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2015


Exciting Engineered Passive Dynamics in a Bipedal Robot
Exciting Engineered Passive Dynamics in a Bipedal Robot

Renjewski, D., Spröwitz, A., Peekema, A., Jones, M., Hurst, J.

{IEEE Transactions on Robotics and Automation}, 31(5):1244-1251, IEEE, New York, NY, 2015 (article)

Abstract
A common approach in designing legged robots is to build fully actuated machines and control the machine dynamics entirely in soft- ware, carefully avoiding impacts and expending a lot of energy. However, these machines are outperformed by their human and animal counterparts. Animals achieve their impressive agility, efficiency, and robustness through a close integration of passive dynamics, implemented through mechanical components, and neural control. Robots can benefit from this same integrated approach, but a strong theoretical framework is required to design the passive dynamics of a machine and exploit them for control. For this framework, we use a bipedal spring–mass model, which has been shown to approximate the dynamics of human locomotion. This paper reports the first implementation of spring–mass walking on a bipedal robot. We present the use of template dynamics as a control objective exploiting the engineered passive spring–mass dynamics of the ATRIAS robot. The results highlight the benefits of combining passive dynamics with dynamics-based control and open up a library of spring–mass model-based control strategies for dynamic gait control of robots.

link (url) DOI Project Page [BibTex]

2015

link (url) DOI Project Page [BibTex]


Comparing the effect of different spine and leg designs for a small bounding quadruped robot
Comparing the effect of different spine and leg designs for a small bounding quadruped robot

Eckert, P., Spröwitz, A., Witte, H., Ijspeert, A. J.

In Proceedings of ICRA, pages: 3128-3133, Seattle, Washington, USA, 2015 (inproceedings)

Abstract
We present Lynx-robot, a quadruped, modular, compliant machine. It alternately features a directly actuated, single-joint spine design, or an actively supported, passive compliant, multi-joint spine configuration. Both spine con- figurations bend in the sagittal plane. This study aims at characterizing these two, largely different spine concepts, for a bounding gait of a robot with a three segmented, pantograph leg design. An earlier, similar-sized, bounding, quadruped robot named Bobcat with a two-segment leg design and a directly actuated, single-joint spine design serves as a comparison robot, to study and compare the effect of the leg design on speed, while keeping the spine design fixed. Both proposed spine designs (single rotatory and active and multi-joint compliant) reach moderate, self-stable speeds.

link (url) DOI Project Page [BibTex]

link (url) DOI Project Page [BibTex]

2012


Development of a Minimalistic Pneumatic Quadruped Robot for Fast Locomotion
Development of a Minimalistic Pneumatic Quadruped Robot for Fast Locomotion

Narioka, K., Rosendo, A., Spröwitz, A., Hosoda, K.

In Proceedings of the 2012 IEEE International Conference on Robotics and Biomimetics (ROBIO), 2012, pages: 307-311, IEEE, Guangzhou, 2012 (inproceedings)

Abstract
In this paper, we describe the development of the quadruped robot ”Ken” with the minimalistic and lightweight body design for achieving fast locomotion. We use McKibben pneumatic artificial muscles as actuators, providing high frequency and wide stride motion of limbs, also avoiding problems with overheating. We conducted a preliminary experiment, finding out that the robot can swing its limb over 7.5 Hz without amplitude reduction, nor heat problems. Moreover, the robot realized a several steps of bouncing gait by using simple CPG-based open loop controller, indicating that the robot can generate enough torque to kick the ground and limb contraction to avoid stumbling.

DOI [BibTex]

2012

DOI [BibTex]


Locomotion through Reconfiguration based on Motor Primitives for Roombots Self-Reconfigurable Modular Robots
Locomotion through Reconfiguration based on Motor Primitives for Roombots Self-Reconfigurable Modular Robots

Bonardi, S., Moeckel, R., Spröwitz, A., Vespignani, M., Ijspeert, A. J.

In Robotics; Proceedings of ROBOTIK 2012; 7th German Conference on, pages: 1-6, 2012 (inproceedings)

Abstract
We present the hardware and reconfiguration experiments for an autonomous self-reconfigurable modular robot called Roombots (RB). RB were designed to form the basis for self-reconfigurable furniture. Each RB module contains three degrees of freedom that have been carefully selected to allow a single module to reach any position on a 2-dimensional grid and to overcome concave corners in a 3-dimensional grid. For the first time we demonstrate locomotion capabilities of single RB modules through reconfiguration with real hardware. The locomotion through reconfiguration is controlled by a planner combining the well-known D* algorithm and composed motor primitives. The novelty of our approach is the use of an online running hierarchical planner closely linked to the real hardware.

link (url) [BibTex]

link (url) [BibTex]

2004


Simple and low-cost compliant leg-foot system
Simple and low-cost compliant leg-foot system

Meyer, F., Spröwitz, A., Lungarella, M., Berthouze, L.

In Proceedings of the IEEE/RSJ International Conference on Intelligent Robots and Systems (IROS 2004), 1, pages: 515-520, IEEE, Sendai, Japan, 2004 (inproceedings)

Abstract
We present the design of a simple and low- cost humanoid leg-foot system featuring compliant joints and springy feet. The mechanical compliance of the individual joints can be adjusted by means of visco-elastic material, or metal. To explore some of the relevant characteristics of the proposed system, we performed a series of experiments in which the leg was dropped from a fixed height. Combinations of different materials in the joints (silicone rubber, latex, and brass) as well as a rigid or a compliant foot were used. Additional data were obtained through of a Lagrangian analysis of the leg-foot system. Our analyses show that compliant joints not only reduce impactive forces, but also induce smoother joint trajectories. Further, by employing a compliant foot, a higher energy efficiency for the movement is achieved.

DOI [BibTex]

2004

DOI [BibTex]