Unfolding the Mystery of Microrobots

Traditional robotic systems have always had difficulty exploring tight or cluttered spaces due to their size and maneuverability limitations. However, the development of centimeter-scale robots has opened up new frontiers in exploration, allowing for unprecedented access to confined areas that larger robots simply cannot navigate. These tiny robots, often no larger than a few centimeters, have great potential in a variety of fields and applications, from search and rescue operations to medical procedures and environmental monitoring.

The main advantage of centimeter-scale robots is that they can access spaces that are too small or complex for larger robots. These robots can navigate through narrow pipelines, inspect machinery with intricate components, or explore collapsed structures in disaster-stricken areas, providing critical insights and information in situations where human intervention may be hazardous or impractical.

Despite this, designing and building these tiny robots presents significant engineering challenges. The complexity arises from the need for the robots to perform complex actions such as walking, crawling, and steering, which typically require a multitude of actuators. Traditional actuators, even when scaled down to tiny dimensions, can be bulky and add to the overall size of the robot, defeating the purpose of creating a compact and agile device. Additionally, the use of these conventional components often makes these robots more expensive, hindering the feasibility of deploying large swarms, especially in scenarios where the robots might not return, such as in one-way missions or hostile environments.

To make highly functional centimeter-scale robots practical for widespread use, significant advancements are necessary. One such advancement has recently been proposed by a team led by researchers at the University of Pennsylvania. They have developed a centimeter-scale quadrupedal robot that walk, crawl, steer, fold, and unfold, all while using only a single actuator. The clever design stores mechanical energy in the robot’s body to limit the power required of (and therefore the size of) the actuator.

The technique that makes this possible, called CurveQuad, relies on origami folds made in the body of the robot. The team did not use conventional, straight-line folds, however, instead opting to leverage curved creases. These curved folds store more mechanical energy and induce bending in the folded sheets. A relatively small force from the actuator can begin the process of unleashing that larger, stored force. And through careful design, that larger force can be utilized to move the robot in specific, useful patterns. These properties of CurveQuad allow for very small robots to be constructed, and at a low cost.

The CurveQuad method is suitable for mass manufacturing. The process of producing a robot is relatively simple, as they can be constructed from just a few flat sheets of material that fold into the final three-dimensional shape. Onboard electronics and the actuator can also be embedded within these sheets.

A prototype robot was built using the team’s techniques that weighs just eleven grams and measures eight centimeters in length. Through the inclusion of simple curved folds, this robot can walk, crawl, and more. A demonstration was conducted that showed the robot can autonomously walk towards a light source. The possibility of creating swarms of these devices was also shown, with the researchers demonstrating a set of four of these light-seeking robots in operation simultaneously.

At present, the robot can only function on level ground, but the team is exploring options that could get it working on sloped or rough terrain. They are also investigating the possibility of adding additional circuitry that could enable wireless communication between robots in a swarm.