Because of their high precision and speed, Delta robots are deployed in industrial processes, including pick-and-place assemblies, machining, welding and food packaging. Delta robots use three individually controlled and lightweight arms that guide a platform to move quickly and accurately in three directions. The platform is either used as a stage, like the ones being used in flight simulators, or coupled to a manipulating device that can, for example, grasp, move, and release objects in prescribed patterns. Over time, roboticists have designed smaller and smaller Delta robots for tasks in limited workspaces, yet shrinking them to the millimetre scale with conventional manufacturing techniques and components has proven fruitless.
By integrating their microfabrication technique with high-performance composite materials that can incorporate flexural joints and bending actuators, the milliDelta can operate with high speed, force, and micrometre precision, which make it compatible with a range of micromanipulation tasks in manufacturing and medicine.
In 2011, inspired by pop-up books and origami, the team developed a micro-fabrication approach that enables the assembly of robots from flat sheets of composite materials. The researchers then applied their approach to develop a 15 x 15 x 20mm Delta robot.
“The physics of scaling told us that bringing down the size of Delta robots would increase their speed and acceleration, and pop-up MEMS manufacturing with its ability to use any material or combination of materials seemed an ideal way to attack this problem,” said Professor Robert Wood, co-leader of the Wyss Institute’s Bioinspired Robotics platform. “This approach also allowed us to rapidly go through a number of iterations that led us to the final milliDelta.”
The milliDelta design incorporates a composite laminate structure with embedded flexural joints that approximate the more complicated joints found in large scale Delta robots. “With the help of an assembly jig, this laminate can be precisely folded into a millimetre-scale Delta robot. The milliDelta also utilises piezoelectric actuators, which allow it to perform movements at frequencies 15 to 20 times higher than those of other currently available Delta robots,” said Hayley McClintock, a researcher on Prof Wood’s team.
In addition, the team demonstrated that the milliDelta can operate in a workspace of about 7mm3 and that it can apply forces and exhibit trajectories that, together with its high frequencies, could make it ideal for micromanipulations in industrial pick-and-place processes and microscopic surgeries such as retinal microsurgeries performed on the human eye.
