Neural networks enhanced adaptive admittance control of optimized robot-environment interaction

In this paper, an admittance adaptation method has been developed for robots to interact with unknown environments. The environment to be interacted with is modeled as a linear system. In the presence of the unknown dynamics of environments, an observer in robot joint space is employed to estimate the interaction torque, and admittance control is adopted to regulate the robot behavior at interaction points. An adaptive neural controller using the radial basis function is employed to guarantee trajectory tracking. A cost function that defines the interaction performance of torque regulation and trajectory tracking is minimized by admittance adaptation. To verify the proposed method, simulation studies on a robot manipulator are conducted

Experimental study of contact transition control incorporating joint acceleration feedback

Joint acceleration and velocity feedbacks are incorporated into a classical internal force control of a robot in contact with the environment. This is intended to achieve a robust contact transition and force tracking performance for varying unknown environments, without any need of adjusting the controller parameters, A unified control structure is proposed for free motion, contact transition, and constrained motion in view of the consumption of the initial kinetic energy generated by a nonzero impact velocity. The influence of the velocity and acceleration feedbacks, which are introduced especially for suppressing the transition oscillation, on the postcontact tracking performance is discussed. Extensive experiments are conducted on the third joint of a three-link direct-drive robot to verify the proposed scheme for environments of various stiffnesses, including elastic (sponge), less elastic (cardboard), and hard (steel plate) surfaces. Results are compared with those obtained by the transition control scheme without the acceleration feedback. The ability of the proposed control scheme in resisting the force disturbance during the postcontact period is also experimentally investigated

Aerospace Medicine and Biology: A continuing bibliography, supplement 216

One hundred twenty reports, articles, and other documents introduced into the NASA scientific and technical information system in January 1981 are listed. Topics include: sanitary problems; pharmacology; toxicology; safety and survival; life support systems; exobiology; and personnel factors

Advanced tracking and data relay experiments study: Multimode transponder experiment equipment

Plans and implementation concepts were developed for a series of experiments utilizing a Multimode Transponder mounted in an aircraft working either through a spacecraft or directly with a ground station which would simulate a TDRSS user working through the TDRSS. The purpose of the experiments is to determine the best modulation and encoding techniques for combating RFI in discreet bands. The experiments also determine the feasibility and accuracy of range and range rate measurements with the various modulation and encoding techniques. An analysis of the Multimode Transponder and ground support equipment is presented, and the additional equipment required to perform the experiments described above is determined

A-10/TF34 Turbine Engine Monitoring System (TEMS)

The hardware and software development of the A-10/TF34 turbine engine monitoring system (TEMS) is described. The operation and interfaces of the A-10/TF34 TEMS hardware are discussed with particular emphasis on function, capabilities, and limitations. The TEMS data types are defined and the various data acquisition modes are explained. Potential data products are also discussed

Utilization Of B-Mode Ultrasound As A Body Fat Estimate In Collegiate Football Players

The purpose of the present study was to validate a 7-site ultrasound imaging protocol to predict percent body fat (%BF) in a Division I football team. Body composition was estimated by ultrasound, seven site skinfolds (SKINFOLD), and the three compartment-water (3C-W) model of Siri (1961), using Bioimpedance spectroscopy (BIS) to estimate total body water (TBW) and air-displacement plethysmography (BODPOD®) to determine body density (Db). Pearson’s product-moment correlation analyses were run to determine between ΣUltrasound and the criterion 3C-W, and between the ΣSkinfold and ΣUltrasound. Strong positive correlations were observed between ΣSkinfold and ΣUltrasound (r=.984; pUltrasound and %BF from 3C-W (r=0.878, pUltrasound, (%BF= 6.194+(.096* ΣUltrasound); standard error of the estimate [SEE]=2.97%). Cross validation analyses were performed using an independent sample of 29 players. Mean observed %BF and mean predicted %BF were 18.32 ± 6.26% and 18.78 ± 6.22%, respectively. The constant error (CE), SEE and validity coefficient (r) were 0.004%, 2.64%, and 0.91, respectively. The total error (TEE) was 2.87%. Conclusion: The positive relationship between ultrasound measurements and the 3C-W model suggests the B-mode ultrasound may be a practical alternative of predicting %BF in Division I football players

Control of master-slave actuation systems for MRI/FMRI compatible haptic interfaces

Master'sMASTER OF ENGINEERIN

Inductive position/velocity sensor design and servo control of linear motor

Thesis (M.S.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 1995.Includes bibliographical references (p. 133-136).by Francis Yee-Hon Wong.M.S

Explicit adaptive time-delay compensation for bilateral teleoperation

This paper proposes a control framework that addresses the destabilizing effect of communication time-delays and system uncertainties in telerobotics, in the presence of force-feedback. Force feedback is necessary to obtain transparency, which is providing the human operator as close a feel as possible of the environment where the slave robot is operating. Achieving stability and providing transparency are conflicting goals. This is the major reason why currently a very few, if at all, fully operational force feedback teleoperation devices exist except for research environments. The proposed framework handles system uncertainty with adaptation and communication time delays with explicit delay compensation. The technology that allows this explicit adaptive time-delay compensation is inspired by MIT's Adaptive Posicast Controller. © 2015 IEEE