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RE2 Robotics
The Era of the Mobile Manipulator has begun
Jorgen Pedersen
When you think “robotic arm”, a vision of a large, fast, powerful arm welding an automobile on an assembly line is likely to be one of the first images to enter your mind. Industrial automation has been the main consumer of the “industrial robotic arm” since 1961, when the Unimate robotic arm was first installed in a General Motors die casting facility. These robotic arms, or “manipulators”, continue to serve the industrial automation market, providing solutions that offer the quality and throughput needed to compete in today’s market.
“The mobile manipulators developed over the past decade for the Defense market were designed specifically for mobile applications”
The traditional industrial manipulator typically features two to six Degrees of Freedom (DOF), where a 6 DOF is the most common as it allows the arm’s end-of-arm tool, or “end-effector”, to be placed in any position or orientation within its workspace. In order to be effective, these arms must be fast, strong, reliable, repeatable, and affordable. Although these traditional arms offer tremendous capability, they are unsafe for humans to be around, requiring fencing or other solutions for keeping humans away from them during operation.
In recent years, lighter weight manipulators have been entering the market to perform tasks that require the robot to work side by side with humans without major external sensing infrastructure. These “collaborative robots” are safer than their industrial counterparts. Safety is achieved primarily by limiting speed and force—relegating the use of these arms to applications that do not require high speed or heaving lifting.
These industrial and collaborative robots are well suited for stationary applications—i.e. mount the arm to a known location and perform a specific
Mobile robots are not new. Robotic platforms that can move throughout their environments have been around for many years. The early adopters for mobile robotics were the military and law enforcement markets. The unfortunate event of 9/11 had a tremendous impact on the proliferation of mobile robotics within these markets. The number of robotic platforms deployed to Afghanistan and later Iraq rose from 12 in 2001 to over 7,000 in 2010, most of which were fitted with a mobile manipulator to tackle dangerous missions such as defusing roadside bombs. As a result, significant core technology was created to provide unprecedented capability for mobile applications. This mobile manipulator capability will not only benefit the Defense market, but will be applicable to other markets as the need for mobility increases.
Traditional industrial robotic arms were designed for structured, indoor environments, where the critical requirements were not size, weight, and power. From the lens of usability for mobile applications, these arms are bulky (especially when considering the control electronics/computing), heavy, and require significant power to operate (i.e. not designed specifically for battery power). In contrast, the mobile manipulators developed over the past decade for the Defense market were designed specifically for mobile applications. Not only were size, weight, and power primary design drivers, but shock, vibration, and environmental (rain, snow, temperature, dust, etc.) requirements were also considered as these robotic arms were being designed. The fact that Soldiers were often carrying robots while on foot drove another tremendous benefit: high strength-to-weight ratio. A mobile manipulator with equivalent lifting capability as an industrial arm may weigh up to ten times less. This means that the run-time of the mobile platform will be less impacted. There is another benefit too – safetycan be directly tied to inertia–the lighter an arm is, the safer it is. This allows mobile manipulators to be considered for collaborative robot applications. The goal now is to drive down the cost.
The day of the mobile manipulator is upon us. The technology has now matured to a level that can provide human-like capability: lightweight, power-efficient, strong, fast, and dexterous robotic arms, including two arms working together. We will see the mobile manipulator solving many unmet needs in the coming years, such as increasing throughput on the factory floor, harvesting specialty crops, helping to transfer patients from wheel chairs to beds, securing our ports using underwater robots, and some day even cleaning our homes!
