TY - GEN
T1 - Comparison of Control Strategies to Excite Intrinsic Oscillations in a SEA-Driven Robotic Joint
AU - Schmidt, Annika
AU - Pasic, Filip
AU - Calzolari, Davide
AU - Sachtler, Arne
AU - Gumpert, Thomas
AU - Keppler, Manuel
AU - Albu-Schäffer, Alin
N1 - Publisher Copyright:
© 2024 EUCA.
PY - 2024
Y1 - 2024
N2 - During the execution of periodic motions, such as locomotion, animals exploit the elasticity in their body to increase efficiency. Adding elasticity in robotic systems, e.g., through a Series Elastic Actuator (SEA), enables to mimic this biological solution by storing energy in the spring. The standard strategy to efficiently drive such systems in periodic motions is to assume the motor static such that the SEA behaves like a single-mass-spring system, excited at its natural frequency. However, when regarding the SEA as a two-mass- spring system, we can derive another control strategy to excite periodic oscillations, where the motor and link inertia exhibit anti-phasic oscillations. This paper compares these two control strategies on a hardware SEA test bed regarding performance metrics such as maximal input torque and electrical power consumption. The control objective for this comparison is to excite a link oscillation with a desired amplitude, as could be needed for a pick-and-place task. We find that less current is needed for the given task and hardware for the first control strategy. The second strategy causes more friction that needs compensation but also increases stored system energy for the desired amplitude. When adding motor inertia shaping to this second strategy, we find a flexible controller that can shift the system to either behave like a single- or two-mass-spring system. Thus, we propose a promising control approach that can adapt system behavior to best suit a given oscillatory task.
AB - During the execution of periodic motions, such as locomotion, animals exploit the elasticity in their body to increase efficiency. Adding elasticity in robotic systems, e.g., through a Series Elastic Actuator (SEA), enables to mimic this biological solution by storing energy in the spring. The standard strategy to efficiently drive such systems in periodic motions is to assume the motor static such that the SEA behaves like a single-mass-spring system, excited at its natural frequency. However, when regarding the SEA as a two-mass- spring system, we can derive another control strategy to excite periodic oscillations, where the motor and link inertia exhibit anti-phasic oscillations. This paper compares these two control strategies on a hardware SEA test bed regarding performance metrics such as maximal input torque and electrical power consumption. The control objective for this comparison is to excite a link oscillation with a desired amplitude, as could be needed for a pick-and-place task. We find that less current is needed for the given task and hardware for the first control strategy. The second strategy causes more friction that needs compensation but also increases stored system energy for the desired amplitude. When adding motor inertia shaping to this second strategy, we find a flexible controller that can shift the system to either behave like a single- or two-mass-spring system. Thus, we propose a promising control approach that can adapt system behavior to best suit a given oscillatory task.
UR - http://www.scopus.com/inward/record.url?scp=85200607387&partnerID=8YFLogxK
U2 - 10.23919/ECC64448.2024.10591121
DO - 10.23919/ECC64448.2024.10591121
M3 - Conference contribution
AN - SCOPUS:85200607387
T3 - 2024 European Control Conference, ECC 2024
SP - 2194
EP - 2199
BT - 2024 European Control Conference, ECC 2024
PB - Institute of Electrical and Electronics Engineers Inc.
T2 - 2024 European Control Conference, ECC 2024
Y2 - 25 June 2024 through 28 June 2024
ER -