A Review of Hierarchical Control Strategies for Lower-Limb Exoskeletons in Children with Cerebral Palsy
Abstract
1. Introduction
2. Control Strategy Design Objectives
2.1. Overall Design Objectives
2.1.1. Adapting to Pediatric CP Population Characteristics
2.1.2. Compensation for Inherent Hardware Limitations
2.2. Specific Design Objectives
2.2.1. Gait Improvement
2.2.2. Muscle Strength Training
2.2.3. Abnormal Gait Correction
2.2.4. Specific Movements
3. Search and Classification Methods
3.1. Scope and Methodological Steps
- Topic 1: (Foot OR Ankle OR Knee OR Hip OR Lower Limb OR Lower Body)
- Topic 2: (Exoskeleton) OR (Assistive Robot*) OR (Wearable Robot*) OR (Robot* Suit) OR (Portable Robot*) OR (Powered Orthotic System)
- Topic 3: (Children OR Pediatric OR Young Patient OR Cerebral Palsy)
3.2. Proposed Classification Method
4. A Hierarchical Review of the Control Strategies
4.1. Supervisory-Layer Control: Gait Phase Recognition
4.1.1. Time-Linear Gait Phase (TLP)
4.1.2. Finite State Machine (FSM)
4.1.3. Machine Learning (ML)
4.1.4. A Summary of Supervisory-Layer Control
4.2. Action-Layer Control: Command Generation
4.2.1. Position Profile (PPR)
- Predefined Position Profiles
- 2.
- Real-time Position Profile Generation
4.2.2. Torque Profile (TPR)
- Constant Torque Profile
- 2.
- Real-Time Torque Profile
4.2.3. Impedance Control (IC)
- Impedance Control Based on Inertia–Stiffness–Damping Dynamic Systems
- 2.
- Force-Field-Based Impedance Control
4.2.4. Virtual Constraints (VC)
4.2.5. Electromyography-Based Control (EBC)
4.2.6. A Summary of Action-Layer Control
4.3. Execution-Layer Control: Command Execution
4.3.1. Closed-Loop Position Control (CLP)
- Rigid Actuation Mechanisms
- 2.
- Flexible Actuation Mechanisms
4.3.2. Closed-Loop Torque Control (CLT)
- Rigid Torque Transmission
- 2.
- Flexible Torque Transmission
4.3.3. Sliding Mode Control (SMC)
4.3.4. Backstepping Control (BC)
4.3.5. A Summary of Execution-Layer Control
5. Clinical Effectiveness
5.1. Clinical Characteristics of the Participants
5.2. Clinical Validation of the Control Strategy
6. Discussion
6.1. Characteristics of Controller Design
6.2. A Summary of Current Research
- A wide range of control strategies have been applied across the three-layer architecture. At the supervisory layer, most studies adopted either time-linear phase (TLP) or finite state machine (FSM) approaches, while machine learning (ML) remains in an exploratory stage.
- At the action layer, position and torque profile controls (PPR and TPR) are the most frequently used, whereas advanced adaptive methods such as impedance control (IC), electromyography-based control (EBC), and virtual constraints (VC) have received comparatively limited attention.
- In the execution layer, closed-loop torque (CLT) and position control (CLP) dominate, while nonlinear control strategies such as sliding mode control (SMC) and backstepping control (BC) are found only in a few isolated cases.
- Despite the diversity in design, only a small subset of these strategies—five out of the 43 identified—have been supported by multiple clinical studies demonstrating significant improvements in CP rehabilitation outcomes. This highlights a considerable gap between technical exploration and clinical validation in the current CPLLE research landscape.
6.3. Discussion on Future Development Directions
6.4. Limitations
7. Conclusions
Author Contributions
Funding
Acknowledgments
Conflicts of Interest
References
- Gonzalez, A.; Garcia, L.; Kilby, J.; McNair, P. Robotic Devices for Paediatric Rehabilitation: A Review of Design Features. Biomed. Eng. OnLine 2021, 20, 89. [Google Scholar] [CrossRef] [PubMed]
- Gesta, A.; Achiche, S.; Mohebbi, A. Design Considerations for the Development of Lower Limb Pediatric Exoskeletons: A Literature Review. IEEE Trans. Med. Robot. Bionics 2023, 5, 768–779. [Google Scholar] [CrossRef]
- Sarajchi, M.; Al-Hares, M.K.; Sirlantzis, K. Wearable Lower-Limb Exoskeleton for Children with Cerebral Palsy: A Systematic Review of Mechanical Design, Actuation Type, Control Strategy, and Clinical Evaluation. IEEE Trans. Neural Syst. Rehabil. Eng. 2021, 29, 2695–2720. [Google Scholar] [CrossRef] [PubMed]
- Narayan, J.; Dwivedy, S.K. Lower Limb Exoskeletons for Pediatric Gait Rehabilitation: A Brief Review of Design, Actuation, and Control Schemes. In Proceedings of the 2023 IEEE International Conference on Advanced Systems and Emergent Technologies (IC_ASET), Hammamet, Tunisia, 29 April–1 May 2023; IEEE: New York, NY, USA, 2023; pp. 1–6. [Google Scholar]
- Baud, R.; Manzoori, A.R.; Ijspeert, A.; Bouri, M. Review of Control Strategies for Lower-Limb Exoskeletons to Assist Gait. J. NeuroEngineering Rehabil. 2021, 18, 119. [Google Scholar] [CrossRef]
- Narayan, J.; Auepanwiriyakul, C.; Jhunjhunwala, S.; Abbas, M.; Dwivedy, S.K. Hierarchical Classification of Subject-Cooperative Control Strategies for Lower Limb Exoskeletons in Gait Rehabilitation: A Systematic Review. Machines 2023, 11, 764. [Google Scholar] [CrossRef]
- Laubscher, C.A.; Farris, R.J.; Sawicki, J.T. Design and Preliminary Evaluation of a Powered Pediatric Lower Limb Orthosis. In Proceedings of the International Design Engineering Technical Conferences and Computers and Information in Engineering Conference, Cleveland, OH, USA, 6 August 2017; American Society of Mechanical Engineers: Cleveland, OH, USA, 2017; Volume 5A, p. V05AT08A061. [Google Scholar]
- Lefmann, S.; Russo, R.; Hillier, S. The Effectiveness of Robotic-Assisted Gait Training for Paediatric Gait Disorders: Systematic Review. J. NeuroEngineering Rehabil. 2017, 14, 1. [Google Scholar] [CrossRef]
- Grau, A.; Morel, Y.; Puig-Pey, A.; Cecchi, F. (Eds.) Tracts in Advanced Robotics, In Advances in Robotics Research: From Lab to Market: ECHORD++: Robotic Science Supporting Innovation; Springer International Publishing: Cham, Switzerland, 2020; Volume 132, ISBN 978-3-030-22326-7. [Google Scholar]
