Joint torque servo of a high friction robot manipulator based on time-delay control with feed-forward friction compensation

Hur, Sung-moon; Kim, Sung-Kyun; Oh, Yonghwan; Oh, Sang-Rok

doi:10.1109/roman.2012.6343728

Cited by 8 publications

(3 citation statements)

References 8 publications

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“…In torque controlled motors however, less complicated models are considered such as hyperbolic tangent [21] or Coulomb-viscous [18]. In general, since the desired direction of motion is unknown in a torque controller, it is not easy to compensate the Coulomb friction.…”

Section: Torque Trackingmentioning

confidence: 99%

“…Although the optimized set of parameters better describe the data, the difference is still considerable in Fig.2. Unlike using the trained parameters [21], we try to estimate the friction based on the torque measurements. knowing the voltage applied in the previous time-step v − and the resulting motor velocitẏ θ , motor accelerationθ and the output torque τ out , we can estimate the friction by:…”

Section: B Control Lawmentioning

confidence: 99%

See 1 more Smart Citation

Practical considerations in using inverse dynamics on a humanoid robot: Torque tracking, sensor fusion and Cartesian control laws

Faraji

Colasanto

Ijspeert

2015

2015 IEEE/RSJ International Conference on Intelligent Robots and Systems (IROS)

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Abstract-Although considering dynamics in the control of humanoid robots can improve tracking and compliance in agile tasks, it requires local and global states of the system, precise torque control and proper modeling. In this paper we discuss practical issues to implement inverse dynamics on a torque controlled robot. By modeling electrical actuators offline, inverting such model and estimating the friction on-line, a high bandwidth torque controller is implemented. In addition, a cascade of optimization problems to fuse all the sensory data coming from IMU, joint encoders and contact force sensors estimate the robot's global state robustly. Our estimation builds the kinematic chain of the legs from the center of pressure which is more robust in case of slight slippage, tilting or rolling of the feet. Thanks to precise and fast torque control, robust state estimation and optimization-based whole body inverse dynamics, the real robot can keep balance with very small stiffness and damping in Cartesian space. It can also recover from strong pushes and perform dexterous tasks. The highly compliant and stable performance is based on pure torque control, without any joint damping or position/velocity tracking.

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Section: Torque Trackingmentioning

confidence: 99%

Section: B Control Lawmentioning

confidence: 99%

Practical considerations in using inverse dynamics on a humanoid robot: Torque tracking, sensor fusion and Cartesian control laws

Faraji

Colasanto

Ijspeert

2015

2015 IEEE/RSJ International Conference on Intelligent Robots and Systems (IROS)

View full text Add to dashboard Cite

show abstract

“…However, the joint friction was not considered explicitly in the analysis of robot dynamics and the controller design. In Hur et al (2012), a time-delay control (TDC) method was used to control the joint torque and overcome high friction and other unknown disturbances without considering joint flexibility produced by the harmonic reducer. TDC does not require a full analytical description of the robot dynamics, while information about higher order derivatives of the output signals is necessary for this controller.…”

Section: Introductionmentioning

confidence: 99%

Impedance control of collaborative robots based on joint torque servo with active disturbance rejection

Ren

Dong

et al. 2019

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Purpose The purpose of this paper is to present a simple yet effective force control scheme for collaborative robots by addressing the problem of disturbance rejection in joint torque: inherent actuator flexibility and nonlinear friction. Design/methodology/approach In this paper, a joint torque controller with an extended state observer is used to decouple the joint actuators from the multi-rigid-body system of a constrained robot and compensate the motor friction. Moreover, to realize robot force control, the authors embed this controller into the impedance control framework. Findings Results have been given in simulations and experiments in which the proposed joint torque controller with an extended state observer can effectively estimate and compensate the total disturbance. The overall control framework is analytically proved to be stable, and further it is validated in experiments with a robot testbed. Practical implications With the proposed robot force controller, the robot is able to change its stiffness in real time and therefore take variable tasks without any accessories, such as the RCC or 6-DOF F/T sensor. In addition, programing by demonstration can be realized easily within the proposed framework, which makes the robot accessible to unprofessional users. Originality/value The main contribution of the presented work is the design of a model-free robot force controller with the ability to reject torque disturbances from robot-actuator coupling effect and motor friction, applicable for both constrained and unconstrained environments. Simulation and experiment results from a 7-DOF robot are given to show the effectiveness and robustness of the proposed controller.

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Contact force detection and control for robotic polishing based on joint torque sensors

Dong

Ren

et al. 2020

Int J Adv Manuf Technol

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Joint torque servo of a high friction robot manipulator based on time-delay control with feed-forward friction compensation

Cited by 8 publications

References 8 publications

Practical considerations in using inverse dynamics on a humanoid robot: Torque tracking, sensor fusion and Cartesian control laws

Practical considerations in using inverse dynamics on a humanoid robot: Torque tracking, sensor fusion and Cartesian control laws

Impedance control of collaborative robots based on joint torque servo with active disturbance rejection

Contact force detection and control for robotic polishing based on joint torque sensors

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