June 10, 2006

From the famous Metropolis of 1927 to the 1987 release Robocop to I, robot (2004), robots have generated a lot of interest among human beings. These machines have come a long way from their sci-fi image. Here, we will talk about robots that have been provided with the capability to move around, explore their environment and survey or manipulate objects. Such robots have been given the name “mobile robots”.

Although similar machines known as Automated Guided Vehicles (AGVs) are being used in the industry for material transportation since the 1950s, there are a few differences between mobile robots and AGVs.

For instance, mobile robots are not only required to accurately move from one place to the other, they also have to perform some task upon reaching the destination or during the course of movement. It means that they have to combine autonomy, mobility and manipulation. Whereas, in most cases, AGVs have to follow a predetermined path, guided by magnetic or optical tracks.

Also, robots have to react and respond in real-time to environmental excitation and in the case of unwanted events. This means that they possess much higher degree of intelligence and decision-making capability as compared to AGVs.

Mobile robots do not always move on wheels, they can also “walk on foot”. The design and development of limbed mobile robots actually represents a major research area.

However, primary limitation associated with wheeled-type robots is the need for ground contact and support along the entire path of motion. In rough terrain or environment cluttered with obstacles such as those found in forests or construction sites or in planetary exploration, it will not always be possible to provide the robot with guaranteed physical ground support along a continuous path. In such applications, a limbed robot may traverse the space without tipping over if it is able to find separate footholds throughout its path.

Constructing walking legged robots is more complex when compared to wheeled robots. There are many issues to deal with, including the number of legs required, balance, stability, proper gait and body control, to name just a few. Limbed robots have been built with as few as one leg, but it is more common to see designs having four-, six- or even eight-legged locomotion facilities. Intensive research is going on on the development of limbed robots and many designs are commercially available.

Mobile robots need to know where they are navigating to, what is out there around them, model both of these in order to think about them, use the representation of the current situation and the mission goals. They should have the capability to plan their next action, take appropriate decisions even when representation is imperfect and, when commands are not executed perfectly, be able to execute and monitor compliance with this plan.

So, we can appreciate that robotics in general and mobile robotics in particular represent an area that presents problems of highly diversified and multi-disciplinary nature. It is a field that throws challenging and often perplexing questions to engineers, mathematicians, software developers and even biologists. The field is wide open and a lot of work is still left to be done.

Applications

Mobile robots are used in all the places where we need an intelligent and self-reliant decision-making (autonomous) servant. They can be found on factory shop floors, warehouses, hospitals and even in outdoor applications like agriculture and mining. Following are a few areas where the benefit of technology is of the highest degree.

1. Under water: During the spring of 2004, scientists from McGill University put “Aqua”, the Canadian-built, microwave oven-sized submersible robot, 25 feet under warm Caribbean waters. They tested Aqua’s most unique feature — six individually controlled flippers which allow the robot to swim, dive, walk and stand nearly motionless at the bottom of the sea floor. With its six flippers, the underwater robot used computer vision and robotics technology and was a result of two years of research and development by a team of Canadians. The team included researchers from York University, McGill University, Dalhousie University, the Canadian Space Agency and MD Robotics of Brampton, Ontario, and their international partners.

Director of the programme, Gregory Dudek, envisioned a number of uses for Aqua, including monitoring the health of coral reefs, accompanying scuba divers and carrying tools and lights for them, and monitoring the bellies of ships that may be concealing drugs, explosives or other contraband. Aqua could also hunt for sunken treasure that, according to Dudek, is a “fanciful sort of application’’ in comparison to more boring stuff like “inspecting telecommunications cables and water pipes”.

A collaborative group of researchers at Rensselaer’s Darrin Fresh Water Institute (DFWI) on Lake George, New York, is also working to develop a network of distributed sensing devices and water-monitoring robots. These will include solar-powered autonomous underwater vehicles (SAUVs) for detection of chemical and biological trends that may guide the management and improvement of water quality.

