Hybrid Adaptive Robust Control Based on CPG and ZMP for a Lower Limb Exoskeleton

Mokhtari, Majid; Taghizadeh, Mohammad Javad; Mazare, Mahmood

doi:10.1017/s0263574720000260

Cited by 26 publications

(14 citation statements)

References 35 publications

Supporting

Mentioning

Contrasting

Unclassified

Order By: Relevance

“…With the development of robot technology, establishing the contact between the robot's end-effector and the environment is becoming a vital part of tasks in robotic applications that involve assembly [1], precise handling or surface processing [e.g., polishing] [2], exoskeleton [3] etc. The main issue in contact establishment concerns the contact force magnitude that may take prohibiting values, which may directly lead to the failure of a task, with even more serious consequences [manipulated object or manipulator itself damaged] at the instant of contact.…”

Section: Introductionmentioning

confidence: 99%

“…But at the same time, some advanced nonlinear control schemes are also applied to handle the uncertainties for complex tasks, such as robust impedance control [3], adaptive fuzzy control [15] and neural net-works control [16]. Moreover, to manage the application of industrial robots, the position-based impedance control was proposed, and the performance and stability were also analysed [17,18].…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Design of a Fuzzy Fractional Order Adaptive Impedance Controller with Integer Order Approximation for Stable Robotic Contact Force Tracking in Uncertain Environment

Cao

2022

Acta Mechanica Et Automatica

View full text Add to dashboard Cite

Current research in robot compliance control is unable to take both transient contact force overshoots and steady-state force tracking problems into account. To address this problem, we propose a fuzzy fractional order (FO) adaptive impedance controller to avoid the force overshoots in the contact stage while keeping force error in the dynamic tracking stage, where traditional control algorithms are not competent. A percentage gain is adopted to map FO parameters to integer order (IO) parameters by their natural properties, and a fuzzy logical controller is introduced to improve the system stability. The simulation results indicate that the proposed controller can be made more stable than and superior to the general impedance controller, and the force tracking results also have been compared with the previous control methods.

show abstract

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Design of a Fuzzy Fractional Order Adaptive Impedance Controller with Integer Order Approximation for Stable Robotic Contact Force Tracking in Uncertain Environment

Cao

2022

Acta Mechanica Et Automatica

View full text Add to dashboard Cite

show abstract

“…Based on the multilayered multi-pattern CPG provided by Nassour [40], Tran et al [41] used reinforcement learning to allow the robot to trigger a reaction to avoid falling. Mokhtari et al [42] based on the CPG and ZMP achieve a hybrid adaptive robust control for a lower limb exoskeleton, where the CPG is applied to determine the desired angles of ankle, knee, and hip of both left and right legs. In our previous work [43], a ML-CPG was proposed and is used as the underlying low-level controller for a quadruped robot to generate adaptive walking patterns in joint place.…”

Section: Introductionmentioning

confidence: 99%

Humanoid adaptive locomotion control through a bioinspired CPG-based controller

Yao

Liu

et al. 2021

Robotica

View full text Add to dashboard Cite

To achieve adaptive gait planning of humanoid robots, a hierarchical central pattern generator (H-CPG) model with a basic rhythmic signal generation layer and a pattern formation layer is proposed to modulate the center of mass (CoM) and the online foot trajectory. The entrainment property of the CPG is exploited for adaptive walking in the absence of a priori knowledge of walking conditions, and the sensory feedback is applied to modulate the generated trajectories online to improve walking adaptability and stability. The developed control strategy is verified using a humanoid robot on sloped terrain and shows good performance.

show abstract

“…15 To address this problem, Nonsingular Terminal Integral SMC has been proposed, 17 and to increase the convergence rate Fast Nonsingular Terminal Integral SMC has been introduced by modifying the sliding manifold. 18,19 Super twisting SMC (STW-SMC) and high order super twisting SMC are developed to eliminate chattering, while improving accuracy and convergence rate. [21][22][23] These approaches have the inherent ability to remove chattering, without defining the boundary layer and sacrificing the robustness.…”

Section: Introductionmentioning

confidence: 99%

Fault tolerant control based on backstepping nonsingular terminal integral sliding mode and impedance control for a lower limb exoskeleton

Mokhtari

Taghizadeh

Ghanbari

2021

Proceedings of the Institution of Mechanical Engineers, Part C:

Self Cite

View full text Add to dashboard Cite

In this paper, an active fault-tolerant control scheme is proposed for a lower limb exoskeleton, based on hybrid backstepping nonsingular fast terminal integral type sliding mode control and impedance control. To increase the robustness of the sliding mode controller and to eliminate the chattering, a nonsingular fast terminal integral type sliding surface is used, which ensures finite time convergence and high tracking accuracy. The backstepping term of this controller guarantees global stability based on Lyapunov stability criterion, and the impedance control reduces the interaction forces between the user and the robot. This controller employs a third order super twisting sliding mode observer for detecting, isolating ad estimating sensor and actuator faults. Motion stability based on zero moment point criterion is achieved by trajectory planning of waist joint. Furthermore, the highest level of stability, minimum error in tracking the desired joint trajectories, minimum interaction force between the user and the robot, and maximum system capability to handle the effect of faults are realized by optimizing the parameters of the desired trajectories, the controller and the observer, using harmony search algorithm. Simulation results for the proposed controller are compared with the results obtained from adaptive nonsingular fast terminal integral type sliding mode control, as well as conventional sliding mode control, which confirm the outperformance of the proposed control scheme.

show abstract

Hybrid Adaptive Robust Control Based on CPG and ZMP for a Lower Limb Exoskeleton

Cited by 26 publications

References 35 publications

Design of a Fuzzy Fractional Order Adaptive Impedance Controller with Integer Order Approximation for Stable Robotic Contact Force Tracking in Uncertain Environment

Design of a Fuzzy Fractional Order Adaptive Impedance Controller with Integer Order Approximation for Stable Robotic Contact Force Tracking in Uncertain Environment

Humanoid adaptive locomotion control through a bioinspired CPG-based controller

Fault tolerant control based on backstepping nonsingular terminal integral sliding mode and impedance control for a lower limb exoskeleton

Contact Info

Product

Resources

About