This paper leverages phased array techniques to determine the positions of multiple reflectors in 3-D space using ultrasonic sensing. The design of a low-cost sensor, consisting of a single narrowband ultrasonic transducer and a receiver array consisting of a small number of MEMS microphones, is discussed. Aspects of system design related to the sensor, analog signal chain, and digital processing are presented. A processing algorithm is described to simultaneously determine the 3-D positions of all the reflectors present in the sensor’s workspace. Further, the processing algorithm is implemented on a low-cost microcontroller and requires low memory resources (64-70 kilobytes). Experiments demonstrate the performance achieved and the detection of multiple objects in the sensor’s workspace. A computation cost analysis is performed exhibiting the rapid execution of the algorithm. High processing throughput (20-45 Hz) is achieved making the sensor suitable for applications such as workspace mapping and the tracking of multiple reflectors.

This paper leverages machine learning principles in combination with an exploratory procedure to estimate the unknown stiffness of a grasped object in a single degree of freedom gripper mechanism. The object stiffness is estimated using regression; sensor measurements of actuator position and actuator current are the regressor inputs, and object stiffness is the regressor output. The proposed approach reduces overall system complexity and cost compared to systems that use tactile sensors to estimate object stiffness. Several datasets are generated using a physics-based simulation model of the system. Regressors are trained on data produced by the simulation model, and their performance is analyzed under variations on simulation model parameters including stick-slip friction parameters; the influence of the actuation command signal used to direct the exploratory procedure is also considered. These regressors are then experimentally evaluated on a representative single degree of freedom mechanism, demonstrating worst-case stiffness estimation errors (based on datasheet spring stiffness values) of 3.4%.

Flexural Ultrasonic Transducers (FUTs) exhibit sustained residual vibrations after their excitation has ceased. This results in a long decaying tail in the FUT’s terminal voltage affecting the Time of Flight estimation and ranging capability for reflectors situated near the FUT. Time optimal control principles are applied to design the excitations to accelerate damping, improve ToF estimation, and improve ranging near the FUT without compromise in the strength of the transmitted pressure wave. Numerical solutions for the control problem are obtained using Nonlinear Programming. An algorithm is described to operate Pulse Width Modulation peripherals found on commercial off-the-shelf microcontroller units to realize the excitation signals at the output of H-Bridge modules. Experimental results show an improvement of 15% in the minimum range with the designed time optimal excitations.

Many single-axis motion systems are driven by electric machines equipped with torque-regulating power converters, and the operation of such systems is often commanded using some type of speed controller. The design of the speed controller involves choosing both the reference command shapes and the signal flow architecture. This paper provides a solution to the problem of speed controller design where the goal is to minimize the electric energy required to transition from one speed to another, for both acceleration and deceleration; this topic is inspired by applications that involve frequently occurring speed transitions. Explicit formulas are derived that characterize the energy minimizing transition time, and the corresponding torque and speed trajectories, and these trajectories are fed as reference commands into a controller architecture that incorporates both feedback and feedforward actions. For comparison, results are also derived for the case in which torque is constrained to be constant throughout the speed transition interval.

The purpose of this paper is to present the required tools for the development, testing and verification of DSP software in Matlab. The paper motivates a DSP Simulator concept that can be combined with the MATLAB executable interface to develop, evaluate and test DSP software within a single environment. Programming guidelines and optimization results are also provided to demonstrate the effectiveness of the intrinsics software development approach.

During the 1995 DOE Robotics Forum at Albuquerque, New Mexico, Georgia Tech's Intelligent Machine Dynamics Laboratory demonstrated remote display capabilities of its telemanipulated long-reach manipulator testbed through the Internet. This paper describes the testbed and addresses the methods, limitations, and capabilities of remote operations.

This work investigates issues related to vibration control in a micro/macro manipulator. This paper provides experimental results obtained by the combination of two dissimilar flexible control techniques to a micro/macro flexible link testbed. Inertial damping and command filtering techniques are implemented simultaneously to form a robust controller that results in minimal residual vibration due to commanded movements or external excitations. Experimental results show the effectiveness of both control techniques in their individual state as well as the improved performance resulting from their combination. The experimental results of the combined controller clearly show the advantages of each technique.

We focus on the fusion of autonomous and teleoperated commands. This combination provides full use of the robot's workspace without requiring large motion amplification between a master and slave robot. Combining autonomous and teleoperated commands provides the potential for large variations in the commanded momentum of the flexible robot. These variations excite the lightly damped, low resonant frequencies associated with these manipulators. Two techniques are proposed to reduce the vibration during sudden stops in the commanded motion of a flexible manipulator. First a new command filtering approach that permits shorter delay times than standard input shaping methods is presented. Next, we propose dynamic alteration of the desired trajectory. Our investigation shows that filtering techniques exhibit an oscillatory response, more so than standard PD control algorithms, during hard stopping conditions. However the shorter time delay filtering algorithm has less vibration than standard input shaping techniques. Furthermore, any vibration may be eliminated by commanding the robot to decelerate instead of immediately stopping the motion.