- Reinkensmeyer, D.J.; Dietz, V. (Eds.) Neurorehabilitation Technology; Springer International Publishing: Cham, Switzerland, 2016; ISBN 978-3-319-28601-3. [Google Scholar]
- Harshe, K.; Tagoe, E.; Bowersock, C.; Lerner, Z.F. Priming Robotic Plantarflexor Resistance with Assistance to Improve Ankle Power During Exoskeleton Gait Training. IEEE Robot. Autom. Lett. 2024, 9, 10511–10518. [Google Scholar] [CrossRef]
- Lee, D.; Mulrine, S.C.; Shepherd, M.K.; Westberry, D.E.; Rogozinski, B.M.; Herrin, K.R.; Young, A.J. Mitigating Crouch Gait with an Autonomous Pediatric Knee Exoskeleton in the Neurologically Impaired. J. Biomech. Eng. 2024, 146, 121005. [Google Scholar] [CrossRef]
- Abdelhady, M.; Damiano, D.L.; Bulea, T.C. Attention-Based Deep Recurrent Neural Network to Estimate Knee Angle During Walking from Lower-Limb EMG. In Proceedings of the 2023 International Conference on Rehabilitation Robotics (ICORR), Singapore, 24–28 September 2023; IEEE: New York, NY, USA, 2023; pp. 1–6. [Google Scholar]
- Goo, A.; Laubscher, C.A.; Farris, R.J.; Sawicki, J.T. Design and Evaluation of a Pediatric Lower-Limb Exoskeleton Joint Actuator. Actuators 2020, 9, 138. [Google Scholar] [CrossRef]
- Tagoe, E.A.; Fang, Y.; Williams, J.R.; Lerner, Z.F. Walking on Real-World Terrain with an Ankle Exoskeleton in Cerebral Palsy. IEEE Trans. Med. Robot. Bionics 2024, 6, 202–212. [Google Scholar] [CrossRef]
- Fang, Y.; Orekhov, G.; Lerner, Z.F. Adaptive Ankle Exoskeleton Gait Training Demonstrates Acute Neuromuscular and Spatiotemporal Benefits for Individuals with Cerebral Palsy: A Pilot Study. Gait Posture 2022, 95, 256–263. [Google Scholar] [CrossRef]
- Bayón, C.; Ramírez, O.; Serrano, J.I.; Castillo, M.D.D.; Pérez-Somarriba, A.; Belda-Lois, J.M.; Martínez-Caballero, I.; Lerma-Lara, S.; Cifuentes, C.; Frizera, A.; et al. Development and Evaluation of a Novel Robotic Platform for Gait Rehabilitation in Patients with Cerebral Palsy: CPWalker. Robot. Auton. Syst. 2017, 91, 101–114. [Google Scholar] [CrossRef]
- Snodgrass, J.; Yan, S.; Lim, H.; Hameedduddin, I.; Wu, M. Design and Implementation of a Portable Knee Actuator for the Improvement of Crouch Gait in Children with Cerebral Palsy. In Proceedings of the 2023 45th Annual International Conference of the IEEE Engineering in Medicine & Biology Society (EMBC), Sydney, Australia, 24–27 July 2023; IEEE: New York, NY, USA, 2023; pp. 1–4. [Google Scholar]
- Bulea, T.C.; Molazadeh, V.; Thurston, M.; Damiano, D.L. Interleaved Assistance and Resistance for Exoskeleton Mediated Gait Training: Validation, Feasibility and Effects. In Proceedings of the 2022 9th IEEE RAS/EMBS International Conference for Biomedical Robotics and Biomechatronics (BioRob) Seoul, Republic of Korea, 21 August 2022; IEEE: New York, NY, USA; pp. 1–8. [Google Scholar]
- Conner, B.C.; Remec, N.M.; Orum, E.K.; Frank, E.M.; Lerner, Z.F. Wearable Adaptive Resistance Training Improves Ankle Strength, Walking Efficiency and Mobility in Cerebral Palsy: A Pilot Clinical Trial. IEEE Open J. Eng. Med. Biol. 2020, 1, 282–289. [Google Scholar] [CrossRef]
- Washabaugh, E.P.; Claflin, E.S.; Gillespie, R.B.; Krishnan, C. A Novel Application of Eddy Current Braking for Functional Strength Training During Gait. Ann. Biomed. Eng. 2016, 44, 2760–2773. [Google Scholar] [CrossRef]
- Washabaugh, E.P.; Krishnan, C. A Wearable Resistive Robot Facilitates Locomotor Adaptations during Gait. Restor. Neurol. Neurosci. 2018, 36, 215–223. [Google Scholar] [CrossRef]
- Devine, T.M.; Alter, K.E.; Damiano, D.L.; Bulea, T.C. A Randomized Cross-over Study Protocol to Evaluate Long-Term Gait Training with a Pediatric Robotic Exoskeleton Outside the Clinical Setting in Children with Movement Disorders. PLoS ONE 2024, 19, e0304087. [Google Scholar] [CrossRef]
- Shideler, B.L.; Bulea, T.C.; Chen, J.; Stanley, C.J.; Gravunder, A.J.; Damiano, D.L. Toward a Hybrid Exoskeleton for Crouch Gait in Children with Cerebral Palsy: Neuromuscular Electrical Stimulation for Improved Knee Extension. J. NeuroEngineering Rehabil. 2020, 17, 121. [Google Scholar] [CrossRef]
- Rodda, J.; Graham, H.K. Classification of Gait Patterns in Spastic Hemiplegia and Spastic Diplegia: A Basis for a Management Algorithm. Eur. J. Neurol. 2001, 8, 98–108. [Google Scholar] [CrossRef]
- Kawamoto, H.; Hayashi, T.; Sakurai, T.; Eguchi, K.; Sankai, Y. Development of Single Leg Version of HAL for Hemiplegia. In Proceedings of the 2009 Annual International Conference of the IEEE Engineering in Medicine and Biology Society, Minneapolis, MN, USA, 3–6 September 2009; IEEE: New York, NY, USA, 2009; pp. 5038–5043. [Google Scholar]
- Sarajchi, M.; Sirlantzis, K. Design and Control of a Single-Leg Exoskeleton with Gravity Compensation for Children with Unilateral Cerebral Palsy. Sensors 2023, 23, 6103. [Google Scholar] [CrossRef]
- Fang, Y.; Lerner, Z.F. How Ankle Exoskeleton Assistance Affects the Mechanics of Incline Walking and Stair Ascent in Cerebral Palsy. In Proceedings of the 2022 International Conference on Rehabilitation Robotics (ICORR), Rotterdam, The Netherlands, 25 July 2022; IEEE: New York, NY, USA; pp. 1–6. [Google Scholar]
- Bulea, T.C.; Chen, J.; Damiano, D.L. Exoskeleton Assistance Improves Crouch during Overground Walking with Forearm Crutches: A Case Study. In Proceedings of the 2020 8th IEEE RAS/EMBS International Conference for Biomedical Robotics and Biomechatronics (BioRob), New York City, NY, USA, 29 November–1 December 2020; IEEE: New York, NY, USA, 2020; pp. 679–684. [Google Scholar]
- Yamada, T.; Kadone, H.; Shimizu, Y.; Suzuki, K. An Exoskeleton Brake Unit for Children with Crouch Gait Supporting the Knee Joint During Stance. In Proceedings of the 2018 International Symposium on Micro-NanoMechatronics and Human Science (MHS), Nagoya, Japan, 9–12 December 2018; IEEE: New York, NY, USA, 2018; pp. 1–7. [Google Scholar]
