The Bertec FIT5: A Fully Instrumented Treadmill for Precise Gait Analysis and Biomechanics Research
PART 1: The FIT5 Instrumented Treadmill and Software
The Bertec Fully Instrumented Treadmill v5 (FIT5) and its accompanying software offer measurement accuracy with a user-friendly interface tailored for gait researchers and biomechanics labs. The integration between the split belt treadmill hardware and device-controlling software gives the researcher the flexibility to build customized repeatable protocols. This advanced system allows for precise control of the treadmill, real-time viewing and capturing of force, moment, and velocity data, and the creation of custom experiments with the Protocol Builder. In this blog, we'll explore how the hardware precision ensures smooth and consistent acceleration, which is crucial for perturbation and fall prevention research. Additionally, we'll discuss how the FIT5 Remote Control API seamlessly integrates with Python and motion capture systems for advanced real-time feedback-based controls, and show how the FIT5 can be used to design customized protocols.
Precision Hardware
The split belt design, featuring individual force plates beneath each foot, provides separate data channels for each foot and is mechanically isolated to reduce crosstalk between the belts. Speeds (up to 11.5 m/s), acceleration (up to 25 m/s²), and treadmill synchronization can be adjusted on the fly. For treadmills with incline capabilities, users can precision-lock angles up to 15 degrees to achieve incline accuracy when simulating uphill or downhill movements.
Precise, smooth, and consistent acceleration is essential for obtaining reliable data. The robust connection between the drive train and belts, paired with industrial grade high-powered motors, enables higher speeds and consistent accelerations crucial for effective perturbation delivery to abruptly disrupt balance. This setup ensures the belt does not slip during treadmill perturbations. The low-friction wear plate minimizes the potential for belt sticking, resulting in steady belt speeds and acceleration. All these features make walking or running on the FIT5 feel natural with minimal vibration while ensuring measurement accuracy.
To ensure safety, the FIT5 features an overhead harness structure to prevent falls and off-track movements. This is especially important during slip or trip perturbations, which can cause balance issues or discomfort, particularly for those with orthopedic impairments. Bertec strongly recommends using the harness during treadmill protocols, especially with any perturbation protocol.
Figure 1: FIT5 Integrated safety harness and optional instrumented handrails
FIT5 Software
The FIT5 user-friendly Workspace interface (Figure 2) enables the researcher to simultaneously control the treadmill while recording data. Treadmill velocity and acceleration can be quickly increased or decreased during an experiment by using the treadmill quick controls. The researcher can monitor the participant’s force, moment, center of pressure (CoP), and velocity data within a 5-second rolling window during data capture throughout the experiment and the six-component force output can be hidden or combined to focus on specific variables and participant performance. The live 2D COP display allows the researcher to monitor the participant’s location on the separated treadmill belts.
Figure 2: Workspace control software user interface
The FIT5 software offers a variety of options to capture data: manually for open-ended recording, using a timer to record data for a specific time, applying a protocol created in Protocol Builder, or triggering an external source such as partner motion capture systems to simultaneously acquire both kinetic and kinematic data. The treadmill software integrates with the remote-control Application Programming Interface (API) to offer researchers advanced programmatic control and accurate replication of research protocols. The user can use the remote-control API to create customized Python scripts to control the treadmill and obtain force data in any instant. For example, Shih (2023) integrated data from motion capture software with the remote-control API to develop a trip perturbation protocol using the Bertec split-belt treadmill. These features offer the sport scientist and researcher full flexibility, and the ability to create custom structured experimental protocols in a fully integrated hardware and software environment.
Protocol Builder
The FIT5 Protocol Builder allows the user to create, save, and synchronize custom treadmill protocols to ensure experiment repeatability, regardless of the operator. A protocol is a sequence of treadmill device states, known as responses, that are played in a user-defined sequence. These response parameters include belt synchronization (the belts can be controlled independently or together), velocity, acceleration, start delay of the next response in the protocol, and how long a response plays in the protocol. Favorite protocols can be saved as a playlist to be used in future experiments. The steps to create a simple jog protocol are shown in Figure 3. The user first creates the desired responses on the left half, then drag the responses to the protocol configuration window on the right.
Figure 3: Simple jog protocol: response list and tied-belt (synched) protocol configuration
Walking patterns constantly adapt through step-by-step modifications based on error feedback from the environment, such as slippery or uneven surfaces. Research on split-belt treadmill adaptation sheds light on the spatiotemporal control of gait driven by proprioceptive input. Sato and Choi (2019) employed a Bertec split-belt protocol to explore the task-specific role of corticospinal drive that occurs during gait adaptation. Figure 4 illustrates their split-belt adaptation gait protocol, showcasing the versatility of the Protocol Builder in creating experimental protocols of varying complexity.
Figure 4: Asymmetric gait adaptation split-belt protocol after Sato and Choi (2019)
The FIT5 instrumented treadmill and Workspace software interface is an easy-to-use system to control and record data simultaneously. The Protocol Builder allows the researcher to develop organized and structured protocols to ensure the experiment is conducted the same way regardless of the operator. The FIT5 is designed to integrate with other motion capture and EMG devices via the remote-control API interface to offer full flexibility for a variety of research areas ranging from gait adaptation, perturbation, fall prevention, and sport performance. A future post will explore platform and treadmill perturbation research in greater depth.
Conclusion: Advancing Gait and Biomechanics Research with the FIT5
In conclusion, the FIT5 and accompanying software provide the researcher with a low-vibration, high-quality treadmill that closely reproduces natural gait and running. The hardware precision and design permit live data visualization, custom treadmill protocol creation for repeatable experiments, and synchronized data capture to obtain precise and accurate data. Perturbation research and training are especially easy to implement with the Protocol Builder on the FIT5, allowing for greater strides in understanding and reducing fall risk.
For more information, contact sales@bertec.com.
References:
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