Human sit-to-stand transfer modeling towards intuitive and biologically-inspired robot assistance

Abstract

Sit-to-stand (STS) transfers are a common human task which involves complex sensorimotor processes to control the highly nonlinear musculoskeletal system. In this paper, typical unassisted and assisted human STS transfers are formulated as optimal feedback control problem that finds a compromise between task end-point accuracy, human balance, energy consumption, smoothness of motion and control and takes further human biomechanical control constraints into account. Differential dynamic programming is employed, which allows taking the full, nonlinear human dynamics into consideration. The biomechanical dynamics of the human is modeled by a six link rigid body including leg, trunk and arm segments. Accuracy of the proposed modelling approach is evaluated for different human healthy and patient/elderly subjects by comparing simulations and experimentally collected data. Acceptable model accuracy is achieved with a generic set of constant weights that prioritize the different criteria. Finally, the proposed STS model is used to determine optimal assistive strategies suitable for either a person with specific body segment weakness or a more general weakness. These strategies are implemented on a robotic mobility assistant and are intensively evaluated by 33 elderlies, mostly not able to perform unassisted

Special Issue on Assistive and Rehabilitation Robotics

“…One key concern, and identified area for robotic assistance, are transfers-for example, in and out of a bed or a wheelchair, or from sitting to standing-because of the risk of falls and injury. In this Special Issue, the work of Geravand et al (2016) formulates sit-to-stand transfers as an optimal feedback control problem, which optimizes over factors like accuracy, human balance, energy, motion smoothness and human biomechanical constraints. Their approach is evaluated with a robotic assistant and aged persons largely unable to perform sit-to-stand transfers unassisted.…”

A systematic review of study results reported for the evaluation of robotic rollators from the perspective of users

“…The sample size of included studies averaged 7.7 ± 4.5 subjects (range, [2][3][4][5][6][7][8][9][10][11][12][13][14][15][16][17][18][19][20]. The mean age of subjects ranged from 25 [37] to 89 years [38], with age information lacking in four studies [17,[25][26][27].…”

“…In our recent systematic review on the methodology of studies evaluating RRs by the user perspective, the identified studies showed large heterogeneity in study population, design of studies/test scenarios, and assessment methods. No generic methodology to evaluate RRs from the user perspective could be identified [19]. We also found major methodological shortcomings related to insufficient sample sizes, lack of appropriate standardized and validated assessment methods, and lack of statistical analyses of study results.…”

“…More specifically, they may cover robotic functionalities that focus on gait assistance [17], sit-to-stand (STS) transfer [18][19][20], partial body weight support (BWS) [21,22], obstacle avoidance [23][24][25], navigation assistance [26][27][28], and/or fall prevention [29,30]. A more detailed survey of the various high-tech functionalities of RRs can be found in Martins et al [31,32].…”

Evaluation and Fault Classification for Service Robot during Sit- to-Stand Movement through Center of Mass

“…Gervand et al [6] formulated unassisted and assisted STS transfers as a control problem and found a balance among the end-point accuracy, human balance, energy consumption, and smoothness of motion. Chuy et al [7] presented two approaches to assisting with the STS movement by using a robotic walking support system and showed that this system can track the desired support force.…”