A lightweight robotic arm with pneumatic muscles for robot learning

Büchler, Dieter; Ott, Heiko; Peters, Jan

doi:10.1109/icra.2016.7487599

Cited by 28 publications

(23 citation statements)

References 28 publications

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“…Generating high accelerations with robotic hardware as seen in human arm flick motions, while maintaining safely during the learning process, are desirable properties for modern robots [40]. In this paper, we built a lightweight arm actuated by PAMs to try to address this issue.…”

Section: Discussionmentioning

confidence: 99%

Learning to Control Highly Accelerated Ballistic Movements on Muscular Robots

Büchler¹,

Calandra²,

Peters³

2019

Preprint

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High-speed and high-acceleration movements are inherently hard to control. Applying learning to the control of such motions on anthropomorphic robot arms can improve the accuracy of the control but might damage the system. The inherent exploration of learning approaches can lead to instabilities and the robot reaching joint limits at high speeds. Having hardware that enables safe exploration of high-speed and high-acceleration movements is therefore desirable. To address this issue, we propose to use robots actuated by Pneumatic Artificial Muscles (PAMs). In this paper, we present a four degrees of freedom (DoFs) robot arm that reaches high joint angle accelerations of up to 28 000 °s−2 while avoiding dangerous joint limits thanks to the antagonistic actuation and limits on the air pressure ranges. With this robot arm, we are able to tune control parameters using Bayesian optimization directly on the hardware without additional safety considerations. The achieved tracking performance on a fast trajectory exceeds previous results on comparable PAM-driven robots. We also show that our system can be controlled well on slow trajectories with PID controllers due to careful construction considerations such as minimal bending of cables, lightweight kinematics and minimal contact between PAMs and PAMs with the links. Finally, we propose a novel technique to control the the co-contraction of antagonistic muscle pairs. Experimental results illustrate that choosing the optimal co-contraction level is vital to reach better tracking performance. Through the use of PAM-driven robots and learning, we do a small step towards the future development of robots capable of more human-like motions.

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Section: Discussionmentioning

confidence: 99%

Learning to Control Highly Accelerated Ballistic Movements on Muscular Robots

Büchler¹,

Calandra²,

Peters³

2019

Preprint

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“…We confirmed a maximum velocity at the racket head of about 19 m/s. It was much faster compared to previous robotic arms, such as WAM arm [7] (8 m/s) and a lightweight robotic arm [10] (13 m/s). However, it was a little bit slower than the only pneumatic robot that we had developed previously, 21 m/s [11], although the racket speed (37.1 m/s at impact) in a jumping smash produced by humans is faster [19].…”

Section: A Swing Speedmentioning

confidence: 93%

“…Indeed, pneumatically driven multi-DoFs robots can perform dynamic tasks such as running [8] and jumping [9]; such tasks cannot be achieved by ordinary electric-driven robots. A lightweight robotic arm driven by pneumatic artificial muscle can achieve speeds up to 13 m/s at the end effector [10]. Furthermore, the arms we have developed previously achieved speeds of 21 m/s [11].…”

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confidence: 99%

High-Speed Humanoid Robot Arm for Badminton Using Pneumatic-Electric Hybrid Actuators

Mori

Tanaka

Nishikawa

et al. 2019

IEEE Robot. Autom. Lett.

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We describe the development of a robot configured to play badminton, a dynamic sport that requires high accuracy. We used pneumatic-electric hybrid actuators, each combining a pneumatic actuator, with high-speed and lightweight attributes, and an electric motor with good controllability. Our first objective was to develop hybrid actuators that are lightweight and compact and with integrated sections. Using parts made of lightweight materials such as plastics and aluminum coils, and using wire for power transmission, we made actuators much lighter and smaller than previous ones. In addition, for high accuracy and power, tension sensor units and a heat countermeasure mechanism were also incorporated. As practice partners, we consider badminton robots to be more useful if they were humanoid in appearance and have a variety of shots. We, therefore, developed a humanoid robot arm. By incorporating actuators as link structures, the overall weight was reduced, and both complex degrees of freedom (DoFs) and a large range of motion were realized. Subsequently, we developed a robot with seven DoFs, three DoFs for the shoulder, two for the elbow, and two for the wrist, similar to the configuration of human arms. The robot, therefore, roughly reproduces human movements. At 19 m/s, the maximum speed of the racket was quite fast. The hybrid control reduced the motion variance, allowing improvements in accuracy of more than three times that of motions with only pneumatic control. In addition, performing path planning and tracking control with high precision was possible, tasks that are difficult for conventional pneumatic dynamic robots. Index Terms-Hydraulic/pneumatic actuators, mechanism design, tendon/wire mechanism, humanoid robots, motion control. I. INTRODUCTION S PORT is a global business and expected to be a popular field for robot applications. With the recent developments in robot technology, robots are helping humans to play sports, specifically in regard to retaining and training professional athletes [1]. For other sports such as football [2], table tennis [3], and

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“…The earliest forms of soft pneumatic actuators, pneumatic artificial muscles (PAMs), create small contractile strains under high pressures, but have been superseded due to their highly non-linear dynamics, poor contraction ratios, and non-back-drivability. 3,12,13 Newer soft pneumatic actuator designs mostly focus on soft bending motions, which can produce high degrees of freedom and large structural deformation achievable in a single actuator, especially useful in grasping tasks involving irregular shaped objects. 2,5,14 The most common topology of these type of actuators utilizes a number of discrete chambers in series combined with a flexible and non-extensible strip along one side to generate a desirable bending motion.…”

Section: Introductionmentioning

confidence: 99%