1
|
Molinaro DD, Kang I, Young AJ. Estimating human joint moments unifies exoskeleton control, reducing user effort. Sci Robot 2024; 9:eadi8852. [PMID: 38507475 DOI: 10.1126/scirobotics.adi8852] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2023] [Accepted: 02/20/2024] [Indexed: 03/22/2024]
Abstract
Robotic lower-limb exoskeletons can augment human mobility, but current systems require extensive, context-specific considerations, limiting their real-world viability. Here, we present a unified exoskeleton control framework that autonomously adapts assistance on the basis of instantaneous user joint moment estimates from a temporal convolutional network (TCN). When deployed on our hip exoskeleton, the TCN achieved an average root mean square error of 0.142 newton-meters per kilogram across 35 ambulatory conditions without any user-specific calibration. Further, the unified controller significantly reduced user metabolic cost and lower-limb positive work during level-ground and incline walking compared with walking without wearing the exoskeleton. This advancement bridges the gap between in-lab exoskeleton technology and real-world human ambulation, making exoskeleton control technology viable for a broad community.
Collapse
Affiliation(s)
- Dean D Molinaro
- George W. Woodruff School of Mechanical Engineering, Georgia Institute of Technology, Atlanta, GA 30332, USA
- Institute for Robotics and Intelligent Machines, Georgia Institute of Technology, Atlanta, GA 30332, USA
| | - Inseung Kang
- Department of Brain and Cognitive Sciences, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
| | - Aaron J Young
- George W. Woodruff School of Mechanical Engineering, Georgia Institute of Technology, Atlanta, GA 30332, USA
- Institute for Robotics and Intelligent Machines, Georgia Institute of Technology, Atlanta, GA 30332, USA
| |
Collapse
|
2
|
Zhu Z, Liu L, Zhang W, Jiang C, Wang X, Li J. Design and motion control of exoskeleton robot for paralyzed lower limb rehabilitation. Front Neurosci 2024; 18:1355052. [PMID: 38456145 PMCID: PMC10918848 DOI: 10.3389/fnins.2024.1355052] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2023] [Accepted: 02/05/2024] [Indexed: 03/09/2024] Open
Abstract
Introduction Patients suffering from limb movement disorders require more complete rehabilitation treatment, and there is a huge demand for rehabilitation exoskeleton robots. Flexible and reliable motion control of exoskeleton robots is very important for patient rehabilitation. Methods This paper proposes a novel exoskeleton robotic system for lower limb rehabilitation. The designed lower limb rehabilitation exoskeleton robot mechanism is mainly composed of the hip joint mechanism, the knee joint mechanism and the ankle joint mechanism. The forces and motion of the exoskeleton robot were analyzed in detail to determine its design parameters. The robot control system was developed to implement closed-loop position control and trajectory planning control of each joint mechanism. Results Multiple experiments and tests were carried out to verify robot's performance and practicality. In the robot angular response experiments, the joint mechanism could quickly adjust to different desired angles, including 15°, 30°, 45°, and 60°. In the trajectory tracking experiments, the exoskeleton robot could complete tracking movements of typical actions such as walking, standing up, sitting down, go upstairs and go downstairs, with a maximum tracking error of ±5°. Robotic wearing tests on normal people were performed to verify the assistive effects of the lower limb rehabilitation exoskeleton at different stages. Discussion The experimental results indicated that the exoskeleton robot has excellent reliability and practicality. The application of this exoskeleton robotic system will help paralyzed patients perform some daily movements and sports.
Collapse
Affiliation(s)
- Zhiyong Zhu
- College of Automation, Nanjing University of Posts and Telecommunications, Nanjing, China
- School of Mechanical Engineering, Southeast University, Nanjing, China
| | - Lingyan Liu
- School of Mechanical Engineering, Southeast University, Nanjing, China
| | - Wenbin Zhang
- College of Computer Science and Software Engineering, Hohai University, Nanjing, Jiangsu, China
| | - Cong Jiang
- School of Mechanical Engineering, Southeast University, Nanjing, China
| | - Xingsong Wang
- School of Mechanical Engineering, Southeast University, Nanjing, China
| | - Jie Li
- College of Automation, Nanjing University of Posts and Telecommunications, Nanjing, China
| |
Collapse
|
3
|
Poggensee KL, Collins SH. Lower limb biomechanics of fully trained exoskeleton users reveal complex mechanisms behind the reductions in energy cost with human-in-the-loop optimization. Front Robot AI 2024; 11:1283080. [PMID: 38357293 PMCID: PMC10864513 DOI: 10.3389/frobt.2024.1283080] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2023] [Accepted: 01/03/2024] [Indexed: 02/16/2024] Open
Abstract
Exoskeletons that assist in ankle plantarflexion can improve energy economy in locomotion. Characterizing the joint-level mechanisms behind these reductions in energy cost can lead to a better understanding of how people interact with these devices, as well as to improved device design and training protocols. We examined the biomechanical responses to exoskeleton assistance in exoskeleton users trained with a lengthened protocol. Kinematics at unassisted joints were generally unchanged by assistance, which has been observed in other ankle exoskeleton studies. Peak plantarflexion angle increased with plantarflexion assistance, which led to increased total and biological mechanical power despite decreases in biological joint torque and whole-body net metabolic energy cost. Ankle plantarflexor activity also decreased with assistance. Muscles that act about unassisted joints also increased activity for large levels of assistance, and this response should be investigated over long-term use to prevent overuse injuries.