- Patane, F.; Rossi, S.; Del Sette, F.; Taborri, J.; Cappa, P. WAKE-Up Exoskeleton to Assist Children With Cerebral Palsy: Design and Preliminary Evaluation in Level Walking. IEEE Trans. Neural Syst. Rehabil. Eng. 2017, 25, 906–916. [Google Scholar] [CrossRef]
- Rossi, S.; Patane, F.; Del Sette, F.; Cappa, P. WAKE-up: A Wearable Ankle Knee Exoskeleton. In Proceedings of the 5th IEEE RAS/EMBS International Conference on Biomedical Robotics and Biomechatronics, Sao Paulo, Brazil, 12–15 August 2014; IEEE: New York, NY, USA, 2014; pp. 504–507. [Google Scholar]
- Zhang, Y.; Bressel, M.; De Groof, S.; Domine, F.; Labey, L.; Peyrodie, L. Design and Control of a Size-Adjustable Pediatric Lower-Limb Exoskeleton Based on Weight Shift. IEEE Access 2023, 11, 6372–6384. [Google Scholar] [CrossRef]
- Villani, M.; Avaltroni, P.; Scordo, G.; Rubeca, D.; Kreynin, P.; Bereziy, E.; Berger, D.; Cappellini, G.; Sylos-Labini, F.; Lacquaniti, F.; et al. Evaluation of EMG Patterns in Children during Assisted Walking in the Exoskeleton. Front. Neurosci. 2024, 18, 1461323. [Google Scholar] [CrossRef] [PubMed]
- Laubscher, C.A.; Sawicki, J.T. Gait Guidance Control for Damping of Unnatural Motion in a Powered Pediatric Lower-Limb Orthosis. In Proceedings of the 2019 IEEE 16th International Conference on Rehabilitation Robotics (ICORR), Toronto, ON, Canada, 24–28 June 2019; IEEE: New York, NY, USA, 2019; pp. 676–681. [Google Scholar]
- Garcia, E.; Sancho, J.; Sanz-Merodio, D.; Prieto, M. ATLAS 2020: The Pediatric Gait Exoskeleton Project. In Proceedings of the CLAWAR 2017: 20th International Conference on Climbing and Walking Robots and the Support Technologies for Mobile Machines, Porto, Portugal, 11–13 September 2017; World Scientific: Singapore, 2017; pp. 29–38. [Google Scholar]
- Pour Aji Bishe, S.S.; Liebelt, L.; Fang, Y.; Lerner, Z.F. A Low-Profile Hip Exoskeleton for Pathological Gait Assistance: Design and Pilot Testing. In Proceedings of the 2022 International Conference on Robotics and Automation (ICRA), Philadelphia, PA, USA, 23–27 May 2022; IEEE: New York, NY, USA, 2022; pp. 5461–5466. [Google Scholar]
- Fang, Y.; Orekhov, G.; Lerner, Z.F. Improving the Energy Cost of Incline Walking and Stair Ascent With Ankle Exoskeleton Assistance in Cerebral Palsy. IEEE Trans. Biomed. Eng. 2022, 69, 2143–2152. [Google Scholar] [CrossRef]
- Bishe, S.S.P.A.; Nguyen, T.; Fang, Y.; Lerner, Z.F. Adaptive Ankle Exoskeleton Control: Validation Across Diverse Walking Conditions. IEEE Trans. Med. Robot. Bionics 2021, 3, 801–812. [Google Scholar] [CrossRef]
- Taketomi, T.; Sankai, Y. Stair Ascent Assistance for Cerebral Palsy with Robot Suit HAL. In Proceedings of the 2012 IEEE/SICE International Symposium on System Integration (SII), Fukuoka, Japan, 16–18 December 2012; IEEE: New York, NY, USA, 2012; pp. 331–336. [Google Scholar]
- Fang, Y.; Lerner, Z.F. Feasibility of Augmenting Ankle Exoskeleton Walking Performance With Step Length Biofeedback in Individuals with Cerebral Palsy. IEEE Trans. Neural Syst. Rehabil. Eng. 2021, 29, 442–449. [Google Scholar] [CrossRef]
- Harshe, K.; Williams, J.R.; Hocking, T.D.; Lerner, Z.F. Predicting Neuromuscular Engagement to Improve Gait Training With a Robotic Ankle Exoskeleton. IEEE Robot. Autom. Lett. 2023, 8, 5055–5060. [Google Scholar] [CrossRef]
- Gasparri, G.M.; Luque, J.; Lerner, Z.F. Proportional Joint-Moment Control for Instantaneously Adaptive Ankle Exoskeleton Assistance. IEEE Trans. Neural Syst. Rehabil. Eng. 2019, 27, 751–759. [Google Scholar] [CrossRef]
- Orekhov, G.; Fang, Y.; Cuddeback, C.F.; Lerner, Z.F. Usability and Performance Validation of an Ultra-Lightweight and Versatile Untethered Robotic Ankle Exoskeleton. J. NeuroEngineering Rehabil. 2021, 18, 163. [Google Scholar] [CrossRef]
- Orekhov, G.; Fang, Y.; Luque, J.; Lerner, Z.F. Ankle Exoskeleton Assistance Can Improve Over-Ground Walking Economy in Individuals with Cerebral Palsy. IEEE Trans. Neural Syst. Rehabil. Eng. 2020, 28, 461–467. [Google Scholar] [CrossRef]
- Orekhov, G.; Luque, J.; Lerner, Z.F. Closing the Loop on Exoskeleton Motor Controllers: Benefits of Regression-Based Open-Loop Control. IEEE Robot. Autom. Lett. 2020, 5, 6025–6032. [Google Scholar] [CrossRef]
- Lerner, Z.F.; Gasparri, G.M.; Bair, M.O.; Lawson, J.L.; Luque, J.; Harvey, T.A.; Lerner, A.T. An Untethered Ankle Exoskeleton Improves Walking Economy in a Pilot Study of Individuals with Cerebral Palsy. IEEE Trans. Neural Syst. Rehabil. Eng. 2018, 26, 1985–1993. [Google Scholar] [CrossRef]
- Spomer, A.M.; Conner, B.C.; Schwartz, M.H.; Lerner, Z.F.; Steele, K.M. Audiovisual Biofeedback Amplifies Plantarflexor Adaptation during Walking among Children with Cerebral Palsy. J. NeuroEngineering Rehabil. 2023, 20, 164. [Google Scholar] [CrossRef]
- Lerner, Z.F.; Harvey, T.A.; Lawson, J.L. A Battery-Powered Ankle Exoskeleton Improves Gait Mechanics in a Feasibility Study of Individuals with Cerebral Palsy. Ann. Biomed. Eng. 2019, 47, 1345–1356. [Google Scholar] [CrossRef]
- Conner, B.C.; Luque, J.; Lerner, Z.F. Adaptive Ankle Resistance from a Wearable Robotic Device to Improve Muscle Recruitment in Cerebral Palsy. Ann. Biomed. Eng. 2020, 48, 1309–1321. [Google Scholar] [CrossRef]
- Conner, B.C.; Schwartz, M.H.; Lerner, Z.F. Pilot Evaluation of Changes in Motor Control after Wearable Robotic Resistance Training in Children with Cerebral Palsy. J. Biomech. 2021, 126, 110601. [Google Scholar] [CrossRef]
- Conner, B.C.; Lerner, Z.F. Improving Ankle Muscle Recruitment via Plantar Pressure Biofeedback during Robot Resisted Gait Training in Cerebral Palsy. In Proceedings of the 2022 International Conference on Rehabilitation Robotics (ICORR), Rotterdam, The Netherlands, 25 July 2022; IEEE: New York, NY, USA, 2022; pp. 1–6. [Google Scholar]
