Total Immersion: Immersive Engineering equals Improved Ergonomics

Engineerblogger
Feb 29, 2012

Technicians at Lockheed Martin wear motion tracking sensors (above) as they mime aircraft carrier deck tasks. The information captured animates digital avatars (below) in simulations.

A large and growing part of safety engineering in factories—a.k.a. human factors—is a sharp focus on ergonomics and what it can tell engineers about injuries. The emphasis is on eliminating over-exertion and awkward work postures in repetitive factory jobs.

The solution is immersive engineering, which integrates virtual reality (VR), digital video and related 3-D technologies, computer-aided design (CAD), simulation and analysis, and solid modeling. These theater-like systems surround problem solvers with real-time engineering data presented digitally in life-sized displays with ergonomically accurate, motion-tracked avatars—digital humans.

Computerization and Ergonomics

These efforts mark a new safety push that comes on top of avoiding workplace accidents, especially around machinery, and preventing illnesses due to chemical exposure and excess noise. This new focus within factory safety is a direct extension of longstanding efforts to eliminate repetitive stress injuries such as lower back pain and carpal tunnel syndrome related to computerized office tasks. After four decades of office automation, nearly every office job has been computerized.

Computerization has revolutionized factory work, too, along with myriad mechanical assistance devices, from simple counter-balanced lifters to programmable industrial robots in foundries, welding and painting. Hundreds of thousands of formerly onerous jobs have been made easier, even though so many jobs have been outsourced to low-labor-cost countries.

Much of the reason for the early initial ergonomic success of immersive
engineering relates to a unique strength of the technology. It lets ergonomists and other safety experts solve workplace problems working in the virtual world of the computer. Immersive engineering lets ergonomists work directly with engineers (mechanical, industrial, and manufacturing), productivity managers, and even cost-control staff.

Information captured by the Lockheed Martin technicians animates digital avatars in simulations.

Reaping the Benefits

The results are dramatic, as shown by data from vehicle assembly operations of Ford Motor Co. in Dearborn, Mich. Ford has documented simultaneous reductions in injuries, fewer claims for compensation, shorter learning curves (getting new vehicles into production), lower cost for tooling changes, reduced production costs in general, and higher workplace productivity. The United Auto Workers and other unions support these efforts.

Ford's premiums for worker's compensation insurance have fell by about 55% since 2000, to under $15 million for 2007 from an average of $40 million in the early 1990s. By far the biggest portion of the drop was in repetitive-stress injuries that ergonomic analyses play such a big role in preventing. This is backed up by company medical records that show dramatic reductions in injuries related to spinal compression, back and upper body strains, and shoulder/rotator cuff injuries.

Allison Stephens directs a study of the physical exertion of an assembly task—installing a console between a vehicle's two front seats—at Ford's Dearborn Ergonomics Laboratory in Michigan.

At the same time, new-vehicle quality has soared five times more than the industry average. Ford now matches Honda and they exceed all other manufacturers. Product development times have shrunk eight to 14 months during the past five years. Cost details have not been released but across the industry such costs fall in line with product development time. In just one year, 2007, Ford new-vehicle quality soared an unprecedented 11%, measured three months after sale. The North American industry average was just 2%. In 2009, Ford added an immersive engineering system to its European operations.

A similar system was installed late in 2010 at the Lockheed Martin Space Systems Co. in Denver, Colo., to generate gains in the final assembly of satellites. That is Lockheed Martin's third immersive engineering system.

Key elements of these systems include Jack (Tecnomatix) and Delmia ergonomic and analysis software. The developers (respectively) are Siemens PLM in Ann Arbor, Mich., and Dassault Systemes in Auburn Hills, Mich. The leading developer of motion tracking and analysis systems is Motion Analysis Corp. in Santa Rosa, Calif. The leading systems integrator for immersive engineering is Mechdyne Corp. in Marshalltown, Iowa.

Source: ASME

UPC team designs customised assistive devices for people with spinal cord injuries

Engineerblogger
Oct 12, 2011

Video simulation: Operation of the orthosis

A team from the Department of Mechanical Engineering and the Biomedical Engineering Research Centre (CREB) of the Universitat Politècnica de Catalunya. BarcelonaTech (UPC) has developed an active knee-ankle orthosis to assist gait in people with incomplete spinal cord injury. The project is being carried out in collaboration with the University of A Coruña and the University of Extremadura.