Collapse
Affiliation(s)
- Katherine L. Poggensee
- Department of Mechanical Engineering, Stanford University, Stanford, CA, United States
- Department of Rehabilitation Medicine, Erasmus MC, Rotterdam, Netherlands
- Faculty of Mechanical, Maritime and Materials Engineering (3mE), Technical University of Delft, Delft, Netherlands
| | - Steven H. Collins
- Department of Mechanical Engineering, Stanford University, Stanford, CA, United States
- Department of Bioengineering, Stanford University, Stanford, CA, United States
| |
Collapse
|
4
|
Lakmazaheri A, Song S, Vuong BB, Biskner B, Kado DM, Collins SH. Optimizing exoskeleton assistance to improve walking speed and energy economy for older adults. J Neuroeng Rehabil 2024; 21:1. [PMID: 38167151 PMCID: PMC10763092 DOI: 10.1186/s12984-023-01287-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2023] [Accepted: 11/29/2023] [Indexed: 01/05/2024] Open
Abstract
BACKGROUND Walking speed and energy economy tend to decline with age. Lower-limb exoskeletons have demonstrated potential to improve either measure, but primarily in studies conducted on healthy younger adults. Promising techniques like optimization of exoskeleton assistance have yet to be tested with older populations, while speed and energy consumption have yet to be simultaneously optimized for any population. METHODS We investigated the effectiveness of human-in-the-loop optimization of ankle exoskeletons with older adults. Ten healthy adults > 65 years of age (5 females; mean age: 72 ± 3 yrs) participated in approximately 240 min of training and optimization with tethered ankle exoskeletons on a self-paced treadmill. Multi-objective human-in-the-loop optimization was used to identify assistive ankle plantarflexion torque patterns that simultaneously improved self-selected walking speed and metabolic rate. The effects of optimized exoskeleton assistance were evaluated in separate trials. RESULTS Optimized exoskeleton assistance improved walking performance for older adults. Both objectives were simultaneously improved; self-selected walking speed increased by 8% (0.10 m/s; p = 0.001) and metabolic rate decreased by 19% (p = 0.007), resulting in a 25% decrease in energetic cost of transport (p = 8e-4) compared to walking with exoskeletons applying zero torque. Compared to younger participants in studies optimizing a single objective, our participants required lower exoskeleton torques, experienced smaller improvements in energy use, and required more time for motor adaptation. CONCLUSIONS Our results confirm that exoskeleton assistance can improve walking performance for older adults and show that multiple objectives can be simultaneously addressed through human-in-the-loop optimization.
Collapse
Affiliation(s)
- Ava Lakmazaheri
- Department of Mechanical Engineering, Stanford University, Stanford, CA, USA
| | - Seungmoon Song
- Department of Mechanical Engineering, Stanford University, Stanford, CA, USA
- Department of Mechanical and Industrial Engineering, Northeastern University, Boston, MA, USA
| | - Brian B Vuong
- Department of Mechanical Engineering, Stanford University, Stanford, CA, USA
| | - Blake Biskner
- Department of Mechanical Engineering, Stanford University, Stanford, CA, USA
| | - Deborah M Kado
- Geriatrics Research Education and Clinical Center, Veterans Affairs, Palo Alto, CA, USA
- Department of Medicine, Stanford University, Stanford, CA, USA
| | - Steven H Collins
- Department of Mechanical Engineering, Stanford University, Stanford, CA, USA.
| |
Collapse
|
5
|
Van Crey N, Cavallin M, Shepherd M, Rouse EJ. Design of a Quasi-Passive Ankle-Foot Orthosis with Customizable, Variable Stiffness. IEEE Int Conf Rehabil Robot 2023; 2023:1-6. [PMID: 37941210 DOI: 10.1109/icorr58425.2023.10304820] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2023]
Abstract
Most commercial ankle-foot orthoses (AFOs) are passive structures that cannot modulate stiffness to assist with a diverse range of activities, such as stairs and ramps. It is sometimes possible to change the stiffness of passive AFOs through reassembly or benchtop adjustment, but they cannot change stiffness during use. Passive AFOs are also limited in their ankle mechanics and cannot replicate a biomimetic, nonlinear torque-angle relationship. Many research labs have developed ankle exoskeletons that show promise as viable alternatives to passive AFOs, but they face challenges with reliability, mass, and cost. Consequently, commercial translation has largely failed to date. Here we introduce the Variable Stiffness Orthosis (VSO), a quasi-passive variable stiffness ankle-foot orthosis that strikes a balance between powered and passive systems, in terms of mass, complexity, and onboard intelligence. The VSO has customizable torque-angle relationships via a cam transmission, and can make step-to-step stiffness adjustments via motorized reconfiguration of a spring support along a lead-screw. In this work, we introduce two versions: a nominal and a stiff prototype, which differ primarily in their mass and available stiffness levels. The available torque-angle relationships are measured on a custom dynamometer and closely match model predictions. The experimental results showed that the prototypes are capable of producing ankle stiffness coefficients between 9 - 330 Nm/rad.
Collapse
|
6
|
Bhardwaj S, Shinde AB, Singh R, Vashista V. Manipulating device-to-body forces in passive exosuit: An experimental investigation on the effect of moment arm orientation using passive back-assist exosuit emulator. WEARABLE TECHNOLOGIES 2023; 4:e17. [PMID: 38487771 PMCID: PMC10936296 DOI: 10.1017/wtc.2023.12] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 10/12/2022] [Revised: 04/03/2023] [Accepted: 04/28/2023] [Indexed: 03/17/2024]
Abstract
Passive exosuits have been vastly researched in the past decade for lifting tasks to alleviate the mechanical loading on the spine and reduce the lower back muscle activities in lifting tasks. Despite promising advantages of exosuits, factors such as comfort directly influence the user's acceptability of such body-worn devices. Exosuits' routing/anchoring points, which transmit device-to-body forces, remain the leading cause of discomfort among users. In the present study, we sought to investigate the effect of the routing element, that is, the "moment arm," in altering the device-to-body forces and perceived discomfort. We first presented a simplified human-exosuit model to establish insight into the effect of the moment arm on the device-to-body forces acting at the shoulder (FS) and waist (FW). Further, an experimental investigation was conducted on 10 participants with six different exosuit moment arm configurations (C1, C2, C3, C4, C5, and C6) to investigate their effect on the device-to-body forces, perceived discomfort, and muscle activity using a passive back-assist exosuit emulator in a lifting/lowering task. Configuration C4 was found to be most beneficial in reducing device-to-body forces at the shoulder and waist by up to 44.6 and 22.2%, respectively, during lifting. Subjective scores also comprehended with the device-to-body forces, indicating that C4 produces significantly less discomfort for participants. The outcome of the study illustrates the importance of selecting an appropriate moment arm configuration for passive back support exosuits in alleviating the device-to-body forces and perceived discomfort.
