Control of bilateral teleoperators with time delays using only position measurements

Abstract

Summary A major drawback in the control of bilateral teleoperators is time delays. The nature of the communication channel that interconnects the local and the remote manipulators imposes these delays, which can be time‐varying. Several commercially available robots do not incorporate velocity sensors, and velocities are usually estimated using dirty derivatives. In this paper, we are interested in the control of bilateral teleoperators with variable time delays and without requiring velocity measurements. The proposal makes use of a second‐order dynamical controller that backpropagates damping to the local and the remote manipulators. If sufficient damping is injected in the controller and under the common passivity assumption of the human operator and the environment, it is proved that position errors and velocities are bounded. Invoking Barbalat's lemma, when the human and the environment do not inject forces in the system, it is shown that position error and velocities globally asymptotically converge to zero. A simulation comparison with other two control techniques shows the performance of the novel proposal. Experimental results evidence the robustness of the proposed scheme to interconnecting time delays.

Sliding Mode Observer-based Control of Teleoperation System With Uncertain Dynamics and Kinematics

“…Theorem 2 Consider the teleoperation system described by dynamics ( 9), (10) and kinematics (11) without external forces, employing the estimation laws (18) and sliding-mode observers (46), with the application of the controllers (51), the dynamic uncertainties and kinematic uncertainties can be tackled within finite time. Further, the task-space position tracking errors between the local manipulator and remote manipulator will asymptotically stabilized.…”

“…Many remarkable results have been obtained for control of teleoperation system [8][9][10][11][12][13][14][15][16]. The passivity-based control innovatively proposed in [8] has been the cornerstone of the teleoperation system control, which is further developed in [9] to address the problem of steadystate position as well as force tracking.…”

“…In [10], position tracking is addressed for teleoperators with a simple PD-like and a scattering-based controller. In an attempt to realize position tracking of bilateral teleoperators with communication delays and without measuring velocity, a second-order dynamical controller is proposed in [11]. In these works, control strategies are usually developed for joint position coordination.…”

Task-Space Bilateral Control of Teleoperators with Time-Varying Delay

“…The technical challenge of realizing this objective is mainly due to the closed architecture of the robots (i.e., no torque design interface is available and typically only the joint velocity or position command can be specified) and due to the typically employed proportional-derivative (PD) or proportional-integral-derivative (PID) control action of the inner control loop with unknown gains. This challenge also renders most existing results developed in the context of an open torque design interface (e.g., [1], [20], [12], [13], [14], [21], [15], [22], [23]) no longer applicable. The involved challenge for bilateral control of teleoperators subjected to closed architecture may be alleviated via measuring interaction force/torque using force/torque sensors mounted on the endeffector, which can, however, only achieve partial force/torque reflection [the reflection of partial interaction force/torque (e.g., that associated with the end-effector) can be guaranteed since it relies on the direct measurement of the interaction via force/torque sensors].…”

Resultados experimentales del control de un sistema de teleoperación bilateral de robots con retardos variantes en el tiempo

“…Sin embargo, para que este funcione, es necesario conocer el modelo del sistema por completo, lo que dificulta su implementación. Como alternativa, enNuño et al (2018) se propone una solución que no requiere el modelo del sistema por completo, basta con el conocimiento del vector de gravedad de cada manipulador para garantizar el consenso. Como se puede ver, por un lado se tiene la dependencia del modelo en algunos esquemas, y por otro lado no se cuenta con mediciones de velocidad, así que con base en estos problemas abiertos, en Arteaga-Pérez et al (2017) se propone un esquema de observación y de control diseñado en conjunto, el cual está basado en técnicas de modos deslizantes de segundo orden permitiendo garantizar que los errores de posición no sólo permanezcan acotados sino que además, con un conjunto adecuado de ganancias se logre hacer estos errores arbitrariamente pequeños para el caso de movimiento libre, resolviendo así el problema de consenso.…”