Can ‘turn on a dime and park on a nickel’

MINI-ROBOT RESEARCH — Sandia National Laboratories researcher Doug Adkins takes a close-up view of the mini-robots he and Ed Heller are developing. At 1/4 cubic inch and weighing less than an ounce, they are possibly the smallest autonomous untethered robots ever created. (Photo by Randy Montoya) Download 300dpi JPEG image, ‘micro_robots.jpg’, 1.7MB (Media are welcome to download/publish this image with related news stories.)

At 1/4 cubic inch and weighing less than an ounce, it is possibly the smallest autonomous untethered robot ever created. Powered by three watch batteries, it rides on track wheels and consists of an 8K ROM processor, temperature sensor, and two motors that drive the wheels. Enhancements being considered include a miniature camera, microphone, communication device, and chemical micro-sensor.

“This could be the robot of the future,” says Ed Heller, one of the project’s researchers. “It may eventually be capable of performing difficult tasks that are done with much larger robots today — such as locating and disabling land mines or detecting chemical and biological weapons.”

He says it could, for example, scramble through pipes or prowl around buildings looking for chemical plumes or human movement. The robots may be capable of relaying information to a manned station and communicating with each other. They will be able to work together in swarms, like insects. The miniature robots will be able to go into locations too small for their larger relatives.

The mini-robot has already maneuvered its way through a field of dimes and nickels and travels at about 20 inches a minute. It can sit easily on a nickel.

The newest robot miniaturization research supports Laboratories Directed Research and Development (LDRD) work started in Sandia’s Intelligent Systems Sensors & Controls Department. In 1996 the department unveiled a Mini Autonomous Robot Vehicle (MARV), a one-cubic-inch robot that contained all the necessary power, sensors, computers, and controls on board. It was made primarily from commercial parts using conventional machining techniques. Over the next several years the department improved the original MARV. The robots’ bodies were made of printed circuit boards, and each had an obstacle detector sensor, radio, temperature sensor, and batteries. At 1.6 x 0.75 x 0.71 inches, they were still larger than was desirable.

Sandia roboticist Ray Byrne, who was involved in the LDRD efforts, says about three years ago Intelligent Systems and Robotics Center teamed with Sandia’s Sensor Technologies Department to further miniaturize the robots. They sought out the department’s help because of its expertise in building sensors and other devices on miniature scales.

By trying new techniques at packaging electronics, wheel design, and body material, the new team of researchers shrunk the robots to 1/4 cubic inch.

Heller, who developed the device’s microelectronics, says one significant innovation that permitted the shrinkage was the use of commercially available unpackaged electronics parts.

“Previous small robots consisted of packaged electronic parts that were more bulky and took up valuable space. By eliminating the packaging and using electronic components in die form, we reduced the size of the robots electronics considerably,” Heller says. “This was a first major step.”

The unpackaged parts are assembled onto a simple multi-chip module on a glass substrate. The assembly was done at Sandia’s Compound Semiconductor Research Laboratory.

Doug Adkins, who developed the mechanical design for the new mini-robot, says the researchers further reduced its size by using a new rapid prototyping technique to form the device’s body. Called stereolithography, the material-building method lays down a very thin polymer deposit that is cured by a laser. The material, which “grows” as each layer is added, is lightweight, strong, and can be formed in complex shapes. The robot bodies have cavities for the batteries, the electronics-embedded glass substrate, axles, tiny motors, switches, and other parts.

MINI-ROBOT “turns on a dime and parks on a nickel.” Download 300dpi JPEG image, ‘microrobot2.jpg’, 332K

Adkins also redesigned the wheel structure of the device. Earlier models had standard wheels. However, the mobility was limited due to the small size of the wheels.

“I thought of how tanks with their track wheels can maneuver over many large objects and realized the mini-robots could benefit from the same type of wheels,” Adkins says. With the addition of tracks, the robot can now move easily on carpet.

The ultimate size of the miniature robots is primarily limited by the size of the power source — the three watch batteries. The body must be large enough to hold batteries to support power requirements of the robot.

“Batteries — both the physical size and battery life — have been one of our biggest issues,” Heller says. “The batteries need to run longer and be smaller.”

Over the next few years, with additional help from other Sandia groups, Heller and Adkins expect to add to the mini-robots either infrared or radio wireless two-way communication capability, as well as miniature video cameras, microphones, and chemical micro-sensors.

Technical contacts:
Doug Adkins, dradkin@sandia.gov, (505) 844-0611
Ed Heller, ejhelle@sandia.gov, 505-844-1798