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This paper proposes a robust control scheme based on a disturbance observer (DOB) for flexible joint robots. In this paper, the DOB is applied only on the motor-side dynamics of the robot, and the uncertainties on the motor-side are successfully eliminated. It is shown that, to guarantee the stability, the estimated motor-side position should be fed back… (More)
This paper proposes a robust PD control scheme for flexible-joint robots based on a disturbance observer (DOB). In this paper, the DOB is applied only to the motor-side dynamics of the robot, and the uncertainties on the motor-side are successfully eliminated. It is shown that the proposed DOB-based approach guarantees global asymptotic stability. To this… (More)
Robustness is a very classical issue in the robotics field. Disturbance observer (DOB) can be a good choice to improve the robustness of the system. It is easy to implement and shows successful results. DOB, however, cannot bring nonlinearity of the system into the formulation. To overcome this problem, nonlinear robust internal loop compensator (NRIC) is… (More)
In this paper, an advanced preoperative planning framework for spinal fusion is presented. The framework is based on spinal pedicle data obtained from computed tomography (CT) images, and provides optimal insertion trajectories and pedicle screw sizes. The proposed approach begins with a safety margin estimation for each potential insertion trajectory that… (More)
Network synchronization is important to time-sensitive applications. Legacy NTP provides the base time to other network devices. Time accuracy gets lower as the stratum goes down, due to jitter/wander. To solve this problem, IEEE 1588 PTP and IEEE 802.1AS were developed. These technologies, however, have problems with too many messages being generated.… (More)
This paper proposes a passivity-based nonlinear disturbance observer (DOB) design for a powered upper-limb robot control. The proposed DOB allows for the nonlinearities of the robot dynamics, whereas the typical DOB designs cannot. Moreover, by virtue of the passivity property, human operator and environmental interactions can be embedded in the control… (More)
This paper demonstrates DOB-based PD+gravity compensation control for flexible joint robots (FJRs). By virtue of the DOB, the controller can recover global asymptotic stability under the friction. One important difference from the typical DOB implementation is that the nominal signal feedback is required, instead of the real (measured) signal feedback.