To realize the coordinated and stable rhythmic motion of quadruped robots （QRs）, the locomotion control method of QRs based on central pattern generator （CPG） was explored. In tradi- tional control strategies base...To realize the coordinated and stable rhythmic motion of quadruped robots （QRs）, the locomotion control method of QRs based on central pattern generator （CPG） was explored. In tradi- tional control strategies based on CPG, few CPG models care about the intra-limb coordination of QRs, and the durations of stance phase and swing phase are always equal. In view of these deficien- cies, a new and simpler multi-joint coordinated control method for both inter-limb and intra-limb was proposed in this paper. A layered CPG control network to realize the locomotion control of QRs was constructed by using modified Hopf oscillators. The coupled relationships among hip joints of all limbs and between hip joint and knee joint within a limb were established. Using the co-simulation method of ADAMS and MATLAB/Simulink, various gait simulation experiments were carried out and the effectiveness of the designed control network was tested. Simulation results show that the pro- posed control method is effective for QRs and can meet the control requirements of QRs＇ gaits with different duty factors.展开更多
The aims of this study were(a)to investigate the effects of a unilateral training program in reducing inter-limb asymmetry in male soccer players;(b)to explore such effects on measures of physical performance and unil...The aims of this study were(a)to investigate the effects of a unilateral training program in reducing inter-limb asymmetry in male soccer players;(b)to explore such effects on measures of physical performance and unilateral inter-limb asymmetry.Twenty-four soccer players,randomly assigned to a 6-week unilateral strength and power training(UNI)(n=12)or a control group(CON)(n=12),performed single countermovement jump(SLCMJ),single leg broad jump(SLBJ),single leg drop jump(SLDJ),10-m sprint,and 505 change of direction(COD)speed test.Raw jump scores revealed small to large improve-ments in SLCMJ,SLBJ,and SLDJ reactive strength index(RSI)(g=0.46 to 1.66)in the UNI group,whereas negligible changes were found in the CON group(g=−0.31 to 0.33).Asymmetry indexes showed a moderate significant reduction in the SLDJ(RSI)and in the SLDJ stiffness(K)(g=1.00 to 1.11)in the UNI group.The between-group comparison indicated a significant change in the SLDJ(RSI)and in the SLDJ(K)(g=1.01 to 1.07)in favour of the UNI group.Thus,a unilateral training program seems to be able to reduce between-limb imbalances and foster improvements in jump performance,without any detrimental effects on linear or COD speed times.Given the importance of these physical characteristics for soccer,it is suggested that unilateral strength and power training are incorporated into strength training routines for players of all levels.展开更多
Purpose Inter-limb coordination may provide insight into why patients with anterior cruciate ligament reconstructive sur-gery(ACLR)have an increased risk for future injury and osteoarthritis.The purpose of this study ...Purpose Inter-limb coordination may provide insight into why patients with anterior cruciate ligament reconstructive sur-gery(ACLR)have an increased risk for future injury and osteoarthritis.The purpose of this study was to compare inter-limb coordination prior-to anterior cruciate ligament(ACL)injury and following ACLR.Methods Unilateral lower extremity biomechanics during a double-leg jump landing were collected prior-to ACL injury(baseline)and after ACLR,rehabilitation,and return to physical activity(follow-up).Sixty-nine participants were included in this analysis:31 participants suffered an ACL injury since baseline:12 injured the leg tested at baseline[ACLR-injured leg(ACLR-INJ),n=12]and 19 injured the leg that was not tested at baseline[ACLR-uninjured leg(ACLR-UNINJ)n=19];38 participants served as matched controls.Inter-limb coordination-calculated as the mean coupling angle-between the hip and knee were measured in the respective leg of each defined group and compared amongst groups at baseline and follow-up.Results We observed no significant change in sagittal or frontal plane inter-limb coordination amongst groups or across time(P>0.05).A significant decrease in inter-limb coordination in the transverse plane from baseline and follow-up was observed but limited to the ACLR-INJ group(P=0.016).Conclusion The primary finding of this study is that inter-limb coordination between the hip and knee in the sagittal and frontal plane is unchanged by ACL injury and ACLR.This may help explain previous observations of changes in kinemat-ics at both the hip and knee in this population.Our observation of alterations in the transverse plane should be interpreted with caution,but may provide additional evidence for potential mechanisms that lead to the development of osteoarthritis in ACLR patients.展开更多
基金Supported by the Ministerial Level Advanced Research Foundation(40401060305)
文摘To realize the coordinated and stable rhythmic motion of quadruped robots （QRs）, the locomotion control method of QRs based on central pattern generator （CPG） was explored. In tradi- tional control strategies based on CPG, few CPG models care about the intra-limb coordination of QRs, and the durations of stance phase and swing phase are always equal. In view of these deficien- cies, a new and simpler multi-joint coordinated control method for both inter-limb and intra-limb was proposed in this paper. A layered CPG control network to realize the locomotion control of QRs was constructed by using modified Hopf oscillators. The coupled relationships among hip joints of all limbs and between hip joint and knee joint within a limb were established. Using the co-simulation method of ADAMS and MATLAB/Simulink, various gait simulation experiments were carried out and the effectiveness of the designed control network was tested. Simulation results show that the pro- posed control method is effective for QRs and can meet the control requirements of QRs＇ gaits with different duty factors.
