Imagine a future where agriculture thrives in multilevel warehouses, thanks to groundbreaking advancements in artificial pollination. Researchers at MIT are striving to turn this vision into reality by developing innovative robotic insects capable of efficiently pollinating crops. These tiny aerial bots could revolutionize farming, enhancing yields while significantly reducing the environmental footprint of traditional agriculture.
Current robotic prototypes, however, still lag behind natural pollinators like bees in terms of endurance, speed, and maneuverability. To bridge this gap, the MIT team has drawn inspiration from the remarkable anatomy of these insects, resulting in a noteworthy redesign of their aerial robots that enhances agility and durability.
The newly engineered bots can now hover for approximately 1,000 seconds—over 100 times longer than earlier models. Weighing less than a paperclip, these miniature robots can achieve impressive speeds and perform intricate aerial maneuvers, including double flips. This revolutionary design not only improves flying precision and agility but also reduces mechanical stress on the wings, resulting in faster movements, greater stamina, and an extended lifespan.
Moreover, the construction of the bots allows for additional space, enabling the potential to carry miniature batteries or sensors, paving the path for autonomous flight outside of laboratory settings. “The amount of flight demonstrated in this research is likely greater than what has been achieved in our field so far with robotic insects. With improved longevity and accuracy, we are getting ever closer to practical applications, such as assistance in pollination,” states Kevin Chen, an associate professor in the Department of Electrical Engineering and Computer Science (EECS) and head of the Soft and Micro Robotics Laboratory.
Chen collaborates with co-lead authors Suhan Kim and Yi-Hsuan Hsiao, along with fellow EECS graduate student Zhijian Ren and visiting student Jiashu Huang. Their research is publicly accessible in the journal Science Robotics.
Enhancing Robotic Performance
Previous iterations of these robots consisted of four identical units, each equipped with two wings, forming a bulky device akin to a microcassette. Chen notes, “No insect has eight wings, and our past design saw individual units perform better than the complete assembly.” The initial configuration caused interference between the flapping wings, limiting the lift produced.
The innovative redesign incorporates a streamlined structure, reducing the number of wings by half. Each unit now features one wing flapping outward from the robot’s center, enhancing stability and lift capacity while freeing up essential space for electronic components.
Alongside the structural modifications, the researchers enhanced the transmission systems that connect the wings to their actuators (artificial muscles). These new transmissions are robust and feature longer wing hinges, alleviating the mechanical strain that hampered prior models. “We can now generate three times the control torque compared to older designs, allowing for intricate and highly accurate flying paths,” Chen explains.
While these advancements are impressive, challenges remain. For instance, bees may only have two wings, yet they can execute rapid, finely tuned movements with unparalleled control. The sophisticated muscle arrangements in bees provide a level of refinement that researchers are eager to replicate.
Minimizing Strain While Maximizing Force
The motion of the robot’s wings is propelled by soft actuators made of layers of elastomer and carbon nanotube electrodes. These actuators compress and expand quickly, generating the force necessary for flight. Earlier versions, however, were prone to buckling at the high frequencies required for efficient flight, reducing their overall power. The updated design minimizes this bending effect, allowing for more effective wing flapping.
A crucial aspect of the new design is an elongated wing hinge that helps mitigate torsional stress during flight. Fabricating this hinge, measuring around 2 centimeters in length with a diameter of just 200 microns, posed considerable challenges for researchers. “Even a slight misalignment during manufacturing could affect the hinge’s shape, ultimately impacting wing performance,” Chen elaborates. Through persistent efforts, the team perfects a multistep laser-cutting process, achieving precise fabrication for each hinge.
The result? The robotic insect can now hover for over 1,000 seconds—almost 17 minutes—without any loss in flight accuracy. Chen humorously recalls how stressful it was for his student during the lengthy experiment, calling it “the slowest 1,000 seconds of his life.” Additionally, the robot attained a record speed of 35 centimeters per second while executing body rolls and flips, showcasing its agility as it accurately traced out the letters M-I-T.
“We’ve demonstrated flight durations that surpass all prior achievements in our field, marking an incredibly exciting milestone,” Chen said. From here, the research team aims to push the boundaries of their design, targeting a flight duration exceeding 10,000 seconds. They also strive to enhance the robot’s capabilities, envisioning it effectively landing and taking off from flowers. Ultimately, the incorporation of sensors, batteries, and computing power will be a central focus in the next few years.
This groundbreaking research is supported by funding from the U.S. National Science Foundation and a Mathworks Fellowship.
Photo credit & article inspired by: Massachusetts Institute of Technology