- Chen, J.; Hochstein, J.; Kim, C.; Damiano, D.; Bulea, T. Design Advancements Toward a Wearable Pediatric Robotic Knee Exoskeleton for Overground Gait Rehabilitation. In Proceedings of the 2018 7th IEEE International Conference on Biomedical Robotics and Biomechatronics (Biorob), Enschede, The Netherlands, 26–29 August 2018; IEEE: New York, NY, USA, 2018; pp. 37–42. [Google Scholar]
- Chen, J.; Hochstein, J.; Kim, C.; Tucker, L.; Hammel, L.E.; Damiano, D.L.; Bulea, T.C. A Pediatric Knee Exoskeleton with Real-Time Adaptive Control for Overground Walking in Ambulatory Individuals with Cerebral Palsy. Front. Robot. AI 2021, 8, 702137. [Google Scholar] [CrossRef]
- Zhang, S.; Zhu, J.; Huang, T.-H.; Yu, S.; Huang, J.S.; Lopez-Sanchez, I.; Devine, T.; Abdelhady, M.; Zheng, M.; Bulea, T.C.; et al. Actuator Optimization and Deep Learning-Based Control of Pediatric Knee Exoskeleton for Community-Based Mobility Assistance. Mechatronics 2024, 97, 103109. [Google Scholar] [CrossRef]
- Chen, J.; Damiano, D.L.; Lerner, Z.F.; Bulea, T.C. Validating Model-Based Prediction of Biological Knee Moment During Walking with an Exoskeleton in Crouch Gait: Potential Application for Exoskeleton Control. In Proceedings of the 2019 IEEE 16th International Conference on Rehabilitation Robotics (ICORR), Toronto, ON, Canada, 24–28 June 2019; IEEE: New York, NY, USA, 2019; pp. 778–783. [Google Scholar]
- Lerner, Z.F.; Damiano, D.L.; Park, H.-S.; Gravunder, A.J.; Bulea, T.C. A Robotic Exoskeleton for Treatment of Crouch Gait in Children with Cerebral Palsy: Design and Initial Application. IEEE Trans. Neural Syst. Rehabil. Eng. 2017, 25, 650–659. [Google Scholar] [CrossRef]
- Lerner, Z.F.; Damiano, D.L.; Bulea, T.C. A Robotic Exoskeleton to Treat Crouch Gait from Cerebral Palsy: Initial Kinematic and Neuromuscular Evaluation. In Proceedings of the 2016 38th Annual International Conference of the IEEE Engineering in Medicine and Biology Society (EMBC), Orlando, FL, USA, 16–20 August 2016; IEEE: New York, NY, USA, 2016; pp. 2214–2217. [Google Scholar]
- Lerner, Z.F.; Damiano, D.L.; Bulea, T.C. A Lower-Extremity Exoskeleton Improves Knee Extension in Children with Crouch Gait from Cerebral Palsy. Sci. Transl. Med. 2017, 9, eaam9145. [Google Scholar] [CrossRef]
- Lerner, Z.F.; Damiano, D.L.; Bulea, T.C. The Effects of Exoskeleton Assisted Knee Extension on Lower-Extremity Gait Kinematics, Kinetics, and Muscle Activity in Children with Cerebral Palsy. Sci. Rep. 2017, 7, 13512. [Google Scholar] [CrossRef]
- Mansilla Navarro, P.; Copaci, D.; Arias, J.; Blanco Rojas, D. Design of an SMA-Based Actuator for Replicating Normal Gait Patterns in Pediatric Patients with Cerebral Palsy. Biomimetics 2024, 9, 376. [Google Scholar] [CrossRef] [PubMed]
- Mansilla Navarro, P.; Copaci, D.; Blanco Rojas, D. Design and Control of a Soft Knee Exoskeleton for Pediatric Patients at Early Stages of the Walking Learning Process. Bioengineering 2024, 11, 188. [Google Scholar] [CrossRef] [PubMed]
- Sarajchi, M.; Sirlantzis, K. Pediatric Robotic Lower-Limb Exoskeleton: An Innovative Design and Kinematic Analysis. IEEE Access 2023, 11, 115219–115230. [Google Scholar] [CrossRef]
- De Groof, S.; Zhang, Y.; Peyrodie, L.; Labey, L. Design and Control of an Individualized Hip Exoskeleton Capable of Gait Phase Synchronized Flexion and Extension Torque Assistance. IEEE Access 2023, 11, 96206–96220. [Google Scholar] [CrossRef]
- Andrade, R.M.; Sapienza, S.; Fabara, E.E.; Bonato, P. Trajectory Tracking Impedance Controller in 6-DoF Lower-Limb Exoskeleton for Over-Ground Walking Training: Preliminary Results. In Proceedings of the 2021 International Symposium on Medical Robotics (ISMR), Atlanta, GA, USA, 17–19 November 2021; IEEE: New York, NY, USA, 2021; pp. 1–6. [Google Scholar]
- Andrade, R.M.; Sapienza, S.; Mohebbi, A.; Fabara, E.E.; Bonato, P. Experimental Evaluation of a Transparent Operation Mode for a Lower-Limb Exoskeleton Designed for Children with Cerebral Palsy. In Proceedings of the 2023 IEEE/RSJ International Conference on Intelligent Robots and Systems (IROS), Detroit, MI, USA, 1–5 October 2023; IEEE: New York, NY, USA, 2023; pp. 6062–6067. [Google Scholar]
- Andrade, R.M.; Sapienza, S.; Bonato, P. Development of a “Transparent Operation Mode” for a Lower-Limb Exoskeleton Designed for Children with Cerebral Palsy. In Proceedings of the 2019 IEEE 16th International Conference on Rehabilitation Robotics (ICORR), Toronto, ON, Canada, 24–28 June 2019; IEEE: New York, NY, USA, 2019; pp. 512–517. [Google Scholar]
- Narayan, J.; Abbas, M.; Patel, B.; Dwivedy, S.K. A Singularity-Free Terminal Sliding Mode Control of an Uncertain Paediatric Exoskeleton System. In Proceedings of the 2022 5th International Conference on Advanced Systems and Emergent Technologies (IC_ASET), Hammamet, Tunisia, 22–25 March 2022; IEEE: New York, NY, USA, 2022; pp. 198–203. [Google Scholar]
- Narayan, J.; Abbas, M.; Dwivedy, S.K. Design and Validation of a Pediatric Gait Assistance Exoskeleton System with Fast Non-Singular Terminal Sliding Mode Controller. Med. Eng. Phys. 2024, 123, 104080. [Google Scholar] [CrossRef]
- Narayan, J.; Abbas, M.; Dwivedy, S.K. Robust Non-Singular Fast Terminal Sliding Mode Gait Tracking Control of a Pediatric Exoskeleton. In Proceedings of the 2023 5th International Conference on Bioengineering for Smart Technologies (BioSMART), Paris, France, 7–9 June 2023; IEEE: New York, NY, USA, 2023; pp. 1–4. [Google Scholar]
- Narayan, J.; Gritli, H.; Dwivedy, S.K. Fast Terminal Sliding Mode Control with Rapid Reaching Law for a Pediatric Gait Exoskeleton System. Int. J. Intell. Robot. Appl. 2024, 8, 76–95. [Google Scholar] [CrossRef]
