Adam Zoss

Biomechanical design of the Berkeley lower extremity exoskeleton (BLEEX)

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.

On the mechanical 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.

On the Biomimetic Design of the Berkeley Lower Extremity Exoskeleton (BLEEX)

Many places in the world are too rugged or enclosed for vehicles to access. Even today, material transport to such areas is limited to manual labor and beasts of burden. Modern advancements in wearable robotics may make those methods obsolete. Lower extremity exoskeletons seek to supplement the intelligence and sensory systems of a human with the significant strength and endurance of a pair of wearable robotic legs that support a payload. This paper outlines the use of Clinical Gait Analysis data as the framework for the design of such a system at UC Berkeley.

Design of an electrically actuated lower extremity exoskeleton

Human exoskeletons add the strength and endurance of robotics to a humans innate intellect and adaptability to help people transport heavy loads over rough, unpredictable terrain. The Berkeley lower extremity exoskeleton (BLEEX) is the first human exoskeleton that was successfully demonstrated to walk energetically autonomous while supporting its own weight plus an external payload. This paper details the design of the electric motor actuation for BLEEX and compares it to the previously designed hydraulic actuation scheme. Clinical gait analysis data was used to approximate the torques, angles and powers required at the exoskeletons leg joints. Appropriately sized motors and gearing are selected, and put through a thorough power analysis. The compact electric joint design is described and the final electric joint performance is compared with BLEEXs previous hydraulic actuation. Overall, the electric actuation scheme is about twice as efficient and twice as heavy as the hydraulic actuation.

Mobile Exoskeleton for Spinal Cord Injury: Development and Testing

For those who have lost the ability to walk due to paralysis or other injuries, eLEGS, a mobile robotic exoskeleton, offers the chance to walk again. The device is a mobile exoskeleton with actuated sagittal plane hip and knee joints which supports the user and moves their legs through a natural gait. The device uses a multi-leveled controller that consists of a state machine to determine the user’s intended motion, a trajectory generator to establish desired joint behavior, and a low level controller to calculate individual joint controller output. The system can be controlled by a physical therapist or can be controlled by the user. Subject testing results are presented from a seven subject pilot study including patients with complete and incomplete injuries. The testing resulted in six of the seven subjects walking unassisted using forearm crutches after a single two hour testing session.Copyright

Prototype Medical Exoskeleton for Paraplegic Mobility: First Experimental Results

Spinal cord injuries leave thousands of patients confined to wheelchairs, resulting in a life of severely limited mobility. This condition also subjects them to the risk of secondary injuries. Because exoskeletons are externally driven machines in which the actuation is coupled to the person’s joints, they offer an ideal method to help paraplegics walk. The exoskeleton presented here is a mobile, battery powered device that uses hydraulically actuated hip and knee joints in the sagittal plane to move a patient’s joints. The control strategy mimics standard human walking using foot sensors to determine the walking state. This activates position control of the joints to follow standard walking trajectories based on clinical gait analysis data. Initial patient testing of the device showed that the exoskeleton enabled one incomplete paraplegic to significantly improve his gait function and three complete paraplegic patients to walk.Copyright

ARCHITECTURE AND HYDRAULICS OF A LOWER EXTREMITY EXOSKELETON

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 seven degrees of freedom per leg, four of which are powered by linear hydraulic actuators. The selection of the degrees of freedom, critical hardware design aspects, and initial performance measurements of BLEEX are discussed.Copyright

Control and Experimental Results for Post Stroke Gait Rehabilitation With a Prototype Mobile Medical Exoskeleton

Repetitive task-oriented exercises are accepted in traditional gait rehabilitation and have given rise to driven gait orthoses, but both methods suffer from limited rehabilitation time for the patient. The presented device proposes a control strategy and implementation unique for a mobile rehabilitation exoskeleton as well as results from initial subject testing. This anthropomorphically designed device has knee and hip joints that are actuated in the sagittal plane using hydraulic actuators. The presented control strategy allows the user or therapist to directly specify the level of rehabilitation assistance desired between complete machine control and a zero impedance joint. The device was experimentally tested on three chronic stroke patients with noticeable gait improvements based on the metric of joint flexion. Other results of step time and step length are presented that do not demonstrate as clear improvements but these are believed to be a function of the limited patient testing time.Copyright