Inertial sensors are small and lightweight. Employees wear them in specially made, breathable sleeves that do not impede their movements. Image: Lintje GbR |
Handling
tools, assembling , inserting, joining and bolting parts, painting
components, operating equipment—innumerable procedures must be executed
before a product can be packaged and shipped. How much time do employees
need for individual procedures? How long does manual assembly take?
Industrial manufacturers have to analyze and optimize their employees’
operations continually in order to remain competitive. They must record
the times of operations if they wish to analyze the individual
procedures. This enables them to identify long handling distances,
impractically located components, overly frequent tool changes or
irregular and superfluous movements, which waste time and make
production processes inefficient.
Until
now, every individual movement has usually been timed by someone with a
stopwatch or with digital time boards manned by employees. This
approach is not really objective, however. It is replete with errors and
disadvantageous for everyone involved: The stress factor for employees
is extremely high and they might not execute their jobs at their usual
speed. For companies, this requires quite a lot of work from staff and
thus incurs high costs. There is, therefore, great need for more
precise, automated and cost effective solutions. Contracted by the
engineering firm Dr. Gruendler in Magdeburg, researchers at the
Fraunhofer Institute for Factory Operation and Automation IFF have
developed such a system.
Three
matchbox-sized sensors integrated in a sleeve record hand and arm
movements precisely and measure the start and end of individual actions,
e.g. reaching, grasping, setting up, joining, checking or releasing.
The interlinked sensor modules are positioned on the upper and lower arm
and the hand. Employees merely have to put on the two sleeves. They are
snug like a second skin yet comfortable and do not impede the wearer.
“The
present stopwatch method only allows a process organizer to time five
individuals simultaneously, depending on the situation. Our solution
makes it possible to record time simultaneously, even at several
workplaces, without requiring additional labor. The system’s greater
precision and objectivity is crucial,” says Martin Woitag, research
manager at the Fraunhofer IFF.
Woitag
and his team relied on inertial sensors for their solution. They
measure the acceleration and angular velocities of arms and hands in the
X, Y and Z axes. Unlike other motion tracking systems, such as GPS, the
inertial measurement system functions without any other infrastructure.
The inertial sensors independently detect objects’ positions in space.
“What
is more, our solution doesn’t require complex calibration. A tool that
teaches in the measuring points directly at the assembly workplace one
time is all that is needed,” according to Woitag.
A
PC application completes the system. The software calculates and
reconstructs the motion sequences based on the sensor data. It breaks
processes down into motion segments and ascertains the related times.
At
present, the sleeves can be used for assembly jobs at sitting
workplaces in logistics and manufacturing. In the next stage, the
researchers in Magdeburg intend to configure the system to also analyze
assembly operations during which workers stand or move around. They
additionally plan to use the sensors to detect posture and thus analyze
workplace ergonomics.