The aim of the project is to design customised assistive devices for each individual case of spinal cord injury. Customisation will improve patient autonomy and facilitate adaptation to the device. It is hoped that the orthosis will improve quality of life for users, save money, and cut the time it takes to acquire the final product.

The first device developed within the framework of the project is an active knee-ankle orthosis. The prototype orthosis was designed and built at the Biomechanics Laboratory of the Barcelona School of Industrial Engineering (ETSEIB), where researchers analyse the dynamics of the human gait and use the results to design body-worn devices that support movement in people with incomplete spinal cord injuries. “The patients these devices are aimed at have limited control over the movement of their knee and ankle joints,” says Josep Maria Font, the UPC researcher responsible for designing the first prototype.

The Biomechanics Laboratory is equipped with an optical system consisting of 12 cameras that measure and capture the movement of the human body while a subject is walking. The system simultaneously measures foot-ground contact force by means of force plates which contain four triaxial force sensors. An electromyography (EMG) system is also used to record muscle activity.

The team involved in the project (made up of professionals in engineering, medicine and orthopaedics) is also developing a computer simulation that will make it possible, based on gait analysis and modelling of the human body, to predict how a person with a spinal cord injury will move when wearing the orthosis. With this information it will be possible to design customised assistive devices for each patient. “The simulation ensures that the orthosis, once it’s made, is as good a match as possible for the end user. It also saves money because it’s no longer necessary to go through a trial-and-error process using real components.”


Active orthosisOne of the novel features of this active orthotic device is the mechanical design of the knee joint (developed at the UPC), which incorporates two independent systems for activating and locking the joint. Thanks to this feature, the device provides better support at different stages of the gait cycle than systems currently on the market.

The devices most widely used at present are passive orthoses and exoskeletons. Passive orthoses do not provide external assistance for the movement of the knee. Exoskeletons work with the entire leg and incorporate six actuators for the hip, knee and ankle joints, which makes the system cumbersome and expensive. Moreover, exoskeleton systems, generally designed for paraplegics, are not ideal for individuals affected by incomplete spinal cord injuries, who do not suffer from complete paralysis.

The system developed at the UPC incorporates technology midway between robotics and orthopaedics. The result is a lightweight device that is more economical than other alternatives. Another novel feature is reduced energy consumption, which translates into greater autonomy. This is achieved by using a mechanical knee locking system rather than an electrical system of the type used in other orthoses and exoskeletons currently available.

Now that the active orthosis prototype has been built by the UPC team, a group at the University of Extremadura’s Department of Mechanical, Energy and Materials Engineering will continue the project. Their role is to design and install the electronic system that controls the movement of the device. The motor, located to the side of the knee, is activated and deactivated based on information received from two sets of sensors: plantar sensors, which detect foot-ground contact, and sensors that measure the angle of joints to determine what stage of the gait cycle the user is at. “The device is a means of assisting muscles affected by a spinal cord injury,” says Josep Maria Font.

The role of the Mechanical Engineering Laboratory of the University of A Coruña, the overall coordinator of the project, is to develop a dynamic simulation program to predict how a person with a spinal cord injury will move when wearing the orthosis. The device will be tested on patients at Juan Canalejo Hospital in A Coruña, a facility linked to the university. Testing will serve to validate the simulator and wider use of the orthosis.


Biomechanics LaboratoryThe Biomechanics Laboratory, which is attached to the UPC’s Biomedical Engineering Research Centre and its Department of Mechanical Engineering, focuses on dynamic analysis of human gait. The facility, located in Building D of the Barcelona School of Industrial Engineering, supports the University’s teaching and research activities, as well as providing services for businesses in the orthopaedics, footwear and sports sectors.

It is equipped with an OptiTrack optical motion capture system with 12 infrared cameras, which is used to measure the movement of relevant segments of the human body during the gait cycle. The system has a walkway with two force plates to measure foot-ground contact force. The laboratory was recently equipped with an 8-channel wireless electromyography (EMG) system to record muscle activity during movement.