Autonomous underwater vehicles (AUVs) are equipped with sensors and are currently used for water monitoring, but must be taken out of the water frequently to recharge the batteries. SAUVs are a new technology that will allow underwater robots to be deployed for a longer period by using solar power. Key technologies used in SAUVs include integrated micro-sensor systems, pervasive computing, wireless communications and sensor mobility with robotics.

2. Military: The underwater mobile robots are also utilised in military applications. The US Navy’s latest wartime technology called “Autonomous Underwater Vehicles (AUVs)” develop and employ mobile robots that resemble everything from torpedoes to bomb disposal robots to small submarines. Although still relatively new, one such small torpedo-looking device called “Remus” was used in Iraq, helping the navy clear mines from the port of Umm Qasar and turning what could have been a seven-day clean-up operation into a two-day one.

3. Security and surveillance applications: Reconnaissance and surveillance tasks can benefit from the use of small, yet highly capable robots. Automatic security and surveillance systems using cameras and other sensors are becoming more common, but static sensors have the problem of requiring human intervention for re-positioning. This problem is exacerbated in many law-enforcement scenarios, where human presence cannot be afforded.

Static sensors have another disadvantage. They do not provide adaptability to changes in the environment or in the task. In case of poor data quality, for instance, the user may want the sensing element to move closer to its target in order to sense it better. Mobile robotics can overcome these problems by giving the sensors wheels and autonomy.

For example, researchers at the University of Minnesota have developed small robotic systems “Scout” to meet these operational requirements. Scouts have two modes of locomotion designed to transport them over different kinds of terrain and obstacles.

In the first mode, the Scouts use their wheels to roll over smooth surfaces (even up a 20-degree slope). When confronted with an obstacle taller that itself, the Scout employs its second locomotion mode, the jump. The spring-loaded tail of the machine is compressed and released to propel the robot over objects upwards of 20cm in height.

Scouts carry a small video camera and video transmitter, which they use to capture information about their environment. They can also transmit and receive digital information over a separate RF communications system that uses a packet-based communications protocol.

The small size of Scouts provides many advantages. They are inexpensive and easily transportable, which makes them ideal for use in large teams. This allows them to be present throughout a wide area, forming a mobile sensor network. This allows individual Scouts to be expendable without jeopardising an entire mission. Scouts are well-suited to clandestine operations since they can be concealed easily.

4. Working in remote and hazardous areas: The Atacama desert in Chile is one of the remotest and most arid regions on Earth, yet it offers attractive research prospects in the fields of biodiversity and astrobiology. Regions where the desert meets the Pacific coastal range, desiccation-tolerant micro-organisms are known to exist.

To achieve their objectives, the researchers must deploy life-detection instruments mounted on a rover capable of long-distance traverse. And so, they have created a robotic astrobiologist “Hyperion” that can navigate over the horizon, detect obstacles at necessary scales; register observations to orbital datasets and limit position error to 5 per cent of the distance travelled.

The robot can also use resources efficiently and enable autonomy with self-awareness. That is, it can establish variable rover autonomy and effective remote investigation (telescience) over low-bandwidth, long-latency communication links and develop rover self-awareness, monitoring hardware and software for fault detection and recovery.

The University of Moratuwa has embarked upon developing sustainable technologies for the humanitarian “demining” programmes in the North and the East of Sri Lanka. This field of research was specially appropriate due to the ceasefire after nearly 20 years of civil war in the country. It is estimated that Sri Lanka has around 2.5 million landmines in the northern region.

Clearing these highly dangerous farmlands will take at least another ten years if it is done with manual labour using present-day technology. A mobile robot platform that can carry the metal detectors will speed up the process of landmine detection and improve safety significantly because it can remove the danger to human operators.

Such a robot has to be designed by taking several constraints into consideration. The most common anti-personnel mines in Sri Lanka are designed to detonate when a mass of 7kg or greater applies pressure on them. Therefore, one challenge is to reduce the weight of all the robotic components if the robot is not meant to detonate the mines.

The writer is a freelance contributor

Please Visit our Sponsor (Ads open in separate window)