Almost human: UK company forges ahead in interactive robots

Written by: Paul Fanning | Published:

If we think about leading-edge robotics research and development, our minds probably wander to such exotic locations as Honda's HQ in Minato, Japan or Lockheed Martin's world-famous 'Skunk Works'. Even if one were to think about robotics in this country, you would probably put the location either in one of the UK's leading engineering universities or at a defence company.

Where one might be unlikely to locate one of this country's most advanced and successful robotics companies is the ancient Cornish port of Penrhyn. But it is here that a company called Engineered Arts has designed, developed and built a series of robots that are finding an expanding market across the globe in some of the most advanced and prestigious locations.

Engineered Arts sprang up in 2004, the brainchild of the company's founder Will Jackson,who wanted to combine art and engineering to extraordinary effect,

The company started out by creating interactive displays for prestigious clients such as Royal Botanic Gardens Kew, Science Museum and Cornwall's Eden Project. And it was this last display that led to Jackson deciding to focus his business on developing a unique product, RoboThespian, a robot actor.

Marcus Hold, Engineered Arts' design and production engineer takes up the story. "We produced three simple robots for the opening of The Eden Project to tell the story of GM crops. People were fascinated with these robots – even though they just had simple wooden faces with clattery wooden jaws- but they triggered something in Will's mind."

What they triggered became RoboThespian, a life-sized humanoid robot designed for human interaction in public places. Today, there are more than 40 of these robots installed around the world in 16 countries. They have been adopted by science museums and visitor attractions such as NASA's Kennedy Space Center, where RoboThespian talks to visitors about the James Webb Space Telescope.

Says Hold: "Traditionally, such exhibits have used notices and posters. However, you can ignore a poster, but it's very hard to ignore a 6ft robot that watches you as you go past and delivers information in an engaging way."

Being fully interactive, multilingual and user-friendly, it offers a new and memorable way to communicate and entertain. Users can set it up for inspirational educational, business or theatrical performances simply by writing their own scripts; these can then be elevated to truly spectacular shows with multiple RoboThespians working together.

One of the singular things about RoboThespian is the smooth, human-like movements and gestures it is able to achieve. It has over 26 axes, powered with a mixture of pneumatic and servo actuators. Its articulated hands each has four independent fingers powered by eight miniature air cylinders.

According to Hold: "We've combined air muscles for human-like movement with servos for accurate rotation, plus high-resolution cameras and sensors that allow the robot to make sense of the world." These air muscles from Festo are used in combination with electric motors, with low-geared, fluid tuning for natural, expressive limb and body movements. The combination of parallel implementations of pneumatic-electric actuators allows for a broader, faster, more precise and more natural-seeming range of movement than that possible with either actuator variety acting alone. Specialised muscle-mimicking material and custom valve design gives an unprecedented degree of control over the non-linear force-driven elements of the robotic system.

This pneumatic fluidic muscle actuation system is capable of generating high tensile forces with a stick-slip-free movement pattern, enabling both slow and fast movements to be executed with equal adroitness. The non-linear nature of the actuation curves provides a highly natural-looking motion. When combined with antagonistic muscle pairings and high-level control algorithms, a sophisticated biomimetic robotic system can be readily achieved.

Since the pneumatic actuators are very low impedance, they can be easily back driven. In addition to the safety aspect, this has the advantage that the robot is able to 'relax', which is not easy to achieve with electrically-actuated robots. In this relaxed state the robot can be guided and manipulated with little to no resistance.

Thanks to parallel pneumatic-electric actuators, and a variety of on-board sensors, RoboThespian offers multi-level force and position feedback and control. This also endows the robot with non-linear, biologically realistic motion. High level control is achieved via a simple, easy-to-understand GUI which allows quick formation of motion and speech routines. For lower-level, more comprehensive control, inputs and outputs can be accessed and modified via a Python based UI.

Another key point about RoboThespian is that it uses as little energy as possible. Indeed, as Hold puts it: "We've done everything we could in the design to retain energy." For instance, the robot is able to move to a squatting position, which uses a lot of mechanical linkages to maintain an upright position as it squats down without the need to drive servos and thus waste energy.

