robotics and Biomechatronics (BioRob), 2012
Locomotion mode recognition is one of the most important aspects for the control of motion rehabi... more Locomotion mode recognition is one of the most important aspects for the control of motion rehabilitation systems, e.g. lower-limb prostheses and exoskeletons. In this paper, we propose a capacitance based sensing system for recognizing human locomotion modes. The proposed system includes two rings as sensing front-ends of body capacitance, two sensing circuits for processing the signals and the gait event detection system. The deformation of muscles can be reflected by the changes of capacitance signals. To validate the developed prototype, nine locomotion modes are monitored and ten channels of capacitance signals are collected for locomotion mode recognition. With the combination of capacitive sensing approach and phase-dependent classification method, satisfactory recognition results are obtained.
Sensors, 2013
In this paper, we present an approach to sense human body capacitance and apply it to recognize l... more In this paper, we present an approach to sense human body capacitance and apply it to recognize lower limb locomotion modes. The proposed wearable sensing system includes sensing bands, a signal processing circuit and a gait event detection module. Experiments on long-term working stability, adaptability to disturbance and locomotion mode recognition are carried out to validate the effectiveness of the proposed approach. Twelve able-bodied subjects are recruited, and eleven normal gait modes are investigated. With an event-dependent linear discriminant analysis classifier and feature selection procedure, four time-domain features are used for pattern recognition and satisfactory recognition accuracies (97.3% ± 0.5%, 97.0% ± 0.4%, 95.6% ± 0.9% and 97.0% ± 0.4% for four phases of one gait cycle respectively) are obtained. The accuracies are comparable with that from electromyography-based systems and inertial-based systems. The results validate the effectiveness of the proposed lower limb capacitive sensing approach in recognizing human normal gaits.
Sensors, 2014
Locomotion intent prediction is essential for the control of powered lower-limb prostheses to rea... more Locomotion intent prediction is essential for the control of powered lower-limb prostheses to realize smooth locomotion transitions. In this research, we develop a multi-sensor fusion based locomotion intent prediction system, which can recognize current locomotion mode and detect locomotion transitions in advance. Seven able-bodied subjects were recruited for this research. Signals from two foot pressure insoles and three inertial measurement units (one on the thigh, one on the shank and the other on the foot) are measured. A two-level recognition strategy is used for the recognition with linear discriminate classifier. Six kinds of locomotion modes and ten kinds of locomotion transitions are tested in this study. Recognition accuracy during steady locomotion periods (i.e., no locomotion transitions) is 99.71% ± 0.05% for seven able-bodied subjects. During locomotion transition periods, all the transitions are correctly detected and most of them can be detected before transiting to new locomotion modes. No significant deterioration in recognition performance is observed in the following five hours after the system is trained, and small number of experiment trials are required to train reliable classifiers.
Robotica, 2012
2012). Modeling and gait selection of passivitybased seven-link bipeds with dynamic series of wal... more 2012). Modeling and gait selection of passivitybased seven-link bipeds with dynamic series of walking phases. Robotica, 30, pp 39-51 SUMMARY This paper presents a seven-link dynamic walking model that is more close to human beings than other passivitybased dynamic walking models. We add hip actuation, upper body, flat feet, and ankle joints with torsional springs to the model. Walking sequence of flat-feet walkers has several substreams, which forms bipedal walking with dynamic series of phases. We investigate the effects of ankle stiffness on gait selection and evaluate different gaits in walking velocity, efficiency, and stability. Experimental results indicate that ankle stiffness plays different roles in different gaits and the gaits, which are more close to human walking with moderate speed, achieve better motion characteristics.
World Journal of Gastroenterology Wjg, Aug 1, 2002
AIM:To study the feasibility of panning and screening phage-displaying recombinant single-chain v... more AIM:To study the feasibility of panning and screening phage-displaying recombinant single-chain variable fragment (ScFv) of anti-tumor monoclonal antibodies for fixed whole cells as the carriers of mAb-binding antigens.
