Our lower extremity exoskeleton is a wearable robotic device that enables a human to walk with a load for a prolonged period of time without reducing the human’s agility. The exoskeleton comprised of two anthropomorphic legs and a spine. The device is designed and controlled autonomously via a spine mounted internal combustion engine and PC104 compliant computer. Custom hardware was designed to accommodate the high-speed network required to link the distributed sensors and actuators. This paper presents the implementation of the high-speed hard real-time network designed to maintain stable control of the exoskeletonduring stance and walk. The high-speed ring protocol necessary to maintain strict hard real-time synchronization between the distributed sensors and actuator of the exoskeleton is presented. Communication latency was considered in the design with respect to its impact on performance, and stability. Error detection and recovery was crucial for operation with the exoskeleton. A cyclic redundancy check (CRC) algorithm was incorporated into the protocol to achieve this error detection. The use of this high-speed serial based network greatly minimized the number of cables required over traditional parallel-based systems. The achieved update time of up to 10 kHz for a six-actuator system enables the architecture to be viable system for most industrial controls.

(далее…)

Категория: Научные статьи | Нет комментариев »

We proposed a power assist method for leg based on the autonomous motion driven by the interaction between human and the robot suit, HAL (hybrid assistive limb) and verified the effectiveness of this method in the experiments in walking. In order to perform walking task autonomically, we used a phase sequence control which generates a task by transiting some simple basic motions called phase. A task was divided into some phases on the basis of the task performed by a normal person. The joint moving modes were categorized into the active, passive and free modes according to the characteristic of the muscle force conditions. The autonomous motion which HAL generates in each phases were designed according to one of the categorized modes. The floor reaction force and joint angle were adopted as the condition to transit each phase. The experiments in power assist were performed for normal person. The experimental results showed that the muscle activation levels in each phase were significantly reduced. With this, we confirmed the effectiveness of the proposed assist method.

(далее…)

Категория: Научные статьи | Нет комментариев »