Now, Disney Research is back at it with 3D printed parts included in designs that allow their animated characters to come to life further, via a system of cables, joints, and hinges. Their method should extend to other artists who also who want to see their cartoon characters in physical form, as well as different movements and poses. They can also use the technique to create other models, objects, and tools.
“The advent of consumer-level 3D printing and affordable, off-the-shelf electronic components has given artists the machinery to make articulated, physical versions of animated characters,” said research scientist Moritz Bächer. “Our approach eliminates much of the complexity of designing those mechanisms.”
The networks used to put the models into motion include a thousand or more cables, with random routing points. The team explains that ‘redundant cables’ are removed and then the routing points are refined to improve movement.
They created an example to show off their new technique with a 2D puppet that can be manipulated into several different stances. Along with that, the team made a gripper tool, along with a simplified robotic hand. All the examples were functional.
“A number of design tools developed over the past 30 years have enabled artists to breathe life into animated characters, creating expressions by posing a hierarchical set of rigid links,” said Markus Gross, Vice President at Disney Research. “In today’s age of robotics and animatronics, we need to give artists and hobbyists similar tools to make animated physical characters just as expressive.”
[Image: Disney Research]
Their work offers ‘the first algorithm’ for kinematic chains and trees, a formula for creating the angles and routing points, as well as two steps for creating a network for the cables which allows movement.
“We tackle the automated design with a two-step approach where we first identify the topology of a network by removing unactuated cables from a large set with routing points chosen at random. In a second step, we refine this network by parameterizing the routing points, taking the path between poses or keyframes into account, and further reducing the network and control forces if possible. To enable co-optimization of cable routing points and actuation forces, we introduce torque equilibrium equations that directly relate joint angles and routing points to the control forces,” state the researchers in their paper.
To 3D print rigid links for the project, the team used an Objet350 Connex 3, printing with both Vero White and Vero Black materials.
[Image: Disney Research]
“We use double torsional springs (parts 8548 and 8555, Lesjofors AB), with tabulated spring stiffnesses of 0.0484 and 0.0950 Nm rad−1, respectively. Pins and bearings are press fitted, speeding up the assembly process.”
Disney Research continues to work on this project in creating hierarchical input and an extension to mechanisms with loops, as well as expanding to include spatial input and more support for the pieces. They also hope to examine the idea of a cable network, as well as better controlling the behavior of the models overall.
The researchers discussed their paper and new method at SCA 2017, the ACM SIGGRAPH/Eurographics Symposium on Computer Animation on July 28 in Los Angeles. Also involved in this project were researchers from ETH Zurich, the Massachusetts Institute of Technology and the University of Toronto. Authors include Vittorio Megaro, Espen Knoop, Andrew Spielberg, David I.W. Levin, Wojciech Matusik, Markus Gross, Bernhard Thomaszewski, and Moritz Bächer. Discuss in the Disney Research forum at 3DPB.com.
[Sources: Disney Research; Phys Org]
