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An energetic control methodology for exploiting the passive dynamics of pneumatically actuated hopping / Yong Zhu in Transactions of the ASME . Journal of dynamic systems, measurement, and control, Vol. 130 n°4 (Juillet 2008) 

Public ISBD [article]  in Transactions of the ASME . Journal of dynamic systems, measurement, and control > Vol. 130 n°4 (Juillet 2008) . - 11 p. Titre : An energetic control methodology for exploiting the passive dynamics of pneumatically actuated hopping Type de document : texte imprimé Auteurs : Yong Zhu, Auteur ; Barth, Eric J., Auteur Année de publication : 2008 Article en page(s) : 11 p. Note générale : dynamic systems Langues : Anglais (eng) Mots-clés : dynamics  (mechanics);  pressure;  motion;  robots;  actuators;  valves;  pistons;  flight;  stiffness;  potential  energy;  solenoids;  flow  (dynamics);  kinetic  energy;  oscillations;  simulation;  force;  pneumatic  actuators;  energy  storage;  equilibrium  (physics);  cylinders;  pneumatic  cylinders;  proportional  valves Résumé : This paper presents an energetically derived control methodology to specify and regulate the oscillatory motion of a pneumatic hopping robot. An ideal lossless pneumatic actuation system with an inertia is shown to represent an oscillator with a stiffness, and hence frequency, related to the equilibrium pressures in the actuator. Following from an analysis of the conservative energy storage elements in the system, a control methodology is derived to sustain a specified frequency of oscillation in the presence of energy dissipation. The basic control strategy is to control the pressure in the upper chamber of the pneumatic cylinder to specify the contact time of the piston, while controlling the total conservative energy stored in the system to specify the flight time and corresponding flight height of the cylinder. The control strategy takes advantage of the natural passive dynamics of the upper chamber to provide much of the required actuation forces and natural stiffness, while the remaining forces needed to overcome the energy dissipation present in a nonideal system with losses are provided by a nonlinear control law for the charging and discharging of the lower chamber of the cylinder. Efficient hopping motion, relative to a traditional nonconservative actuator, is achieved by allowing the energy storing capability of a pneumatic actuator to store and return energy to the system at a controlled specifiable frequency. The control methodology is demonstrated through simulation and experimental results to provide accurate and repeatable hopping motion for pneumatically actuated robots in the presence of dissipative forces. En ligne : http://dynamicsystems.asmedigitalcollection.asme.org/issue.aspx?journalid=117&is [...] [article] An energetic control methodology for exploiting the passive dynamics of pneumatically actuated hopping [texte imprimé] / Yong Zhu, Auteur ; Barth, Eric J., Auteur . - 2008 . - 11 p. dynamic systems Langues : Anglais (eng) in Transactions of the ASME . Journal of dynamic systems, measurement, and control > Vol. 130 n°4 (Juillet 2008) . - 11 p. Mots-clés : dynamics  (mechanics);  pressure;  motion;  robots;  actuators;  valves;  pistons;  flight;  stiffness;  potential  energy;  solenoids;  flow  (dynamics);  kinetic  energy;  oscillations;  simulation;  force;  pneumatic  actuators;  energy  storage;  equilibrium  (physics);  cylinders;  pneumatic  cylinders;  proportional  valves Résumé : This paper presents an energetically derived control methodology to specify and regulate the oscillatory motion of a pneumatic hopping robot. An ideal lossless pneumatic actuation system with an inertia is shown to represent an oscillator with a stiffness, and hence frequency, related to the equilibrium pressures in the actuator. Following from an analysis of the conservative energy storage elements in the system, a control methodology is derived to sustain a specified frequency of oscillation in the presence of energy dissipation. The basic control strategy is to control the pressure in the upper chamber of the pneumatic cylinder to specify the contact time of the piston, while controlling the total conservative energy stored in the system to specify the flight time and corresponding flight height of the cylinder. The control strategy takes advantage of the natural passive dynamics of the upper chamber to provide much of the required actuation forces and natural stiffness, while the remaining forces needed to overcome the energy dissipation present in a nonideal system with losses are provided by a nonlinear control law for the charging and discharging of the lower chamber of the cylinder. Efficient hopping motion, relative to a traditional nonconservative actuator, is achieved by allowing the energy storing capability of a pneumatic actuator to store and return energy to the system at a controlled specifiable frequency. The control methodology is demonstrated through simulation and experimental results to provide accurate and repeatable hopping motion for pneumatically actuated robots in the presence of dissipative forces. En ligne : http://dynamicsystems.asmedigitalcollection.asme.org/issue.aspx?journalid=117&is [...]

