Design and Implementation of Programmable Drawing Automata based on Cam Mechanisms for Representing Spatial Trajectory

This paper presents the design and implementation of a preliminary version of a programmable drawing automaton (PDA-0) that draws a user-specified 3D trajectory. PDA-0 is strongly inspired by Jaquet Droz's a programmable drawing automaton built in the 1770s using 6,000 moving parts, which was hand-coded. PDA-0 consists of RSSR (Revolute-Spherical-S-R) linkage and cam mechanisms with three interchangeable cams. Interchangeable cams make PDA-0 programmable because a user-specified 2D/3D trajectory is encoded into the set of three cams. The user programs PDA-0 by specifying a trajectory via a GUI or 3D animation. Subsequently, the compiler estimates a 3D trajectory mathematically from the user-specified 2D/3D trajectory and calculates the shape of the three cams, i.e., a code for PDA-0 by solving kinematic constraints. Finally, PDA-0 with the 3D-printed cams executes the code to draw the user-specified trajectory. The current PDA-0 with three cams demonstrates drawing simple trajectories such as letters and symbols.