Multi-contact haptic exploration and grasping with tactile sensors

Abstract

Haptic exploration has received a great deal of attention of late thanks to the variety of commercially available tactile sensors. While the majority of previous works consider control of a single contact point at a time, we tackle simultaneous control of multiple contact points on several links. In addition, we use information from the existing tactile signals to increase the number of points in contact. We demonstrate the usefulness of this form of control to speed up exploration, scanning and to compliantly grasp unknown objects. Our controller requires to know only the parts of the robot on which it is desirable to make contact and does not need a model of the environment besides the robot itself. We validate the algorithm in a set of experiments using a robotic hand covered with tactile sensors and arm. In a grasping application, the active adaptation of the fingers to the shape of the object ensures that the hand encloses the object with multiple contact points. We show that this improves the robustness of the grasp compared to simple enclosing strategies. When combined with an exploration strategy, our multi-contact approach offers an efficient use of tactile sensors on the whole surface of robotic fingers, and enables the robot to perform a rapid exploration of complex, non convex shapes while maintaining low contact forces. It is robust to variation in the approach angle and to changes in the geometry and orientation of the object.

Exploratory Tactile Servoing With Active Touch

“…Over the last few years, multiple approaches have been proposed that combine tactile sensor control with perception. When the control of the sensor is the main goal, then the work has has been termed tactile servoing [4], exploration [20] or manipulation [1], [5], [21]. When the perception is the main goal, this work has been termed active perception [11] or active exploration [22].…”

“…Over the last few years there have been several physical demonstrations of combined tactile control and perception, e.g. [1]- [5]. However, progress is still far from a general purpose solution with the flexibility and robustness of human touch.…”

iCLAP: shape recognition by combining proprioception and touch sensing

“…With the collected tactile patterns and contact locations, the algorithm proposed in this paper can be implemented for the object recognition task. To explore the unknown object, the planning methods in the literature [5], [45] can be applied to design the exploration strategies. In the haptic exploration, a confidence level of object recognition can be defined, and multiple grasps are implemented to explore the object surfaces iteratively until the defined confidence level is achieved.…”

Adaptive force and velocity control based on intrinsic contact sensing during surface exploration of dynamic objects

“…Yang and Lepora (2017) tried to combine vision for object exploration for edge estimation. Sommer and Billard (2016) presented a Multi-contact haptic exploration method manly for grasping tasks. Su et al (2012) controlled the movement of the robot arm in the contact normal direction with haptic feedback to characterize the compliance of the pressed object.…”