Suits design in motion

4 min read

Some clever design in sensor technology has developed a tool with interesting possibilities for design engineers, particularly those whose designs cater for human movement. Tim Fryer reports

Wearable electronics can mean many different things. It can be a form of display perhaps, for those who want to constantly change the appearance of their garment. It can be a source of information – while some struggled with the appearance of the smart glasses, the latest tranche of smart watches are more stylish, safer and debatably more useful. However, where wearable technology has really taken off is in monitoring the body.

There is nothing new in having a heart monitor and various health and fitness devices have successfully followed, quite often the make or break factor being in the smartphone app that supports them. When complex analytical software takes over from the app, and the sensor technology moves further forward, a new strain of wearable technology has design implications both when designing the systems in, and when using the system for design. Hopefully that sentence will make sense by the end of the article.

Sensing motion

The MVN Biomech system from Dutch company Xsens is wearable technology providing 3D human motion tracking that can be used on production lines, sports fields, in vehicles and aircraft, in the home or any location where human body movement needs to be analysed with high accuracy.

"Xsens' systems are now considered the de-facto industry standard for human motion measurement. They are well established with trailblazers in entertainment, research and industry," claimed Per Slycke, CTO and general manager at Xsens. "MVN Biomech is moving inertial motion tracking to the next level by taking it from research laboratories to where the action is. Combined with reduced pricing, this means that digitising 3D motion is now accessible to a much wider user base."

MVN Biomech comes either as a full-body suit or a strap-based system. It is intuitive and can be set up for use anywhere, within minutes. Based on lightweight, wearable inertial sensors, MVN Biomech is portable, fitting into an average-sized backpack.

The core technology here, according to product manager Colleen Monaghan, is sensor fusion - the sensors being fused here are gyroscopes, accelerometers and magnetometers. "The gyro is the work horse, calculating the angular velocity," explained Monaghan. "But to get orientation you need to integrate that signal and if you continuously integrate a signal it will drift. So it then leans on the accelerometer to get the gravity signal – and therefore knows which way is down. Using mag data it knows which way is north, so it can constantly correct itself."

This inertial sensor – the 'fused' gyro, accelerometer, magnetometers sensor – is physically this collection of MEMS sensors on a PCB in a small orange enclosure. In the full-body suit 17 of these motion tracking units are deployed.

"The inertial sensors send the sensor fused data and display it on the computer through a software programme called MVN Studio Biomech," commented Monaghan. This contains things like the biomechanical models." Inside the biomechanical model the lengths of all the segments can be entered, like foot size and length from foot to knee and knee to hip. Monoghan continued: "Using the sensor data and also knowing the length of the segments and the length of the body and feet, it can keep quite a tight control also on the position calculation. So when you stream all of this data through in MVN Studio, you basically see this lovely 3D character run around the screen and you can see it from all different camera angles or from one plane."

The overall technology has been gradually developed and improved over the 15 years the company has been in existence, and it has been used very successfully to bring animated characters to life in games and films. Some of its higher profile applications have been in Alice in Wonderland, Ted and for Gollum in Lord of the Rings. Most recently it was used in Walt Disney's UK-filmed Maleficent.

However, the detail that allows it to create such lifelike characters in film can also be utilised to study 3D human movement in other sectors.

Biomech in industrial design

Moving away from the big screen and games consoles, obvious users for this technology would be doctors, physiotherapists and sports coaches. Monaghan said: "People are actually doing research with skis and snowboarding, kinematics - that's about the posture of the person, how does their knee move, what is and what is not a good ski pose - with the goal of how can we improve people's technique."

However there are other applications in the research and industrial sectors.

"Automotive is a growing field," said Monaghan, "and also aeroplane and train manufacturers, but then there are also people who want to design manufacturing plant using products like Siemens and Catia and within the process simulate humans. Then you can tell by having the actual person submerged in this environment if this layout of the plant makes sense - sometimes on paper things look great and then in a simulation it even looks great, but then when you put the person into that, you know, when they finally build their manufacturing plant, then it's too late to realise that things weren't actually optimal."

For example the system could be used to see how certain tasks might be performed, using a real person in a virtual environment, to see if a repetitious movement might cause too much strain in the back or knees. Do work surfaces need to be moved closer together or at different angles, or are the spaces between equipment sufficient for actual human movement? "If you can already evaluate this with a person in a simulated environment, before you've built the whole thing only to later discover when you put a person on a factory floor that it didn't really work, this saves so much money and so much time," observed Monaghan.

The suit is actually made of lycra and the trackers are attached to specific points on Velcro patches. Wires connect to the back pack which sends over the data wirelessly. There is also a completely wireless version where the trackers are on straps. There is no back pack for this as each one sends its data to the 'window master' which ensures all data is completely synchronised before feeding through the MVN Studio software.

Apparently it is a very easy system to use and links seamlessly into Siemens and Dassault design environments amongst others. Car manufacturers for example have been early adopters. "They can see, in the software that they're used to, and in real time because it's real time streaming, they can see these characters move around on screen. They use our system to help speed up the process of their work."