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Barbara Frank

Research

Motion Planning in Environments with Deformable Objects

The ability to plan their own motions and to reliably execute them is an important precondition for truly autonomous robots. In our work, we consider the problem of motion planning for robots in environments with non-rigid obstacles such as curtains or plants. We combine probabilistic roadmap planning with a physical simulation of object deformations to determine a path that optimizes the trade-off between the deformation cost and the distance to be traveled. Our approach utilizes Finite Element theory for computing the deformation costs. Carrying out the corresponding simulations during planning time, however, is time-consuming. Therefore, we present an approach to model object deformation cost functions based on Gaussian process regression, which can be efficiently evaluated when answering path queries. For stationary objects, the simulations of robot motions to generate data for regression can be done in a preprocessing step. We implemented our approaches on real robots and applied the developed planning framework to different platforms, a wheeled robot and a manipulator with seven degrees of freedom. The examples below demonstrate that our robots are able to successfully navigate in environments with deformable obstacles.
  • Robot Navigation in 2D
In this simulated planning example, the deformation of rubber ducks is more expensive than the deformation of curtains. Accordingly, the robot chooses a path that avoids the rubber ducks.
Query Time: 0.13s.
This real world experiment demonstrates how our robot Albert navigates in an environment with deformable curtains. Furthermore, it shows how the robot performs a basic collision avoidance and is able to distinguish allowed contacts with the curtains from collisions with dynamic obstacles.
Query Time: 0.1s.
  • Planning for Manipulators in 3D
 
In this real-world planning example, the manipulator has to reach a goal configuration behind a deformable foam mat. If deformable obstacles are ignored, the shortest path to the goal is chosen (left figure). The robot destroys the experimental setup when executing this path. Our planner, in contrast, chooses a path that trades off deformation costs and motion costs (right figure). When moving along this trajectory, the robot keeps the deformation of the foam mat to a minimum. The videos demonstrate how our manipulation robot Zora executes the planned motions.
Query Time: 8.6s.
 
The robot has to move its endeffector to the target position behind the deformable teddy bear (indicated in red). The left image shows the shortest path to the goal while the right image shows the computed path that trades off path and deformation cost. The video illustrates the execution of these paths in our deformation simulation.
 
The robot has to move its end effector from its current position to the target position left of the deformable teddy bear (indicated in red). The left image shows the shortest path to the goal while the right image shows the computed path that trades off path and deformation cost. The video illustrates the execution of these paths in our deformation simulation.
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