Motion analyses are most commonly used for sports
motor skills. The primary task here is to study, train and optimize
motion sequences. This applies to both individual and team sports as
well as sports that involve the use of equipment or animals.
The applications are multifaceted. Wit the help
of slow motion studies swimmers seek to optimize their butterfly stroke
after the turn, horse and rider train to achieve a harmonious riding
style and athletes improve their long jump.
Motion analysis is also used in the development
and testing of sports equipment and gear. The high-speed video to the
right shows a golf stroke that was captured using the MotionBLITZ
EoSens® mini1 high-speed camera. This high-speed recording aimed to
optimally adapt the club to the player’s movements.
The club head can reach speeds of up to 200 km/h.
To capture all the details, a sufficiently high frame rate must be
used. This recording was taken at a frame rate of 2,009 frames per
second and a resolution of 528 x 518 pixels. A case study explains how
swing analysis can be put to good use when equipping golfers.
Motion analysis is also often used in medicine,
particularly in the field of rehabilitation: Doctors and other medical
professionals seek to visualize motion or gait disorders in order to
develop targeted therapies. High-speed imaging helps them to develop
individual training plans, to adjust and optimize aids such as insoles,
orthotics and prosthetics and to assess the chances of successful
orthopedic surgery.
Finding the Right Camera for Every Motion Analysis
At the heart of every motion laboratory is the
high-speed camera. Often, multiple synchronously running cameras are
used for three-dimensional analyses. To achieve the best results, there
are some important points to be considered when selecting the camera.
The decisive parameters are the frame rates, resolution and recording
times that will be required. Other important criteria include the
handling and ease of integration of the high-speed camera.
High Frame Rates
The required frame rate is determined based on
the requirements of the motion to be analyzed. A gait analysis, for
example, requires a lower frame rate than the analysis of the forehand
stop in tennis. Motions in competitive sports are often especially fast.
To analyze these processes in sufficient detail, the high-speed camera
used must have a high frame rate of at least 500 pictures per second.
The high-speed recording on the left shows the
golf club head at impact. This is the critical moment for the analysis,
the moment of the impact. It determines the ball’s takeoff velocity,
direction of flight and spin. Here, the small image region meant the
resolution could be reduced to 832 x 172 pixels. This allowed the
MotionBLITZ EoSens®mini1 to reach a frame rate of 4,188 frames per second.
High-Precision Resolution
Resolution is crucial for the sharpness and the
detail level of the recordings. This also depends on the specific
requirements: For example, to achieve the same level of detailed
sharpness, high-speed recordings of lower limb prostheses require a
higher resolution than the images of prosthetic feet.
The slow-motion sequence to the left was
recording using the MotionBLITZ EoSens® Cube6. With a pixel resolution
of 1,280 x 1,024 the camera delivered 150 frames per second. The video
shows a jetski driver performing a bootleg turn.
The
MotionBLITZ EoSens® mini2
offers a resolution of 1,696 x 1,710 pixels; thus, it delivers
extremely sharp images at maximum recording speeds of 523 frames per
second. Here, the resolution is proportional to the recording speed.
The Right Recording Time
Since the entire motion process must be stored in
the camera’s memory, the recording time is another important criterion
when selecting the camera. For example, there are different requirements
depending on whether you are recording a complete obstacle course run
or only the start of it. In general, the camera should follow the
defined test protocol – and not vice versa; the camera should not affect
or even define the test sequence.
Memory cameras offer recording times between 2
seconds and a maximum of 15 seconds. The MotionBLITZ® Cube records at
full resolution and speed for up to 13 seconds. For a longer recording
time, the frame rate and/or resolution can be reduced. For example, for a
recording time of 30 seconds, a resolution of 100 x 800 pixels and a
frame rate of 300 frames per second can be set. If longer recording
times are required, Mikrotron offers
long-time recording systems that can record from several minutes up to a few hours.
This underwater video shows a diver during immersion.
Having the right position is crucial: The diver should dive
perpendicularly into the water and no longer be in the final stages of a
turn. The video was taken with the
MotionBLITZ EoSens® Cube6
at a frame rate of 718 frames per second and a resolution of 1,280 x
720 pixels. These settings allowed a recording time of 3.25 seconds. The
camera was operated by hand.
Compact Handling
When selecting the right camera, the performance
characteristics are of foremost importance. However, the design may
also be an important criterion: overly large high-speed cameras can be
more difficult to handle and reduce the usability, especially when space
for the camera is limited. At the same time, the size of the camera is a
characteristic that often only becomes apparent in the field: For
example, if you want to record each part of a pole vault sequence on a
training field, you need a fast and flexible high-speed camera.
Confusing cables or unwieldy devices make it difficult to concentrate on
the task at hand and should therefore be avoided. Mikrotron offers
compact systems with ideal sizes of 65 x 65 x 65 mm to 200 x 200 x 350
mm.
The high-speed video on the left shows a high jumper
at the critical point of take-off. During the jump, the jumper must
convert the horizontal velocity into vertical velocity and initiate the
turn to cross the bar. The image sequence was created within 1 ¾ seconds
and consists of a total of 1,764 images. The images were taken with the
MotionBLITZ® Cube1 at a resolution of 640 x 512 pixels. Thanks to the
compact size, flexible use in the field is also possible.
The high-speed Cube and eosens TS3 cameras by
MIKROTRON can also operate completely selfsufficiently, without an
external power supply, and run on battery power for up to one hour. In
addition, the cameras have an internal SSD memory, where all data can be
stored for final analysis. For example, the eosens TS3 can record
without being connected to a computer for up to 13 seconds at full
recording resolution and speed.
The software included in the delivery allows for easy
use of the cameras. It will win you over with its well-executed and
intuitive workflows, easily recognizable features and easy-to-use
elements. It also offers the option to synchronize multiple cameras so
that they can record at the same time. The software can be easily
installed and operated on all computers – special hardware is not
required.
A Range of Interfaces
MIKROTRON high-speed cameras
are supplied with a C- or F-Mount lens connection. The C-Mount can be
adapted to the greatest range of systems, including special optical
systems such as endoscopes or telecentric lenses. F-Mount lenses also
offer a particularly good imaging quality at focal lengths of over 50
mm. Open interfaces on the cameras allow users to select their own
optical systems. For example, camera lenses, zoom lenses and microscopes
can be connected without problems. Moreover, all MIKROTRON cameras are
equipped with a trigger input. This means you do not have to stand next
to the camera to start the recording – it can be easily started with a
trigger. In addition, the models have interfaces that facilitate a
parallel recording of analogue and digital signals.
An Extensive Portfolio
When choosing the right camera for the high-speed
imaging of movements, several parameters play a crucial role. This
includes the frame rate, resolution, and recording time, but also the
handling, us ility and flexibility of the camera. It is equally
important to consider the specific demands of each task. MIKROTRON’s
product portfolio offers different options depending on the specific
parameters and thus offers a suitable solution for each task.
Contact Details
Address: 4, A-Wing, Bezzola Complex,
Sion Trombay Road, Chembur
400071 Mumbai, India
Tel:(+91) 22 67993158
Fax: (+91) 22 67993159
Mobile:+91 9323786005 / 9820143131
E-mail: info@mvrpl.com
