Xiangrong Shen

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This paper presents a control methodology that enables nonlinear model-based control of pulse width modulated (PWM) pneumatic servo actuators. An averaging approach is developed to describe the equivalent continuous-time dynamics of a PWM controlled nonlinear system, which renders the system, originally discontinuous and possibly nonaffine in the input,(More)
Proper traffic control is critical in highway work zone safety. Traffic control devices such as signs, barricades, cones, and safety barrels are used. Automated safety devices could improve work zone design and housekeeping and therefore increase safety. This thesis presents a mobile safety barrel robot. The robotic safety barrels can self-deploy and(More)
This paper presents the design of a gas-actuated anthropomorphic arm prosthesis with 21 degrees of freedom and nine independent actuators. The prosthesis utilizes the monopropellant hydrogen peroxide as a gas generator to power nine pneumatic type actuators. Of the nine independent actuators, one provides direct- drive actuation of the elbow, three provide(More)
This paper presents a control methodology that enables nonlinear model based sliding mode control of PWMcontrolled pneumatic servo actuators. An averaging approach is developed to describe the equivalent continuous-time dynamics of a PWM controlled nonlinear system, which renders the originally discontinuous system, possibly non-affine in the input, into an(More)
The stable simulation of high-stiffness surfaces remains a challenge in impedance-type haptic simulations of mechanical environments. In this paper, the authors propose an approach to achieving a stable, high-stiffness surface in a haptic interface by leveraging the open-loop properties of pneumatic actuators. By using the open-loop component of the(More)
This paper proposes a control approach that controls the stiffness and force of pneumatic actuator independently. This independent control of stiffness and force removes a primary cause of contact instability when utilizing stiffness or impedance based force control during interaction with stiff environments. Specifically, in typical stiffness or impedance(More)
The presence of an intonational phrase boundary is often marked by three major acoustic cues: pause, final lengthening, and pitch reset. The present study investigates how these three acoustic cues are weighted in the perception of intonational phrase boundaries in two experiments. Sentences that contained two intonational phrases with a critical boundary(More)
A powered lower extremity orthotic brace can potentially be used to assist frail elderly during daily activities. This paper presents a method for an early detection of the initiation of sit-to-stand (SiSt) posture transition that can be used in the control of the powered orthosis. Unlike the methods used in prosthetic devices that rely on surface(More)