Design of a Passively Balanced Spatial Linkage Haptic Interface

Abstract

This paper describes the design and implementation of a compact high fidelity desktop haptic interface that provides three-degree-of-freedom point-force interaction through a handheld pen-like stylus. The complete haptic device combines a spatial linkage, actuation, power amplification, and control electronics in a standalone package with a footprint similar to that of a notebook computer 33cm×25cm×10cm. The spatial linkage is composed of one planar and two spherical subloops. Two versions of the spatial linkage were designed: a lightweight polycarbonate plastic version suitable for inexpensive mass production, and an aluminum and stainless steel linkage that offers greater reliability and higher stiffness. Both linkages were designed to be statically balanced over their full workspace.

Discrimination of Real and Virtual Surfaces with Sinusoidal and Triangular Gratings Using the Fingertip and Stylus

“…The device is based on the mechanical linkage described by Adelstein [38] and implemented by Steger et al [39], but with a revised ethernet-enabled embedded controller for stand-alone operation designed and built by Traylor et al [37]. The ministick has a calibrated position resolution of 1:5 m [20].…”

Discriminability of Real and Virtual Surfaces with Triangular Gratings

“…The virtual textures were rendered by the ministick, a 3-DOF high position-resolution force display [5,6] (see Fig. 4).…”

Design Considerations for Stand-Alone Haptic Interfaces Communicating via UDP Protocol

“…Its single planar loop is effectively an extendable parallelogram arm that pivots about the shared center of the two spherical loops. In the current finger-scale implementations [9][10], the parallelogram's upper and lower arm links are each 50.8 mm (2 in) in length. The device's usable, interference-free workspace is enclosed within the hemispherical volume bounded by singularities in the plane of the actuator axes and the radius of maximum arm reach [8] and occupies a region roughly 9 cm by 9 cm by 6 cm (see Figure 1).…”

“…In addition to reducing inertia and mass by mounting its three actuators on its base plate, the mechanism is passively balanced through individual link shape design and alloy selection [10]. The passive mass balance allows actuator effort to be allocated completely to endpoint simulation force production and not the support of individual link weight against gravity.…”