Collapse
Affiliation(s)
- Siddharth Bhardwaj
- Human-Centered Robotics Lab, Indian Institute of Technology Gandhinagar, Gandhinagar, India
| | - Akshayraj B. Shinde
- Human-Centered Robotics Lab, Indian Institute of Technology Gandhinagar, Gandhinagar, India
| | - Randheer Singh
- Human-Centered Robotics Lab, Indian Institute of Technology Gandhinagar, Gandhinagar, India
| | - Vineet Vashista
- Human-Centered Robotics Lab, Indian Institute of Technology Gandhinagar, Gandhinagar, India
| |
Collapse
|
7
|
Siviy C, Baker LM, Quinlivan BT, Porciuncula F, Swaminathan K, Awad LN, Walsh CJ. Opportunities and challenges in the development of exoskeletons for locomotor assistance. Nat Biomed Eng 2022; 7:456-472. [PMID: 36550303 DOI: 10.1038/s41551-022-00984-1] [Citation(s) in RCA: 12] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2020] [Accepted: 11/08/2022] [Indexed: 12/24/2022]
Abstract
Exoskeletons can augment the performance of unimpaired users and restore movement in individuals with gait impairments. Knowledge of how users interact with wearable devices and of the physiology of locomotion have informed the design of rigid and soft exoskeletons that can specifically target a single joint or a single activity. In this Review, we highlight the main advances of the past two decades in exoskeleton technology and in the development of lower-extremity exoskeletons for locomotor assistance, discuss research needs for such wearable robots and the clinical requirements for exoskeleton-assisted gait rehabilitation, and outline the main clinical challenges and opportunities for exoskeleton technology.
Collapse
Affiliation(s)
- Christopher Siviy
- John A Paulson School of Engineering and Applied Sciences, Harvard University, Cambridge, MA, USA
| | - Lauren M Baker
- John A Paulson School of Engineering and Applied Sciences, Harvard University, Cambridge, MA, USA
| | - Brendan T Quinlivan
- John A Paulson School of Engineering and Applied Sciences, Harvard University, Cambridge, MA, USA
| | - Franchino Porciuncula
- John A Paulson School of Engineering and Applied Sciences, Harvard University, Cambridge, MA, USA.,Department of Physical Therapy, College of Health and Rehabilitation Sciences: Sargent, Boston University, Boston, MA, USA
| | - Krithika Swaminathan
- John A Paulson School of Engineering and Applied Sciences, Harvard University, Cambridge, MA, USA
| | - Louis N Awad
- Department of Physical Therapy, College of Health and Rehabilitation Sciences: Sargent, Boston University, Boston, MA, USA
| | - Conor J Walsh
- John A Paulson School of Engineering and Applied Sciences, Harvard University, Cambridge, MA, USA.
| |
Collapse
|
8
|
Li G, Su Q, Xi W, Song Z, Bao R, Du Z. Dynamic analysis and design of a multipurpose lower limb exoskeleton for rehabilitation. INT J ADV ROBOT SYST 2022. [DOI: 10.1177/17298806221135140] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
Abstract
To solve some defects of exoskeleton robot at present, this article establishes the dynamic model of human lower limb. The torque curves for hip joint and knee joint are obtained. A dynamics simulation is conducted in ADAMS which will guide the selection of motors and reducers for exoskeleton joints. Three structural design projects for leg and an integrated joint with the function of force perception are proposed. Then a lightweight exoskeleton is put forward and a kinematics simulation of man–machine coupling system is carried out in ADAMS. This article sets up a 24-V low-voltage control electrical system and a rehabilitation training expert system. Some performance tests and clinical experiments are carried out by an experimental prototype. The results show that the joints have sufficient driving torque. Leg structure has large adjustment range and self-locking function. The exoskeleton has lightweight and does not interfere with human body during movement. The expert system has a friendly operation interface and abundant functions. Clinical experimental results show that lower limb exoskeleton has good rehabilitation effect for some diseases.
Collapse
Affiliation(s)
- Gang Li
- SIASUN Robot & Automation Co. Ltd, Shenyang, China
| | - Qiying Su
- School of Automation Science and Electrical Engineering, Beihang University, Beijing, China
| | - Wenqiu Xi
- The First Affiliated Hospital of Harbin Medical University, Harbin, China
| | | | - Renren Bao
- SIASUN Robot & Automation Co. Ltd, Shenyang, China
| | - Zhenjun Du
- SIASUN Robot & Automation Co. Ltd, Shenyang, China
| |
Collapse
|
9
|
Heap WE, Keeley CT, Yao EB, Naclerio ND, Hawkes EW. Miniature, Lightweight, High-Force, Capstan Winch for Mobile Robots. IEEE Robot Autom Lett 2022. [DOI: 10.1109/lra.2022.3192758] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Affiliation(s)
- William E. Heap
- College of Engineering, University of California, Santa Barbara, CA, USA
| | - Chris T. Keeley
- College of Engineering, University of California, Santa Barbara, CA, USA
| | - Elvy B. Yao
- College of Engineering, University of California, Santa Barbara, CA, USA
| | - Nicholas D. Naclerio
- Department of Mechanical Engineering, University of California, Santa Barbara, CA, USA
| | - Elliot W. Hawkes
- Department of Mechanical Engineering, University of California, Santa Barbara, CA, USA
| |
Collapse
|
10
|
Liang J, Zhang Q, Liu Y, Wang T, Wan G. A review of the design of load-carrying exoskeletons. SCIENCE CHINA. TECHNOLOGICAL SCIENCES 2022; 65:2051-2067. [PMID: 36032505 PMCID: PMC9392988 DOI: 10.1007/s11431-022-2145-x] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/11/2022] [Accepted: 07/07/2022] [Indexed: 06/15/2023]
Abstract
The increasing necessity of load-carrying activities has led to greater human musculoskeletal damage and an increased metabolic cost. With the rise of exoskeleton technology, researchers have begun exploring different approaches to developing wearable robots to augment human load-carrying ability. However, there is a lack of systematic discussion on biomechanics, mechanical designs, and augmentation performance. To achieve this, extensive studies have been reviewed and 108 references are selected mainly from 2013 to 2022 to address the most recent development. Other earlier 20 studies are selected to present the origin of different design principles. In terms of the way to achieve load-carrying augmentation, the exoskeletons reviewed in this paper are sorted by four categories based on the design principles, namely load-suspended backpacks, lower-limb exoskeletons providing joint torques, exoskeletons transferring load to the ground and exoskeletons transferring load between body segments. Specifically, the driving modes of active and passive, the structure of rigid and flexible, the conflict between assistive performance and the mass penalty of the exoskeleton, and the autonomy are discussed in detail in each section to illustrate the advances, challenges, and future trends of exoskeletons designed to carry loads.