Zhonghua zhong liu za zhi [Chinese journal of oncology], 2002
To analyze the distribution and significance of occludin mRNA expression in human gastric cancer,... more To analyze the distribution and significance of occludin mRNA expression in human gastric cancer, as well as its relationship with gastric cancer pathology and multidrug resistance (MDR) in vivo. In situ hybridization (ISH) technique was used to evaluate the expression of occludin mRNA in 42 gastric carcinoma specimens obtained by surgery and 23 relatively normal gastric mucosa obtained by gastric endoscopy. All specimens had been stored in cryostatic section. Occludin mRNA was found positive in the cytoplasm of gastric glandulous epithelia as blue particles with intensive stain in 14 of 42 gastric carcinomas (33.3%), 23 of 42 paracancerous gastric tissues (54.8%), 14 of 23 relatively normal gastric tissues (60.9%), 9 of 16 well differentiated carcinomas (56.3%), 4 of 14 moderately differentiated carcinomas (28.6%), 1 of 10 poorly differentiated carcinomas (10.0%) and none of 2 mucosal carcinomas. There were significant differences in occludin mRNA positive rate between relatively n...
Ultrasound in Medicine & Biology, 2009
The cytological results of FNAB were as followed; benign (856, 54.94%), malignant (262, 16.82%), ... more The cytological results of FNAB were as followed; benign (856, 54.94%), malignant (262, 16.82%), indeterminate (238, 15.28%), and inadequate samples (202, 12.96%). In the univariate analysis, it showed statistically significant (pϭ0.02, pϭ0.05 and pϽ0.0001, respectively) for the following facts: 1) echogenicity, 2) calcification, 3) final op pathology. In sub categorized calcifications, macro-puls eggshell calcification group and eggshell calcification were more significant than others (pϭ0.02 and pϭ0.01). Among them malignant lesion on final op. pathology was the strong contributor. However, the following factors did not make significant effects (pϭ0. 06, pϭ0.70, pϭ0.65, pϭ0.74, pϭ0.97, pϭ0.18, pϭ0.41, pϭ0.65, pϭ0.12 and pϭ0.07 respectively): size, performing doctor, faculty vs. trainee group, aspiration technique, composition, margin, shape, parenchymal echogenicity, vascularity and final assessment. Conclusion: Marked hypoechogenic nodule and malignant nodule tend to make more adequate FNAB samples, compared with others. On the other hand, inadequate sampling is more common in the nodule with eggshell or macro-calcification.
Trials, 2013
Background: It is becoming increasingly necessary for community health centers to make rehabilita... more Background: It is becoming increasingly necessary for community health centers to make rehabilitation services available to patients with osteoarthritis of the knee. However, for a number of reasons, including a lack of expertise, the small size of community health centers and the availability of only simple medical equipment, conventional rehabilitation therapy has not been widely used in China. Consequently, most patients with knee osteoarthritis seek treatment in high-grade hospitals. However, many patients cannot manage the techniques that they were taught in the hospital. Methods such as acupuncture, tuina, Chinese medical herb fumigation-washing and t'ai chi are easy to do and have been reported to have curative effects in those with knee osteoarthritis. To date, there have been no randomized controlled trials validating comprehensive traditional Chinese medicine for the rehabilitation of knee osteoarthritis in a community health center. Furthermore, there is no standard rehabilitation protocol using traditional Chinese medicine for knee osteoarthritis. The aim of the current study is to develop a comprehensive rehabilitation protocol using traditional Chinese medicine for the management of knee osteoarthritis in a community health center.
Journal of Immunotherapy, 2003
Tumor-specific cytotoxic T lymphocytes (CTLs) from patients with early-stage tumors are usually m... more Tumor-specific cytotoxic T lymphocytes (CTLs) from patients with early-stage tumors are usually more efficient at attacking tumor cells than CTLs from the progressing tumor stages. The authors investigated the antitumor activity of CTLs from gastric cancer patents and healthy donors. In this study, peripheral blood lymphocytes (PBLs) from gastric cancer patients and healthy donors were stimulated with HLA-A matched allogeneic gastric cancer cells such as KATO-3, MKN45, and SGC7901. Three different populations of lymphocyte, p5-CTL-KATO, h4-CTL-MKN45, and h4-CTL-KATO, were induced and expanded. Flow cytometry analyses showed that 85.2% to 97.8% of these cells were CD3-positive and 45.5% to 51.2% were CD8-positive. The induced CTLs efficiently kill HLA-A2 or HLA-A24 gastric cancer cells through CTL-mediated cytotoxicity. However, no effects were observed for other cancer cells or HLA-A2 negative gastric cancer cells. The specific cytotoxicity of the induced CTLs was further confirmed by cold-target inhibition and monoclonal antibody blockage. These results suggest that CTL-mediated cytotoxicity specific for tumor cells can be produced by stimulating PBLs from healthy donors using HLA-A matched tumor cells, which will lead to the development of new immunotherapeutic strategies to kill cancer cells.
