Learning-based design and control for quadrupedal robots with parallel-elastic actuators
Bjelonic, Filip ; Lee, Joonho ; Arm, Philip ; Sako, Dhionis ; Tateo, Davide LU
; Peters, Jan
and Hutter, Marco
(2023)
In IEEE Robotics and Automation Letters
8(3).
p.1611-1618
- Abstract
Parallel-elastic joints can improve the efficiency and strength of robots by assisting the actuators with additional torques. For these benefits to be realized, a spring needs to be carefully designed. However, designing robots is an iterative and tedious process, often relying on intuition and heuristics. We introduce a design optimization framework that allows us to co-optimize a parallel elastic knee joint and locomotion controller for quadrupedal robots with minimal human intuition. We design a parallel elastic joint and optimize its parameters with respect to the efficiency in a model-free fashion. In the first step, we train a design-conditioned policy using model-free Reinforcement Learning, capable of controlling the quadruped... (More)
Parallel-elastic joints can improve the efficiency and strength of robots by assisting the actuators with additional torques. For these benefits to be realized, a spring needs to be carefully designed. However, designing robots is an iterative and tedious process, often relying on intuition and heuristics. We introduce a design optimization framework that allows us to co-optimize a parallel elastic knee joint and locomotion controller for quadrupedal robots with minimal human intuition. We design a parallel elastic joint and optimize its parameters with respect to the efficiency in a model-free fashion. In the first step, we train a design-conditioned policy using model-free Reinforcement Learning, capable of controlling the quadruped in the predefined range of design parameters. Afterwards, we use Bayesian Optimization to find the best design using the policy. We use this framework to optimize the parallel-elastic spring parameters for the knee of our quadrupedal robot ANYmal together with the optimal controller. We evaluate the optimized design and controller in real-world experiments over various terrains. Our results show that the new system improves the torque-square efficiency of the robot by 33% compared to the baseline and reduces maximum joint torque by 30% without compromising tracking performance. The improved design resulted in 11% longer operation time on flat terrain.
(Less)
- author
- Bjelonic, Filip
; Lee, Joonho
; Arm, Philip
; Sako, Dhionis
; Tateo, Davide
LU
; Peters, Jan
and Hutter, Marco
- publishing date
- 2023-03-01
- type
- Contribution to journal
- publication status
- published
- subject
- keywords
- Compliant joints and mechanisms, legged robots, Mechanism design, Reinforcement learning
- in
- IEEE Robotics and Automation Letters
- volume
- 8
- issue
- 3
- pages
- 8 pages
- publisher
- IEEE - Institute of Electrical and Electronics Engineers Inc.
- external identifiers
-
- scopus:85147225048
- ISSN
- 2377-3766
- DOI
- 10.1109/LRA.2023.3234809
- language
- English
- LU publication?
- no
- id
- 9cf840cc-f128-4a47-9d84-67f5e80aa28c
- date added to LUP
- 2025-10-16 14:02:26
- date last changed
- 2025-10-17 11:52:45
@article{9cf840cc-f128-4a47-9d84-67f5e80aa28c,
abstract = {{<p>Parallel-elastic joints can improve the efficiency and strength of robots by assisting the actuators with additional torques. For these benefits to be realized, a spring needs to be carefully designed. However, designing robots is an iterative and tedious process, often relying on intuition and heuristics. We introduce a design optimization framework that allows us to co-optimize a parallel elastic knee joint and locomotion controller for quadrupedal robots with minimal human intuition. We design a parallel elastic joint and optimize its parameters with respect to the efficiency in a model-free fashion. In the first step, we train a design-conditioned policy using model-free Reinforcement Learning, capable of controlling the quadruped in the predefined range of design parameters. Afterwards, we use Bayesian Optimization to find the best design using the policy. We use this framework to optimize the parallel-elastic spring parameters for the knee of our quadrupedal robot ANYmal together with the optimal controller. We evaluate the optimized design and controller in real-world experiments over various terrains. Our results show that the new system improves the torque-square efficiency of the robot by 33% compared to the baseline and reduces maximum joint torque by 30% without compromising tracking performance. The improved design resulted in 11% longer operation time on flat terrain.</p>}},
author = {{Bjelonic, Filip and Lee, Joonho and Arm, Philip and Sako, Dhionis and Tateo, Davide and Peters, Jan and Hutter, Marco}},
issn = {{2377-3766}},
keywords = {{Compliant joints and mechanisms; legged robots; Mechanism design; Reinforcement learning}},
language = {{eng}},
month = {{03}},
number = {{3}},
pages = {{1611--1618}},
publisher = {{IEEE - Institute of Electrical and Electronics Engineers Inc.}},
series = {{IEEE Robotics and Automation Letters}},
title = {{Learning-based design and control for quadrupedal robots with parallel-elastic actuators}},
url = {{http://dx.doi.org/10.1109/LRA.2023.3234809}},
doi = {{10.1109/LRA.2023.3234809}},
volume = {{8}},
year = {{2023}},
}