Motion control of a robotic transtibial prosthesis during transitions between level ground and stairs

Abstract

This paper presents a hierarchical control strategy for a robotic transtibial prosthesis to realize smooth locomotion transitions between level ground and stairs. The high level controller identifies current terrain with a fuzzy logic based method and decides the corresponding parameters for lower level controllers. The middle level controller detects different gait phases of one gait cycle on a specific terrain and decides which control method to be used for the current phase. Based on the recognized terrain and gait phase, the low level controller performs damper control for the stance phase and angle control for the swing phase. To evaluate the effectiveness of the proposed control method, we design and construct a robotic transtibial prosthesis prototype. Experimental results of a transtibial amputee subject show improved gait symmetry on level ground and stairs with the proposed control strategy. A 12-s long trial that includes different terrains and terrain transitions indicates that the proposed method can realize smooth locomotion transitions between level ground and stairs.

Intent Prediction of Multi-axial Ankle Motion Using Limited EMG Signals

“…The development of powered prostheses has necessitated the implementation of control systems to ensure desired functionality of these prostheses. Most of the control strategies implemented to date have been hierarchical in nature (Lawson et al, 2013; Hargrove et al, 2014; Young et al, 2014b; Yuan et al, 2014; Spanias et al, 2018). These have consisted of a high level (decision) control system, which deciphers the type of motion a user wants to perform, and a low level (execution) controller that oversees the actuation of said motion by the prosthesis.…”

Current overview of the state of disabled population, regarding the use of transtibial prosthesis

“…They use the mechanical system to simulate the effect of compensation forces necessary for the patient to maintain balance as s/he moves (Adebayo et al, 2011;Arotaritei, Turnea, Filep, Ilea and Rotariu, 2015;Casallas et al, 2011;Chen and Wang, 2015;Wang et al, 2015). The prototype is able to absorb the force generated when the prosthesis comes into contact with a surface, avoiding bounce effects, and it also compensates the angle between the basis of the prosthesis and the coupling axis, thus allowing the user to walk on steep surfaces ( Bravo and Rengifo, 2014; Morgenroth et al, 2011;Yuan et al, 2014;Zheng and Wang, 2016;Zhu, Wang, Li, Sun and She, 2015;Zhu, Wang and Wang, 2014).…”

“…In the prototype by Yuan et al(2011) a digital control system is implemented to calculate the magnitude of the force necessary for the patient to maintain balance from its own weight; the angle between the components of the prosthesis regarding the ground and the part of the prosthesis coming into contact with the floor (Adebayo et al, 2011;Bellman et al, 2008;Cherelle et al, 2014Cherelle et al, , 2012Yuan et al, 2011;Yuan et al, 2014;Zheng and Wang, 2016;Zhu et al, 2015Zhu et al, , 2014. There is only one parameter left to the patient, the other ones are calculated by sensors located in diffrent parts of the prostesis.…”

“…Achieving behavior similar to that of the muscles requires the use of several mechanic elements combined (Mancinelli et al, 2011;Shultz et al, 2016;Yuan et al, 2015Yuan et al, , 2014Zheng and Shen, 2013); however, the system is subjected to effects proper to the mechanical elements used, thus altering the dynamics intended to be simulated (Bravo and Rengifo, 2014;Fang, Jia, Wang and Suo, 2009;Gabriel et al, 2008;Mancinelli et al, 2011). Lee et al(2014), Silverman and Neptune (2012), Wang and Brown (2016) state that a mechanical system formed by a spring, and an engine exerting compression force on it, as well as contention of spring elongation simulate the behavior of a muscle (Au et al, 2007;Brasil and Rosa, 2011;Chen, Wang, and Wang, 2015;Cherelle et al, 2014;Hill and Herr, 2013;Huang et al, 2016).…”

“…The mechanical principles of each limb are studied for design, in order to obtain an approximate model of the biomechanics of the limb to be replaced with the prosthesis (Au et al, 2015;Casallas et al, 2011;Cherelle, Grosu, Matthys, Vanderborght and Lefeber, 2014;Huang, Wensman and Ferris, 2016;Shultz, Lawson and Goldfarb, 2016;Sinitski et al, 2012;Yuan et al, 2014). …”