Experimental Analysis of Structural Vibration Problems of a Biped Walking Robot

Berninger, Tobias F. C.; Sygulla, Felix; Fuderer, Sebastian; Rixen, Daniel J.

doi:10.1109/icra40945.2020.9197282

Cited by 7 publications

(8 citation statements)

References 17 publications

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“…the stiffness of the backbone and shoulders -a T-shaped, riveted tubular scaffolding -was too low. As a result, the first critical eigenmode (visible to the low-level controller) occurred at 9.7 Hz already, see [4] for a full Experimental Modal Analysis (EMA) of the previous setup. Unfortunately, bipedal walking excites modes in such low frequency domains, which limits the performance of the lowlevel controller, [4].…”

Section: Previous Limitations and Requirementsmentioning

confidence: 99%

“…As a result, the first critical eigenmode (visible to the low-level controller) occurred at 9.7 Hz already, see [4] for a full Experimental Modal Analysis (EMA) of the previous setup. Unfortunately, bipedal walking excites modes in such low frequency domains, which limits the performance of the lowlevel controller, [4]. Finally, it was clear that the previous upper body design would not have been able to withstand the increased loads in a multi-contact setting.…”

Section: Previous Limitations and Requirementsmentioning

confidence: 99%

“…This may be because, in most cases, the torso has no active or passive Degrees of Freedom (DoF). However, it has been shown in [4] that the structural dynamics of a stiff torso can be critical to the performance of the low-level controller and need to be designed carefully. We will return to this issue in Section III.…”

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

LOLA v1.1 – An Upgrade in Hardware and Software Design for Dynamic Multi-Contact Locomotion

Seiwald

Sygulla

et al. 2021

2020 IEEE-RAS 20th International Conference on Humanoid Robots (Humanoids)

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This paper presents recent and ongoing hardware and software upgrades to our humanoid robot LOLA. The purpose of these modifications is to achieve dynamic multicontact locomotion, i. e., fast bipedal walking with additional hand-environment support for increased stability and robustness against unforeseen disturbances. The upper body of LOLA has been completely redesigned with an enhanced lightweight torso frame and more robust arms with additional degrees of freedom, which extend the reachable workspace. The mechanical structure of the torso is optimized for stiffness with the help of an experimental modal analysis performed on the real hardware, while the new arm topology is the result of kinematic optimization for typical use-cases in a multi-contact setting. We also propose extensive changes to our software framework, which include a complete redesign of the onboard, real-time perception and navigation module. Although the hardware upgrade is finished and the overall software design is complete, the implementation of various modules is still work in progress.

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Section: Previous Limitations and Requirementsmentioning

confidence: 99%

Section: Previous Limitations and Requirementsmentioning

confidence: 99%

See 1 more Smart Citation

LOLA v1.1 – An Upgrade in Hardware and Software Design for Dynamic Multi-Contact Locomotion

Seiwald

Sygulla

et al. 2021

2020 IEEE-RAS 20th International Conference on Humanoid Robots (Humanoids)

Self Cite

View full text Add to dashboard Cite

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“…The frame data is not padded at its end. We choose the FFT length based on the minimum resolvable frequency f min = fs nfft ≈ 9.8 Hz -a value where typically the lowest mechanical eigenfrequencies of robots reside, [17]. The amplitudes resulting from the FFTs are used for the spectrogram; phase data is not used.…”

Section: A Data Preprocessingmentioning

confidence: 99%

Learning the Noise of Failure: Intelligent System Tests for Robots

Sygulla¹,

Rixen²

2021

Preprint

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Roboticists usually test new control software in simulation environments before evaluating its functionality on real-world robots. Simulations reduce the risk of damaging the hardware and can significantly increase the development process's efficiency in the form of automated system tests.However, many flaws in the software remain undetected in simulation data, revealing their harmful effects on the system only in time-consuming experiments. In reality, such irregularities are often easily recognized solely by the robot's airborne noise during operation. We propose a simulated noise estimate for the detection of failures in automated system tests of robots. The classification of flaws uses classical machine learning -a support vector machine -to identify different failure classes from the scalar noise estimate.The methodology is evaluated on simulation data from the humanoid robot LOLA. The approach yields high failure detection accuracy with a low false-positive rate, enabling its use for stricter automated system tests. Results indicate that a single trained model may work for different robots. The proposed technique is provided to the community in the form of the open-source tool NoisyTest, making it easy to test data from any robot. In a broader scope, the technique may empower real-world automated system tests without human evaluation of success or failure.

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“…The impulse excitation produced by impact hammer is actuated on the robot end effector. The actuated force and the corresponding acceleration response are simultaneously recorded to perform experimental modal analysis for obtaining the modal parameters information of industrial robots (Berninger et al, 2020; Lich et al, 2021; Ondra & Titurus, 2020; Saito & Kuno, 2020). To identify the accurate modal information hidden in the excitation and response process, many system identification methods had been gradually introduced in this field.…”

Section: Introductionmentioning

confidence: 99%

Improved subspace modal identification of industrial robots

Qiao

Cao

Huang

et al. 2023

Journal of Field Robotics

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Industrial robots have become key components for manufacturing automations due to their larger workspaces and flexibility. However, low stiffness and high compliance of industrial robots may inevitably lead to vibration by self-excitation or periodic force dependent on workspace configuration. Therefore, the knowledge of the robot's modal properties should be accurately required to enhance the operation accuracy of industrial robots. To improve the identification accuracy of experimental modal parameters of field industrial robots, an improved subspace identification method is proposed to perform nonlinear iterative optimization for updating the state parameters of industrial robots. Experimental response measurement of a six-degrees-of-freedom industrial robot is carried out to obtain modal

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Experimental Analysis of Structural Vibration Problems of a Biped Walking Robot

Cited by 7 publications

References 17 publications

LOLA v1.1 – An Upgrade in Hardware and Software Design for Dynamic Multi-Contact Locomotion

LOLA v1.1 – An Upgrade in Hardware and Software Design for Dynamic Multi-Contact Locomotion

Learning the Noise of Failure: Intelligent System Tests for Robots

Improved subspace modal identification of industrial robots

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