- Narayan, J.; Dwivedy, S.K. Robust Gait Tracking Control of a Pediatric Exoskeleton System: An Adaptive Non-Singular Fast Terminal Sliding Mode Approach. In Proceedings of the 2023 9th International Conference on Control, Decision and Information Technologies (CoDIT), Rome, Italy, 3–6 July 2023; IEEE: New York, NY, USA, 2023; pp. 2337–2341. [Google Scholar]
- Narayan, J.; Abbas, M.; Dwivedy, S.K. Robust Adaptive Backstepping Control for a Lower-Limb Exoskeleton System with Model Uncertainties and External Disturbances. Automatika 2023, 64, 145–161. [Google Scholar] [CrossRef]
- Narayan, J.; Patel, B.M.; Abbas, M.; Shivhare, G.; Dwivedy, S.K. Cooperative Control of a Pediatric Exoskeleton System for Active-Assist Gait Rehabilitation. In Proceedings of the 2022 IEEE International Conference on Electronics, Computing and Communication Technologies (CONECCT), Bangalore, India, 8–10 July 2022; IEEE: New York, NY, USA, 2022; pp. 1–6. [Google Scholar]
- Narayan, J.; Dwivedy, S.K. Towards Neuro-Fuzzy Compensated PID Control of Lower Extremity Exoskeleton System for Passive Gait Rehabilitation. IETE J. Res. 2023, 69, 778–795. [Google Scholar] [CrossRef]
- Narayan, J.; Abbas, M.; Patel, B.; Dwivedy, S.K. Adaptive RBF Neural Network-Computed Torque Control for a Pediatric Gait Exoskeleton System: An Experimental Study. Intell. Serv. Robot. 2023, 16, 549–564. [Google Scholar] [CrossRef]
- Laubscher, C.A.; Farris, R.J.; Van Den Bogert, A.J.; Sawicki, J.T. An Anthropometrically Parameterized Assistive Lower Limb Exoskeleton. J. Biomech. Eng. 2021, 143, 105001. [Google Scholar] [CrossRef]
- Laubscher, C.A.; Farris, R.J.; Sawicki, J.T. Angular Momentum-Based Control of an Underactuated Orthotic System for Crouch-to-Stand Motion. Auton. Robots 2020, 44, 1469–1484. [Google Scholar] [CrossRef]
- Goo, A.C.; Laubscher, C.A.; Wajda, D.A.; Sawicki, J.T. Preliminary Virtual Constraint-Based Control Evaluation on a Pediatric Lower-Limb Exoskeleton. Bioengineering 2024, 11, 590. [Google Scholar] [CrossRef] [PubMed]
- Goo, A.; Laubscher, C.A.; Wiebrecht, J.J.; Farris, R.J.; Sawicki, J.T. Hybrid Zero Dynamics Control for Gait Guidance of a Novel Adjustable Pediatric Lower-Limb Exoskeleton. Bioengineering 2022, 9, 208. [Google Scholar] [CrossRef]
- Everaert, L.; Sevit, R.; Dewit, T.; Janssens, K.; Vanloocke, J.; Van Campenhout, A.; Labey, L.; Muraru, L.; Desloovere, K. Evaluation of the Working Mechanism of a Newly Developed Powered Ankle–Foot Orthosis. Sensors 2024, 24, 6562. [Google Scholar] [CrossRef]
- Mohammadi, V.; Tajdani, M.; Masaei, M.; Mohammadi Ghalehney, S.; Lee, S.C.K.; Behboodi, A. DE-AFO: A Robotic Ankle Foot Orthosis for Children with Cerebral Palsy Powered by Dielectric Elastomer Artificial Muscle. Sensors 2024, 24, 3787. [Google Scholar] [CrossRef]
- Gonzalez-Vazquez, A.; Garcia, L.; Kilby, J. Paediatric Ankle Rehabilitation System Based on Twisted and Coiled Polymer Actuators. Smart Mater. Struct. 2024, 33, 075009. [Google Scholar] [CrossRef]
- Eguren, D.; Cestari, M.; Luu, T.P.; Kilicarslan, A.; Steele, A.; Contreras-Vidal, J.L. Design of a Customizable, Modular Pediatric Exoskeleton for Rehabilitation and Mobility. In Proceedings of the 2019 IEEE International Conference on Systems, Man and Cybernetics (SMC), Bari, Italy, 6–9 October 2019; IEEE: New York, NY, USA, 2019; pp. 2411–2416. [Google Scholar]
- Bayon, C.; Ramirez, O.; Del Castillo, M.D.; Serrano, J.I.; Raya, R.; Belda-Lois, J.M.; Poveda, R.; Molla, F.; Martin, T.; Martinez, I.; et al. CPWalker: Robotic Platform for Gait Rehabilitation in Patients with Cerebral Palsy. In Proceedings of the 2016 IEEE International Conference on Robotics and Automation (ICRA), Stockholm, Sweden, 16–21 May 2016; IEEE: New York, NY, USA, 2016; pp. 3736–3741. [Google Scholar]
- Bayón, C.; Martín-Lorenzo, T.; Moral-Saiz, B.; Ramírez, Ó.; Pérez-Somarriba, Á.; Lerma-Lara, S.; Martínez, I.; Rocon, E. A Robot-Based Gait Training Therapy for Pediatric Population with Cerebral Palsy: Goal Setting, Proposal and Preliminary Clinical Implementation. J. NeuroEngineering Rehabil. 2018, 15, 69. [Google Scholar] [CrossRef]
- Bayon, C.; Ramirez, O.; Velasco, M.; Serrano, J.I.; Lerma Lara, S.; Martinez-Caballero, I.; Rocon, E. IEEE Pilot Study of a Novel Robotic Platform for Gait Rehabilitation in Children with Cerebral Palsy; IEEE: New York, NY, USA, 2016; pp. 882–887. [Google Scholar]
- Cifuentes, C.A.; Bayon, C.; Lerma, S.; Frizera, A.; Rocon, E. IEEE Human-Robot Interaction Strategy for Overground Rehabilitation in Patients with Cerebral Palsy; IEEE: New York, NY, USA, 2016; pp. 729–734. [Google Scholar]
- Mohd Adib, M.A.H.; Han, S.Y.; Ramani, P.R.; You, L.J.; Yan, L.M.; Mat Sahat, I.; Mohd Hasni, N.H. Restoration of Kids Leg Function Using Exoskeleton Robotic Leg (ExRoLEG) Device. In Proceedings of the 10th National Technical Seminar on Underwater System Technology 2018, Singapore, 26–27 September 2018; Md Zain, Z., Ahmad, H., Pebrianti, D., Mustafa, M., Abdullah, N.R.H., Samad, R., Mat Noh, M., Eds.; Lecture Notes in Electrical Engineering. Springer: Singapore, 2019; Volume 538, pp. 335–342, ISBN 978-981-13-3707-9. [Google Scholar]
- Sanz-Merodio, D.; Cestari, M.; Carlos Arevalo, J.; Garcia, E. IEEE A Lower-Limb Exoskeleton for Gait Assistance in Quadriplegia; IEEE: New York, NY, USA, 2012. [Google Scholar]
- Tokhi, M.O.; Virk, G.S. Advances in Cooperative Robotics. In Proceedings of the 19th International Conference on CLAWAR, London, UK, 12–14 September 2016; World Scientific: Singapore, 2016. ISBN 978-981-314-912-0. [Google Scholar]
- Cestari, M.; Sanz-Merodio, D.; Arevalo, J.C.; Garcia, E. ARES, a Variable Stiffness Actuator with Embedded Force Sensor for the ATLAS Exoskeleton. Ind. Robot Int. J. 2014, 41, 518–526. [Google Scholar] [CrossRef]
- Sanz-Merodio, D.; Cestari, M.; Arevalo, J.C.; Carrillo, X.A.; Garcia, E. Generation and Control of Adaptive Gaits in Lower-Limb Exoskeletons for Motion Assistance. Adv. Robot. 2014, 28, 329–338. [Google Scholar] [CrossRef]
