H-wall: Encountered-type Haptic Display

INTRODUCTION

We show a novel encountered-type haptic system, H-Wall, to enable haptic feedback using a 7-DoF manipulator suitable for simulating indoor VR environments, which are characterized and confined by a set of vertical walls and revolving doors. At runtime, our system tracks hand motion using an RGBD sensor and locates its configuration. Then, the robotic manipulator plans a trajectory for the end-effector, attached to a rectangular rigid board, to make a contact with the hand to deliver a sense of touch, as long as the perceived hand contact force is substantial. The force feedback is generated in a passive sense for static walls that the rigid board, corresponding to a vertical wall, holds its position as long as the perceived hand contact force is substantial. For a revolving door, the force feedback is generated in an active sense based on impedance control. In order to address the issue of limited workspace, we also propose a new reachability map, called per-plane reachability maps, that is optimized to answer whether passive haptic feedback can be generated by a manipulator when the user touches a vertical wall at a given orientation. These maps are generated offline using optimization and are looked up at runtime.

SYSTEM

SYSTEM SETUP

We use KUKA LBR IIWA 7 R800 manipulator as a haptic device.

A transparent, lightweight Acrylic Panel is attached to the IIWA end-effector and serves as a proxy for a virtual walls and doors.

We use Kinect for Windows for tracking usesr hand and head position.

Oculus Rift CV1 is used for rendering virtual environment and virtual hand.

SYSTEM

H-WALL SYSTEM

User Tracking

Head and hand positions of user are tracked by a RGBD Sensor.

Tracked data are transformed from the camera frame to the robot base frame.

Checking Reachability

Using pre-computed per-plane reachability maps(PPRM), check if the user's hand pose is realizable in runtime.

When an input value is inside the PPRM, update the position of manipulator and a avatar hand.

When an input value is outside the PPRM, manipulator and virtual hand maintain their position and wait for the next update.

Haptic Rendering

A 7-DoF manipulator, capable of human-robot-coexistence, operates as a haptic device.

Passive haptic feedback is provided by both position-based and force based control.

Active haptic feedback is provided by both position-based and impedance based control.

Visual Rendering

A user's virtual hand and an indoor virtual environment are rendered through the HMD.

OUR APPROACH

PER-PLANE REACHABILITY MAPS

Reachability map is a set of points that can be reached by a robot reference point.

We impose the characteristics of vertical object as additional constraints.

We take sampling based method and compute reachable boundary of manipulator per plane.

OUR APPROACH

OPTIMIZATION-BASED COMPUTATION

Per-plane reachability maps with a fixed orienrtation

We formulate a set of equality constraints in terms of orientation and position.

Based on the constraint formaulation, we set up an objective function to calculate extremal y values.

Solve the non-linear optimization problem and get boundary points of each per-plane reachability map.

RESULT

Passive Haptic Interaction

The end effector of the manipulator follows the hand position while maintaining its configuration toward the virtual static object.

RESULT

Active Haptic Interaction

The manipulator serves as an active haptic device representing the virtual dynamic object.

CONTACT

ewha graphics lab

Department of Computer Science & Engineering, Ewha Womans University

52, Ewhayeodae-gil, Seodaemun-gu, Seoul, Korea, 03760
+82-2-3277-6798
  Yaesol Kim, yaesol91@ewhain.net

  Hyun Jung Kim, hjkim013@ewhain.net

  Young J. Kim, kimy@ewha.ac.kr

Encountered-type Haptic Display for Large VR Environment
using Per-plane Reachability Maps

Yaesol Kim, Hyun Jung Kim, and Young J. Kim

RESULT

Passive Haptic Interaction

RESULT

Active Haptic Interaction

CONTACT

ewha graphics lab