A collocation method for real-time walking pattern generation

Buschmann, Thomas; Lohmeier, Sebastian; Bachmayer, M.; Ulbrich, H.; Pfeiffer, Friedrich

doi:10.1109/ichr.2007.4813841

Cited by 89 publications

(103 citation statements)

References 19 publications

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“…The foot trajectories and the CoM trajectories are the p optdependent components of w d . The boundary problem of the CoM movement is solved applying the collocation method as described in [26]. This generates the CoM horizontal 3 For the sake of simplicity, we replace v(t i ) = v i .…”

Section: F Gradientmentioning

confidence: 99%

Real-time predictive kinematic evaluation and optimization for biped robots

Hildebrandt

Demmeler

Wittmann

et al. 2016

2016 IEEE/RSJ International Conference on Intelligent Robots and Systems (IROS)

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Abstract-Collision-free walking in cluttered environments is still an open issue for humanoids. Most current approaches use heuristics with large safety margins to plan the robot's motion. That way, the chance of collisions can be greatly reduced but the robot movements are limited artificially. In this context, we extend our framework for motion generation and whole-body collision-avoidance by an online predictive kinematic parameter evaluation and optimization: We propose to evaluate the initial parameter set describing the walking pattern by integrating the full kinematic model of the robot. In the model our local optimization technique for collision avoidance is taken into account. Initial parameter sets, which are kinematically infeasible due to kinematic limits or collisions can be identified and adapted before the motion is executed. Additionally, the parameter set is optimized according to a chosen cost function using a gradient method and the step time is adapted according to a desired mean velocity. The optimization method is applicable to different representations of the walking pattern. The method is presented with simulation results obtained with our multi-body simulation. The method is suitable for real-time control, since the optimization can be stopped if it exceeds a predetermined time budget. In that case, an executable but suboptimal result is used. The proposed procedure is executed before each step which makes it very reactive to changes in the environment or in the user input. We have also validated the real-time performance in experiments with our humanoid Lola.

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Section: F Gradientmentioning

confidence: 99%

Real-time predictive kinematic evaluation and optimization for biped robots

Hildebrandt

Demmeler

Wittmann

et al. 2016

2016 IEEE/RSJ International Conference on Intelligent Robots and Systems (IROS)

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“…III-B). Note that the collocation method proposed in [31] would also enable modifications of the vertical CoM trajectory, which might be valuable for very large obstacles. This has, however, not been necessary so far.…”

Section: Step-planner and Heuristic Trajectory Adaption (Spta)mentioning

confidence: 99%

Real-time pattern generation among obstacles for biped robots

Hildebrandt

Wahrmann

Wittmann

et al. 2015

2015 IEEE/RSJ International Conference on Intelligent Robots and Systems (IROS)

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Abstract-In this paper we present a step-planner embedded in a framework which enables a humanoid robot to navigate among obstacles, exploiting its overall capacities. The system allows the robot to react to changes of user input in real-time while walking at reasonable speeds. The proposed method relies neither on external sensors nor on color coding or textured surfaces. The key idea is to use a fast collision model based on swept-sphere-volumes (SSVs) for real-time generation of collision-free footsteps and whole-body trajectories. Using a SSV-based 3D approximation in all control modules enables the robot to avoid collisions with itself and the environment. Obstacles are detected with an on-board RGB-D sensor while the robot navigates through an environment which is not known in advance. A step-planner reacts to high-level user commands like desired velocity and direction within less than a step. Instead of investigating only the footholds an articulated 3D approximation of the lower leg and the foot is considered to find feasible and optimal footstep locations. Additionally, it provides an initial solution for the swing-foot movement. Final, Collision-free swing-foot trajectories are created in real-time in the feedback control layer using all the foot's degrees of freedom. We validated this approach in experiments with our robot Lola.

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“…A generation of walking trajectories using a three pointwise mass model to compute reference torque instead of ZMP trajectories has been proposed in [13].…”

Section: Introductionmentioning

confidence: 99%

Optimal Pattern Generator for Dynamic Walking in humanoid Robotics

Galdeano¹,

Chemori²,

Krut³

et al. 2016

Systems, Analysis and Automatic Control

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Abstract-This paper deals with an optimal ZMP based pattern generator for stable dynamic walking. The proposed method is based on a Three-Mass Linear Inverted Pendulum Model (3MLIPM), used as a simplified dynamics of the biped robot. The 3MLIPM simplifies the biped robot as a three point masses and two-link system. A ZMP based criterion is then used in an optimization problem whose solution gives the best values of the model's parameters w.r.t. dynamic walking stability. Numerical simulations are presented to show the effectiveness of the proposed optimal pattern generator.

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A collocation method for real-time walking pattern generation

Cited by 89 publications

References 19 publications

Real-time predictive kinematic evaluation and optimization for biped robots

Real-time predictive kinematic evaluation and optimization for biped robots

Real-time pattern generation among obstacles for biped robots

Optimal Pattern Generator for Dynamic Walking in humanoid Robotics

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