- Garcia, E.; Cestari, M.; Sanz-Merodio, D. Wearable Exoskeletons for the Physical Treatment of Children with Quadriparesis. In Proceedings of the 2014 IEEE-RAS International Conference on Humanoid Robots, Madrid, Spain, 18–20 November 2014; IEEE: New York, NY, USA, 2015; pp. 425–430. [Google Scholar]
- Kawamoto, H.; Sankai, Y. Power Assist System HAL-3 for Gait Disorder Person. In Computers Helping People with Special Needs; Miesenberger, K., Klaus, J., Zagler, W., Eds.; Lecture Notes in Computer Science; Springer: Berlin/Heidelberg, Germany, 2002; Volume 2398, pp. 196–203. ISBN 978-3-540-43904-2. [Google Scholar]
- Matsuda, M.; Mataki, Y.; Mutsuzaki, H.; Yoshikawa, K.; Takahashi, K.; Enomoto, K.; Sano, K.; Mizukami, M.; Tomita, K.; Ohguro, H.; et al. Immediate Effects of a Single Session of Robot-Assisted Gait Training Using Hybrid Assistive Limb (HAL) for Cerebral Palsy. J. Phys. Ther. Sci. 2018, 30, 207–212. [Google Scholar] [CrossRef]
- Matsuda, M.; Iwasaki, N.; Mataki, Y.; Mutsuzaki, H.; Yoshikawa, K.; Takahashi, K.; Enomoto, K.; Sano, K.; Kubota, A.; Nakayama, T.; et al. Robot-Assisted Training Using Hybrid Assistive Limb® for Cerebral Palsy. BRAIN Dev. 2018, 40, 642–648. [Google Scholar] [CrossRef] [PubMed]
- Mataki, Y.; Kamada, H.; Mutsuzaki, H.; Shimizu, Y.; Takeuchi, R.; Mizukami, M.; Yoshikawa, K.; Takahashi, K.; Matsuda, M.; Iwasaki, N.; et al. Use of Hybrid Assistive Limb (HAL) for a Postoperative Patient with Cerebral Palsy: A Case Report. BMC Res. Notes 2018, 11, 201. [Google Scholar] [CrossRef]
- Pérez-San Lázaro, R.; Salgado, I.; Chairez, I. Adaptive Sliding-Mode Controller of a Lower Limb Mobile Exoskeleton for Active Rehabilitation. ISA Trans. 2021, 109, 218–228. [Google Scholar] [CrossRef]
- Zaway, I.; Jallouli-Khlif, R.; Maalej, B.; Medhaffar, H.; Derbel, N. From PD to Fractional Order PD Controller Used for Gait Rehabilitation. In Proceedings of the 2021 18th International Multi-Conference on Systems, Signals & Devices (SSD), Monastir, Tunisia, 22–25 March 2021; IEEE: New York, NY, USA, 2021; pp. 948–953. [Google Scholar]
- Kim, S.K.; Park, D.; Yoo, B.; Shim, D.; Choi, J.-O.; Choi, T.Y.; Park, E.S. Overground Robot-Assisted Gait Training for Pediatric Cerebral Palsy. Sensors 2021, 21, 2087. [Google Scholar] [CrossRef]
- Kawasaki, S.; Ohata, K.; Yoshida, T.; Yokoyama, A.; Yamada, S. Gait Improvements by Assisting Hip Movements with the Robot in Children with Cerebral Palsy: A Pilot Randomized Controlled Trial. J. NeuroEngineering Rehabil. 2020, 17, 87. [Google Scholar] [CrossRef]
- Delgado-Oleas, G.; Romero-Sorozabal, P.; Lora-Millan, J.; Gutierrez, A.; Rocon, E. Bioinspired Hierarchical Electronic Architecture for Robotic Locomotion Assistance: Application in Exoskeletons. IEEE Access 2023, 11, 131610–131622. [Google Scholar] [CrossRef]
- Varela, I.D.; Romero-Sorozabal, P.; Delgado-Oleas, G.; Gutiérrez, Á.; Muñoz, J.; Rocon, E. A Cable-Driven Exoskeleton to Control Ankle Mobility During Gait in Children with Cerebral Palsy. In Proceedings of the 2024 7th Iberian Robotics Conference (ROBOT), Madrid, Spain, 6–8 November 2024; IEEE: New York, NY, USA, 2024; pp. 1–6. [Google Scholar]
- Maalej, B.; Jribi, R.; Ayadi, N.; Abdelhedi, F.; Derbel, N. On a Robotic Application for Rehabilitation Systems Dedicated to Kids Affected by Cerebral Palsy. In Proceedings of the 2018 15th International Multi-Conference on Systems, Signals & Devices (SSD), Yasmine Hammamet, Tunisia, 19–22 March 2018; IEEE: New York, NY, USA; pp. 414–419. [Google Scholar]
- Patritti, B.; Sicari, M.; Deming, L.; Romaguera, F.; Pelliccio, M.; Benedetti, M.G.; Nimec, D.; Bonato, P. Enhancing robotic gait training via augmented feedback. In Proceedings of the 32nd Annual International Conference of the IEEE Engineering in Medicine and Biology Society (EMBC 2010), Buenos Aires, Argentina, 31 August–4 September 2010; IEEE: New York, NY, USA; pp. 2271–2274. [Google Scholar]
- Kirtas, O.; Savas, Y.; Bayraker, M.; Baskaya, F.; Basturk, H.; Samur, E. Design, Implementation, and Evaluation of a Backstepping Control Algorithm for an Active Ankle–Foot Orthosis. Control Eng. Pract. 2021, 106, 104667. [Google Scholar] [CrossRef]
- Wu, Y.-N.; Hwang, M.; Ren, Y.; Gaebler-Spira, D.; Zhang, L.-Q. Combined Passive Stretching and Active Movement Rehabilitation of Lower-Limb Impairments in Children with Cerebral Palsy Using a Portable Robot. Neurorehabil. Neural Repair 2011, 25, 378–385. [Google Scholar] [CrossRef]
- Eguren, D.; Luu, T.P.; Kilicarslan, A.; Akinwande, S.; Zanovello, M.; Arunkumar, A.; Gorges, J.; Contreras-Vidal, J.L. Development of a Pediatric Lower-Extremity Gait System. In Proceedings of the 2017 International Symposium on Wearable Robotics and Rehabilitation (WeRob), Houston, TX, USA, 5–8 November 2017; IEEE: New York, NY, USA, 2017; p. 1. [Google Scholar]
- Park, E.J.; Kang, J.; Su, H.; Stegall, P.; Miranda, D.L.; Hsu, W.-H.; Karabas, M.; Phipps, N.; Agrawal, S.K.; Goldfield, E.C.; et al. Design and Preliminary Evaluation of a Multi-Robotic System with Pelvic and Hip Assistance for Pediatric Gait Rehabilitation; Amirabdollahian, F., Burdet, E., Masia, L., Eds.; IEEE: New York, NY, USA, 2017; pp. 332–339. [Google Scholar]
- Tong, S.F.; Liang, D.; Su, Y.; Liu, M.; Kai-yu Tong, R. A Soft Pneumatic Hip-Assistive Robot for Reducing Scissor Gait on a Five-Year Old Child with Cerebral Palsy. In Proceedings of the 2024 17th International Convention on Rehabilitation Engineering and Assistive Technology (i-CREATe), Shanghai, China, 23–26 August 2024; IEEE: New York, NY, USA, 2024; pp. 1–6. [Google Scholar]
- Alcivar-Molina, E.; Hurel, J.; Teran, E.; Zamora-Olea, G.; Ponguillo, R.; Loayza, F.R. Six-Axis Lower-Limb Exoskeleton Control System Based on Neural Networks. In Proceedings of the 2018 IEEE Third Ecuador Technical Chapters Meeting (ETCM), Cuenca, Ecuador, 15–19 October 2018; IEEE: New York, NY, USA, 2018; pp. 1–5. [Google Scholar]
