Design and Validation of a Torque-Controllable Knee Exoskeleton for Sit-to-Stand Assistance

Shepherd, Max K.; Rouse, Elliott J.

doi:10.1109/tmech.2017.2704521

Cited by 144 publications

(64 citation statements)

References 30 publications

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“…Over the last two decades, various studies have demonstrated that industrial exoskeletons can decrease total work, fatigue, and load while increasing productivity and work quality [2][3]. Another prominent field where exoskeletons have been heralded as a promising technology is medical rehabilitation focusing on walking assistance [4][5][6][7][8][9][10][11][12]. Recently, the feasibility of exoskeletonassisted energetics reduction has been demonstrated in walkers X. Yang, T. Huang, H. Hu, S. Yu, S. Zhang, and H. Su are with the Lab of Biomechatronics and Intelligent Robotics, Department of Mechanical Engineering, The City University of New York, City College, New York, NY, 10031, US.…”

Section: Introductionmentioning

confidence: 99%

Spine-Inspired Continuum Soft Exoskeleton for Stoop Lifting Assistance

Yang

Huang

et al. 2019

IEEE Robot. Autom. Lett.

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Back injuries are the most prevalent work-related musculoskeletal disorders and represent a major cause of disability. Although innovations in wearable robots aim to alleviate this hazard, the majority of existing exoskeletons are obtrusive because the rigid linkage design limits natural movement, thus causing ergonomic risk. Moreover, these existing systems are typically only suitable for one type of movement assistance, not ubiquitous for a wide variety of activities. To fill in this gap, this paper presents a new wearable robot design approach continuum soft exoskeleton. This spineinspired wearable robot is unobtrusive and assists both squat and stoops while not impeding walking motion. To tackle the challenge of the unique anatomy of spine that is inappropriate to be simplified as a single degree of freedom joint, our robot is conformal to human anatomy and it can reduce multiple types of forces along the human spine such as the spinae muscle force, shear, and compression force of the lumbar vertebrae. We derived kinematics and kinetics models of this mechanism and established an analytical biomechanics model of human-robot interaction. Quantitative analysis of disc compression force, disc shear force and muscle force was performed in simulation. We further developed a virtual impedance control strategy to deliver force control and compensate hysteresis of Bowden cable transmission. The feasibility of the prototype was experimentally tested on three healthy subjects. The root mean square error of force tracking is 6. 63 N (3.3 % of the 200N peak force) and it demonstrated that it can actively control the stiffness to the desired value. This continuum soft exoskeleton represents a feasible solution with the potential to reduce back pain for multiple activities and multiple forces along the human spine.

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Section: Introductionmentioning

confidence: 99%

Spine-Inspired Continuum Soft Exoskeleton for Stoop Lifting Assistance

Yang

Huang

et al. 2019

IEEE Robot. Autom. Lett.

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“…Using subject-specific inverse dynamics modelling, this research computed maximum hip, knee, and ankle joint torques during stand-to-sit movements of approximately 0.7 ± 0.1 Nm/kg, 1.1 ± 0.3 Nm/kg, and 0.4 ± 0.1 Nm/kg, respectively. In comparison, previous investigations involving the mechatronic design and evaluation of lower-limb exoskeletons and prostheses for sitting and standing movements reported maximum knee joint torques ranging from 0.8-1.0 Nm/kg [36,[38][39][40]. The relatively good quantitative agreement between the current (1.1 ± 0.3 Nm/kg) and previous (0.8-1.0 Nm/kg) [36,[38][39][40] maximum normalized knee joint torques for sitting and standing movements further supported the model validation.…”

Section: Discussionmentioning

confidence: 74%

“…The average human performs approximately 60 sitting and standing movements each day [36]. Several robotic lower-limb prostheses and exoskeletons have been designed and evaluated for sitting and standing movements (example shown in Figure 2) [7][8][9][36][37][38][39][40][41][42].…”

Section: Previous Investigations Of Lower-limb Prostheses and Exoskelmentioning

confidence: 99%

“…Building on previous investigations, which often involved fewer than 3 participants [7,[38][39][41][42], this research included 9 participants (height: 180 ± 4 cm, weight: 78 ± 7 kg, age: 25 ± 3 years, sex: male). Informed written consent was obtained, and the University of Waterloo Office of Research Ethics approved this research.…”

