Vincent Bonnet | Università degli Studi di Roma Foro Italico (original) (raw)

Papers by Vincent Bonnet

Research paper thumbnail of Ankle-hip coordination during supra-postural tracking by stroke patients

Research paper thumbnail of Understanding bistable human postural coordination dynamics to guide bio-inspired control of humanoids

Research paper thumbnail of Modeling human postural coordination to improve the control of balance in humanoids

Humanoid Robots, …, Jan 1, 2007

This paper models recent data in the field of postural coordination showing the existence of self... more This paper models recent data in the field of postural coordination showing the existence of self-organized postural states, and transition between them, underlying supra-postural tracking movements. The proposed biomechanical model, capitalizing on stability and optimization criteria, captures the complex postural behaviors observed in humans and can be used to implement efficient balance control principles in humanoids. Experimental results on humanoids show the relevance of this work.

Research paper thumbnail of A structurally optimal control model for predicting and analyzing human postural coordination

Journal of …, Jan 1, 2011

This paper proposes a closed-loop optimal control model predicting changes between in-phase and a... more This paper proposes a closed-loop optimal control model predicting changes between in-phase and anti-phase postural coordination during standing and related supra-postural activities. The model allows the evaluation of the influence of body dynamics and balance constraints onto the adoption of postural coordination. This model minimizes the instantaneous norm of the joint torques with a controller in the head space, in contrast with classical linear optimal models used in the postural literature and defined in joint space. The balance constraint is addressed with an adaptive ankle torque saturation. Numerical simulations showed that the model was able to predict changes between in-phase and anti-phase postural coordination modes and other non-linear transient dynamics phenomena.

Research paper thumbnail of A closed loop musculoskeletal model of postural coordination dynamics

… and Control, 2009 …, Jan 1, 2009

A closed-loop model with actuator dynamics and sensory feedback has been developed to capture the... more A closed-loop model with actuator dynamics and sensory feedback has been developed to capture the complex postural behaviors observed in a human head tracking task. In motor-control litterature, spindle feedback gains are scaled by the central nervous system to adapt muscle stiffness depending on the postural task. We propose to identify spindle reflex equivalent feedback gains for several target's frequency values. Comparison with experimental results on human shows the relevance of this modeling, since our musculoskeletal model is able to exhibit reasonably well the behavioral invariants observed in human postures.

Research paper thumbnail of Improving Valid and Deficient Body Segment Coordination to Improve FES-ASSISTED SIT-TO-STAND in Paraplegic Subjects

We investigated dynamic optimization as a tool to improve functional electrical stimulation (FES)... more We investigated dynamic optimization as a tool to improve functional electrical stimulation (FES) assisted sit to stand transfers of paraplegic subjects. The objective would be to find optimal strategy for voluntary trunk movement, which would minimize hip, knee and ankle torques and demand minimal upper limb participation during the motion. Motion of the knee and the ankle were constrained by electrical stimulation. Motion capture (MOCAP) data, and signals from handle force sensors were acquired during FES-assisted rising motion of one paraplegic subject. Based on a 3 DOF dynamic model, we used an optimization algorithm in order to determine optimal trajectories in terms of minimizing joint torques for various conditions of force level applied to handles. Motion computed using the optimization process is compared with the one recorded during the experiment. Our results suggest that in order to minimize the sum of joint torques and arm effort participation, paraplegic patients should bend their body forward in order to use linear momentum of the trunk in sit off phase. This information can be used to design controller for closed-loop FES-assisted standingup. The controller could use trunk motion to trigger legs stimulation in order to optimize body segment coordination.

Research paper thumbnail of A robotic closed-loop scheme to model human postural coordination

… and Systems, 2009. …, Jan 1, 2009

This paper models recent data in the field of postural coordination showing the existence of self... more This paper models recent data in the field of postural coordination showing the existence of self-organized postural states, and transition between them, underlying suprapostural tracking movements. The proposed closed-loop controller captures the complex postural behaviors observed in humans and can be used to implement efficient and simple balance control principles in humanoids.

Research paper thumbnail of Modeling postural coordination dynamics using a closed-loop controller

… 2008. 8th IEEE- …, Jan 1, 2008

This paper models recent data in the field of postural coordination showing the existence of self... more This paper models recent data in the field of postural coordination showing the existence of self-organized postural states, and transition between them, underlying supra-postural tracking movements. The proposed closed-loop controller captures the complex postural behaviors observed in humans and can be used to implement efficient and simple balance control principles in humanoids.