Biochemistry and Cell Biology, 2006
MG7-Ag is a human gastric-carcinoma-associated antigen with a high specificity. So far it is rema... more MG7-Ag is a human gastric-carcinoma-associated antigen with a high specificity. So far it is remained unclear whether MG7-Ag is correlated with the in vivo cellular immune response of patients with gastric cancer. In this study, we detected the expression of the T cell receptor (TCR) repertoire of T cell subpopulations and cytokines in tumor-infiltrating lymphocytes (TIL), peripheral blood lymphocytes (PBL), and residue benign mucosal lymphocytes (NML) of patients with gastric cancer using semiquantitative RT-PCR. Our data showed that the expanded clones in CD8(+) NML and TIL and CD4+ NML and PBL in MG7-Ag-positive patients were significantly fewer than those of MG7-Ag-negative patients (p = 0.0360; p = 0.0026; p = 0.0065 p = 0.0109, respectively). The levels of IL-8 in CD8(+) TIL and TNF in CD4(+) TIL from the MG7-Ag-positive group were significantly higher than those from the MG7-Ag-negative group (p = 0.0302; p = 0.0177, respectively). Taken together, the results demonstrated a weaker T cell immune response and more proinflammatory cytokine secretion in MG7-Ag-positive patients with gastric cancer than in MG7-Ag-negative ones. This likely contributes to the poor prognosis in MG7-Ag-positive gastric-cancer patients.
Informatics in Control Automation and Robotics: Revised and Selected Papers from the International Conference on Informatics in Control Automation and Robotics 2009, Mar 16, 2011
Author Index Alici, Gursel 63 Azinheira, José R. 269 Birattari, Mauro 217 Bonforte, A. 317 Bouraq... more Author Index Alici, Gursel 63 Azinheira, José R. 269 Birattari, Mauro 217 Bonforte, A. 317 Bouraqadi, Noury 201 Braiek, Naceur Benhadj 113 Brutschy, Arne 217 Bujorianu, Manuela L. 337 Bujorianu, Marius C. 337 Burriss, Elise T. 63 Chai, Yi 49 Chen, Baojun 187 Chesi, Graziano 159 Chiu, David KY 49 Dahmen, Christian 243 Defoort, Michael 201 Dertimanis, Vasilis K. 301 de Paul Garcıa-Alvizu, Vicente 143 Doniec, Arnaud 201 Dorigo, Marco 217 Dragos, Claudia-Adina 99 Dymond, Patrick 229 Fanti, Maria Pia 3 Garcıa-Valdovinos, Luis G. 143 ...
IEEE/ASME Transactions on Mechatronics, 2014
Allowing amputees to volitionally control robotic prostheses can improve the adaptability to terr... more Allowing amputees to volitionally control robotic prostheses can improve the adaptability to terrain changes. In this paper, we propose a myoelectric controller for a robotic transtibial prosthesis to realize adaptive slope walking. It works together with the intrinsic controller, enabling amputee users to pay relatively less attention on myoelectric control during walking. Amputee users convey the information of ground slope to prostheses by consciously performing dorsiflexion and plantar flexion of the "phantom ankle" with different intensities at the beginning of the swing phase. Two channels of surface electromyographic signals are measured from the residual shank, and they are mapped to the inclination angle of the slope. Control parameters of the intrinsic controller are then calculated according to the estimated inclination angle. In this preliminary study, two transtibial amputee subjects were recruited. They were asked to convey six targeted inclination angles ( ± 5 • , ±10 • , and ±15 • ) to the prosthesis with the trained myoelectric controller during level-ground walking, and satisfactory control performance was achieved. This experiment was designed to simulate the scenario of transiting from level-ground walking to slope walking. Experimental results of controlling the robotic prosthesis to walk on level ground and slopes further verified that it is promising for amputees to adaptively walk on the ground with varied inclination angles in daily life.