- Durfee, W.; Hashemi, S.; Ries, A. Hydraulic Ankle Foot Orthosis Emulator for Children with Cerebral Palsy. In Proceedings of the BATH/ASME 2020 Symposium on Fluid Power and Motion Control; American Society of Mechanical Engineers, Virtual, Online, 9 September 2020; ASME: New York, NY, USA; p. V001T01A044. [Google Scholar]
- Ding, Y.; Wang, Z.; Yang, P.; Yu, S. Design and Experiment of a Compact Intelligent Mobile Rehabilitation Exoskeleton Robot for Children with Cerebral Palsy Aged 3 to 6 Years. In Proceedings of the 2024 17th International Convention on Rehabilitation Engineering and Assistive Technology (i-CREATe), Shanghai, China, 23–26 August 2024; IEEE: New York, NY, USA, 2024; pp. 1–6. [Google Scholar]
- Maalej, B.; Chemori, A.; Derbel, N. Towards an Effective Robotic Device for Gait Rehabilitation of Children with Cerebral Palsy. In Proceedings of the 2019 International Conference on Signal, Control and Communication (SCC), Hammamet, Tunisia, 16–18 December 2019; IEEE: New York, NY, USA, 2019; pp. 268–273. [Google Scholar]
- Maalej, B.; Medhaffar, H.; Chemori, A.; Derbel, N. A Fuzzy Sliding Mode Controller for Reducing Torques Applied to a Rehabilitation Robot. In Proceedings of the 2020 17th International Multi-Conference on Systems, Signals & Devices (SSD), Monastir, Tunisia, 20 July 2020; IEEE: New York, NY, USA; pp. 740–746. [Google Scholar]
- Narayan, J.; Bharti, R.R.; Dwivedy, S.K. Robust Sliding Mode Control with Reaching Laws for a Pediatric Lower-Limb Exoskeleton System. In Proceedings of the 2022 Second International Conference on Power, Control and Computing Technologies (ICPC2T), Raipur, India, 1–3 March 2022; p. 6. [Google Scholar]
- Wallard, L.; Dietrich, G.; Kerlirzin, Y.; Bredin, J. Robotic-Assisted Gait Training Improves Walking Abilities in Diplegic Children with Cerebral Palsy. Eur. J. Paediatr. Neurol. 2017, 21, 557–564. [Google Scholar] [CrossRef]
- Lora-Millan, J.S.; Sanchez-Cuesta, F.J.; Romero, J.P.; Moreno, J.C.; Rocon, E. A Unilateral Robotic Knee Exoskeleton to Assess the Role of Natural Gait Assistance in Hemiparetic Patients. J. NeuroEngineering Rehabil. 2022, 19, 109. [Google Scholar] [CrossRef]
- Qian, Y.; Wang, Y.; Geng, H.; Du, H.; Xiong, J.; Leng, Y.; Fu, C. Adaptive Oscillator-Based Gait Feature Extraction Method of Hip Exoskeleton for Stroke Patients. IEEE Trans. Med. Robot. Bionics 2024, 6, 235–244. [Google Scholar] [CrossRef]
- Diot, C.M.; Thomas, R.L.; Raess, L.; Wrightson, J.G.; Condliffe, E.G. Robotic Lower Extremity Exoskeleton Use in a Non-Ambulatory Child with Cerebral Palsy: A Case Study. Disabil. Rehabil. Assist. Technol. 2023, 18, 497–501. [Google Scholar] [CrossRef]
- Bradley, S.S.; De Holanda, L.J.; Chau, T.; Wright, F.V. Physiotherapy-Assisted Overground Exoskeleton Use: Mixed Methods Feasibility Study Protocol Quantifying the User Experience, as Well as Functional, Neural, and Muscular Outcomes in Children with Mobility Impairments. Front. Neurosci. 2024, 18, 1398459. [Google Scholar] [CrossRef]
- Kolakowsky-Hayner, S.A.; Jones, K.; Kleckner, A.; Kuchinski, K.; Metzger, A.; Schueck-Plominski, J. Preliminary Assessment of a Robotic System for Overground Gait in Children with Cerebral Palsy. J. Enabling Technol. 2024, 18, 276–287. [Google Scholar] [CrossRef]
- Castro, P.; Martí, M.; Oliván-Blázquez, B.; Boñar, N.; García, V.; Gascón-Santos, S.; Panzano, A.; Vela, S.; Tajadura, S.; Peña, A.; et al. Benefits of Robotic Gait Assistance with ATLAS 2030 in Children with Cerebral Palsy. Front. Pediatr. 2024, 12, 1398044. [Google Scholar] [CrossRef]
- Cumplido-Trasmonte, C.; Ramos-Rojas, J.; Delgado-Castillejo, E.; Garcés-Castellote, E.; Puyuelo-Quintana, G.; Destarac-Eguizabal, M.A.; Barquín-Santos, E.; Plaza-Flores, A.; Hernández-Melero, M.; Gutiérrez-Ayala, A.; et al. Effects of ATLAS 2030 Gait Exoskeleton on Strength and Range of Motion in Children with Spinal Muscular Atrophy II: A Case Series. J. NeuroEngineering Rehabil. 2022, 19, 75. [Google Scholar] [CrossRef]
- Delgado, E.; Cumplido, C.; Ramos, J.; Garcés, E.; Puyuelo, G.; Plaza, A.; Hernández, M.; Gutiérrez, A.; Taverner, T.; Destarac, M.A.; et al. ATLAS2030 Pediatric Gait Exoskeleton: Changes on Range of Motion, Strength and Spasticity in Children with Cerebral Palsy. A Case Series Study. Front. Pediatr. 2021, 9, 753226. [Google Scholar] [CrossRef]
Study | Device Name | Joints Under Control | Actuator | Control Strategy | ||
---|---|---|---|---|---|---|
Supervisory | Action | Execution | ||||
Lerner et al. [15,16,41,42,43,44,45,46,47,48,49] | - | A | EM | FSM | TPR | CLT |
Lerner et al. [11,20,50,51,52] | - | A | EM | FSM | TPR | CLT |
Lerner et al. [28,38,39] | - | A | EM | FSM | TPR | CLT |
Bulea et al. [19,23,24,29,53,54] | P.REX | KA | EM | FSM | TPR/IC | CLT/CLP |
Bulea et al. [13,55] | - | K | EM | ML | TPR | CLT |
Lerner et al. [13,56,57,58,59,60] | - | K | EM | FSM | TPR | CLT/BC |
Lerner et al. [37] | - | H | EM | FSM | TPR | CLT |
Mansilla Navarro et al. [61,62] | - | KA | SMA | TLP | PPR | CLP |
Lee et al. [12] | - | HK | EM | FSM | IC | CLT |
Sarajchi et al. [27,63] | SLE | HKA | EM | - | IC | CLT |
Zhang et al. [33] | MOTION | HKA | EM | FSM | PPR | CLP |
De Groof et al. [64] | - | H | EM | FSM * | IC/TPR | CLT |
Andrade et al. [65,66,67] | ExoRoboWalker | HKA | EM | FSM | IC | CLT |
Narayan et al. [68,69,70,71,72] | LLE | HKA | EM | TLP | PPR | SMC |
Narayan et al. [73] | LLE | HKA | EM | TLP | PPR | BC |
Narayan et al. [74,75] | LLE | HKA | EM | TLP | PPR | CLP * |
Narayan et al. [76] | LLE | HKA | EM | - | TPR * | CLT |
Laubscher et al. [35,77] | - | HK | EM | FSM | TPR * | CLT |
Laubscher et al. [78,79] | - | HK | EM | - | TPR/VC | CLT |
