Humans can precisely sense the position, speed, and torque of their body parts. This sense is known as proprioception and is essential to human motor control. Although there have been many attempts to create humanmechatronic interactions, there is still no robust, repeatable methodology to reflect proprioceptive information from a synthetic device onto the nervous system. To address this shortcoming, we present an agonist-antagonist myoneural interface (AMI). The AMI is composed of (i) a surgical construct made up of two muscle-tendons-an agonist and an antagonist-surgically connected in series so that contraction of one muscle stretches the other and (ii) a bidirectional efferent-afferent neural control architecture. The AMI preserves the dynamic muscle relationships that exist within native anatomy, thereby allowing proprioceptive signals from mechanoreceptors within both muscles to be communicated to the central nervous system. We surgically constructed two AMIs within the residual limb of a subject with a transtibial amputation. Each AMI sends control signals to one joint of a two-degreeof-freedom ankle-foot prosthesis and provides proprioceptive information pertaining to the movement of that joint. The AMI subject displayed improved control over the prosthesis compared to a group of four subjects having traditional amputation. We also show natural reflexive behaviors during stair ambulation in the AMI subject that do not appear in the cohort of subjects with traditional amputation. In addition, we demonstrate a system for closed-loop joint torque control in AMI subjects. These results provide a framework for integrating bionic systems with human physiology.

Biomechanical tissue properties have been hypothesized to play a critical role in the quantification of prosthetic socket production for individuals with limb amputation. In this investigation, a novel indenter platform is presented and its performance evaluated for the purposes of residual-limb tissue characterization. The indenter comprised 14 position- and force-controllable actuators that circumferentially surround a biological residuum to form an actuator ring. Each indenter actuator was individually controllable in position ( [Formula: see text] accuracy) and force (330 mN accuracy) at a PC controller feedback rate of 500 Hz, allowing for a range of measurement across a residual stump. Data were collected from 162 sensors over an EtherCAT fieldbus to characterize the mechanical hyperviscoelastic tissue response of two transtibial residual-limbs from a study participant with bilateral amputations. At five distinct anatomical locations across the residual-limb, force versus deflection data-including hyperviscoelastic tissue properties-are presented, demonstrating the accuracy and versatility of the multi-indenter platform for residual-limb tissue characterization.

The work of this thesis aims to enable the fast prototyping of multi-axis wearable robotic systems by developing a new modular electronics system. The flexible, scalable electronics architecture (FlexSEA) developed for this thesis fills the void between embedded systems used in commercial devices and in research prototypes. This system provides the required hardware and software for precise motion control, data acquisition, and networking. Scalability is obtained through the use of fast industrial communication protocols between the modules, and the standardization of the peripheral interfaces. Hardware and software encapsulation is used to provide highperformance, real-time control of the actuators while keeping the high-level control development fast, safe and simple.The FlexSEA kits are composed of two custom circuit boards (advanced brushless motor driver and microcontroller board), one commercial embedded computer, a complete software stack and documentation. During its development it has been integrated into a powered prosthetic knee as well as an autonomous ankle exoskeleton. To assess the usability of the FlexSEA kit, a new user successfully used a kit to read sensors and control an output device in less than three hours. FlexSEA simplifies and accelerates wearable robotics prototyping.

We present an actuator designed for untethered, lower-extremity powered-prostheses that replicates biological kinetic and kinematic function of both human knees and ankles. An electric energy optimal hardware specification is defined by kinematically clamping walking gait data to the dynamic model of a series elastic actuator (SEA) and searching for motor, reduction ratio, and spring. The actuator is shown to achieve the required torque, angle, and velocity requirements for nominal walking conditions on level ground as well as varied terrain. The performance of the actuator is demonstrated on benchtop and as worn by a human subject with unilateral below knee amputation. The resulting design is a moment-coupled cantileverbeam reaction-force SEA (MC-RFSEA) that has a nominal torque rating of 85Nm, repeated peak torque of 175Nm, 105 o range of motion, and a hardware mass of 1.6kg. Preliminary results from level-ground walking with the actuator tested in an ankle configuration show an electric cost of transport of 0.053J/kg when walking at 1.5m/s.

Wearable robots, such as powered prostheses and active exoskeletons, often rely on electric motors for actuation. Emulating biological joint angle and torque profiles requires special sensors, high peak power and advanced real-time controls. Safety is paramount and fail-safe circuits are required to detect and correct problematic situations. A smaller, lighter circuit can lead to a more efficient and affordable robot. Few commercial motor drivers accommodate all of these requirements. In this paper we present FlexSEA-Execute (Figure 1), the advanced motion controller part of FlexSEA, the FLEXible, Scalable Electronics Architecture designed for wearable robotic applications. At 36cm³ and 34.8g, this PSoCbased design integrates a 8A/25A (continuous/pulse) brushed/brushless motor driver, a safety co-processor, multidrop RS-485, a strain gauge amplifier, a 6-axis inertial motion unit (IMU), USB, and a programmable expansion connector.