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 article first outlines the use of Clinical Gait Analysis data as the framework for the design of such a system at UC Berkeley. This data is used to design the exoskeleton degrees of freedom and size its actuators. It will then give an overview of one of the control schemes implemented on the BLEEX. The control algorithm described here increases the system closed loop sensitivity to its wearer’s forces and torques without any measurement fromthe wearer (such as force, position, or electromyogram signal). The control algorithm uses the inverse dynamics of the exoskeleton, scaled by a number smaller than unity, as a positive feedback controller. This controller almost destabilizes the system since it leads to an overall loop gain slightly smaller than unity and results in a large sensitivity to all wearer’s forces and torques thereby allowing the exoskeleton to shadow its wearer.

(далее…)

Категория: Научные статьи | Нет комментариев »

Microelectromechanical systems (MEMS) are revolutionizing a multitude of industries world wide, from consumer products to the scientific community. Rehabilitation robotics is a robotic field specially interested in using the advantages of inertial sensors. The essential aspect in this area is the intrinsic interaction between human and robot, which imposes several restrictions in the design of this sort of robots. This paper addresses the analysis of the application of inertial sensors as sensing technologies in controlled orthotic devices with a detailed analysis with two biomechatronic robotics rehabilitation exoskeletons, one for the upper and other for the lower limb. Eventually, the results and conclusion of the experiments are given.

(далее…)

Категория: Научные статьи | Нет комментариев »

It is proposed that copepods grow between one moult and the next in much the same fashion as established by Klaus Anger and others for decapod crustacean larvae. The analogy is justified by commonality of approximately isochronal development patterns, potential for continuously exponential growth at stage-to-stage resolution, and demonstrated points of reserve saturation. Thus, as for crab zoeae, the copepod pattern should be very fast initial growth, then slowing as activity shifts to preparation of the new exoskeleton prior to moult. As much as 80% of growth may occur in the first half of the moult cycle, with no growth at all in the last third. Establishing the exact patterns for copepods faces difficulties not presented by decapod larvae, and some solutions to these problems are suggested. Obtaining precise data will help to predict and interpret (model correctly) the effects of food limitation in the field.

(далее…)

Категория: Научные статьи | Нет комментариев »

We propose a novel control method for lower-limb assist that produces a virtual modification of the mechanical impedance of the human limbs. This effect is accomplished by making the exoskeleton display active impedance properties. Active impedance control emphasizes control of the exoskeleton’s dynamics and regulation of the transfer of energy between the exoskeleton and the user. Its goal is improving the dynamic response of the human limbs without sacrificing the user’s control authority. The proposed method is an alternative to myoelectrical exoskeleton control, which is based on estimating muscle torques from electromyographical (EMG) activity. Implementation of an EMG-based controller is a complex task that involves modeling the user’s musculoskeletal system and requires recalibration. In contrast, active impedance control is less dependent on estimation of the user’s attempted motion, thereby avoiding conflicts resulting from inaccurate estimation. In this paper we also introduce a new form of human assist based on improving the kinematic response of the limbs. Reduction of average muscle torques is a common goal of research in human assist. However, less emphasis has been placed so far on improving the user’s agility of motion. We aim to use active impedance control to attain such effects as increasing the user’s average speed of motion, and improving their acceleration capabilities in order to compensate for perturbations from the environment.

(далее…)

Категория: Научные статьи | Нет комментариев »

Robotic gait training is an emerging technique for retraining walking ability following spinal cord injury (SCI). A key challenge in this training is determining an appropriate stepping trajectory and level of assistance for each patient, since patients have a wide range of sizes and impairment levels. Here, we demonstrate how a lightweight yet powerful robot can record subject- specific, trainer-induced leg trajectories during manually assisted stepping, then immediately replay those trajectories. Replay of the subject-specific trajectories reduced the effort required by the trainer during manual assistance, yet still generated similar patterns of muscle activation for six subjects with a chronic SCI. We also demonstrate how the impedance of the robot can be adjusted on a step-by-step basis with an error-based, learning law. This impedance-shaping algorithm adapted the robot’s impedance so that the robot assisted only in the regions of the step trajectory where the subject consistently exhibited errors. The result was that the subjects stepped with greater variability, while still maintaining a physiologic gait pattern. These results are further steps toward tailoring robotic gait training to the needs of individual patients.

(далее…)

Категория: Научные статьи | Нет комментариев »