Frequently Asked Questions

QSense offers complete solutions including charging stations, wireless BLE dongles and straps. It’s up to the user if they need additional accessories. We offer the following straps:

Order number Description

QSM210050 Hook-and-Loop strap – XS (25 cm)
QSM210051 Hook-and-loop strap – S (35 cm)
QSM210052 Hook-and-Loop strap – M (45 cm)
QSM210053 Hook-and-loop strap – L (65 cm)
QSM210054 Hook-and-loop strap – XL (102 cm)
QSM210055 Shoulder strap
QSM210056 Hook counterpart (soft) for backside of Qsense sensor (10pcs)
QSM210057 Inline-Strap Sensor Holder – Silicone
QSM210058 Inline-Strap Sensor Holder – Hook & Loop
QSM210059 Parallel-Wrist Sensor Holder – Silicone
QSM210060 Parallel-Wrist Sensor Holder – Hook & Loop

For specific products or projects we can also provide customised straps with unique specifications.

We provide an application for Windows machines to quickly visualising in 3D a puppet and record data. We also offer iOS and Android demo applications to demonstrate basic functions like setting up a connection, calibrating the sensor and displaying sensor measurements in a graphical form.

The QSense Docking Station provides a convenient charging solution for the QSense Sensors. It enables simultaneous charging for up to 5 QSense Motion Sensors. Each docking slot in the station is equipped with a built-in micro-USB port. To power the docking station, simply connect a power adapter (5V, 1500mA) to the micro-USB port located on the side.

To achieve optimal BLE performance with QSense and minimize packet loss, we recommend the following best practices:

Wireless Dongle placement

• Place the dongle above or away from the laptop, not directly behind or next to the screen
• Keep the dongle free from obstructions within approximately 50 cm
• Ensure a clear line-of-sight (LOS) between the dongle and the sensors whenever possible

Sensor placement

• Avoid placing the sensor where the human body blocks the direct path to the dongle
• Avoid mounting the sensor on the back when the dongle is positioned in front of the user
• When body-mounted, orient the sensor to maximize exposure toward the dongle

Environment considerations

• Be aware that the human body can attenuate the BLE signal by up to 25 dB
• Laptop screens, metal objects, and enclosures can significantly reduce signal strength
• In open environments with few reflections, LOS becomes even more critical

System setup

• Increasing transmission power generally provides less benefit than proper placement and LOS
• Focus on stable positioning rather than maximum distance
• Monitor RSSI values where available; sustained RSSI below –80 dBm may result in packet loss

Following these guidelines typically results in significantly more stable connections than relying on higher transmission power alone.

BLE connectivity is highly sensitive to antenna placement and line-of-sight (LOS) between the sensor and the dongle. Even small obstructions such as a laptop screen or a human body can significantly reduce signal strength.

Very important.

Measurements show that:

• Blocking LOS with objects (e.g. laptop screen) typically reduces signal strength by 5–10 dB
• Blocking LOS with the human body can reduce signal strength by 10–25 dB

Maintaining LOS has a much larger impact than increasing transmission power

Yes. The human body absorbs RF energy.

In worst-case scenarios (e.g. sensor pressed against the back, signal forced through the body), signal attenuation of up to 25 dB was observed, often leading to packet loss or connection drops.

Only marginally.

Higher-power dongles increase transmission power from dongle → sensor, but:

• The sensor → dongle link remains the limiting factor
• Overall improvements are small compared to effects of distance and LOS
• Non-CE-certified dongles are not suitable for production use

Correct placement is far more effective than higher TX power.

For best performance:

Place it so the antenna is unobstructed in the plane where radiation is strongest

Keep the dongle free of obstructions within ~50 cm

Maintain clear LOS to the sensor

Position the dongle above the laptop, not behind or next to the screen. Use the USB dongle extension cable provided in the starterkit.

Yes. Strongly.

Avoid placements where:

• The body is directly between sensor and dongle
• The sensor is mounted on the back while the dongle is in front

Such configurations are sub-optimal and should be avoided when reliable streaming is required.

Yes. RSSI depends heavily on environment and setup.

Typical observations:

• Good LOS at short distances: approx. –50 to –60 dBm
• LOS blocked or longer distances: –65 to –75 dBm
• Below –80 dBm, packet loss is likely

RSSI values are indicative only, not guaranteed performance metrics.

There is no fixed guaranteed range.

While theoretical free-space models suggest long distances, real-world performance is dominated by:

• LOS
• Obstructions
• Body absorption
• Reflections and interference

For this reason, absolute distances and RSSI values are not used as product specifications.

QSense sensors can be configured via the interface to sample between 1 and 800Hz. With 800Hz the available wireless BLE bandwidth will be limited so you can only do this for a limited number of IMU sensors. Our wireless BLE dongle is restricted and can handle 1-2 sensors upto 400Hz, 3-6 sensors upto 200Hz and 7-12 sensors upto 100Hz.

QSense supports discrete sample rates of 1, 2, 4, 5, 10, 20, 25, 50, 100, 200, 400, and 800 Hz.
Keep in mind that the higher the sampling rate, the fewer sensors can share the wireless link, because the total bandwidth is finite. The BLE data throughput and the number of sensors will determine the maximum sampling rate with no data loss.

In quaternion mode the maximal states error is < 1 degrees and the maximum drift <0.5 degrees. Accuracy of the quaternion output will be affected by magnetic disturbance and gyroscope bias. Internal compensation strategies are implemented to minimize the effects of magnetic disturbance and gyroscopic bias.