What is a spinal cord injury?Spinal cord injury, or myelopathy, is an alteration of the spinal cord that can result in loss of sensation and/or mobility. It can be caused by trauma due to car accidents or rupture of the intervertebral disc, or by some diseases, such as poliomyelitis, spina bifida, primary or metastatic tumours, Friedreich’s ataxia, or hypertrophic osteitis of the spine.

Spinal cord injuries can be “complete” or “incomplete”. A complete injury leads to loss of motor function below the injury site, while a person suffering from an incomplete injury may have some sensory function below the injury site. Those with incomplete injuries may be able to move one limb more than another. They may also have sensation in parts of the body they cannot move, or have more functionality in some parts of the body than in others.

In Spain 40,000 are currently affected by spinal cord injuries. Each year some 1200 people incur injuries of this type, in most cases as the result of a traffic accident.

Source: Universitat Politècnica de Catalunya(UPC)

Design space: The airline sea

Financial Times
June 15, 2011

• Challenge: Create a lighter airline seat to help cut fuel costs
• Product: Superlight seating
• Agency: Factory design
• Territory: Europe

Acro Aircraft, a British aerospace engineering start-up, wanted to launch a product that would offer significant savings to airlines and, therefore, give it a competitive edge. Weight is a big issue for economy carriers because it has a big effect on fuel consumption. So Acro planned to introduce a seat that was lighter than any other on the market for short-haul, single-aisle aircraft.

Standard seat backs are between 50mm and 100mm thick and are made of cushioning attached to a metal frame. Design agency Factorydesign was asked to reduce the seat’s weight without sacrificing structural integrity so that it would still comply with airworthiness regulations.

Airline seats are usually designed with these regulations as the starting point. But the Superlight design started with the passenger.

Factorydesign created a thin, contoured seat back shell that wraps over the metal frame, resulting in a 3mm-thick seat back. By giving it an ergonomic form, the seat back needs upholstery of only 3mm-5mm thickness, using a lightweight material called E-leather, to make it comfortable.

The armrest’s metal chassis was left exposed to become part of the aesthetic, which did away with the need for an armrest cover.

At 30kg per row of three seats, Superlight is the lightest seat in its class. According to Acro Aircraft, on a typical low-cost carrier’s aircraft, such as a Boeing 737, that could mean a weight saving of 950kg, which could equate to fuel savings of $150,000-$200,000 a year.

The smart shoe

University of Twente

June 1, 2011

Researchers from University of Twente's MIRA research institute have developed a shoe that can show exactly how a person walks. The shoe contains a range of sensors which measure the foot's movements and the forces exerted on the ground. The shoe has primarily been developed to help the rehabilitation of stroke patients who are coping with paralysis on one side of the body. In the long term, the researchers expect to achieve many more applications, for example in sport at the highest level. Xsens, a University of Twente spin-off company, is bringing the shoe onto the market.

Many patients who have suffered a stroke are left with a degree of paralysis on one side of the body. During their rehabilitation process, they often have to learn to walk all over again. For successful rehabilitation, it is useful to be able to determine exactly how someone is walking at a given moment. What precise movements are being made? How much force is being exerted on the ground and at which moments? Until now, such analysis could only take place at an expensive specialized movement laboratory. Such state-of-the-art facilities are few and far between.

Researchers from the University of Twente's MIRA research institute have now developed a shoe which contains all the technology needed to carry out such an analysis, enabling it to take place at any rehabilitation centre or nursing home. The shoe contains four sensor modules, at the heel and the front of the foot. In turn, these modules contain a range of sensors which measure such aspects as force and movement. The data collected by the shoe can be sent to a computer through a wireless connection.

The shoe has been developed by the University of Twente in cooperation with Xsens, a spin-off company of the university, and Roessingh Research and Development. Xsens is bringing the shoe onto the market under the name ForceShoe. In the years to come, within the framework of the European project Interaction, a new shoe will be developed which patients can also use at home in their everyday lives.

In addition to rehabilitation, Prof. Peter Veltink believes that a range of other applications are possible. "Ergonomics is an interesting area, for example. You can use the shoe to form an objective impression of the physical burden placed on people in their work situation. This is something that insurance companies are very interested in." Prof. Veltink also sees long-term possibilities in top-level sport. "But for this application we have to find a way to further reduce the size of the sensor modules. That's an innovation we are currently working on."

Copyrighted from University of Twente