A sensor-less approach of a torque controller for pneumatic muscle actuator driven joints

Martens, Mirco; Passon, Arne; Boblan, Ivo

doi:10.1109/iccar.2017.7942742

Cited by 9 publications

(8 citation statements)

References 14 publications

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“…However, the maximum torque can only be exerted if the force F IT equals zero. In case of F IT > 0 (see Figure 4b), the maximum torque as well as the angle range are decreasing [26].…”

Section: A Comparison Of Two Torque Characteristicsmentioning

confidence: 93%

“…As an alternative approach, discussed in Section 2.2.3, it is possible to separate the torque in two PMA forces such that each force equation can be solved separately. This idea was first presented in [26].…”

Section: Torque Characteristicmentioning

confidence: 99%

“…As first presented in [26], separating the torque in two forces and defining that each PMA is only responsible for a torque in one direction, the forces are given through…”

Section: Pressure Trajectory Generation By Force Separation-"fit-apprmentioning

confidence: 99%

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A Novel Framework for a Systematic Integration of Pneumatic-Muscle-Actuator-Driven Joints into Robotic Systems Via a Torque Control Interface

et al. 2018

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In this paper, two different torque control approaches for PMA-driven (PMA = Pneumatic muscle actuator) revolute joints are presented and tested. In previous work controllers for PMA-driven robots are typically customized for the use on a specific robotic system. In contrast, the proposed controllers define a general control interface for every robot that is actuated by PMA-driven joints. It will be shown that controlling the torque of a PMA-driven joint enables the use of standard robotic motion control frameworks, because the torque represents the natural input of the robotic equation of motion. Therefore, both proposed torque control approaches are interconnecting PMAs and their challenging characteristics on the one hand and “conventional” motion control strategies for robots on the other hand. After a detailed discussion of two different torque control approaches, we show that a torque controller handles all characteristics and dynamics of a PMA-driven joint internally, which implies that only its bandwidth and its static torque characteristic must be taken into account for the design of the outer motion control loop. This feature simplifies the integration of PMA-driven joints in robotic systems enormously, as will be demonstrated by a design of a cascade-structured, flatness-based motion controller for an exemplary robot with one degree of freedom.

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“…However, the maximum torque can only be exerted if the force F IT equals zero. In case of F IT > 0 (see Figure 4b), the maximum torque as well as the angle range are decreasing [26].…”

Section: A Comparison Of Two Torque Characteristicsmentioning

confidence: 93%

Section: Torque Characteristicmentioning

confidence: 99%

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A Novel Framework for a Systematic Integration of Pneumatic-Muscle-Actuator-Driven Joints into Robotic Systems Via a Torque Control Interface

et al. 2018

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“…Fiber-reinforced gaiters are used in an antagonistic setup to create a robotic joint, see [12]. The control of single PAMs is presented in [8,13,14] and the control of drive configuration comprising two antagonistic PAMs is presented in [15][16][17][18][19][20]. Besides the configurations with identical but antagonistic working chambers, configurations with different types of antagonistic elements are also described in research.…”

Section: Related Workmentioning

confidence: 99%

Mechatronic Control System for a Compliant and Precise Pneumatic Rotary Drive Unit

Stoll

Schanz

Pott³

2019

Actuators

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Robots that enable safe human-robot collaboration can be realized by using compliant drive units. In previous works, different mechanical designs of compliant pneumatic rotary drive units with similar characteristics have been presented. In this paper, we present the overall control approach that we use to operate one of these compliant pneumatic rotary drive units. We explain the mechanical design and derive the differential equation that describes the dynamics of the system. In order to successfully operate a pneumatic drive unit with three or more working chambers, the torque specified by the controller has to be split up onto the working chambers. We transfer the well-known field-oriented control approach from electric motors to the investigated pneumatic drive unit to create such a torque mapping. Moreover, we develop optimized torque mappings that are tailored to work with this type of drive unit. Furthermore, we introduce and compare two control algorithms based on different implementations of state feedback to realize position control. Finally, we present the step responses that we achieve when we implement either one of the control algorithms in combination with the different torque mappings.

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“…The use of a force sensor (i.e., a load cell) and an encoder enabled torque and stiffness control of a PAM joint actuator [19]- [21]. Among sensor-less approaches, one study [18] showed that the use of a force map instead of a force sensor helps to estimate the joint torque of the PAM system, and another study applied a force-sensor-less approach to achieve torque control of an antagonist PAM actuator system under a fixed joint angle [22]. However, conventional studies still use a sensor, such as an encoder, for measuring the joint angle.…”

Section: Introductionmentioning

confidence: 99%

Detailed Dynamic Model of Antagonistic PAM System and Its Experimental Validation: Sensorless Angle and Torque Control With UKF

Shin

Ibayashi²,

Kogiso

2022

IEEE/ASME Trans. Mechatron.

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This paper proposes a detailed nonlinear mathematical model of an antagonistic pneumatic artificial muscle (PAM) actuator system for estimating the joint angle and torque using an unscented Kalman filter (UKF). The proposed model is described in a hybrid state-space representation. It includes the contraction force of the PAM, joint dynamics, fluid dynamics of compressed air, mass flows of a valve, and friction models. A part of the friction models is modified to obtain a novel form of Coulomb friction depending on the inner pressure of the PAM. For model validation, offline and online UKF estimations and sensor-less tracking control of the joint angle and torque are conducted to evaluate the estimation accuracy and tracking control performance. The estimation error is less than 7.91 %, and the steady-state tracking control performance is more than 94.75 %. These results confirm that the proposed model is detailed and could be used as the state estimator of an antagonistic PAM system.

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A sensor-less approach of a torque controller for pneumatic muscle actuator driven joints

Cited by 9 publications

References 14 publications

A Novel Framework for a Systematic Integration of Pneumatic-Muscle-Actuator-Driven Joints into Robotic Systems Via a Torque Control Interface

A Novel Framework for a Systematic Integration of Pneumatic-Muscle-Actuator-Driven Joints into Robotic Systems Via a Torque Control Interface

Mechatronic Control System for a Compliant and Precise Pneumatic Rotary Drive Unit

Detailed Dynamic Model of Antagonistic PAM System and Its Experimental Validation: Sensorless Angle and Torque Control With UKF

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