Collapse
Affiliation(s)
- JieJunYi Liang
- State Key Laboratory of Digital Manufacturing Equipment and Technology, Huazhong University of Science and Technology, Wuhan, 430074 China
| | - QinHao Zhang
- State Key Laboratory of Digital Manufacturing Equipment and Technology, Huazhong University of Science and Technology, Wuhan, 430074 China
| | - Yang Liu
- State Key Laboratory of Digital Manufacturing Equipment and Technology, Huazhong University of Science and Technology, Wuhan, 430074 China
| | - Tao Wang
- State Key Laboratory of Digital Manufacturing Equipment and Technology, Huazhong University of Science and Technology, Wuhan, 430074 China
| | - GuangFu Wan
- State Key Laboratory of Digital Manufacturing Equipment and Technology, Huazhong University of Science and Technology, Wuhan, 430074 China
| |
Collapse
|
11
|
Slucock T. A Systematic Review of Low-Cost Actuator Implementations for Lower-Limb Exoskeletons: a Technical and Financial Perspective. J INTELL ROBOT SYST 2022; 106:3. [PMID: 35990171 PMCID: PMC9379875 DOI: 10.1007/s10846-022-01695-0] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2022] [Accepted: 07/07/2022] [Indexed: 02/02/2023]
Abstract
A common issue with many commercial rehabilitative exoskeletons and orthoses are that they can be prohibitively expensive for an average individual to afford without additional financial support. Due to this a user may have limited to the usage of such devices within set rehabilitation sessions as opposed to a continual usage. The purpose of this review is therefore to find which actuator implementations would be most suitable for a simplistic, low-cost powered orthoses capable of assisting those with pathologic gait disorders by collating literature from Web of Science, Scopus, and Grey Literature. In this systematic review paper 127 papers were selected from these databases via the PRISMA guidelines, with the financial costs of 25 actuators discovered with 11 distinct actuator groups identified. The review paper will consider a variety of actuator implementations used in existing lower-limb exoskeletons that are specifically designed for the purpose of rehabilitating or aiding those with conditions inhibiting natural movement abilities, such as electric motors, hydraulics, pneumatics, cable-driven actuators, and compliant actuators. Key attributes such as technical simplicity, financial cost, power efficiency, size limitations, accuracy, and reliability are compared for all actuator groups. Statistical findings show that rotary electric motors (which are the most common actuator type within collated literature) and compliant actuators (such as elastic and springs) would be the most suitable actuators for a low-cost implementation. From these results, a possible actuator design will be proposed making use of both rotary electric motors and compliant actuators. Supplementary Information The online version contains supplementary material available at 10.1007/s10846-022-01695-0.
Collapse
Affiliation(s)
- T. Slucock
- School of Engineering and Digital Arts, University of Kent, Giles Lane, Canterbury, CT2 7NT England
| |
Collapse
|
12
|
Franks PW, Bryan GM, Reyes R, O'Donovan MP, Gregorczyk KN, Collins SH. The Effects of Incline Level on Optimized Lower-Limb Exoskeleton Assistance: a Case Series. IEEE Trans Neural Syst Rehabil Eng 2022; 30:2494-2505. [PMID: 35930513 DOI: 10.1109/tnsre.2022.3196665] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
For exoskeletons to be successful in real-world settings, they will need to be effective across a variety of terrains, including on inclines. While some single-joint exoskeletons have assisted incline walking, recent successes in level-ground assistance suggest that greater improvements may be possible by optimizing assistance of the whole leg. To understand how exoskeleton assistance should change with incline, we used human-in-the-loop optimization to find whole-leg exoskeleton assistance torques that minimized metabolic cost on a range of grades. We optimized assistance for three able-bodied, expert participants on 5 degree, 10 degree, and 15 degree inclines using a hip-knee-ankle exoskeleton emulator. For all assisted conditions, the cost of transport was reduced by at least 50% relative to walking in the device with no assistance, which is a large improvement to walking comparable to the benefits of whole-leg assistance on level-ground (N = 3). Optimized extension torque magnitudes and exoskeleton power increased with incline. Hip extension, knee extension and ankle plantarflexion often grew as large as allowed by comfort-based limits. Applied powers on steep inclines were double the powers applied during level-ground walking, indicating that greater exoskeleton power may be optimal in scenarios where biological powers and costs are higher. Future exoskeleton devices could deliver large improvements in walking performance across a range of inclines if they have sufficient torque and power capabilities.
