Hybrid position/force control for biped robot stabilization with integrated center of mass dynamics

Sygulla, Felix; Wittmann, Robert; Seiwald, Philipp; Hildebrandt, Arne-Christoph; Wahrmann, Daniel; Rixen, Daniel J.

doi:10.1109/humanoids.2017.8246955

Cited by 9 publications

(10 citation statements)

References 28 publications

(35 reference statements)

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“…[41][42][43] Others rely on the estimation of the Center of Pressure (COP) by using the data from sensors installed under the feet. [44][45][46] In Ref. 47 a motion primitives switching methodology is introduced that provides a more e±cient posture control to compensate for di®erent disturbances patterns.…”

Section: Resultsmentioning

confidence: 99%

Design and Modeling of a Lightweight and Low Power Consumption Full-Scale Biped Robot

Folgheraiter

Aubakir

2018

Int. J. Human. Robot.

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This paper introduces the design methodology, the modeling and the power consumption tests for a newly developed biped robot equipped with 12 DOFs. The robot is 1.1 meters tall (lower limbs) which makes it comparable in dimension with other state-of-the-art full-scale humanoids. By using a combination of 3D printing techniques and lightweight materials, the system weighs only 10.8[Formula: see text]kg (without batteries) while retaining high links strength and rigidity. Without compromising the workspace dimension, the robot presents a very low weight-to-height ratio (9.8[Formula: see text]kg/m) that translates into a safer operation and reduced energy consumption. To perform elementary locomotion primitives, e.g., changing the support from one foot to the other or lifting its body, the robot prototype consumes only 65 watts. Simulation results demonstrate the suitability of the robot’s kinematics to perform walking motion and predict an average power consumption of 200 watts. The direct kinematics of the robot is presented together with its inverse dynamics based on a Chaotic Recurrent Neural Network (CRNN). The adaptive model is identified using a recursive least squares algorithm that allows the CRNN to predict the torques at different step lengths with a MSE of 0.0057 on normalized data.

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Section: Resultsmentioning

confidence: 99%

Design and Modeling of a Lightweight and Low Power Consumption Full-Scale Biped Robot

Folgheraiter

Aubakir

2018

Int. J. Human. Robot.

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“…21 The resulting desired forces/torques l f ;d for each foot f are then fed into corresponding instances of a hybrid position/force-control scheme. 12 The included force controller tracks the desired ground reaction forces based on the measured forces l f ;m by modification of the task-space trajectories. These newly modified trajectories w mod ; _ w mod are then passed to a velocity-level inverse kinematics.…”

Section: Control Structurementioning

confidence: 99%

“…6 To compensate for such disturbances and model inaccuracies caused by the planning of the center of mass (CoM) trajectories, fast feedback loops are typically deployed. [7][8][9][10][11][12] For robots with torque-controlled joints, this is usually the position control of the CoM to track a desired reference trajectory based on the estimated robot state. 11,[13][14][15] Robots with position-controlled joints usually require an additional force-control loop to track desired ground reaction forces based on force/torque sensor data.…”

Section: Introductionmentioning

confidence: 99%

“…11,[13][14][15] Robots with position-controlled joints usually require an additional force-control loop to track desired ground reaction forces based on force/torque sensor data. 7,10,12 So far, uneven terrains are traversed at low walking speeds 2,5,[16][17][18][19] to keep the perception errors low and maintain stability. We focus, however, on a force-control approach for the traversal of uneven terrain at high walking speeds (v !…”

Section: Introductionmentioning

confidence: 99%

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A force-control scheme for biped robots to walk over uneven terrain including partial footholds

Sygulla

Rixen

2020

International Journal of Advanced Robotic Systems

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The robustness of biped walking in unknown and uneven terrains is still a major challenge in research. Traversing such environments is usually solved through vision-based reasoning on footholds and feedback loops—such as ground force control. Uncertain terrains are still traversed slowly to keep inaccuracies in the perceived environment model low. In this article, we present a ground force-control scheme that allows for fast traversal of uneven terrain—including unplanned partial footholds—without using vision-based data. The approach is composed of an early-contact method, direct force control with an adaptive contact model, and a strategy to adapt the center of mass height based on contact force data. The proposed method enables the humanoid robot Lola to walk over a complex uneven terrain with 6 cm variation in ground height at a walking speed of 0.5 m/s. We consider our work a general improvement on the robustness to terrain uncertainties caused by inaccurate or even lacking information on the environment.

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“…The ideal task-space trajectories are then passed to the Stabilization and Inverse Kinematics (SIK) module, which additionally takes into account direct sensor input to modify the planned motion and thus stabilizes the robot in the presence of disturbances. An overview of the implemented hybrid position/force control is given in [26]. For this paper, we use the version specified in [27] where support for partial contacts is disabled.…”

Section: B Softwarementioning

confidence: 99%

Quintic Spline Collocation for Real-Time Biped Walking-Pattern Generation with variable Torso Height

Seiwald

Sygulla

Staufenberg

et al. 2019

2019 IEEE-RAS 19th International Conference on Humanoid Robots (Humanoids)

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This paper presents our newest findings in planning a dynamically and kinematically feasible center of mass motion for bipedal walking robots. We use a simplified robot model to incorporate multi-body dynamics and kinematic limits, while still being able to meet hard real-time requirements. The vertical center of mass motion is obtained through interpolation of a quintic spline whose control points are projected onto the kinematically feasible region. Subsequently, the horizontal motion is computed from multi-body dynamics which we approximate by solving an overdetermined boundary value problem via spline collocation based on quintic polynomials. The proposed algorithm is an improvement of our previous method, which used a parametric torso height optimization for vertical and cubic spline collocation for horizontal components. The novel center of mass motion improves stability, especially for stepping up and down platforms. Moreover, the new method leads to a less complex overall algorithm since it removes the necessity of manually tuned parameters and strongly simplifies the incorporation of boundary values. Lastly, the new approach is more efficient, which leads to a significantly reduced total runtime. The proposed method is validated through successfully conducted simulations and experiments on our humanoid robot platform, LOLA.

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Hybrid position/force control for biped robot stabilization with integrated center of mass dynamics

Cited by 9 publications

References 28 publications

Design and Modeling of a Lightweight and Low Power Consumption Full-Scale Biped Robot

Design and Modeling of a Lightweight and Low Power Consumption Full-Scale Biped Robot

A force-control scheme for biped robots to walk over uneven terrain including partial footholds

Quintic Spline Collocation for Real-Time Biped Walking-Pattern Generation with variable Torso Height

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