This study reports the initial testing of a gait exoskeleton for Spinal Muscular Atrophy (SMA) patients having variable muscle strength with no balance or ambulation capabilities. To improve the quality of life of such patients, a pediatric gait exoskeleton was developed. The ATLAS exoskeleton has 8 active degrees of freedom (DOF): 2 at the hip (adduction/abduction and flexion/extension), 1 at the knee and ankle joint for flexion and extension. A feasibility test was performed to gauge the initial response of the patients. This study demonstrates that the exoskeleton was able to provide gait assistance and sit-to-stand movements effectively to the subjects. This kind of wearable exoskeleton will play a key role in the rehabilitation of SMA patients and delay further metabolic degeneration in the future.

Many robotics applications require contact with the environment, from traditional pick and place task to legged locomotion. Nevertheless, to increase adaptability to different terrains it is necessary to know its contact properties. These properties can be known beforehand or extracted from contact forces. In this paper a practical evaluation using adaptive filtering techniques to extract the properties from different environmental conditions, with the intention to increase the adaptability of the robot to different environments is presented. We use the well-known linear spring-dashpot model and fit its parameters to four different materials in order to establish which of the reviewed methods (the recursive and windowed least squares algorithms) perform better to describe the material properties. The results show that the recursive least squares provide better tracking performance while the windowed least squares gives a smoother response.

The application of impedance control strategies to modern legged locomotion is analyzed, paying special attention to the concepts behind its implementation which is not straightforward. In order to implement a functional impedance controller for a walking mechanism, the concepts of contact, impact, friction, and impedance have to be merged together. A literature review and a comprehensive analysis are presented compiling all these concepts along with a discussion on position-based versus force-based impedance control approaches, and a theoretical model of a robotic leg in contact with its environment is introduced. A theoretical control scheme for the legs of a general legged robot is also introduced, and some simulations results are presented.

Research on legged locomotion has encountered its limits in human-made actuation technology. Building a structure and an actuation system capable of performing like a biological muscle for the dynamic locomotion of a mid- to large-sized machine is prohibitive. Novel technologies are being explored with the aim of improving actuator performance. This paper describes the development of a robotic leg for agile locomotion. The main aim is to imitate the multidisciplinary performance of the natural muscle by means of hybridizing conventional and new technologies for the development of large power, large force, lightweight, force-controlled, compliant robotic legs. A preliminary leg prototype has been developed. The actuation system is based on the hybrid use of series elasticity and magneto-rheological dampers which provides variable compliance for natural-looking motion and improved interaction with the ground. Experiments with the real leg prototype provide a positive assessment of the target leg features.

It is a widespread idea that animal-legged locomotion is better than wheeled locomotion on natural rough terrain. However, the use of legs as a locomotion system for vehicles and robots still has a long way to go before it can compete with wheels and trucks, even on natural ground. This paper aims to solve two main disadvantages plaguing walking robots: their inability to react to external disturbances (which is also a drawback of wheeled robots); and their extreme slowness. Both problems are reduced here by combining: 1) a gait-parameter-adaptation method that maximizes a dynamic energy stability margin and 2) an active-compliance controller with a new term that compensates for stability variations, thus helping the robot react stably in the face of disturbances. As a result, the combined gait-adaptation approach helps the robot achieve faster, more stable compliant motions than conventional controllers. Experiments performed with the SILO4 quadruped robot show a relevant improvement in the walking gait.

Walking-robot technology has reached an advanced stage of development, as has already been demonstrated by a number of real applications. However, further improvement is still needed if walking robots are to compete with traditional vehicles. Some potential improvements could be gained through optimization. Thus, this paper presents a method for distributing the legs around the robot’s body such as to reduce the forces the legs must exert to support and propel the robot. The method finds through non-linear optimization techniques the middle leg displacement that nulls the difference between foot forces in a middle leg and a corner leg. A walking robot has been built to assess the theoretical results.

The study of molecular interactions in biological fluids is important as a research tool to elucidate molecular and biological function, for discovering or designing molecules that have a desirable function, and for measuring or detecting analytes for clinical diagnostic purposes. Microfluidics is an emerging technology that has proven useful for studying and controlling molecular interactions with the potential advantages of reduced sample and reagent volumes, short reaction times, portable instrumentation, and high throughput. At microscale dimensions, diffusive transport of many biologically relevant molecules can cover large fractions of a fluid channel in a short time (seconds to minutes). We have exploited this feature to analyze molecular interactions based on changes in the diffusive transport of one of the reacting components. Here, we present a new assay configuration for studying molecular binding interactions and report new developments in the fabrication and use of hydrogels for diffusion-based analysis. We also overview system configurations and analysis techniques that have proven useful for studying molecular interactions of biological analytes and discuss their ability to operate using complex fluids such as blood.