Collapse
|
13
|
Yang C, Yu L, Xu L, Yan Z, Hu D, Zhang S, Yang W. Current developments of robotic hip exoskeleton toward sensing, decision, and actuation: A review. WEARABLE TECHNOLOGIES 2022; 3:e15. [PMID: 38486916 PMCID: PMC10936331 DOI: 10.1017/wtc.2022.11] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 04/06/2022] [Revised: 05/22/2022] [Accepted: 06/09/2022] [Indexed: 03/17/2024]
Abstract
The aging population is now a global challenge, and impaired walking ability is a common feature in the elderly. In addition, some occupations such as military and relief workers require extra physical help to perform tasks efficiently. Robotic hip exoskeletons can support ambulatory functions in the elderly and augment human performance in healthy people during normal walking and loaded walking by providing assistive torque. In this review, the current development of robotic hip exoskeletons is presented. In addition, the framework of actuation joints and the high-level control strategy (including the sensors and data collection, the way to recognize gait phase, the algorithms to generate the assist torque) are described. The exoskeleton prototypes proposed by researchers in recent years are organized to benefit the related fields realizing the limitations of the available robotic hip exoskeletons, therefore, this work tends to be an influential factor with a better understanding of the development and state-of-the-art technology.
Collapse
Affiliation(s)
- Canjun Yang
- Ningbo Research Institute, Zhejiang University, Ningbo, China
- School of Mechanical Engineering, Zhejiang University, Hangzhou, China
- School of Mechanical and Energy Engineering, NingboTech University, Ningbo, China
| | - Linfan Yu
- Ningbo Research Institute, Zhejiang University, Ningbo, China
- School of Mechanical Engineering, Zhejiang University, Hangzhou, China
| | - Linghui Xu
- Ningbo Research Institute, Zhejiang University, Ningbo, China
- School of Mechanical Engineering, Zhejiang University, Hangzhou, China
| | - Zehao Yan
- Ningbo Research Institute, Zhejiang University, Ningbo, China
- School of Mechanical Engineering, Zhejiang University, Hangzhou, China
| | - Dongming Hu
- School of Mechanical and Energy Engineering, NingboTech University, Ningbo, China
| | - Sheng Zhang
- Ningbo Research Institute, Zhejiang University, Ningbo, China
- School of Mechanical Engineering, Zhejiang University, Hangzhou, China
| | - Wei Yang
- Ningbo Research Institute, Zhejiang University, Ningbo, China
- School of Mechanical Engineering, Zhejiang University, Hangzhou, China
- School of Mechanical and Energy Engineering, NingboTech University, Ningbo, China
| |
Collapse
|
14
|
Anderson AJ, Hudak YF, Gauthier KA, Muir BC, Aubin PM. Design and Evaluation of a Knee Flexion Assistance Exoskeleton for People with Transtibial Amputation. IEEE Int Conf Rehabil Robot 2022; 2022:1-6. [PMID: 36176102 DOI: 10.1109/icorr55369.2022.9896485] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
People with below-knee amputation walk with asymmetric gaits that over time can lead to further musculoskeletal disorders and decreased quality of life. While prosthesis technology is improving, prosthetic ankles may be fundamentally limited in their ability to restore healthy walking patterns because they do not assist the residual knee joint. The knee on the residual limb has muscular deficits due to the loss of the gastrocnemius, a biarticular muscle that crosses both the ankle and knee. Here we present the design, development, and preliminary evaluation of a robotic knee exoskeleton for people with transtibial amputation. The device is intended to restore gastrocnemius-like flexion moments to the knee on the residual limb. The exoskeleton uses a custom offboard actuation and control system to allow for a simple and lightweight design with high torque capabilities. A preliminary walking experiment with one person with transtibial amputation was conducted. The exoskeleton provided a range of knee flexion torque profiles and had an RMS tracking error of 1.9 Nm across four assistance conditions. This device will be used in future studies to explore the effects of providing knee flexion assistance to people with transtibial amputation during walking. Long term, findings from studies with this exoskeleton could motivate future assistive device designs that improve walking mechanics and quality of life for people with limb loss.
Collapse
|
15
|
Bhardwaj S, Shinde AB, Singh R, Vashista V. Passive Exosuit Emulator for Material Handling Applications. IEEE Robot Autom Lett 2022. [DOI: 10.1109/lra.2022.3183748] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Affiliation(s)
- Siddharth Bhardwaj
- Human-Centered Robotics Lab, Indian Institute of Technology Gandhinagar, Palaj, Gujarat, India
| | - Akshayraj B. Shinde
- Human-Centered Robotics Lab, Indian Institute of Technology Gandhinagar, Palaj, Gujarat, India
| | - Randheer Singh
- Human-Centered Robotics Lab, Indian Institute of Technology Gandhinagar, Palaj, Gujarat, India
| | - Vineet Vashista
- Human-Centered Robotics Lab, Indian Institute of Technology Gandhinagar, Palaj, Gujarat, India
| |
Collapse
|
16
|
Zhong B, Guo K, Yu H, Zhang M. Toward Gait Symmetry Enhancement via a Cable-Driven Exoskeleton Powered by Series Elastic Actuators. IEEE Robot Autom Lett 2022. [DOI: 10.1109/lra.2021.3130639] [Citation(s) in RCA: 10] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
|
17
|
Antonellis P, Mohammadzadeh Gonabadi A, Myers SA, Pipinos II, Malcolm P. Metabolically efficient walking assistance using optimized timed forces at the waist. Sci Robot 2022; 7:eabh1925. [PMID: 35294219 DOI: 10.1126/scirobotics.abh1925] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
The metabolic rate of walking can be reduced by applying a constant forward force at the center of mass. It has been shown that the metabolically optimal constant force magnitude minimizes propulsion ground reaction force at the expense of increased braking. This led to the hypothesis that selectively assisting propulsion could lead to greater benefits. We used a robotic waist tether to evaluate the effects of forward forces with different timings and magnitudes. Here, we show that it is possible to reduce the metabolic rate of healthy participants by 48% with a greater efficiency ratio of metabolic cost reduction per unit of net aiding work compared with other assistive robots. This result was obtained using a sinusoidal force profile with peak timing during the middle of the double support. The same timing could also reduce the metabolic rate in patients with peripheral artery disease. A model explains that the optimal force profile accelerates the center of mass into the inverted pendulum movement during single support. Contrary to the hypothesis, the optimal force timing did not entirely coincide with propulsion. Within the field of wearable robotics, there is a trend to use devices to mimic biological torque or force profiles. Such bioinspired actuation can have relevant benefits; however, our results demonstrate that this is not necessarily optimal for reducing metabolic rate.
