Two adaptively combined gyro and triaxial accelerometer arrays of commercial-grade Micro Electro-Mechanical Systems (MEMS) inertial sensors and a real-time embedded algorithm suite significantly enhance accuracy over that of single commercial-grade devices. Denoised sensor data is combined with a Kalman-filter bias compensation algorithm to achieve better than 0.1 degree/hour in-run gyro bias stability (standard deviation). One denoise-filtered triaxial accelerometer sensor array provides better than 30µg accelerometer bias stability. The hardware is embedded in an exoskeleton that maintains accurate fine alignment adjustments and provides protection when in rugged environments. Analysis of results measured from Allan variance computations of real-time data from several different IMU hardware units demonstrates that each of three orthogonally positioned precision gyro arrays, and their associated processing, achieve less than 0.03 deg integrated angle drift over 5 hours. New IMU hardware is now in fabrication for delivery in early 2010, when received, we expect to overcome the limits of the present hardware design to produce additional significant improvements. The size, weight, and power of these new IMU’s are suitable for man-portable, hand-held systems, UAVs, and munitions systems. Early work for this technology was first published at ION/PLANS 2008.

Категория: Ищем научные статьи | Нет комментариев »

The present paper describes a power-assist robot arm that uses pneumatic artificial rubber muscles (PARMs) covered withexoskeleton suits to mimic the motion of biarticular muscles. One robot arm uses a single PARM, which assists the wrist and elbow joint of the user. This robot arm is linked to a waist belt through a suspender-like structure of three PARMs. PI control (Proportional Integral control), which is based on the pressure value from a balloon sensor, is used to achieve accurate power-assist motion, and the present study focuses on the motions associated with lifting an object. In order to evaluate the validity of the proposed power-assist robot arm, skin surface electromyography (EMG) signals of forearm muscles are measured during a lifting task and a follow-up questionnaire survey is conducted.

Категория: Ищем научные статьи | Нет комментариев »

We are attempting to develop therapeutic technology that individuals with substantial arm weakness and minimal hand function after stroke can use to improve their movement ability without the continuous presence of a rehabilitation therapist. We have developed a device called Therapy WREX (T-WREX) that is comprised of four main features: 1) a passive, gravity-balancing arm support (based on WREX ¿Wilmington Robotic Exoskeleton) that allows a wide range of arm motion 2) a grip sensor that detects even trace amounts of grasp 3) virtual reality exercises that simulate activities of daily living, and 4) software that provides feedback about task performance. Initial clinical testing indicates that chronic stroke patients can significantly improve their movement ability with T-WREX. We have also found that patients strongly prefer using T-WREX for therapy compared to conventional, self-directed, tabletop exercises. This paper reports the results of a follow-up survey conducted with 11 subjects to gain further understanding about the basis for this preference. The results suggest that subjects prefer T-WREX because it is more interesting, and because it allows them to be more successful with their movement attempts. Further, each of the four features of TWREX had significant value to the subjects, suggesting that their combination is synergistic.

Категория: Ищем научные статьи | Нет комментариев »

The aim of this paper is to arbitrarily modify the load force of any selected muscle by using an exoskeleton, thus enabling «pinpointed» motion support, rehabilitation, and training. An advanced dynamic model, called a musculoskeletal-exoskeletal integrated human model, is developed. The driving-forces of the pneumatic actuators are designated by a muscle force control algorithm using the integrated model. A prototype power-assisting system is developed using pneumatic rubber actuators. The feasibility of the muscle force control is analyzed from a view point of nonlinear programming. The validity of the method is confirmed by measuring surface electromyographic signals of related muscles.

Категория: Ищем научные статьи | Нет комментариев »

In the design of exoskeletons for gait rehabilitation, the choice of degrees of freedom (DoFs) is one of the main issues. The goal of this research is to evaluate the effect of availability of additional DoFs related to balance-keeping on the normality of walking. These additional DoFs are the horizontal translations of the pelvis and the frontal rotation of the hip. Measurements on the gait of ten healthy subjects showed that kinematics and EMG differ only slightly when these DoFs are blocked (and only the sagittal joint rotations are available), in the impedance-controlled LOPES exoskeleton. This shows that omitting the additional DoFs allows walking with close-to-normal motor control, and also that effects of waking in this robot per se overshadow the additional effects of the mentioned DoFs. All subjects however reported a more difficult and uncomfortable walking when the horizontal pelvis motions were blocked. An additional motivation for keeping the DoFs despite these results is that they allow implementation of balance training.

Категория: Ищем научные статьи | Нет комментариев »