The internal rechargeable 140mAHr LiPo battery lasts at least 20 hours in low latency mode and 12 hours in time sync mode. Sensors can start in shutdown mode when not used for more than 1 year. This is based on 80% battery capacity after 500 charge/discharge cycles.

QSense Motion Sensor is an Inertial Measurement Unit (IMU) measuring accelerations (g), gyroscopic velocities (degrees per second (dps)) and the magnetic field (Gauss). The QSense sensor can be configured to stream different data, from the raw IMU data to quaternions.

The QSense Motion Sensor can be run in two distinct modes, optimised for different tasks:

Low-Latency Mode

Real-time rendering and closed-loop control with an end-to-end latency < 25ms. Samples are not synchronized accrues multiple sensors (error +/- 2 samples). Typical use cases: AR/VR head-tracking, haptics, robotics.

Time Sync Mode (default)

Multi-sensor motion capture and precise analysis. Alle sensors are timestamped to a common clock within ± 60 µs. This adds 2-3 ms of buffering. Typical use case, biomechanics, sensor fusion, research.

QSense Motion currently provides 5 different data modes:

Mixed mode: collects accelerometer, gyroscope, and magnetometer data at the selected sampling rate. It also provides quaternion and free acceleration data at a lower (downsampled) rate. The downsampling ratio for these data types is determined by the buffering configuration.

Raw mode: collects accelerometer, gyroscope, and magnetometer data at the selected sampling rate.

Quaternion mode: provides orientation data (quaternions) at the selected sampling rate.

Optimized mode: collects orientation data (quaternions), accelerometer, and gyroscope data at the selected sampling rate.

Quat+Mag: provides orientation data (quaternions) and magnetometer data at the selected sampling rate.

The QSense sensor offers two different algorithms to compute quaternions:

9 DoF (default): The 9DoF Madgwick algorithm uses data from the accelerometer, gyroscope, and magnetometer to calculate quaternions. The magnetometer helps correct for gyroscope drift, providing more accurate orientation tracking.

6 DoF: The 6DoF Madgwick algorithm combines accelerometer and gyroscope data to compute quaternions, making it immune to magnetometer interference; however, without magnetometer input, it may suffer from gradual drift in heading (yaw) over time.

When a data output format is used that uses the magnetic sensor there might be drift problems over time.

Ferromagnetic materials (like iron or steel), magnets, or strong electrical currents (several amperes) near the sensor can distort the local magnetic field. The magnetometer in the QSense Sensor acts as a 3D compass to determine true north (heading direction), which helps correct gyroscope bias in the 9DoF Madgwick algorithm. Magnetic disturbances prevent accurate heading estimation, leading to orientation drift.

In case drift is observed:

– Change to an environment where there are no metal objects in the environment (chairs with iron inside, metal cabinets, etc.). For best measurement results, try to avoid magnetic fields during measurements.

– Perform Magnetic Field Mapping in the new environment.

Important: It is recommended to perform Magnetic Field Mapping for every new location.

The QSense PC application will show when there are soft-iron effects coming from electronic devices, or hard-iron effects coming from metal objects and magnets.

Yes the QSense Motion Sensor is waterproof and has an IP classification or IP67 or better.

1. Try charging the device. If the charging animation appears, the battery was completely drained. Note that it may take longer than usual to fully recharge.
2. If charging doesn’t resolve the issue, the QSense device may have encountered an internal error. Press and hold the button for 10 seconds to reset the device.

If the sensor is unresponsive and the LEDs remain unchanged, the QSense device may have encountered an internal error. To resolve this, press and hold the button for 10 seconds to reset the device.

Yes, but it is not recommended. Metal objects and electronic devices can interfere with the magnetometer data. Performing magnetic field mapping can reduce these disturbances, but the quaternion output may still be affected.

Ensure that the QSense device is not already connected to another central device.
If it is not connected elsewhere, try resetting the sensor by pressing and holding the button for 10 seconds.

The number of devices you can connect simultaneously depends on your device’s operating system, manufacturer, and the configuration of the QSense devices. Refer to the table below for the maximum connections allowed for different operating systems based on sampling and transmission rates.

This could happen for two reasons:

1. Wireless communication issues: Examples include physical obstructions blocking the QSense devices or interference from multiple wireless devices in the area.
2. Inadequate device configuration: Ensure that the sampling and transmission rates are compatible with the number of devices you are connecting and your operating system.

Sampling rate: The amount of data per second the sensors collect.

Transmission rate: The number of packets the sensors send per second.

Together, these parameters determine how many QSense devices you can connect to a single device without data loss.

The QSense Motion Sensor has been tested and found to be in compliance with the standards for electrical safety, EMF, EMC and radio testing.

Ensure the reference sensor is correctly oriented. Additionally, perform both offset compensation and magnetic field mapping before recording any data. If the problem persists, please contact us.

You can, but not calibrating the devices when the environment changes will result in poorer quaternion output.

Place the recorders inside the box after removing any cables and docking. Rotate the box around its three axes until all points are collected. Avoid wide movements; the box should rotate as if its center were fixed in space.

The interference level shows the presence of magnetic disturbances. Ideally, the environment should be interference-free. However, even if disturbances are present, the sensor fusion algorithm used to compute the quaternions can reduce their impact on the output.