Passivity-based impact and force control of a pneumatic actuator / Yong Zhu in Transactions of the ASME . Journal of dynamic systems, measurement, and control, Vol. 130 N°2 (Mars/Avril 2008) 

Public ISBD [article]  in Transactions of the ASME . Journal of dynamic systems, measurement, and control > Vol. 130 N°2 (Mars/Avril 2008) . - 7 p. Titre : Passivity-based impact and force control of a pneumatic actuator Type de document : texte imprimé Auteurs : Yong Zhu, Auteur ; Barth, Eric J., Auteur Année de publication : 2008 Article en page(s) : 7 p. Note générale : dynamic systems Langues : Anglais (eng) Mots-clés : force  control;  pneumatic  actuators;  force;  valves;  actuators;  feedback Résumé : To carry out stable and dissipative contact tasks with an arbitrary environment, it is critical for a pneumatic actuator to be passive with respect to a supply rate consisting of the spool valve position input and the actuation force output. A pseudo-bond graph model with the inner product between spool valve position input and actuation force output as a pseudo-supply rate is developed. Using this pseudo-bond graph model, an open-loop pneumatic actuator controlled by a four-way proportional valve can be proven to not be passive with respect to the pseudo-supply rate. Conversely, it can also be proven to be passive with respect to the pseudo-supply rate under a closed-loop feedback control law. The passivity of the closed-loop pneumatic actuator is verified in impact and force control experiments. The experimental results also validate the pseudo-bond graph model. The pseudo-bond graph model is intended for passivity analysis and controller design for pneumatic actuation applications where contact stability (such as robotic assembly) and/or stable interaction with a passive environment (such as human-robot interaction) is required. En ligne : http://dynamicsystems.asmedigitalcollection.asme.org/issue.aspx?journalid=117&is [...] [article] Passivity-based impact and force control of a pneumatic actuator [texte imprimé] / Yong Zhu, Auteur ; Barth, Eric J., Auteur . - 2008 . - 7 p. dynamic systems Langues : Anglais (eng) in Transactions of the ASME . Journal of dynamic systems, measurement, and control > Vol. 130 N°2 (Mars/Avril 2008) . - 7 p. Mots-clés : force  control;  pneumatic  actuators;  force;  valves;  actuators;  feedback Résumé : To carry out stable and dissipative contact tasks with an arbitrary environment, it is critical for a pneumatic actuator to be passive with respect to a supply rate consisting of the spool valve position input and the actuation force output. A pseudo-bond graph model with the inner product between spool valve position input and actuation force output as a pseudo-supply rate is developed. Using this pseudo-bond graph model, an open-loop pneumatic actuator controlled by a four-way proportional valve can be proven to not be passive with respect to the pseudo-supply rate. Conversely, it can also be proven to be passive with respect to the pseudo-supply rate under a closed-loop feedback control law. The passivity of the closed-loop pneumatic actuator is verified in impact and force control experiments. The experimental results also validate the pseudo-bond graph model. The pseudo-bond graph model is intended for passivity analysis and controller design for pneumatic actuation applications where contact stability (such as robotic assembly) and/or stable interaction with a passive environment (such as human-robot interaction) is required. En ligne : http://dynamicsystems.asmedigitalcollection.asme.org/issue.aspx?journalid=117&is [...]