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Sensor Placement in Xsens Link System

Introduction

This step-by-step guide aims to explain the recommended placement of the sensors when using an Xsens Link system.

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 are 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 Link System

The Xsens Link system is composed of wired trackers, a battery pack, and a body pack that are all attached with Velcro to a full body suit.

Here we describe the placement for one side of the human body. For the other side please place the sensors symmetrically.

 

 

Head

head1.jpg   head2.jpg   head3.jpg

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 remains stable.

 

 

Shoulder

shoulder1.jpg   shoulder2.jpg   shoulder3.jpg

 

Sensor label – Shou

Guide the end of the cable with the label Shou through the back of the suit. Place the sensors on the Velcro patches in the back of the suit. For better attachment of the sensor to the shirt place it horizontally so the entirety of the sensor contacts the Velcro patch.

 

 

Upper Arm

uarm1.jpg   uarm2.jpg   uarm3.jpg

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.

 

 

Forearm

farm1.jpg   farm2.jpg   farm3.jpg

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.

 

Hand

hand1.jpg   hand2.jpg   hand3.jpg

 

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. Make sure you leave the cable with a loop to allow more range of motion for the hand. This also prevents the sensor from breaking connection with the cable.

 

Sternum

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Sensor label – Stern

Feed the end of the sternum cable through the small cavity in the top of the suit. The end of the string should appear on the back side of the suit. Place the sensor in the pocket inside the front of the suit. The preferable position for better attachment of the sensor to the Velcro is a vertical placement with the sensor completely covered by the fabric.

 

 Cables connection for the upper body

cablesubody1.jpg   cablesubody2.jpg

To connect all the sensors of the upper body (head, sternum, right arm and left arm), pick the cable with 4 endings of the same size as shown in the picture.

Connect the black ends with all the string ends of the upper body sensors.

 

Pelvis

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Sensor label – Pelvis

For pelvis motion measurement, place the pelvis sensor on the plastic Velcro case in the back of the suit. This sensor should be placed vertically with the letters “XSENS” as a reference.

 

 

Upper Leg

uleg1.jpg   uleg2.jpg   uleg3.jpg

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 to slide 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 get loose. 

 

Lower Leg

lleg1.jpg   lleg2.jpg

Sensor label – LLeg

On the lower leg, two locations have been described in literature as good placement.

  1. On the tibia, close to the knee.
  2. On the lateral side of the lower leg, aligned with the fibula, 6cm above the lateral malleolus.

 

Foot

There are different options to place the foot sensors. Inside a shoe or attached with a strap around the foot.

Inside a shoe:

foot1.jpg   foot2.jpg   foot3.jpg

Sensor label – Foot

First, feed the foot sensor through a cavity below the zipper on the leg. Then, 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.

 

Cables connection for the lower body

To connect all the sensors of the lower body (pelvis, right leg and left leg), pick the cable with 3 endings as shown in the picture.

cableslbody1.jpg

Connect the black ends with all the string ends of the lower body sensors.

  • The shorter end connects with the pelvis sensor
  • The second to shorter end connects with the leg string on the side of the body pack
  • The longest end connects to the opposite leg of the side of the body pack. 

Connect leg contrarily to the body pack side.

cableslbody2.jpg   cableslbody3.jpg   cableslbody4.jpg

In the suit you can find a small hole that will connect with the leg division. Then you can connect the end with the leg string.

 

Pelvis sensor connection

pelvissens2.jpg   pelvissens1.jpg   pelvissens3.jpg

For the pelvis, there is a cavity in the suit that allows connection to the compartment where the body pack is located.

 

Cables connection to the body pack

cablesbpack1.jpg   cablesbpack2.jpg   cablesbpack3.jpg

 

Battery Connection

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Finally, close all the zippers. If done correctly, all cables should be hidden within the suit, with the except of the head cable and short lengths of the hand and feet cables.

final1.jpg   final2.jpg

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