Force Feedback Control of Lower Extremity Exoskeleton Assisting of Load Carrying Human

Abstract

Lower extremity exoskeletons are wearable robot manipulators that integrate human intelligence with the strength of legged robots. Recently, lower extremity exoskeletons have been specifically developed for rehabilitation, military, industrial applications and rescuing, heavy-weight lifting and civil defense applications. This paper presents controller design of a lower-extremity exoskeleton for a load carrying human to provide force feedback control against to external load carried by user during walking, sitting, and standing motions. Proposed exoskeleton system has two legs which are powered and controlled by two servo-hydraulic actuators. Proportional and Integral (PI) controller is designed for force control of system. Six flexible force sensors are placed in exoskeleton shoe and two load cells are mounted between the end of the piston rod and lower leg joint. Force feedback control is realized by comparing ground reaction force and applied force of hydraulic cylinder. This paper discusses control simulations and experimental tests of lower extremity exoskeleton system.

A State-Dependent Damping Method to Reduce Collision Force and Its Variability

“…However, this method raises challenges in terms of placing several sensors at the point of contact [10], [11] for the closed-loop control. Authors in [9] focused on applying a reaction force by searching policy for optimum gains for a feedback controller. Other methods involve predicting the consequence of variability on the stability of the system [12], [13].…”

“…The complexity in robot-environment interaction that involves dynamics that are punctuated by collisions is a major challenge for closed-loop control systems. Several studies have investigated fast collision detection and reactive behaviour mechanisms [9]- [11] or different numerical methods of predicting the consequence of variability on the stability [12], [13] or search for impedance parameters that can reduce the variability [14]. However, in the studies mentioned above, intensive computational algorithms for real-time control were used.…”

Toward Standardizing the Classification of Robotic Gait Rehabilitation Systems

“…The actual walking process in the case of a healthy person can be described as a direct relationship between the walker and the environment in which the walker performs a set of movements, while the ground responds with a set of physical reactions allowing the walker to change their location. However, due to the disability, this reciprocal relationship can be missing or weakened from the patient side, which could be repaired either with assistive tools (such as crutches or assistive robotic devices) [31]- [33] or simply by restoring the damaged function through therapeutic rehabilitation. The latter consists of two main elements, approach and executive.…”

Fuzzy cerebellar model articulation controller-based adaptive tracking control for load-carrying exoskeleton

“…After BLEEX, SAC is seldom being used in other exoskeletons for its strick requirements of the model. MBC, such as direct force control 7,8 and impedance control, 9,10 is relatively easy to implement. HEXAR-CR50 developed by Hanyang University uses direct force control to calculate the desired joint torques in the stance phase and then applied a proportional–integral–derivative (PID) controller at each joint.…”