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In the nearly six decades since researchers began to explore methods of creating them, exoskeletons have progressed from the stuff of science fiction to nearly commercialized products. While there are still many challenges associated with exoskeleton development that have yet to be perfected, the advances in the field have been enormous. In this paper, we review the history and discuss the state-of-the-art of lower limb exoskeletons and active orthoses. We provide a design overview of hardware, actuation, sensory, and control systems for most of the devices that have been described in the literature, and end with a discussion of the major advances that have been made and hurdles yet to be overcome.

Lower Extremity Exoskeletons and Active Orthoses: Challenges and State-of-the-Art

Wheeled vehicles are often incapable of transporting heavy materials over rough terrain or up staircases. Lower extremity exoskeletons supplement human intelligence with the strength and endurance of a pair of wearable robotic legs that support a payload. This paper summarizes the design and analysis of the Berkeley lower extremity exoskeleton (BLEEX). The anthropomorphically based BLEEX has 7 DOF per leg, four of which are powered by linear hydraulic actuators. The selection of the DOF, critical hardware design aspects, and initial performance measurements of BLEEX are discussed.

Biomechanical design of the Berkeley lower extremity exoskeleton (BLEEX)

The first energetically autonomous lower extremity exoskeleton capable of carrying a payload has been demonstrated at U.C. Berkeley. This paper summarizes the mechanical design of the Berkeley Lower Extremity Exoskeleton (BLEEX). The anthropomorphically-based BLEEX has seven degrees of freedom per leg, four of which are powered by linear hydraulic actuators. The selection of the degrees of freedom and their ranges of motion are described. Additionally, the significant design aspects of the major BLEEX components are covered.

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On the mechanical design of the Berkeley Lower Extremity Exoskeleton (BLEEX)

Wearable lower limb robotics: A review

Plant-Input-Mapping Discretization Method for a Feedback System in the State-Space Form

A patient lift is an assistive device for patients who lack sufficient strength or muscle control to be transferred between a wheelchair and a toilet or other places. Patient lifts of two kinds are commonly used: overhead lifts and mobile lifts. Nevertheless, because of its size and weight, carrying even a mobile lift with a wheelchair is difficult when leaving home. This study examined a novel portable patient lift that is small and light, sufficient to be carried using a wheelchair in a folded state. It is compact, light, and portable because it has no actuator. Moreover, its operation is simple. It is useful not only at home or in a nursing home but on any flat surface during daily excursions and activities, even in a conventional lavatory. A caregiver can transfer a user with a small force because this lift has a sliding mechanism that brings the fulcrum closer to the patient's center of mass. Experimental results underscore the effectiveness of the proposed patient lift.

Wheelchair-Portable Patient Lift

This study attempts to extend a digital redesign method, called the Plant-Input-Mapping (PIM) method, to nonlinear control systems. The PIM method in the linear case can preserve the stability of the underlying continuous-time feedback control system without respect to the selection of the sampling interval. The PIM method is a model-based approach, and thus, the key of the extension scheme is to overcome the absence of the exact discrete-time model for nonlinear systems. In this paper, we propose a PIM method incorporating the feedback linearization. The proposed method can discretize the continuous-time controller designed by using the linearization technique, which is numerically verified through an example of a robotic manipulator with a flexible joint.

A Study on the Plant-Input-Mapping Discretization for Nonlinear Control Systems Utilizing Feedback Linearization

The paper is concerned with force-sensorless estimation of human joint impedance utilizing an impulsive force. We analyze the dynamic response of a human joint induced by the impulsive perturbation...

Force-sensorless human joint impedance estimation utilizing impulsive force

In this paper, we propose a robot behavior generation scheme that generates behaviors based on the senses of "curiosity" and "boredom," to create a companion robot named SELF with which humans do not get bored. The scheme was developed using a simple but unique simulation environment. A red ball and a blue ball were displayed on the computer, and the human subject moved the red ball. A behavior generator was designed based on natural inter human interaction patterns, utilizing conditional probability. The autonomous learning capability of SELF was realized by updating this conditional probability. Our studies reveal that interaction capability and animal-like speed are required for a companion robot. In addition, this paper shows how SELF can have a sense of curiosity and boredom as seen in animals, including humans, by using the developed scheme. The impressions of the robot behavior generated by the proposed scheme were examined using the simulation environment where the blue ball was controlled by the proposed scheme.

Yoshikazu Mori

Papers

Plant-Input-Mapping Discretization Method for a Feedback System in the State-Space Form

Wheelchair-Portable Patient Lift

A Study on the Plant-Input-Mapping Discretization for Nonlinear Control Systems Utilizing Feedback Linearization

Force-sensorless human joint impedance estimation utilizing impulsive force

Autonomous Behavior Generator for a Companion Robot "SELF" with which Humans Do Not Get Bored