Characterization of Spatio-Temporal Parameters of Human Gait Assisted by a Robotic Walker Anselmo Frizera, Member, IEEE, Arlindo Elias, Antonio J. del-Ama, Ramon Ceres and Teodiano Freire Bastos Abstract— Investigations of the biomechanical parameters of robotic walker assisted gait are needed to allow modern rehabilitation strategies and to improve further technological developments. In this study, spatio-temporal gait parameters were assessed during normal and assisted ambulation with the Simbiosis walker model, a robotic walker with forearm supports. Six infra-red video cameras, integrated in a movement analysis system, were used for three-dimensional reconstruction of body segments and measurement of biomechanical variables during assisted ambulation. Results showed that walker-assisted gait was marked by an overall reduction of spatio-temporal parameters, especially gait speed, without modification in cadence-speed and stride length-speed relationships. Future work investigating such modality of assisted gait in clinical conditions are warranted and may contribute for a better understanding of user-device interaction forces and its impact over gait biomechanics. I. INTRODUCTION Spatio-temporal parameters are a basic pre-requisite for the complete analysis of human gait [1]. Variations of such parameters are observed in different clinical conditions, as well as within groups of healthy individuals [2]. The knowl- edge of how these parameters are affected by pathological or environmental factors are essential for the development of novel assistive devices to help in the design of modern rehabilitation strategies. Rollator-type walkers are important examples of assistive technology, which aim to empower the mobility of impaired individuals [3]. Due to its versatility and rehabilitation po- tential, the popularity of these models has increased, not only among people with restricted mobility, but also among research groups currently working in robotic versions of the device [4] [5]. However, when considering both conventional and robotic rollators, there are few studies in literature that address the biomechanical events that take place during this modality of assisted ambulation. Variations within walker models and implemented systems further complicate the analysis of the The Simbiosis Project is placed in the framework of the Spanish National Program of R&D Anselmo Frizera and Teodiano Freire Bastos are with Department of Electrical Engineering, Federal University of Espirito Santo - UFES, 512, Vitoria-ES, Brazil. anselmo@ele.ufes.br teodiano@ele.ufes.br Arlindo Elias is with the Department of Biotechnology, Fed- eral University of Espirito Santo - UFES, 512, Vitoria-ES, Brazil. arlindofisio@yahoo.com.br Antonio J. del-Ama is with the Spinal Cord Injury Hospital of Toledo, Spain. ajdela@sescam.jccm.es Ramon Ceres is with the Bioengineering Group, Consejo Superior de Investigaciones Cientificas (CSIC), Spain. ceres@iai.csic.es impact of such technology in user-device interactions and spatio-temporal gait parameters. Thus, for the prescription of the most adequate robotic model in clinical or domiciliary settings, a thorough analysis of the motion patterns that occur during assisted ambulation are needed. Moreover, the ways in which the action of walk- ing with the device modifies the pathological gait patterns of impaired subjects must also be assessed. In this paper, healthy volunteers were enrolled in a pilot investigation of gait biomechanics during normal and walker- assisted ambulation using the Simbiosis model, a robotic walker with forearm supports [6]. The objective was to obtain reference standard parameters of walker-assisted gait [7]. After an initial discussion of the experimental protocol and the addressed parameters, the analysis of assisted ambulation, considering the spatio-temporal gait parameters, is presented. II. METHODS A. Participants Seven healthy male, age and height-matched, with no history of gait dysfunction, volunteered to participate in this pilot study. The subjects were not familiarized with the device and no previous test sessions were performed. Written informed consent for publication was obtained from all individuals. The Simbiosis Project was approved, along with the experimental and validation procedures, by Spanish Ministry of Science and Innovation (MICINN). B. Experimental Setting For the experiments conducted in this study, the BTS Bioengineering movement analysis system was used. Six infra-red video cameras were used for 3D reconstruction of the position of reflexive markers, placed over the subject’s body according to the protocol described by Davis et al. [8]. Combining such information with the biomechanical model and subject’s anthropometric data, it was possible to obtain the complete 3D motion of the subject’s body segments during ambulation (Fig.1). The subjects were asked to walk in the laboratory walk- way, while the video cameras tracked the attached markers during the trial. The subjects performed three different test sessions, which consisted of normal unassisted, slow unas- sisted and walker-assisted ambulation. The test procedure involving slow, unassisted ambulation was performed by five of the seven subjects. The objective was to observe if the relationship between speed, cadence and stride length were changed by the assisted gait modality. The Fourth IEEE RAS/EMBS International Conference on Biomedical Robotics and Biomechatronics Roma, Italy. June 24-27, 2012 978-1-4577-1198-5/12/$26.00 ©2012 IEEE 1087