Functional electrical stimulation (FES) can be used as a neuroprosthesis in which muscles are stimulated by electrical pulses to compensate for the loss of voluntary movement control. Modulating the stimulation intensities to reliably generate movements is a challenging control problem. This paper introduces a feedback controller for a multi-muscle FES system to control hand movements in a 2-D (table-top) task space. This feedback controller is based on a recent human motor control model, which uses muscle synergies to simplify its calculations and improve the performance. This synergy-based controller employs direct relations between the muscle synergies and the produced hand force, therefore allowing for the real-time calculation of six muscle stimulation levels required to reach an arbitrary target. The experimental results show that this control scheme can perform arbitrary point-to-point reaching tasks in the 2-D task space in real time, with an average of ~2 cm final hand position error from the specified targets. The success of this prototype demonstrates the potential of the proposed method for the feedback control of functional tasks with FES.

This article introduces a trajectory planning approach for the catching of projectiles with a serial robotic manipulator. A description of the trajectory of the projectiles to be caught is first given. Then, a heuristic approach is introduced in order to determine the interception (catching) point. The planning of the robot trajectory that is required to reach the interception point with the proper velocity is then presented, based on polynomial interpolation. Finally, the trajectory of the robot used to decelerate and stop the projectile is planned. Examples of catching maneuvers are provided in order to illustrate the proposed trajectory planning technique.

In interferometry, reaching a high signal-to-noise ratio at low frequencies can be challenging when the additive noise is nonstationary. Although this problem is typically solved by inserting a frequency shifter into one of the arms, in some cases, the interferometer cannot or should not be modified in this way. This Letter presents an alternative solution, based on external serrodyne frequency modulation, which is comparable to the typical approach in terms of complexity and performance yet does not require the modification of a passive interferometer. We demonstrate a prototype that achieves frequency shifting at 500 kHz with 89% power efficiency, leading to the wideband suppression of low-frequency additive noise by more than 19 dB. This enables a fully passive measurement of the thermoconductive noise of a 100 m single-mode fiber.

Based on the cat-righting reflex, this paper presents two reorientation maneuvers for legged robots that can produce roll and pitch reorientation during free fall. In order to better describe and plan these maneuvers, two separate, but equivalent, theoretical frameworks that describe the kinematic and dynamic behavior of free-floating articulated architectures are explored and developed. A nine-degree-of-freedom quadruped robot architecture is then presented and used to demonstrate the proposed maneuvers. Finally, kinematic and dynamic simulations of this architecture are performed. The results validate the presented theoretical framework and demonstrate that both roll and pitch reorientations are obtained through the application of the presented maneuvers.

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