Guffanti, Diego
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Guffanti, Diego
Main Affiliation
Quito
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Scopus Author ID
57200385407

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Performance of a Mobile 3D Camera to Evaluate Simulated Pathological Gait in Practical Scenarios

2023 , Guffanti, Diego , Lemus D. , Vallery H. , Brunete A. , Hernando M. , Horemans H.

Three-dimensional (3D) cameras used for gait assessment obviate the need for bodily markers or sensors, making them particularly interesting for clinical applications. Due to their limited field of view, their application has predominantly focused on evaluating gait patterns within short walking distances. However, assessment of gait consistency requires testing over a longer walking distance. The aim of this study is to validate the accuracy for gait assessment of a previously developed method that determines walking spatiotemporal parameters and kinematics measured with a 3D camera mounted on a mobile robot base (ROBOGait). Walking parameters measured with this system were compared with measurements with Xsens IMUs. The experiments were performed on a non-linear corridor of approximately 50 m, resembling the environment of a conventional rehabilitation facility. Eleven individuals exhibiting normal motor function were recruited to walk and to simulate gait patterns representative of common neurological conditions: Cerebral Palsy, Multiple Sclerosis, and Cerebellar Ataxia. Generalized estimating equations were used to determine statistical differences between the measurement systems and between walking conditions. When comparing walking parameters between paired measures of the systems, significant differences were found for eight out of 18 descriptors: range of motion (ROM) of trunk and pelvis tilt, maximum knee flexion in loading response, knee position at toe-off, stride length, step time, cadence; and stance duration. When analyzing how ROBOGait can distinguish simulated pathological gait from physiological gait, a mean accuracy of 70.4%, a sensitivity of 49.3%, and a specificity of 74.4% were found when compared with the Xsens system. The most important gait abnormalities related to the clinical conditions were successfully detected by ROBOGait. The descriptors that best distinguished simulated pathological walking from normal walking in both systems were step width and stride length. This study underscores the promising potential of 3D cameras and encourages exploring their use in clinical gait analysis. © 2023 by the authors.

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Robust Model Predictive Control with a Dynamic Look-Ahead Re-Entry Strategy for Trajectory Tracking of Differential-Drive Robots

2026 , Guffanti, Diego , Moisés Filiberto Mora Murillo , Santiago Bustamante Sanchez , Javier Oswaldo Obregón Gutiérrez , Marco Alejandro Hinojosa , Alberto Brunete , Miguel Hernando , David Álvarez

Accurate trajectory tracking remains a central challenge in differential-drive mobile robots (DDMRs), particularly when operating under real-world conditions. Model Predictive Control (MPC) provides a powerful framework for this task, but its performance degrades when the robot deviates significantly from the nominal path. To address this limitation, robust recovery mechanisms are required to ensure stable and precise tracking. This work presents an experimental validation of an MPC controller applied to a four-wheel DDMR, whose odometry is corrected by a SLAM algorithm running in ROS 2. The MPC is formulated as a quadratic program with state and input constraints on linear (v) and angular (ω) velocities, using a prediction horizon of Np=15 future states, adjusted to the computational resources of the onboard computer. A novel dynamic look-ahead re-entry strategy is proposed, which activates when the robot exits a predefined lateral error band (δ=0.05 m) and interpolates a smooth reconnection trajectory based on a forward look-ahead point, ensuring gradual convergence and avoiding abrupt re-entry actions. Accuracy was evaluated through lateral and heading errors measured via geometric projection onto the nominal path, ensuring fair comparison. From these errors, RMSE, MAE, P95, and in-band percentage were computed as quantitative metrics. The framework was tested on real hardware at 50 Hz through 5 nominal experiments and 3 perturbed experiments. Perturbations consisted of externally imposed velocity commands at specific points along the path, while configuration parameters were systematically varied across trials, including the weight R, smoothing distance Lsmooth, and activation of the re-entry strategy. In nominal conditions, the best configuration (ID 2) achieved a lateral RMSE of 0.05 m, a heading RMSE of 0.06 rad, and maintained 68.8% of the trajectory within the validation band. Under perturbations, the proposed strategy substantially improved robustness. For instance, in experiment ID 6 the robot sustained a lateral RMSE of 0.12 m and preserved 51.4% in-band, outperforming MPC without re-entry, which suffered from larger deviations and slower recoveries. The results confirm that integrating MPC with the proposed re-entry strategy enhances both accuracy and robustness in DDMR trajectory tracking. By combining predictive control with a spatially grounded recovery mechanism, the approach ensures consistent performance in challenging scenarios, underscoring its relevance for reliable mobile robot navigation in uncertain environments.

