This step-by-step guide aims to explain the recommended placement of the sensors when using an Xsens Awinda system or an Xsens Link system.
The position of the sensors in the body in both systems is very similar. Only small details need to be taken into account according to the system used.
It is important to notice that all Xsens technology is based on inertial measurement units (IMU’s), which directly measure orientation and not position. For this reason the precision of the sensors' positions is not very relevant. This is a very important characteristic since it removes the operator bias that can be introduced when different people use the system or when an experiment is made in different days.
Additionally, the recommendations we describe here correlate with better accuracy in data acquisition, prevention of early dysfunction of the sensors, and ergonomic commodity of the system.
When performing the calibration in the MVN software the orientation of each sensor will align with the orientation of each body segment. In this way it is very important that every time you use the system you do a calibration. Also, if a sensor becomes misaligned during a trial and you need to place it again, it is highly recommended that you redo the calibration.
Xsens Awinda System
The Xsens Awinda system is composed of wireless trackers that are attached to the body with a t-shirt and a set of straps.
Here we describe the placement for one side of the human body. For the other side please place the sensors symmetrically.
Sensor label - Head
Place the sensor inside the headband and place it around your head. Place the sensor with the long edge in the direction of the band for stability of the sensor. The orientation of the headband on the head is not important as long as the sensor is stable.
Sensor label – Shou
Place the sensors in the Velcro patches in the back of the t-shirt. For better attachment of the sensor to the shirt place it horizontally so the entirety of the sensor contacts the Velcro patch.
Sensor label - Uarm
It is recommended to place the sensor on the lateral side of the upper arm in between the muscle groups of the biceps and the triceps. In this way, the movement of the sensor due to movement of the muscles can be reduced.
Sensor label – Farm
Place the sensor closer to the wrist, as this provides more information about pronation and supination rotations than if the sensor was placed higher on the forearm. Also, right above the wrist area has less fatty tissue, decreasing the chances of skin motion artifacts.
Sensor label – Hand
Place the hand sensor vertically in the pocket in the glove, to allow better fit of the glove.
Each glove has two letter markings. The lateral marking (orange circle) is the size of the glove and the upper marking (blue circle) is the hand (left or right) of the glove.
Sensor label – Pelvis
For pelvis motion measurement, tighten the pelvis strap (largest strap provided) around the pelvis bone at the height of the anterior superior iliac spine. Place the sensor on the first layer of the strap and underneath the second layer if possible. This sensor should be placed vertically, using the letters “XSENS” as a reference. Please make sure the sensor is placed on the pelvis, not high on the waist.
Sensor label – Stern
Place in the pocket inside the front of the t-shirt. The preferable position for better attachment of the sensor to the Velcro is a vertical placement with the fabric completely covering the sensor.
Sensor label – Uleg
Place on the middle of the lateral thigh, as this has less probability of having fatty tissue and also reduces the chance of the strap sliding down. Be careful to not leave the tip of the Velcro in the inner part of the leg, since when moving it can easily scratch with the other leg and loosen.
Sensor label – LLeg
On the lower leg, two locations have been described as good placement.
- On the tibia, close to the knee.
- On the lateral side of the lower leg, aligned with the fibula, 6cm above the lateral malleolus.
There are different options to place the foot sensors.
Sensor label – Foot
Inside a shoe:
Place the sensor on the foot pad and place it inside your shoe. The sensor should be placed on the front upper part of the foot, in between the ankle joint and the toes joint. The sensor pad can also be placed in the same location below the shoelaces.
On bare foot:
Place the sensor on a strap and pass the strap around the foot. The sensor should be placed on the front upper part of the foot, in between the ankle joint and the toes joint. The sensor can also be place with tape. The only requirement is that it will stay fixed in place.