Laubscher et al. [7,14,77,80] | - | HK | EM | TLP | PPR/VC | CLP |
Everaert et al. [81] | - | A | EM | - | IC | TPR |
Mohammadi et al. [82] | DE-AFO | A | SEA | FSM | PPR | CLP |
Gonzalez-Vazquez et al. [83] | - | A | TCP | TLP | PPR | CLP |
Yamada et al. [30] | - | K | EM | FSM | TPR * | OLT |
Eguren et al. [84] | P-LEGS | HKA | EM | TLP | PPR/IC | CLT/CLP |
Bayón et al. [17,85,86,87,88] | CP-Walker | HKA | EM | - | PPR/IC | CLT/CLP |
Mohd Adib et al. [89] | ExRoLEG | K | EM | - | - | CLP |
Patané et al. [31,32] | WAKE-up | KA | SEA | FSM | PPR | CLP |
Cestari et al. [36,90,91,92,93,94] | ATLAS 2020 | HKA | SEA | FSM | PPR/IC | CLT/CLP |
Kawamoto et al. [26,40,95,96,97,98] | HAL | HK | EM | FSM | EBC | CLT |
Snodgrass et al. [18] | - | K | EM | FSM | TPR | CLT |
Pérez-San Lázaro et al. [99] | - | HKA | EM | TLP | PPR | SMC |
Zaway et al. [100] | - | HK | EM | - | - | CLP |
Kim et al. [101] | Angel-legs | HK | EM | FSM | IC */TPR | CLT |
Kawasaki et al. [102] | HWA | H | EM | FSM | TPR | CLT |
Romero-Sorozabal et al. [103,104] | Discover2Walk | A | EM | - | IC | CLT |
Villani et al. [34] | ExoAtlet Bambini | HKA | EM | - | TPR/PPR | CLP |
Maalej et al. [105,106] | Lokomat | HK | EM | TLP | PPR | CLP |
Kirtas et al. [107] | - | A | EM | - | PPR | BC |
Wu et al. [108] | - | A | EM | - | TPR/PPR | CLT/CLP |
Eguren et al. [109] | - | HKA | EM | - | TPR | CLT |
Park et al. [110] | - | H | EM | FSM | PPR | CLP |
Tong et al. [111] | - | H | PN | FSM | - | OLT |
Alcivar-Molina et al. [112] | - | HKA | EM | ML | PPR | CLP |
Durfee et al. [113] | - | A | HA | - | PPR | CLP |
Ding et al. [114] | ChMER | HKA | EM | TLP | PPR | CLP |
Output | Adaptability | Real-Time | Complexity | Application | Validation Metrics | |
---|---|---|---|---|---|---|
TLP | Continuous | Low | High | Low | Early-stage development, low-cost, low-complexity LLE, fixed rhythm training | Biomechanical: gait symmetry, step length, GMFM; Testing during the early development of CPLLE |
FSM | Discrete | Medium | High | Medium | Personalized control, precise control of multi-joint exoskeletons | Biomechanical: joint timing, phase-triggered EMG assist |
ML | Continuous | High | Depends on the model (usually slower) | High | Complex gait recognition and intention prediction, personalized rehabilitation strategies | Validated in small-scale lab settings or offline analysis; few pilot studies in CP |
Output | Adaptability | Real-Time | Complexity | Application | Validation Metrics | |
---|---|---|---|---|---|---|
PPR | Motion trajectory (variation of angle or velocity) | Low | Lower | Low | Early-stage and fixed-mode training, predefined gait cycle | Biomechanical: gait symmetry, step length, GMFM-88 |
TPR | Joint torque (torque signal varying over time) | Medium | Higher | Higher | Active training mode, gait correction, muscle strength training | Biomechanical: joint torque, walking speed, metabolic cost |
IC | Dynamic adjustment values of joint stiffness and damping | Higher | Higher | High | Applicable for gait optimization, enhancing user-initiated movement | Biomechanical: gait parameters, patient-triggered adaptation |
VC | Constrained gait trajectory and torque output | Medium | Medium | Higher | Gait stability optimization, enhancing user active control | Healthy children only: gait pattern shaping, GRF modulation; |
EMG | Assistance signal calculated based on EMG | High | Medium | Higher | Motion intention recognition, personalized optimal training | Biomechanical: EMG activation, GMFM, step length |
Control Variables | Adaptability | Complexity | Actuator | Validation Metrics | |
---|---|---|---|---|---|
CLP | Position | Low | Low | Rigid Actuators (High-Precision Gears, Harmonic Reducers) | Validated during early rehabilitation stages; improved gait symmetry and GMFM scores in CP children |
CLT | Torque | Medium | Medium | Both Rigid and Flexible Actuators Applicable | Tested in multiple CP studies; improvements in torque regulation, step length, and metabolic cost |
SMC | State Variables | Higher | Higher | Requires Enhanced System Robustness, Suitable for Systems with Individual Differences | Pilot validation in laboratory settings and small-scale trials involving healthy children |
BC | Recursive Virtual Control Variables | High | High | Suitable for Handling Mismatched Disturbances in Complex Environments | No CP clinical validation; tested in healthy children for GRF and motion pattern modulation |
Disclaimer/Publisher’s Note: The statements, opinions and data contained in all publications are solely those of the individual author(s) and contributor(s) and not of MDPI and/or the editor(s). MDPI and/or the editor(s) disclaim responsibility for any injury to people or property resulting from any ideas, methods, instructions or products referred to in the content. |
© 2025 by the authors. Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (https://creativecommons.org/licenses/by/4.0/).
Share and Cite
Kang, Z.; Li, H.; Wang, Y.; Yu, H. A Review of Hierarchical Control Strategies for Lower-Limb Exoskeletons in Children with Cerebral Palsy. Machines 2025, 13, 442. https://doi.org/10.3390/machines13060442
Kang Z, Li H, Wang Y, Yu H. A Review of Hierarchical Control Strategies for Lower-Limb Exoskeletons in Children with Cerebral Palsy. Machines. 2025; 13(6):442. https://doi.org/10.3390/machines13060442
Chicago/Turabian StyleKang, Ziwei, Hui Li, Yang Wang, and Hongliu Yu. 2025. "A Review of Hierarchical Control Strategies for Lower-Limb Exoskeletons in Children with Cerebral Palsy" Machines 13, no. 6: 442. https://doi.org/10.3390/machines13060442
APA StyleKang, Z., Li, H., Wang, Y., & Yu, H. (2025). A Review of Hierarchical Control Strategies for Lower-Limb Exoskeletons in Children with Cerebral Palsy. Machines, 13(6), 442. https://doi.org/10.3390/machines13060442