Emerging Trends in Mobile Robotics - Proceedings of the 13th International Conference on Climbing and Walking Robots and the Support Technologies for Mobile Machines, 2010
Advances in Intelligent Systems and Computing, 2014
2010 IEEE/RSJ International Conference on Intelligent Robots and Systems, 2010
This paper presents a seven-link dynamic walking model that is more close to human beings. We add... more This paper presents a seven-link dynamic walking model that is more close to human beings. We add hip actuation, upper body, flat feet and compliant ankle joints to the model. Walking sequence of the flat-foot walker has several sub-streams that form bipedal walking with dynamic series of phases, which is different with the motion of roundfoot and point-foot models. We investigate the characteristics of three different walking gaits with different step lengths. Comparison of these walking gaits in walking velocity, efficiency and stability reveals the relation between step length and walking performance. Experimental results indicate that the gait which is more close to human normal walking achieves higher stability and energetic efficiency.
2010 IEEE/ASME International Conference on Advanced Intelligent Mechatronics, 2010
This paper presents a passive dynamic walking model with segmented feet. The model extends the Si... more This paper presents a passive dynamic walking model with segmented feet. The model extends the Simplest Walking Model with the addition of flat feet and torsional springs based compliance on ankle joints and toe joints, to achieve stable walking on a slope driven by gravity. The pushoff phase includes foot rotations around toe joint and around toe tip, which shows a great resemblance to human normal walking. The segmented foot model is compared with single rigid foot model in simulations to study the advantages of adding toe joints to passive dynamic walkers. We investigate the effects of segmented foot structure on dynamic bipedal walking. Experimental results show that the model achieves efficient and stable walking on even or uneven slope.
Conference proceedings : ... Annual International Conference of the IEEE Engineering in Medicine and Biology Society. IEEE Engineering in Medicine and Biology Society. Annual Conference, 2014
Improving the intuitiveness of the interaction between human and machine is an important issue fo... more Improving the intuitiveness of the interaction between human and machine is an important issue for powered lower-limb prosthesis control. In this research, we aimed to evaluate the potential of using surface electromyography (EMG) signals measured from transtibial amputees' residual muscles to directly control the position of prosthetic ankle. In this research, one transtibial amputee subject and five able-bodied subjects were recruited. They were asked to control a virtual ankle to reach different target positions. The amputee subject finished these tasks in an average time of 1.29 seconds for different target positions with the residual limb, which was comparable with that using the amputee's sound limb and those with able-bodied subjects' dominant legs. Due to human's strong adaptability, the amputee subject was able to adapt to the control model trained one day before or trained in a posture which was different from that during performing control tasks. These res...
IEEE ... International Conference on Rehabilitation Robotics : [proceedings], 2011
This paper investigates the effects of ankle joint stiffness on gait selection of dynamic bipedal... more This paper investigates the effects of ankle joint stiffness on gait selection of dynamic bipedal walking with flat feet. We present a dynamic bipedal walking model with upper body, flat feet and compliant joints. The model can generate the three common gaits of dynamic bipedal walking. Simulation experiments are carried out to verify the analytical results and provide further results on gait comparison and selection.
Lecture Notes in Electrical Engineering, 2011
In this paper, we present an approach for passivity-based bipedal robots to achieve stable dynami... more In this paper, we present an approach for passivity-based bipedal robots to achieve stable dynamic walking on uneven terrain. A powered two-dimensional seven-link walking model with flat feet and compliant ankles has been proposed to analyze and simulate the walking dynamics. We further describe a Particle Swarm Optimization based method, which uses optimized hip actuation and ankle compliance as control parameters of bipedal walking. Satisfactory results of simulations and real robot experiments show that the passivity-based walker can achieve stable bipedal walking with larger ground disturbance by the proposed method in view of stability and efficiency.