Research paper thumbnail of Ankle-hip coordination during supra-postural tracking by stroke patients

Research paper thumbnail of Understanding bistable human postural coordination dynamics to guide bio-inspired control of humanoids

Research paper thumbnail of Modeling human postural coordination to improve the control of balance in humanoids

Humanoid Robots, …, Jan 1, 2007

This paper models recent data in the field of postural coordination showing the existence of self... more This paper models recent data in the field of postural coordination showing the existence of self-organized postural states, and transition between them, underlying supra-postural tracking movements. The proposed biomechanical model, capitalizing on stability and optimization criteria, captures the complex postural behaviors observed in humans and can be used to implement efficient balance control principles in humanoids. Experimental results on humanoids show the relevance of this work.

Research paper thumbnail of A structurally optimal control model for predicting and analyzing human postural coordination

Journal of …, Jan 1, 2011

This paper proposes a closed-loop optimal control model predicting changes between in-phase and a... more This paper proposes a closed-loop optimal control model predicting changes between in-phase and anti-phase postural coordination during standing and related supra-postural activities. The model allows the evaluation of the influence of body dynamics and balance constraints onto the adoption of postural coordination. This model minimizes the instantaneous norm of the joint torques with a controller in the head space, in contrast with classical linear optimal models used in the postural literature and defined in joint space. The balance constraint is addressed with an adaptive ankle torque saturation. Numerical simulations showed that the model was able to predict changes between in-phase and anti-phase postural coordination modes and other non-linear transient dynamics phenomena.

Research paper thumbnail of A closed loop musculoskeletal model of postural coordination dynamics

… and Control, 2009 …, Jan 1, 2009

A closed-loop model with actuator dynamics and sensory feedback has been developed to capture the... more A closed-loop model with actuator dynamics and sensory feedback has been developed to capture the complex postural behaviors observed in a human head tracking task. In motor-control litterature, spindle feedback gains are scaled by the central nervous system to adapt muscle stiffness depending on the postural task. We propose to identify spindle reflex equivalent feedback gains for several target's frequency values. Comparison with experimental results on human shows the relevance of this modeling, since our musculoskeletal model is able to exhibit reasonably well the behavioral invariants observed in human postures.

Research paper thumbnail of Improving Valid and Deficient Body Segment Coordination to Improve FES-ASSISTED SIT-TO-STAND in Paraplegic Subjects

We investigated dynamic optimization as a tool to improve functional electrical stimulation (FES)... more We investigated dynamic optimization as a tool to improve functional electrical stimulation (FES) assisted sit to stand transfers of paraplegic subjects. The objective would be to find optimal strategy for voluntary trunk movement, which would minimize hip, knee and ankle torques and demand minimal upper limb participation during the motion. Motion of the knee and the ankle were constrained by electrical stimulation. Motion capture (MOCAP) data, and signals from handle force sensors were acquired during FES-assisted rising motion of one paraplegic subject. Based on a 3 DOF dynamic model, we used an optimization algorithm in order to determine optimal trajectories in terms of minimizing joint torques for various conditions of force level applied to handles. Motion computed using the optimization process is compared with the one recorded during the experiment. Our results suggest that in order to minimize the sum of joint torques and arm effort participation, paraplegic patients should bend their body forward in order to use linear momentum of the trunk in sit off phase. This information can be used to design controller for closed-loop FES-assisted standingup. The controller could use trunk motion to trigger legs stimulation in order to optimize body segment coordination.

Research paper thumbnail of A robotic closed-loop scheme to model human postural coordination

… and Systems, 2009. …, Jan 1, 2009

This paper models recent data in the field of postural coordination showing the existence of self... more This paper models recent data in the field of postural coordination showing the existence of self-organized postural states, and transition between them, underlying suprapostural tracking movements. The proposed closed-loop controller captures the complex postural behaviors observed in humans and can be used to implement efficient and simple balance control principles in humanoids.

Research paper thumbnail of Modeling postural coordination dynamics using a closed-loop controller

… 2008. 8th IEEE- …, Jan 1, 2008

This paper models recent data in the field of postural coordination showing the existence of self... more This paper models recent data in the field of postural coordination showing the existence of self-organized postural states, and transition between them, underlying supra-postural tracking movements. The proposed closed-loop controller captures the complex postural behaviors observed in humans and can be used to implement efficient and simple balance control principles in humanoids.