Collapse
Affiliation(s)
- Prokopios Antonellis
- Department of Biomechanics and Center for Research in Human Movement Variability, University of Nebraska at Omaha, 6160 University Drive South, Omaha, NE 68182, USA.,Department of Neurology, School of Medicine, Oregon Health & Science University, 3181 SW Sam Jackson Park Road, OP-32, Portland, OR 97239, USA
| | - Arash Mohammadzadeh Gonabadi
- Department of Biomechanics and Center for Research in Human Movement Variability, University of Nebraska at Omaha, 6160 University Drive South, Omaha, NE 68182, USA.,Rehabilitation Engineering Center, Institute for Rehabilitation Science and Engineering, Madonna Rehabilitation Hospital, 5401 South Street, Lincoln, NE 68506, USA
| | - Sara A Myers
- Department of Biomechanics and Center for Research in Human Movement Variability, University of Nebraska at Omaha, 6160 University Drive South, Omaha, NE 68182, USA.,Department of Surgery and Research Service, Veterans Affairs Nebraska-Western Iowa Medical Center, Omaha, NE 68105, USA
| | - Iraklis I Pipinos
- Department of Surgery and Research Service, Veterans Affairs Nebraska-Western Iowa Medical Center, Omaha, NE 68105, USA.,Department of Surgery, University of Nebraska Medical Center, 982500 Nebraska Medical Center, Omaha, NE 68198, USA
| | - Philippe Malcolm
- Department of Biomechanics and Center for Research in Human Movement Variability, University of Nebraska at Omaha, 6160 University Drive South, Omaha, NE 68182, USA
| |
Collapse
|
18
|
Visual guidance can help with the use of a robotic exoskeleton during human walking. Sci Rep 2022; 12:3881. [PMID: 35273244 PMCID: PMC8913727 DOI: 10.1038/s41598-022-07736-w] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2021] [Accepted: 02/15/2022] [Indexed: 11/29/2022] Open
Abstract
Walking is an important activity that supports the health-related quality of life, and for those who need assistance, robotic devices are available to help. Recent progress in wearable robots has identified the importance of customizing the assistance provided by the robot to the individual, resulting in robot adaptation to the human. However, current implementations minimize the role of human adaptation to the robot, for example, by the users modifying their movements based on the provided robot assistance. This study investigated the effect of visual feedback to guide the users in adapting their movements in response to wearable robot assistance. The visual feedback helped the users reduce their metabolic cost of walking without any changes in robot assistance in a given time. In a case with the initially metabolic expensive (IMExp) exoskeleton condition, both training methods helped reduce the metabolic cost of walking. The results suggest that visual feedback training is helpful to use the exoskeleton for various conditions. Without feedback, the training is helpful only for the IMExp exoskeleton condition. This result suggests visual feedback training can be useful to facilitate the use of non-personalized, generic assistance, where the assistance is not tuned for each user, in a relatively short time.
Collapse
|
19
|
Medrano RL, Thomas GC, Rouse EJ. Can humans perceive the metabolic benefit provided by augmentative exoskeletons? J Neuroeng Rehabil 2022; 19:26. [PMID: 35219335 PMCID: PMC8881941 DOI: 10.1186/s12984-022-01002-w] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2021] [Accepted: 02/15/2022] [Indexed: 11/30/2022] Open
Abstract
BACKGROUND The purpose of augmentative exoskeletons is to help people exceed the limitations of their human bodies, but this cannot be realized unless people choose to use these exciting technologies. Although human walking efficiency has been highly optimized over generations, exoskeletons have been able to consistently improve this efficiency by 10-15%. However, despite these measurable improvements, exoskeletons today remain confined to the laboratory. To achieve widespread adoption, exoskeletons must not only exceed the efficiency of human walking, but also provide a perceivable benefit to their wearers. METHODS In this study, we quantify the perceptual threshold of the metabolic efficiency benefit provided during exoskeleton-assisted locomotion. Ten participants wore bilateral ankle exoskeletons during continuous walking. The assistance provided by the exoskeletons was varied in 2 min intervals while participants provided feedback on their metabolic rate. These data were aggregated and used to estimate the perceptual threshold. RESULTS Participants were able to detect a change in their metabolic rate of 22.7% (SD: 17.0%) with 75% accuracy. This indicates that in the short term and on average, wearers cannot yet reliably perceive the metabolic benefits of today's augmentative exoskeletons. CONCLUSIONS If wearers cannot perceive the benefits provided by these technologies, it will negatively affect their impact, including long-term adoption and product viability. Future exoskeleton researchers and designers can use these methods and results to inform the development of exoskeletons that reach their potential.