文摘The aims of this study were(a)to investigate the effects of a unilateral training program in reducing inter-limb asymmetry in male soccer players;(b)to explore such effects on measures of physical performance and unilateral inter-limb asymmetry.Twenty-four soccer players,randomly assigned to a 6-week unilateral strength and power training(UNI)(n=12)or a control group(CON)(n=12),performed single countermovement jump(SLCMJ),single leg broad jump(SLBJ),single leg drop jump(SLDJ),10-m sprint,and 505 change of direction(COD)speed test.Raw jump scores revealed small to large improve-ments in SLCMJ,SLBJ,and SLDJ reactive strength index(RSI)(g=0.46 to 1.66)in the UNI group,whereas negligible changes were found in the CON group(g=−0.31 to 0.33).Asymmetry indexes showed a moderate significant reduction in the SLDJ(RSI)and in the SLDJ stiffness(K)(g=1.00 to 1.11)in the UNI group.The between-group comparison indicated a significant change in the SLDJ(RSI)and in the SLDJ(K)(g=1.01 to 1.07)in favour of the UNI group.Thus,a unilateral training program seems to be able to reduce between-limb imbalances and foster improvements in jump performance,without any detrimental effects on linear or COD speed times.Given the importance of these physical characteristics for soccer,it is suggested that unilateral strength and power training are incorporated into strength training routines for players of all levels.
基金This work was supported by the National Institute of Arthritis and Musculoskeletal and Skin Diseases(RO1-AR050461-01)the American Orthopedic Society for Sports Medicine。
文摘Purpose Inter-limb coordination may provide insight into why patients with anterior cruciate ligament reconstructive sur-gery(ACLR)have an increased risk for future injury and osteoarthritis.The purpose of this study was to compare inter-limb coordination prior-to anterior cruciate ligament(ACL)injury and following ACLR.Methods Unilateral lower extremity biomechanics during a double-leg jump landing were collected prior-to ACL injury(baseline)and after ACLR,rehabilitation,and return to physical activity(follow-up).Sixty-nine participants were included in this analysis:31 participants suffered an ACL injury since baseline:12 injured the leg tested at baseline[ACLR-injured leg(ACLR-INJ),n=12]and 19 injured the leg that was not tested at baseline[ACLR-uninjured leg(ACLR-UNINJ)n=19];38 participants served as matched controls.Inter-limb coordination-calculated as the mean coupling angle-between the hip and knee were measured in the respective leg of each defined group and compared amongst groups at baseline and follow-up.Results We observed no significant change in sagittal or frontal plane inter-limb coordination amongst groups or across time(P>0.05).A significant decrease in inter-limb coordination in the transverse plane from baseline and follow-up was observed but limited to the ACLR-INJ group(P=0.016).Conclusion The primary finding of this study is that inter-limb coordination between the hip and knee in the sagittal and frontal plane is unchanged by ACL injury and ACLR.This may help explain previous observations of changes in kinemat-ics at both the hip and knee in this population.Our observation of alterations in the transverse plane should be interpreted with caution,but may provide additional evidence for potential mechanisms that lead to the development of osteoarthritis in ACLR patients.
