Autocalibrated Gravity Compensation for 3DoF Impedance Haptic Devices

Abstract

Abstract. The apparent mass of haptic device end-effector depends on its position inside the workspace. This paper presents a recursive algorithm to detect effective direction of gravity force, and to automatically estimate the apparent mass of the end-effector when placed at the vertices of a cubic grid contained into the device workspace. Then an on-line technique is proposed to actively compensate gravity, exploiting trilinear interpolation to compute an estimate of end-effector apparent mass in any position of the workspace. Experiments have been performed with three different haptic devices, and results shown that the apparent mass of the end-effector is compensated almost homogeneously with respect to its position in the workspace.

Fall detection for robotic endoscope holders in Minimally Invasive Surgery

“…It requires a first phase where data from random configurations of the robot with a known payload is collected to estimate an inverse equilibrium model. In [10] a method is developed to automatically estimate apparent mass of a 3D haptic device. In a off-line phase they estimate a 3D mapping of apparent masses for the workspace of the robot for each new unknown payload.…”

“…8b m 0 and x G0 are seed values for endoscope's gravity parameters of mass and position of center of mass, respectively. F u represents a Cartesian force applied by the robot at its end-effector by means of (10).…”

Using Postural Synergies to Animate a Low-Dimensional Hand Avatar in Haptic Simulation

“…The demo application was coded in C++ on Win32 API for WindowsXP, using the DirectX 9.0c library and HLSL shaders for the graphic rendering on the Graphic Processing Unit (GPU) [36]. Haptik Library was used for the low-level access to haptic devices [37], Libralis Library [38] for apparent gravity compensation and nVidia PhysX SDK as physics engine on the GPU [39]. The haptic rendering was performed using the god-object algorithm, friction-cone [40], [41].…”

A teleoperation system for micro-invasive brain surgery

“…Compensating these e ects of gravity is not straightforward, since generally they depend on the end-e ector position in the workspace through a non-linear relationship. We adopted the Autocalibrated Gravity Compensation technique [19]. The strategy consists of performing an o -line recursive estimation of the apparent gravity force acting at a certain set of positions inside the workspace.…”