Robot impedance control and passivity analysis with inner torque and velocity feedback loops

Focchi, Michele; Medrano-Cerda, Gustavo A.; Boaventura, Thiago; Frigerio, Marco; Semini, Claudio; Buchli, Jonas; Caldwell, Darwin G.

doi:10.1007/s11768-016-5015-z

Cited by 62 publications

(42 citation statements)

References 33 publications

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“…(1) where the parameter definitions are given in Table III. This model is very similar to the one found in [21]. In practice we found out on HRP-2 that most of the problems arised from: power limitation (P = V i a ), temperature overheating, limitation in torques from the motor (τ m ) or the HD (τ ts ).…”

Section: Actuatorssupporting

confidence: 76%

TALOS: A new humanoid research platform targeted for industrial applications

Stasse

Flayols

Budhiraja

et al. 2017

2017 IEEE-RAS 17th International Conference on Humanoid Robotics (Humanoids)

132

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Abstract-The upcoming generation of humanoid robots will have to be equipped with state-of-the-art technical features along with high industrial quality, but they should also offer the prospect of effective physical human interaction. In this paper we introduce a new humanoid robot capable of interacting with a human environment and targeting industrial applications. Limitations are outlined and used together with the feedback from the DARPA Robotics Challenge, and other teams leading the field in creating new humanoid robots. The resulting robot is able to handle weights of 6 kg with an out-stretched arm, and has powerful motors to carry out fast movements. Its kinematics have been specially designed for screwing and drilling motions. In order to make interaction with human operators possible, this robot is equipped with torque sensors to measure joint effort and high resolution encoders to measure both motor and joint positions.The humanoid robotics field has reached a stage where robustness and repeatability is the next watershed. We believe that this robot has the potential to become a powerful tool for the research community to successfully navigate this turning point, as the humanoid robot HRP-2 was in its own time.

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Section: Actuatorssupporting

confidence: 76%

TALOS: A new humanoid research platform targeted for industrial applications

Stasse

Flayols

Budhiraja

et al. 2017

2017 IEEE-RAS 17th International Conference on Humanoid Robotics (Humanoids)

132

View full text Add to dashboard Cite

show abstract

“…2. Similar to [8,25,27], we implement a cascaded joint impedance controller with an inner force loop to track desired torque, position, and velocity setpoints. Using the THOR dual-axis motor controller, we are able to achieve distributed control of 2 DOF joints with parallel or serial actuation at sample rates of 2 kHz.…”

Section: B Electrical Designmentioning

confidence: 99%

“…Joint-space stiffness and damping can be used to improve performance in the presence of unmodeled dynamics [13,14]. Several authors have proposed cascade controller architectures featuring an outer impedance loop that introduces joint position and velocity feedback into the inner force or torque loop [8,19,[23][24][25][26][27]. The stability margins of the joint impedance loop can be affected by factors including communication delay, derivative filtering, and selection of inner loop gains [27].…”

Section: Introductionmentioning

confidence: 99%

“…Several authors have proposed cascade controller architectures featuring an outer impedance loop that introduces joint position and velocity feedback into the inner force or torque loop [8,19,[23][24][25][26][27]. The stability margins of the joint impedance loop can be affected by factors including communication delay, derivative filtering, and selection of inner loop gains [27]. Since the control bandwidth of an SEA is limited by the stiffness of the spring element and available motor current [28], careful consideration must be given to the design of cascaded joint impedance controllers for robots featuring series elastic actuation.…”

Section: Introductionmentioning

confidence: 99%

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Embedded joint-space control of a series elastic humanoid

Hopkins

Ressler

Lahr

et al. 2015

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

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This paper provides an overview of the embedded joint-space control approach developed for THOR, a new series elastic humanoid. The 60 kg robot features electromechanical linear series elastic actuators (SEAs), enabling low-impedance control of each joint in the lower body via linear to rotary and parallel mechanisms. We present a distributed joint impedance control framework that leverages a custom dual-axis motor controller to track position, velocity, and torque setpoints for each pair of joints. The required actuator forces are tracked using an inner force control loop combining feedforward and PID control with a model-based disturbance observer (DOB). Unlike previous approaches, we utilize an inverse plant model based on the open-loop actuator dynamics to simplify tuning of the cascaded controller by decoupling DOB estimates from the inner loop gains. The effectiveness of the proposed approach is verified through trajectory tracking and dynamic walking experiments conducted on the THOR humanoid utilizing a complementary optimization-based whole-body controller. † M. A. Hopkins and A. Leonessa are with the Terrestrial Robotics, Engineering & Controls Lab at Virginia

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“…Moreover, hydraulic actuators have a good power/weight ratio because their drive sources do not need to be located on robotic joints. Therefore, actuators allow more freedom in designing the configuration of the robot than electric actuators and many studies on the use of hydraulic actuators in robots have been reported (1)- (3) . Hydraulic actuators are driven by controlling the flow rate using servo-valves, and such drive circuits are popular in construction machinery (4) .…”

Section: Introductionmentioning

confidence: 99%

Reaction Force Estimation of Electro-hydrostatic Actuator Using Reaction Force Observer

et al. 2018

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Electro-hydrostatic actuators (EHAs) are hydraulic actuators that are flexible and exhibit high backdrivability. Flexible operation and accurate detection of reaction forces are required for robots to be able to perform in environments in which they will be cohabiting with humans. However, nonlinear elements that degrade detection accuracy, such as static friction, backlash, and oil leakage, are present in hydraulic systems. In addition, pressure sensors in hydraulic systems are not very accurate at estimating reaction forces, because they cannot estimate internal forces and viscous friction. In this study, we propose a combination of control algorithms for accurately estimating reaction forces. Static friction is compensated by using feedback modulators. In addition, we use a backlash and oil leakage compensator, which do not require any models, to suppress the relative velocity between the motor-side and load-side. Then, the use of a reaction force observer (RFOB) that exploits both pressure sensors and encoders is proposed. The RFOB can be implemented because disturbances are linearized by the compensators. Experimental results show that reaction forces can be estimated with very high accuracy using the proposed RFOB. In addition, we implemented force control using the RFOB and evaluate the force tracking performances by improving the estimation accuracy.

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Robot impedance control and passivity analysis with inner torque and velocity feedback loops

Cited by 62 publications

References 33 publications

TALOS: A new humanoid research platform targeted for industrial applications

TALOS: A new humanoid research platform targeted for industrial applications

Embedded joint-space control of a series elastic humanoid

Reaction Force Estimation of Electro-hydrostatic Actuator Using Reaction Force Observer

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