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RoboGait: a robotic system for non-invasive gait analysis. [RoboGait: sistema robótico no invasivo para el análisis de la marcha humana]

2024 , Álvarez D. , Guffanti, Diego , Brunete A. , Hernando M. , Gambao E.

The most common methods used in gait analysis laboratories are systems based on the use of markers and/or sensors positioned all over the patient’s body while performing a walking test. These approaches usually require individual calibration, a long time to set up the patient, and, therefore, discomfort of the users. Besides, some of the methods can only be performed in specific small scenarios that need to be previously set-up with external sensors. The presented system, RoboGait, is designed to overcome these problems while maintaining a good performance in terms of quality of the measurements provided. RoboGait is a mobile robotic platform that moves in front of a patient that is walking. The system measures the configuration of the patient’s body using an RGBD camera mounted on the top. Initial measurements provided by the camera are processed using an Artificial Neural Network that improves the estimated kinematic and spatio-temporal signals of the patient’s movement. This paper shows the effectiveness of the system by comparing with a validated method that uses a Vicon® system. Then, the work shows the usefulness of RoboGait in a clinical environment by using it to classify healthy and pathological gaits. In this case, the results have been compared to a reference system based on inertial sensors called Xsens®. The results show a great potential for the use of RoboGait for clinical patient assessment and monitoring, and for pathology identification. © 2024 Universidad Politecnica de Valencia.. All rights reserved.

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Supervised learning for improving the accuracy of robot-mounted 3D camera applied to human gait analysis

2024 , Guffanti, Diego , Brunete A. , Hernando M. , Álvarez D. , Rueda J. , Navarro E.

Background and Objective: the use of 3D cameras for gait analysis has been highly questioned due to the low accuracy they have demonstrated in the past. The objective of the study presented in this paper is to improve the accuracy of the estimations made by robot-mounted 3D cameras in human gait analysis by applying a supervised learning stage. Methods: the 3D camera was mounted in a mobile robot to obtain a longer walking distance. This study shows an improvement in detection of kinematic gait signals and gait descriptors by post-processing the raw estimations of the camera using artificial neural networks trained with the data obtained from a certified Vicon system. To achieve this, 37 healthy participants were recruited and data of 207 gait sequences were collected using an Orbbec Astra 3D camera. There are two basic possible approaches for training and both have been studied in order to see which one achieves a better result. The artificial neural network can be trained either to obtain more accurate kinematic gait signals or to improve the gait descriptors obtained after initial processing. The former seeks to improve the waveforms of kinematic gait signals by reducing the error and increasing the correlation with respect to the Vicon system. The second is a more direct approach, focusing on training the artificial neural networks using gait descriptors directly. Results: the accuracy of the 3D camera to objectify human gait was measured before and after training. In both training approaches, a considerable improvement was observed. Kinematic gait signals showed lower errors and higher correlations with respect to the ground truth. The accuracy of the system to detect gait descriptors also showed a substantial improvement, mostly for kinematic descriptors rather than spatio-temporal. When comparing both training approaches, it was not possible to define which was the absolute best. Conclusions: supervised learning improves the accuracy of 3D cameras but the selection of the training approach will depend on the purpose of the study to be conducted. This study reveals the great potential of 3D cameras and encourages the research community to continue exploring their use in gait analysis. © 2024 The Authors

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