Because of their high precision and speed, Delta robots are deployed in many industrial processes, including pick-and-place assemblies, machining, and welding. Delta robots use three individually controlled and lightweight arms that guide a platform to move fast and accurately in three directions. The platform is either used as a stage — similar to those 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 further to the millimeter scale with conventional manufacturing techniques and components has proven fruitless.

Completely unfolded, the milliDelta’s size roughly compares to a penny. It uses piezoelectric actuators and flexural joints in its three arms to control high-frequency movements of a stage on top. (Wyss Institute at Harvard University)

The milliDelta robot measures 15 × 15 × 20 mm, and integrates microfabrication with high-performance composite materials that can incorporate flexural joints and bending actuators. It can operate with high speed, force, and micrometer precision, making it compatible with a range of micromanipulation tasks in manufacturing and medicine.

The microfabrication approach enables the assembly of robots from flat sheets of composite materials. Pop-up MEMS (micro-electromechanical systems) manufacturing has since been used for the construction of dynamic centimeter-scale machines that can walk away or fly.

The milliDelta design incorporates a composite laminate structure with embedded flexural joints that approximate the more complicated joints found in largescale Delta robots. Using an assembly jig, this laminate can be precisely folded into a millimeter-scale Delta robot. The milliDelta also utilizes piezoelectric actuators, which allow it to perform movements at frequencies 15 to 20 times higher than those of other currently available Delta robots.

In addition, the milliDelta can operate in a workspace of about 7 cubic millimeters, and can apply forces and exhibit trajectories that, together with its high frequencies, could make it ideal for micromanipulation in industrial pick-and-place processes and microscopic surgeries such as retinal microsurgeries performed on the human eye.

The robot has been tested as a hand tremor-canceling device. The paths that the tip of a toothpick circumscribed when held by an individual were mapped, computed, and fed into the milliDelta robot, which was able to match and cancel them out. Specialized milliDelta robots could either be added on to existing robotic devices, or be developed as standalone devices like, for example, platforms for the manipulation of cells in research and clinical laboratories.

Watch a video of the milliDelta robot on Tech Briefs TV here.


Motion Design Magazine

This article first appeared in the April, 2018 issue of Motion Design Magazine.

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