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In this paper, we present an assist-as-needed scheme that effectively adapted the assistance provided by an ankle rehabilitation robot according to patient's participation and performance during therapeutic movements. We performed an error-based estimation of the ankle impedance as a valid measure of the patient participation. Then, we computed the amount of robotic assistance by three steps: normalization...
Rehabilitation robotic systems may afford better care and telerehabilitation may extend the use and benefits of robotic therapy to the home. Data transmissions over distance are bound by intrinsic communication delays which can be significant enough to deem the activity unfeasible. Here we describe an approach that combines unilateral robotic telerehabilitation and serious games. This approach has...
This paper deals with the evaluation of an exoskeleton designed for assisting individuals to rehabilitate compromised lower limb movements resulting from stroke or incomplete spinal cord injury. The exoskeleton is composed of lightweight tubular structures and six free joints that provide a modular feature to the system. This feature allows the exoskeleton to be adapted to assist the movement of one...
Background In this paper we propose the use of global Kalman filters (KFs) to estimate absolute angles of lower limb segments. Standard approaches adopt KFs to improve the performance of inertial sensors based on individual link configurations. In consequence, for a multi-body system like a lower limb exoskeleton, the inertial measurements of one link (e.g., the shank) are not taken into account in...
Impedance control based on robust force control can improves rehabilitation therapies. In this paper, we formulate and validate a model of a series-elastic-actuator-based ankle rehabilitation device that includes a second-order description of the human joint dynamics. In order to control the output impedance of the platform we used a cascade configuration with a PD position controller as outer loop...
This chapter deals with nonlinear $${\mathcal{H}}_{\infty}$$ control methodologies for robot manipulators. The nonlinear $${\mathcal{H}}_{\infty}$$ control considered guarantees an appropriate attenuation of the torque disturbance effect on the joint positions. We deal with two fundamental approaches for this class of controllers; the first is based on game theory and the second is based on...
This paper deals with optimal impedance control of robotic devices designed for rehabilitation of walking after stroke. The proposed optimal solution is based on the estimation of torque and impedance parameters of the patient during the gait. The patient's torque is estimated using the generalized momenta-based disturbance observer associated with the Kalman filter algorithm. The stiffness and damping...
This article proposes an approach to adapt a game to ankle movement for a rehabilitation mechanism. Thus, a game was developed for ankle rehabilitation, which is inspired in the commercial version, already used with the AnkleBot (by Interactive Motion Technologies - IMT), changing both aesthetics and gameplay characteristics aiming a more intuitive and softer gameplay, improving the game experience.
In this chapter we present three nonlinear $${\mathcal{H}}_{\infty}$$ control techniques for underactuated cooperative manipulators. Two are based on a quasi-linear parameter varying (quasi-LPV) representation of the nonlinear system with solutions based on game theory. These controllers take into account a fundamental characteristic of cooperative manipulator control, namely, that squeeze force...
In this chapter we present a fault tolerance framework for cooperative manipulators. The fault detection and isolation (FDI) system uses the kinematic constraints of the cooperative system and neural networks to detect and treat four categories of faults: free-swinging joint faults (FSJF), where one or more joints lose actuation and become free-swinging; locked joint faults (LJF), where one or more...
In this chapter, we present adaptive nonlinear $${\mathcal{H}}_{\infty}$$ controllers for robot manipulators. Similarly to the controllers presented in Chap. 3, the ones here guarantee robustness to parametric uncertainty and external disturbances. They go beyond, however, by allowing us to estimate the parametric uncertainties and the unmodeled dynamics. These adaptive control laws are added...
This chapter deals with linear robust control of robot manipulators. The approach we consider is based on the combination of two controllers, computed torque and linear $${\mathcal{H}}_\infty.$$ Experimental results using the UARM manipulator and CERob environment are presented to illustrate the validity of the method.
This chapter describes the main features of the underactuted manipulators we use to validate the control approaches proposed throughout the book. It describes also a control environment for robots which we use to simulate the controllers and to operate the manipulators.
In this chapter we deal with the problem of fault tolerant control of robotic manipulators. We present a fault-modeling framework based on Markovian jump linear systems. An important feature of this approach is that it does not require that the manipulator be stopped when a fault is detected, i.e., the manipulator can continue moving until all joints have reached their respective desired positions...
In this chapter we present the application of the $${\mathcal{H}}_{\infty}$$ and adaptive $${\mathcal{H}}_{\infty}$$ control methodologies to underactuated robotic manipulators, or manipulators with more joints than actuators. We begin by presenting a taxonomy to classify the different types of underactuation. Next, we present both model-based and non-model-based controller design approaches...
In this chapter we present control strategies for cooperative manipulators with passive joints. These systems differ from the ones presented earlier because, here, one must control not only the position of the common load being manipulated by the various robots, but also the internal forces in the object to ensure it will not be damaged during the operation. Therefore, we use a hybrid motion and squeeze...
Robust Control of Robots bridges the gap between robust control theory and applications, with a special focus on robotic manipulators. It is divided into three parts: robust control of regular, fully-actuated robotic manipulators; robust post-failure control of robotic manipulators; and robust control of cooperative robotic manipulators. In each chapter the mathematical concepts are illustrated...
This paper presents an assist-as-needed method for ankle rehabilitation based on adaptive impedance control strategies. First, the dynamic contribution of the patient during the motion is estimated from robot's torque and kinematic information. Then, two robot assistance control strategies (complementary and optimal) are proposed to calculate the stiffness parameter of the impedance controller. In...
This paper presents a gait-pattern adaptation algorithm for exoskeletons based on the Zero Moment Point criterion. The proposed exoskeleton is developed for lower limbs and based on a commercially available orthosis. The step length and duration are considered as the adaptation parameters, they are computed through minimization based on direct dynamics and considering the orthosis-patient interaction...
This paper summarizes our on-going efforts to design adaptive assist-as-needed impedance controllers for ankle rehabilitation. Two robot assistance control strategies were evaluated: the first one attempted to normalize the combined robot and patient impedance via a complementary robot stiffness based on the estimate of the patient's stiffness and the second one searched for an optimal solution that...
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