# Design and Implementation of a Robotic Hip Exoskeleton for Gait Rehabilitation

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## Abstract

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## 1. Introduction

## 2. Design and Building of Robotic Hip Exoskeleton

#### 2.1. Robotic Hip Exoskeleton Building

#### 2.2. Electronics Design

## 3. Walking Dynamics and LESO-Based Controller Design

#### 3.1. Walking Dynamics

#### 3.2. LESO Design

**L**= ${\left[\begin{array}{ccc}{\beta}_{1}& {\beta}_{2}& {\beta}_{3}\end{array}\right]}^{T}$ is the observer gain vector, and $\widehat{y}$ is the estimate of the system output y.

**e**=

**x**–

**z**; the error dynamics are then derived by Equations (3) and (4) as

#### 3.3. LESO-Based PD Controller Design

_{d}can be specified as ${k}_{d}=2{\omega}_{c}$, ${k}_{p}={\omega}_{c}{}^{2}$ according to the separation principle of eigenvalues, in which ω

_{c}is the user-defined frequency bandwidth [23].

#### 3.4. LESO-Based SMC Design

#### 3.5. LESO-Based FTSMC Design

## 4. Implementation of Walking Rehabilitation

#### 4.1. Walking Rehabilitation Experiment

#### 4.2. Gait Rehabilitation while Suffering from Instant Spasm and Tremor

#### 4.3. Rehabilitation Experiment on Ascending

#### 4.4. Walking Experiments for Different Subjects

## 5. Evaluation of Rehabilitation Assistance

## 6. Discussion of the Robotic Hip Exoskeleton for Rehabilitation

## 7. Conclusions

## Author Contributions

## Funding

## Institutional Review Board Statement

## Informed Consent Statement

## Data Availability Statement

## Conflicts of Interest

## References

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**Figure 1.**(

**a**) Proposed robotic hip exoskeleton design, and (

**b**) back pack for integration of electric devices.

**Figure 11.**Trajectories of hip joint by LADRC with spasm and tremor occurring at walking speed = 0.15 m/s.

**Figure 12.**Trajectories of hip joint by LADRC with spasm and tremor occurring at walking speed = 0.225 m/s.

**Figure 13.**Trajectories of hip joint by LESO-based SMC with spasm and tremor occurring at walking speed = 0.15 m/s.

**Figure 14.**Trajectories of hip joint by LESO-based SMC with spasm and tremor occurring at walking speed = 0.225 m/s.

**Figure 15.**Trajectories of hip joint by LESO-based FTSM with spasm and tremor occurring at walking speed = 0.15 m/s.

**Figure 16.**Trajectories of hip joint by LESO-based FTSM with spasm and tremor occurring at walking speed = 0.225 m/s.

**Figure 21.**A subject wore the robotic exoskeleton with EMG sensors and reflectors attached to his body.

Walking Speed | 0.225 m/s | 0.15 m/s | |
---|---|---|---|

Controller | |||

LADRC | 6.008533° | 3.685461° | |

LESO-based SMC | 1.858353° | 1.172696° | |

LESO-based FTSMC | 1.821815° | 1.145927° |

**Table 2.**RMSE of different subjects’ hip joint trajectories for LADRC, LESO-based SMC, and LESO-based FTSMC.

Subject | A | B | C | |
---|---|---|---|---|

Controller | ||||

LADRC | 3.685461° | 0.654712° | 3.688961° | |

LESO-based SMC | 1.172696° | 0.62858° | 1.15422° | |

LESO-based FTSMC | 1.145927° | 0.627559° | 1.141448 |

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**MDPI and ACS Style**

Hsu, S.-H.; Changcheng, C.; Lee, H.-J.; Chen, C.-T.
Design and Implementation of a Robotic Hip Exoskeleton for Gait Rehabilitation. *Actuators* **2021**, *10*, 212.
https://doi.org/10.3390/act10090212

**AMA Style**

Hsu S-H, Changcheng C, Lee H-J, Chen C-T.
Design and Implementation of a Robotic Hip Exoskeleton for Gait Rehabilitation. *Actuators*. 2021; 10(9):212.
https://doi.org/10.3390/act10090212

**Chicago/Turabian Style**

Hsu, Shi-Heng, Chuan Changcheng, Heng-Ju Lee, and Chun-Ta Chen.
2021. "Design and Implementation of a Robotic Hip Exoskeleton for Gait Rehabilitation" *Actuators* 10, no. 9: 212.
https://doi.org/10.3390/act10090212