Another major factor in reducing energy usage is weight and here, the fact that the robot uses igus iglidur plastic bearings on each of its axes. The robot employs 85 such bearings from top to toe, as well as using lightweight, aerospace-grade aluminium.

But the real draw of RoboThespian lies in its interactivity. The robot can do remarkable things in this regard, such as recognise when people are in front of him. Says Hold: "He can recognise what pose your body is in and can pick up on waves. He can even tell what your approximate age and gender and can even pick up if you're happy or sad, angry or surprised."

In order to be interactive, the robot obviously needs to talk and RoboThespian currently has more than 40 synthetic text-to-speech voices. The other key thing is that it needs to be able to express itself emotionally. The robot has LCD screens for eyes that allow a range of expressions.
These screens also include eyebrows that are large enough to allow your brain to interpret emotions from them , such as anger or surprise.

RoboThespian also has a range of pre-programmed expressive gestures. It also includes sophisticated movement tracking and gesture recognition features that allow it to track multiple people with its gaze; recognise gestures, such as a wave to say hello; or copy a body pose with his arms.

The system's voice interaction features also offer a huge amount. For instance, the RoboThespian can have keywords defined to trigger set responses; or it can get answers from the internet. It is also possible for RoboThespian to listen and try to repeat what you say; meaning visitors can try to catch him out with tongue twisters and rhymes. or tell a story.

Looking forward, of course, there are a number of features that Engineered Arts is seeking to add to the next iteration of RoboThespian. Hold lists some of the areas on which the company is working, saying: "We want him to have more ability to express himself and more interactivity.

For the next generation, though, we're looking at a new arm design with a grasping hand that's able to grab and manipulate objects accurately with pneumatic digit actuation for improved grip – the current fingers are just either closed or open. A bi-articulated upper arm design will also allow the hand to move in a constant vector between hand and shoulder, which should allow robot to throw and catch objects."

The big question, however, is when RoboThespian is going to walk? According to Will Jackson: "People have been asking us for a long time when we would make RoboThespian walk. From a cold, rational point of view, there seem to be very few commercial reasons to develop a full sized bipedal robot... But the question doesn't go away: 'Can it walk? Can it walk?'

"Who wants to see a walking robot? – I realised that most people would love to see it. And they can, in perfect safety - at a show or public event. But just walking is not enough. It must run, jump hop and leap. "

For this reason, Engineered Arts is working on a separate, walking robot named Byrun, which is currently 18mths into three-year project and on the third iteration of prototype . Says Hold: "So how will we get our robot walking? Well the first thing is dynamic stability, which is throwing up a number of design challenges, but by using a biomimetic design, we are hoping to achieve a natural gait, more fluid, human-like movement and using force control is allowing us to make elegant compensation for uneven terrain."

Dynamic balance is vital to a human-like robot. Most walking robots that currently exist are statically balanced and their centre of gravity remains over their feet. This means that, if you were to turn off the motors part way through a walking movement, they would remain upright.

However, humans move much more dynamically and are essentially falling from one foot to the other, swinging our legs like a pendulum. Byrun is going to incorporate that into its design to generate a walking, running, jumping, hopping robot.

Byrun will also use custom-built BLDC motors for a greater power to weight ratio, with bi-articulate links between the hip and lower leg. Something you've seen on this robot. The torso maintains an upright position without using any energy.

A series of parallel pneumatic actuators act like tubular springs that can be used to vary the walking gait of the walking robot, while a series of actuators in the lower leg give force control and there are further springs at the back of the leg to maintain angular relationships without sacrificing independent axis control

Says Will Jackson: "Achieving these goals is a daunting task. It requires not just engineering expertise, but radical and novel approaches to the problems of dynamic balance, actuation efficiency, and locomotion. We are creating not just an exciting piece of hardware, but one that will make a great development platform for others to build on. When Byrun takes his next step, so shall we."

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