Exact Bounds on the Contact Driven Motion of a Sliding Object, With Applications to Robotic Pulling

Abstract

Abstract-This paper explores the quasi-static motion of a planar slider being pushed or pulled through a single contact point assumed not to slip. The main contribution is to derive a method for computing exact bounds on the object's motion for classes of pressure distributions where the center of pressure is known but the distribution of support forces is unknown. The second contribution is to show that the exact motion bounds can be used to plan robotic pulling trajectories that guarantee convergence to the final pose. The planner was tested on the task of pulling an acrylic rectangle to random locations within the robot workspace. The generated plans were accurate to 4.00mm ± 3.02mm of the target position and 4.35 degrees ± 3.14 degrees of the target orientation.

Push-Net: Deep Planar Pushing for Objects with Unknown Physical Properties

“…The model-based approaches propose analytic and deterministic models which explain the dynamics of pushing. In order to achieve tractable representation of the dynamics, assumptions and approximations are often adopted in these works [16,14,4,8]. Such simplification inevitably introduces modelling errors which lead to poor generalizability, i.e.…”

“…Motion of an object is determined by physical properties of the object, its environment and external push forces. Some physical properties, such as pressure distributions of objects, are statistically indeterminate [8]. This renders pushing a hard problem in robotics.…”

“…These contribute to making the effect of pushing difficult to determine [16]. Various attempts have been made to come up with forcemotion models for pushing an object [23,8], but these models typically require strong assumptions.…”

Quasi-static analysis of planar sliding using friction patches

“…Note that the result of Theorem 13 applies to the case when no angular velocity for the patch is permitted and it is analogous to pulling/pushing results (compare with Theorem 1 of Huang et al (2017)). However, if angular velocity is allowed, under the same assumption of isotropic frictions, the sticking direction with the largest margin will be perpendicular to the line passing through the COPs of the object and the patch.…”

“…Ruiz-Ugalde et al (2011) studied pushing objects with rectangular support. Under uncertainty of the center of pressure (COP), Huang et al (2017) provided exact bounds for the motion of a sliding object. Pushing on the edge of blocks was revisited based on differential flatness for planning and control (Zhou and Mason, 2017).…”