Collapse
Affiliation(s)
- Roberto Leo Medrano
- Department of Mechanical Engineering, University of Michigan, Ann Arbor, 48109 USA
- Robotics Institute, University of Michigan, 48109 Ann Arbor, USA
| | - Gray Cortright Thomas
- Department of Mechanical Engineering, University of Michigan, Ann Arbor, 48109 USA
- Department of Electrical Engineering and Computer Science, University of Michigan, Ann Arbor, 48109 USA
- Robotics Institute, University of Michigan, 48109 Ann Arbor, USA
| | - Elliott J. Rouse
- Department of Mechanical Engineering, University of Michigan, Ann Arbor, 48109 USA
- Robotics Institute, University of Michigan, 48109 Ann Arbor, USA
| |
Collapse
|
20
|
Franks PW, Bryan GM, Martin RM, Reyes R, Lakmazaheri AC, Collins SH. Comparing optimized exoskeleton assistance of the hip, knee, and ankle in single and multi-joint configurations. WEARABLE TECHNOLOGIES 2021; 2:e16. [PMID: 38486633 PMCID: PMC10936256 DOI: 10.1017/wtc.2021.14] [Citation(s) in RCA: 15] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 05/11/2021] [Revised: 09/13/2021] [Accepted: 10/20/2021] [Indexed: 03/17/2024]
Abstract
Exoskeletons that assist the hip, knee, and ankle joints have begun to improve human mobility, particularly by reducing the metabolic cost of walking. However, direct comparisons of optimal assistance of these joints, or their combinations, have not yet been possible. Assisting multiple joints may be more beneficial than the sum of individual effects, because muscles often span multiple joints, or less effective, because single-joint assistance can indirectly aid other joints. In this study, we used a hip-knee-ankle exoskeleton emulator paired with human-in-the-loop optimization to find single-joint, two-joint, and whole-leg assistance that maximally reduced the metabolic cost of walking. Hip-only and ankle-only assistance reduced the metabolic cost of walking by 26 and 30% relative to walking in the device unassisted, confirming that both joints are good targets for assistance (N = 3). Knee-only assistance reduced the metabolic cost of walking by 13%, demonstrating that effective knee assistance is possible (N = 3). Two-joint assistance reduced the metabolic cost of walking by between 33 and 42%, with the largest improvements coming from hip-ankle assistance (N = 3). Assisting all three joints reduced the metabolic cost of walking by 50%, showing that at least half of the metabolic energy expended during walking can be saved through exoskeleton assistance (N = 4). Changes in kinematics and muscle activity indicate that single-joint assistance indirectly assisted muscles at other joints, such that the improvement from whole-leg assistance was smaller than the sum of its single-joint parts. Exoskeletons can assist the entire limb for maximum effect, but a single well-chosen joint can be more efficient when considering additional factors such as weight and cost.
Collapse
Affiliation(s)
- Patrick W. Franks
- Department of Mechanical Engineering, Stanford University, Stanford, California, USA
| | - Gwendolyn M. Bryan
- Department of Mechanical Engineering, Stanford University, Stanford, California, USA
| | - Russell M. Martin
- Department of Mechanical Engineering, Stanford University, Stanford, California, USA
| | - Ricardo Reyes
- Department of Mechanical Engineering, Stanford University, Stanford, California, USA
| | - Ava C. Lakmazaheri
- Department of Mechanical Engineering, Stanford University, Stanford, California, USA
| | - Steven H. Collins
- Department of Mechanical Engineering, Stanford University, Stanford, California, USA
| |
Collapse
|
21
|
Bryan GM, Franks PW, Song S, Reyes R, O'Donovan MP, Gregorczyk KN, Collins SH. Optimized hip-knee-ankle exoskeleton assistance reduces the metabolic cost of walking with worn loads. J Neuroeng Rehabil 2021; 18:161. [PMID: 34743714 PMCID: PMC8572578 DOI: 10.1186/s12984-021-00955-8] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2021] [Accepted: 10/27/2021] [Indexed: 11/21/2022] Open
Abstract
BACKGROUND Load carriage is common in a wide range of professions, but prolonged load carriage is associated with increased fatigue and overuse injuries. Exoskeletons could improve the quality of life of these professionals by reducing metabolic cost to combat fatigue and reducing muscle activity to prevent injuries. Current exoskeletons have reduced the metabolic cost of loaded walking by up to 22% relative to walking in the device with no assistance when assisting one or two joints. Greater metabolic reductions may be possible with optimized assistance of the entire leg. METHODS We used human-in the-loop optimization to optimize hip-knee-ankle exoskeleton assistance with no additional load, a light load (15% of body weight), and a heavy load (30% of body weight) for three participants. All loads were applied through a weight vest with an attached waist belt. We measured metabolic cost, exoskeleton assistance, kinematics, and muscle activity. We performed Friedman's tests to analyze trends across worn loads and paired t-tests to determine whether changes from the unassisted conditions to the assisted conditions were significant. RESULTS Exoskeleton assistance reduced the metabolic cost of walking relative to walking in the device without assistance for all tested conditions. Exoskeleton assistance reduced the metabolic cost of walking by 48% with no load (p = 0.05), 41% with the light load (p = 0.01), and 43% with the heavy load (p = 0.04). The smaller metabolic reduction with the light load may be due to insufficient participant training or lack of optimizer convergence. The total applied positive power was similar for all tested conditions, and the positive knee power decreased slightly as load increased. Optimized torque timing parameters were consistent across participants and load conditions while optimized magnitude parameters varied. CONCLUSIONS Whole-leg exoskeleton assistance can reduce the metabolic cost of walking while carrying a range of loads. The consistent optimized timing parameters across participants and conditions suggest that metabolic cost reductions are sensitive to torque timing. The variable torque magnitude parameters could imply that torque magnitude should be customized to the individual, or that there is a range of useful torque magnitudes. Future work should test whether applying the load to the exoskeleton rather than the person's torso results in larger benefits.
Collapse
Affiliation(s)
- Gwendolyn M Bryan
- Department of Mechanical Engineering, Stanford University, Stanford, USA.
