Gait patterns generation based on basis functions interpolation for the TWIN lower-limb exoskeleton

Vassallo, Christian; Giuseppe, Samuele De; Piezzo, Chiara; Maludrottu, Stefano; Cerruti, Giulio; D'Angelo, Maria Laura; Gruppioni, Emanuele; Marchese, Claudia; Castellano, Simona; Guanziroli, Eleonora; Molteni, Franco; Laffranchi, Matteo; Michieli, Lorenzo De

doi:10.1109/icra40945.2020.9197250

Cited by 17 publications

(18 citation statements)

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“…Another significant outcome of the clinical test on the SCI subject is that TWIN's trajectory patterns facilitate the stability of the user due to its emphasized heel strike, as explained in detail in our previous work (Vassallo et al, 2020) and this is agreeable with respect to usability too.…”

Section: Discussionsupporting

confidence: 62%

“…The load scenario used in this simulation replicated that measured by a motorized dummy exoskeleton which was equipped with force/torque sensors (please refer to section Structure and Actuation Unit for more details on this device). To obtain this data, a healthy subject simulating leg impairment wore the exoskeleton while position controlled to perform the walking patterns described in our previous work (Vassallo et al, 2020). The worst-case load scenario is summarized in Table 4, where the Y axis represents longitudinal axis of the lower limb, the Z axis is the medio-lateral axis and the X axis completes the triad.…”

Section: Mechanicsmentioning

confidence: 99%

“…To obtain more realistic data, we therefore developed and used a custom-made "dummy" motorized lower limb exoskeleton that was fully sensorized for the purpose of recording the load applied to the exoskeleton actuators and structure during position-controlled walking, standing and sitting and use them for appropriate actuators dimensioning. A classical robotic trajectory was set as reference for the position-controlled system, Figure 6A (T1 as explained in Vassallo et al, 2020), and a healthy male subject, 60 kg, wore the exoskeleton performing a few steps simulating full leg impairment.…”

Section: Actuator Sizingmentioning

confidence: 99%

“…The identification of predefined gait trajectories to be employed on lower limb exoskeletons is typically obtained by fitting mathematical curves to temporal sequences of desired joint angles that are often inspired by biological gait patterns. In contrast to this, in Vassallo et al (2020) we proposed predefined gait trajectories for the TWIN lower-limb exoskeleton, generated in Cartesian space, by using a basis function interpolation method which was designed so as to maximize stable walk as outlined by requirement #3. Such approach allows to guarantee the length and clearance of each step, despite the variation of tibia and femur lengths.…”

Section: Control Systemmentioning

confidence: 99%

“…These functions are normalized and assume a value which can range from 0 to 1. A more detailed description of the definition of the basis function is given in Vassallo et al (2020). Given the reference trajectory in the Cartesian space x F , z F , x T , we compute the joint angles based on the following assumptions: (i) θ T = β + q1 + q2 with {β∈ R, β min ≤ β ≤ β flex }, (ii) θ T (t) = 0, ∀t ∈ [0, t S ] where t S is the step duration.…”

Section: The Design Of the Gait Patternmentioning

confidence: 99%

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User-Centered Design and Development of the Modular TWIN Lower Limb Exoskeleton

et al. 2021

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For decades, powered exoskeletons have been considered for possible employment in rehabilitation and personal use. Yet, these devices are still far from addressing the needs of users. Here, we introduce TWIN, a novel modular lower limb exoskeleton for personal use of spinal-cord injury (SCI) subjects. This system was designed according to a set of user requirements (lightweight and autonomous portability, quick and autonomous donning and setup, stability when standing/walking, cost effectiveness, long battery life, comfort, safety) which emerged during participatory investigations that organically involved patients, engineers, designers, physiatrists, and physical therapists from two major rehabilitation centers in Italy. As a result of this user-centered process, TWIN's design is based on a variety of small mechatronic modules which are meant to be easily assembled and donned on or off by the user in full autonomy. This paper presents the development of TWIN, an exoskeleton for personal use of SCI users, and the application of user-centered design methods that are typically adopted in medical device industry, for its development. We can state that this approach revealed to be extremely effective and insightful to direct and continuously adapt design goals and activities toward the addressment of user needs, which led to the development of an exoskeleton with modular mechatronics and novel lateral quick release systems. Additionally, this work includes the preliminary assessment of this exoskeleton, which involved healthy volunteers and a complete SCI patient. Tests validated the mechatronics of TWIN and emphasized its high potential in terms of system usability for its intended use. These tests followed procedures defined in existing standards in usability engineering and were part of the formative evaluation of TWIN as a premise to the summative evaluation of its usability as medical device.

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Section: Discussionsupporting

confidence: 62%

Section: Mechanicsmentioning

confidence: 99%

Section: Actuator Sizingmentioning

confidence: 99%

Section: Control Systemmentioning

confidence: 99%

Section: The Design Of the Gait Patternmentioning

confidence: 99%

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