Section: Motion Capture Experimentsmentioning

confidence: 99%

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Simulation of Stand-to-Sit Biomechanics for Design of Lower-Limb Exoskeletons and Prostheses with Energy Regeneration

Laschowski¹,

Razavian²,

McPhee³

2019

Preprint

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BACKGROUND: Regenerative powertrain systems can extend the operating durations of robotic lower-limb prostheses and exoskeletons. These energy-efficient biomechatronic devices have been exclusively designed and evaluated for level-ground walking. Building on previous investigations, this research assessed the lower-limb joint biomechanical powers during stand-tosit movements using inverse dynamics modelling to estimate the biomechanical energy available for electrical regeneration. METHODS: Nine participants performed 20 sitting and standing movements while lower-limb kinematics and ground reaction forces were measured. Following the biomechanical model design, dynamic parameter identification computed the subject-specific body segment inertial parameters that minimized the differences in ground reaction forces and moments between the experimental measurements and inverse dynamic simulations. Joint biomechanical powers were calculated from net joint torques and rotational velocities and numerically integrated over time to determine biomechanical energy. RESULTS: The hip joint generated the largest maximum negative biomechanical power (1.8 ± 0.5 W/kg), followed by the knee joint (0.8 ± 0.3 W/kg) and ankle joint (0.2 ± 0.1 W/kg). Negative biomechanical energy from the hip, knee, and ankle joints per stand-to-sit movement were 0.36 ± 0.06 J/kg, 0.16 ± 0.08 J/kg, and 0.03 ± 0.01 J/kg, respectively. CONCLUSIONS: Using previously published maximum energy regeneration efficiencies (i.e., approximately 37 %), robotic knee prostheses and exoskeletons could theoretically regenerate 0.06 ± 0.03 J/kg of electrical energy while sitting down. These findings have implications on design optimization of regenerative powertrains for energy-efficient lower-limb biomechatronic devices.

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“…First, it is recognized that excessive mass and high impedance are two key drawbacks of state of the art wearable robots [15]. Quasi-passive knee design was studied in [16] as prosthesis and [17] as exoskeletons [18] using series elastic actuators (SEA) to decouple motor inertia and reduce passive output impedance. Keeogo exoskeleton [15] uses high ratio harmonic gear to amplify torque of a brushless direct current (BLDC) motor.…”

Section: Introductionmentioning

confidence: 99%

Design and Control of a High-Torque and Highly Backdrivable Hybrid Soft Exoskeleton for Knee Injury Prevention During Squatting

Huang

Wang

et al. 2019

IEEE Robot. Autom. Lett.

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This paper presents design and control innovations of wearable robots that tackle two barriers to widespread adoption of powered exoskeletons, namely restriction of human movement and versatile control of wearable co-robot systems. First, the proposed quasi-direct drive actuation comprising of our customized hightorque density motors and low ratio transmission mechanism significantly reduces the mass of the robot and produces high backdrivability. Second, we derive a biomechanics model-based control that generates biological torque profile for versatile control of both squat and stoop lifting assistance. The control algorithm detects lifting postures using compact inertial measurement unit (IMU) sensors to generate an assistive profile that is proportional to the biological torque produced from our model. Experimental results demonstrate that the robot exhibits low mechanical impedance (1.5 Nm resistive torque) when it is unpowered and 0.5 Nm resistive torque with zero-torque tracking control. Root mean square (RMS) error of torque tracking is less than 0.29 Nm (1.21% error of 24 Nm peak torque). Compared with squatting without the exoskeleton, the controller reduces 87.5%, 80% and 75% of the of three knee extensor muscles (average peak EMG of 3 healthy subjects) during squat with 50% of biological torque assistance.To overcome the limitations of restriction of natural movement and versatile control of human-robot interaction [2,26], the contributions of this work include: 1) a quasi-direct drive actuation paradigm using our high torque density motors

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Design and Validation of a Torque-Controllable Knee Exoskeleton for Sit-to-Stand Assistance

Cited by 144 publications

References 30 publications

Spine-Inspired Continuum Soft Exoskeleton for Stoop Lifting Assistance

Spine-Inspired Continuum Soft Exoskeleton for Stoop Lifting Assistance

Simulation of Stand-to-Sit Biomechanics for Design of Lower-Limb Exoskeletons and Prostheses with Energy Regeneration

Design and Control of a High-Torque and Highly Backdrivable Hybrid Soft Exoskeleton for Knee Injury Prevention During Squatting

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