| | - Patrick W Franks
- Department of Mechanical Engineering, Stanford University, Stanford, USA
| | - Seungmoon Song
- Department of Mechanical Engineering, Stanford University, Stanford, USA
| | - Ricardo Reyes
- Department of Mechanical Engineering, Stanford University, Stanford, USA
| | - Meghan P O'Donovan
- Development and Engineering Center, U.S. Army Natick Soldier Research, Natick, USA
| | - Karen N Gregorczyk
- Development and Engineering Center, U.S. Army Natick Soldier Research, Natick, USA
| | - Steven H Collins
- Department of Mechanical Engineering, Stanford University, Stanford, USA
| |
Collapse
|
22
|
Bryan GM, Franks PW, Song S, Voloshina AS, Reyes R, O'Donovan MP, Gregorczyk KN, Collins SH. Optimized hip-knee-ankle exoskeleton assistance at a range of walking speeds. J Neuroeng Rehabil 2021; 18:152. [PMID: 34663372 PMCID: PMC8521270 DOI: 10.1186/s12984-021-00943-y] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2021] [Accepted: 09/27/2021] [Indexed: 01/18/2023] Open
Abstract
BACKGROUND Autonomous exoskeletons will need to be useful at a variety of walking speeds, but it is unclear how optimal hip-knee-ankle exoskeleton assistance should change with speed. Biological joint moments tend to increase with speed, and in some cases, optimized ankle exoskeleton torques follow a similar trend. Ideal hip-knee-ankle exoskeleton torque may also increase with speed. The purpose of this study was to characterize the relationship between walking speed, optimal hip-knee-ankle exoskeleton assistance, and the benefits to metabolic energy cost. METHODS We optimized hip-knee-ankle exoskeleton assistance to reduce metabolic cost for three able-bodied participants walking at 1.0 m/s, 1.25 m/s and 1.5 m/s. We measured metabolic cost, muscle activity, exoskeleton assistance and kinematics. We performed Friedman's tests to analyze trends across walking speeds and paired t-tests to determine if changes from the unassisted conditions to the assisted conditions were significant. RESULTS Exoskeleton assistance reduced the metabolic cost of walking compared to wearing the exoskeleton with no torque applied by 26%, 47% and 50% at 1.0, 1.25 and 1.5 m/s, respectively. For all three participants, optimized exoskeleton ankle torque was the smallest for slow walking, while hip and knee torque changed slightly with speed in ways that varied across participants. Total applied positive power increased with speed for all three participants, largely due to increased joint velocities, which consistently increased with speed. CONCLUSIONS Exoskeleton assistance is effective at a range of speeds and is most effective at medium and fast walking speeds. Exoskeleton assistance was less effective for slow walking, which may explain the limited success in reducing metabolic cost for patient populations through exoskeleton assistance. Exoskeleton designers may have more success when targeting activities and groups with faster walking speeds. Speed-related changes in optimized exoskeleton assistance varied by participant, indicating either the benefit of participant-specific tuning or that a wide variety of torque profiles are similarly effective.
Collapse
Affiliation(s)
- Gwendolyn M Bryan
- Department of Mechanical Engineering, Stanford University, Stanford, USA.
| | - Patrick W Franks
- Department of Mechanical Engineering, Stanford University, Stanford, USA
| | - Seungmoon Song
- Department of Mechanical Engineering, Stanford University, Stanford, USA
| | | | - Ricardo Reyes
- Department of Mechanical Engineering, Stanford University, Stanford, USA
| | - Meghan P O'Donovan
- U.S. Army Natick Soldier Research, Development and Engineering Center, Natick, USA
| | - Karen N Gregorczyk
- U.S. Army Natick Soldier Research, Development and Engineering Center, Natick, USA
| | - Steven H Collins
- Department of Mechanical Engineering, Stanford University, Stanford, USA
| |
Collapse
|
23
|
Wang S, Zhang B, Yu Z, Yan Y. Differential Soft Sensor-Based Measurement of Interactive Force and Assistive Torque for a Robotic Hip Exoskeleton. SENSORS (BASEL, SWITZERLAND) 2021; 21:6545. [PMID: 34640867 PMCID: PMC8512818 DOI: 10.3390/s21196545] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 09/06/2021] [Revised: 09/24/2021] [Accepted: 09/25/2021] [Indexed: 11/24/2022]
Abstract
With the emerging of wearable robots, the safety and effectiveness of human-robot physical interaction have attracted extensive attention. Recent studies suggest that online measurement of the interaction force between the robot and the human body is essential to the aspects above in wearable exoskeletons. However, a large proportion of existing wearable exoskeletons monitor and sense the delivered force and torque through an indirect-measure method, in which the torque is estimated by the motor current. Direct force/torque measuring through low-cost and compact wearable sensors remains an open problem. This paper presents a compact soft sensor system for wearable gait assistance exoskeletons. The contact force is converted into a voltage signal by measuring the air pressure within a soft pneumatic chamber. The developed soft force sensor system was implemented on a robotic hip exoskeleton, and the real-time interaction force between the human thigh and the exoskeleton was measured through two differential soft chambers. The delivered torque of the hip exoskeleton was calculated based on a characterization model. Experimental results suggested that the sensor system achieved direct force measurement with an error of 10.3 ± 6.58%, and torque monitoring for a hip exoskeleton which provided an understanding for the importance of direct force/torque measurement for assistive performance. Compared with traditional rigid force sensors, the proposed system has several merits, as it is compact, low-cost, and has good adaptability to the human body due to the soft structure.
Collapse
Affiliation(s)
- Sun’an Wang
- School of Mechanical Engineering, Xi’an Jiaotong University, No. 28, Xianning West Road, Xi’an 710049, China; (B.Z.); (Z.Y.); (Y.Y.)
| | | | | | | |
Collapse
|
24
|
Active Loading Control Design for a Wearable Exoskeleton with a Bowden Cable for Transmission. ACTUATORS 2021. [DOI: 10.3390/act10060108] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
Exoskeletons with a Bowden cable for power transmission have the advantages of a concentrated mass and flexible movement. However, their integrated motor is disturbed by the Bowden cable’s friction, which limits the performance of the force loading response. In this paper, we solve this problem by designing an outer-loop feedforward-feedback proportion-differentiation controller based on an inner loop disturbance observer. Firstly, the inner loop’s dynamic performance is equivalent to the designed nominal model using the proposed disturbance observer, which effectively compensates for the parameter perturbation and friction disturbance. Secondly, based on an analysis of the stability of the inner loop controller, we obtain the stability condition and discuss the influence of modeling errors on the inner loop’s dynamic performance. Thirdly, to avoid excessive noise from the force sensors being introduced into the designed disturbance observer, we propose the feedforward-feedback proportion-differentiation controller based on the nominal model and pole configuration, which improves the outer loop’s force loading performance. Experiments are conducted, which verify the effectiveness of the proposed methods.
Collapse
|