Experts predict that an ageing world population and continuing global military conflicts will be the two main drivers of robot design and function in the coming years.

Speaking at the Robo Business 2009 Conference and Expo in Boston, Tandy Trower, the general manager of Microsoft Robotics, noted that in the next 40 years, the number of pensioners - those aged 65 and over - is set to increase by two billion worldwide.

With that ageing will come the need to help families and other caregivers cope with decreased mobility and chronic diseases such as Parkinson's and Alzheimer's.

Mr Trower said that robots could have a "profound impact" when it comes to helping seniors communicate with family members and each other, or reminding someone to take their medications.

"Even just having robots do lightweight transport of objects from one room to another, whether it's grandma's knitting or a cup of coffee, could be tremendously valuable."

 This is not as far away as you might think, judging by some of the robots wandering around the Expo.

Robosoft, a French company, was showing off robuLAB10, a proof-of-concept robot that has been specifically designed to follow and assist an elderly person in their own home.

It comes equipped with a touch-screen computer, a voice interface, and special robot navigation software developed by Silicon Valley's SRI International.

"The market for home-centric robots that provide assistance to the elderly is one of our priorities," says the head of Robosoft, Vincent Dupourque.

The company said it hopes to have large-scale deployment of such eldercare robots in the next three years.

This could be future of elderly care

Mr Trower noted that the Japanese might beat them to it.

Toyota, he pointed out, is developing an entire line of "assistive robots" and has plans to put them in car showrooms by 2010.

By then, predicts the Japanese Robotics Association, the global market for service and personal robots will reach $17bn (£11.4bn).

Robowar

However, the growing market for military robots dwarfs that figure and it showed on the Expo floor in Boston, where just about every company with a booth was touting what its robot could do on the battlefield.

Robots are, of course, already making an impact in warfare.

In Iraq, the US military is using robots to help defuse improvised explosive devices. In Afghanistan, tele-operated robots, not soldiers, are being sent into caves to scout for enemies.

"But what will the robot-inhabited battlefield of the future look like?" asked retired Vice Admiral Joseph Dyer in a keynote address.

Vice Admiral Dyer thinks about this question quite a bit as he now serves as president of the government and Industrial Robots Division at iRobot, one of the leading suppliers of robots to the US military.

"Very integrated and very unmanned," was his answer.

"You're going to see ships that arrive on foreign shores, that put in unmanned underwater systems to do anti-submarine warfare and clear mines.

"And then those systems will carry ground robots ashore, and will launch unmanned aerial vehicles. It's going to dramatically reduce what would have been required of special operations folks."

This operator controlled robot was refitted to carry a weapon

And yes, Vice Admiral Dyer predicted, armed robots will be part of that picture, although they should not be autonomous. He argued that a soldier should always remain in control.

In fact, remote-controlled armed robots are already in the pipeline. Qinetiq, which supplies a line of robots to the US military and law enforcement agencies, refit its TALON model with a weapon.

"Certainly the soldiers in the field that recognise its value," said Ed Godere, head of the Technology Solutions Group at Qinetiq.

"But we always want a soldier in the loop, making those life-and-death decisions that a robot could never make."

Sentient

Robot autonomy, and its accompanying ethical dilemmas, is only one of the big issues facing robotics companies.

The other is a much more practical concern - power.

Walk the Expo floor in Boston, and you were sure to see people constantly plugging in their 'bots, or regularly swapping out batteries.

These power concerns are changing the way people design their machines.

"Power consumption is one of our most difficult design considerations," said Brain Zenowich, who works for Barrett Technology.

"We designed our robot from the ground up, so that it would draw as little power as possible, knowing that the battery technology is going to take many, many years to catch up."

Mr Zenowich was demonstrating the company's robotic arm and hand system, which allows a user to remotely manipulate objects and carry out tasks.

The new twist is that the user does not just see what he or she is doing, but also feels what the arm and hand are feeling.

"If it encounters an object along the way, you can know that, you can feel that," Mr Zenowich said.

"It gives you that much more freedom and flexibility to accomplish a task, when you have visceral, force-feedback from the robot."

Segway was on hand to show its latest robot models

One of the main selling points, he noted, is that the arm is able to run for almost a full day on just one lithium-ion battery.

Like just about every company at the Expo, Mr Barrett sees multiple markets for its 'bot.

It is currently in service at hospitals in the US, helping doctors perform knee surgeries. But the company says a "ruggedised" version might be able to help soldiers remotely defuse roadside bombs.

And the market of the future for a robotic arm system with torque sensors and force control?

"We went to an expo in Italy, and we had one guy come up to us and say 'this would be perfect for making my shoes,'" Mr Zenowich said.

"That's something we would never think of."

Clark Boyd is technology correspondent for The World, a BBC World Service and WGBH-Boston co-production