Exploratory design of mechanical devices with motion constraints

Abstract

Mechanical devices are ubiquitous in our daily lives, and the motion they are able to transmit is often a critical part of their function. While digital fabrication devices facilitate their realization, motiondriven mechanism design remains a challenging task. We take drawing machines as a case study in exploratory design. Devices such as the Spirograph can generate intricate patterns from an assembly of simple mechanical elements. Trying to control and customize these patterns, however, is particularly hard, especially when the number of parts increases. We propose a novel constrained exploration method that enables a user to easily explore feasible drawings by directly indicating pattern preferences at different levels of control. The user starts by selecting a target pattern with the help of construction lines and rough sketching, and then finetunes it by prescribing geometric features of interest directly on the drawing. The designed pattern can then be directly realized with an easy-to-fabricate drawing machine. The key technical challenge is to facilitate the exploration of the high dimensional configuration space of such fabricable machines. To this end, we propose a novel method that dynamically reparameterizes the local configuration space and allows the user to move continuously between pattern variations, while preserving user-specified feature constraints. We tested our framework on several examples, conducted a user study, and fabricated a sample of the designed examples.

Computational Design and Optimization of Non‐Circular Gears

“…To address the challenges, Zhang et al [ZAC∗17] retargeted an existing mechanism to a user‐specified input shape, while Hergel and Lefebvre [HL15] generated mechanisms from 2D designs crafted by users. Rather than relying on existing mechanisms or user sketches, a number of research works gain more flexibility in designing the mechanisms by automatically constructing and connecting various classes of mechanical components, including traditional mechanical elements (such as cams [ZXS∗12], gears [CTN∗13, RCLM18], and linkages [TCG∗14, BCT15, NBA19]), mechanical modules for oscillation [CLM∗13], elemental mechanisms with higher pair joints [SWT∗17], and even flexible mechanisms with compliant joints [MZB∗17] or kinetic wires [XKCB18]. Among the above works, Coros et al [CTN∗13] incorporate non‐circular gears for designing mechanical characters that can display user‐specified motions, in which the relation between the gears profile and transmission function is also modelled.…”