Neurocomputing, 2015
Phase-dependent recognition strategy is an effective approach for lower-limb locomotion mode reco... more Phase-dependent recognition strategy is an effective approach for lower-limb locomotion mode recognition. However, in previous studies, classifiers, feature sets and other parameters for the classification are the same for all the phases. The potential of this method could therefore be limited, as movement characteristics of different phases are not the same. In this paper, we aim to further improve phase-dependent recognition by proposing a new parameter optimization strategy which optimizes classifier, feature set and window size individually for each phase. Seven able-bodied subjects and one transtibial amputee subject are recruited in this research and they are required to perform six kinds of locomotion tasks. Signals recorded from two inertial measurement units and one pressure insole of the measured side are used for feature set calculation. And phase-dependent recognition method with four phases defined is applied for locomotion mode identification. The proposed strategy for parameter optimization is proved to be more efficient than the conventional optimization strategy by providing better overall recognition performance and lower computation burden.
2012 4th IEEE RAS & EMBS International Conference on Biomedical Robotics and Biomechatronics (BioRob), 2012
Locomotion mode recognition is one of the most important aspects for the control of motion rehabi... more Locomotion mode recognition is one of the most important aspects for the control of motion rehabilitation systems, e.g. lower-limb prostheses and exoskeletons. In this paper, we propose a capacitance based sensing system for recognizing human locomotion modes. The proposed system includes two rings as sensing front-ends of body capacitance, two sensing circuits for processing the signals and the gait event detection system. The deformation of muscles can be reflected by the changes of capacitance signals. To validate the developed prototype, nine locomotion modes are monitored and ten channels of capacitance signals are collected for locomotion mode recognition. With the combination of capacitive sensing approach and phase-dependent classification method, satisfactory recognition results are obtained.
Sensors, 2013
In this paper, we present an approach to sense human body capacitance and apply it to recognize l... more In this paper, we present an approach to sense human body capacitance and apply it to recognize lower limb locomotion modes. The proposed wearable sensing system includes sensing bands, a signal processing circuit and a gait event detection module. Experiments on long-term working stability, adaptability to disturbance and locomotion mode recognition are carried out to validate the effectiveness of the proposed approach. Twelve able-bodied subjects are recruited, and eleven normal gait modes are investigated. With an event-dependent linear discriminant analysis classifier and feature selection procedure, four time-domain features are used for pattern recognition and satisfactory recognition accuracies (97.3% ± 0.5%, 97.0% ± 0.4%, 95.6% ± 0.9% and 97.0% ± 0.4% for four phases of one gait cycle respectively) are obtained. The accuracies are comparable with that from electromyography-based systems and inertial-based systems. The results validate the effectiveness of the proposed lower limb capacitive sensing approach in recognizing human normal gaits.
Sensors, 2014
Locomotion intent prediction is essential for the control of powered lower-limb prostheses to rea... more Locomotion intent prediction is essential for the control of powered lower-limb prostheses to realize smooth locomotion transitions. In this research, we develop a multi-sensor fusion based locomotion intent prediction system, which can recognize current locomotion mode and detect locomotion transitions in advance. Seven able-bodied subjects were recruited for this research. Signals from two foot pressure insoles and three inertial measurement units (one on the thigh, one on the shank and the other on the foot) are measured. A two-level recognition strategy is used for the recognition with linear discriminate classifier. Six kinds of locomotion modes and ten kinds of locomotion transitions are tested in this study. Recognition accuracy during steady locomotion periods (i.e., no locomotion transitions) is 99.71% ± 0.05% for seven able-bodied subjects. During locomotion transition periods, all the transitions are correctly detected and most of them can be detected before transiting to new locomotion modes. No significant deterioration in recognition performance is observed in the following five hours after the system is trained, and small number of experiment trials are required to train reliable classifiers.
Robotica, 2012
2012). Modeling and gait selection of passivitybased seven-link bipeds with dynamic series of wal... more 2012). Modeling and gait selection of passivitybased seven-link bipeds with dynamic series of walking phases. Robotica, 30, pp 39-51 SUMMARY This paper presents a seven-link dynamic walking model that is more close to human beings than other passivitybased dynamic walking models. We add hip actuation, upper body, flat feet, and ankle joints with torsional springs to the model. Walking sequence of flat-feet walkers has several substreams, which forms bipedal walking with dynamic series of phases. We investigate the effects of ankle stiffness on gait selection and evaluate different gaits in walking velocity, efficiency, and stability. Experimental results indicate that ankle stiffness plays different roles in different gaits and the gaits, which are more close to human walking with moderate speed, achieve better motion characteristics.