A Screw Theory Approach to Computing the Instantaneous Rotation Centers of Indeterminate Planar Linkages

Valderrama-Rodríguez, Juan Ignacio; Rico, José M.; Cervantes-Sánchez, J. Jesús; García-García, Ricardo

doi:10.3390/robotics11010006

Cited by 4 publications

(1 citation statement)

References 22 publications

(33 reference statements)

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“…A kind of lowermobility mechanism was also studied in [47,48]. The screw theory has also been applied to computing rotation centers in [49], and we used the screw theory approach applied to kinematics and statics. We also applied direct kinematics, but there are alternative methods [50].…”

Section: Introductionmentioning

confidence: 99%

Applying Screw Theory to Design the Turmell-Bot: A Cable-Driven, Reconfigurable Ankle Rehabilitation Parallel Robot

Vargas-Riaño,

Agudelo-Varela,

Valera

2023

Robotics

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The ankle is a complex joint with a high injury incidence. Rehabilitation Robotics applied to the ankle is a very active research field. We present the kinematics and statics of a cable-driven reconfigurable ankle rehabilitation robot. First, we studied how the tendons pull mid-foot bones around the talocrural and subtalar axes. We proposed a hybrid serial-parallel mechanism analogous to the ankle. Then, using screw theory, we synthesized a cable-driven robot with the human ankle in the closed-loop kinematics. We incorporated a draw-wire sensor to measure the axes’ pose and compute the product of exponentials. We also reconfigured the cables to balance the tension and pressure forces using the axis projection on the base and platform planes. Furthermore, we computed the workspace to show that the reconfigurable design fits several sizes. The data used are from anthropometry and statistics. Finally, we validated the robot’s statics with MuJoCo for various cable length groups corresponding to the axes’ range of motion. We suggested a platform adjusting system and an alignment method. The design is lightweight, and the cable-driven robot has advantages over rigid parallel robots, such as Stewart platforms. We will use compliant actuators for enhancing human–robot interaction.

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Section: Introductionmentioning

confidence: 99%

Applying Screw Theory to Design the Turmell-Bot: A Cable-Driven, Reconfigurable Ankle Rehabilitation Parallel Robot

Vargas-Riaño,

Agudelo-Varela,

Valera

2023

Robotics

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show abstract

Using Screw Theory for the Kinematics and Statics Design of the Turmell-Bot: a Cable-Driven, Reconfigurable and Compliant Ankle Rehabilitation Parallel Robot

Vargas-Riaño,

Agudelo-Varela,

Valera Fernández

2023

Preprint

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The ankle is a complex joint with a high injury incidence. Rehabilitation Robotics applied to the ankle is a very active research field. We present cable-driven reconfigurable robot kinematics and statics. We studied how the tendons pull mid-foot bones around the talocrural and subtalar axes. Likewise, we propose a hybrid serial-parallel mechanism analogous to the ankle. Then, using screw theory, we synthesized a cable-driven robot with the human ankle in the closed-loop kinematics. We incorporate a draw-wire sensor to measure the axes’ pose and compute the product of exponentials. We reconfigure the cables to balance the tension and pressure forces using the axis projection on the base and platform planes. Likewise, we also computed the workspace to show that the reconfigurable design fits several sizes. The data used is from anthropometry and statistics. Finally, we validated the robot’s statics with MuJoCo for various cable length groups corresponding to the axes’ range of motion. We suggested a platform adjusting system and an alignment method. The design is lightweight, and the cable-driven robot has advantages over rigid parallel robots, such as Stewart platforms. We will use compliant actuators.

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Instant Center Identification of Single-Loop Multi-DOF Planar Linkage Using Virtual Link

et al. 2021

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Instant center is an important kinematic characteristic which can be used for velocity and singularity analysis, configuration synthesis and dynamics modeling of multi-degree of freedom (multi-DOF) planar linkage. The Aronhold–Kennedy theorem is famous for locating instant centers of four-bar planar linkage, but for single-loop multi-DOF linkages, it fails. Increasing with the number of the links of single-loop multi-DOF planar linkages, the lack of link relationship makes the identification of instant center become a recognized difficulty. This paper proposes a virtual link method to identify instant centers of single-loop multi-DOF planar linkage. First, three types of instant centers are redefined and the instant center identification process graph is introduced. Then, based on coupled loop chain characteristic and definition of instant center, two criteria are presented to convert single-loop multi-DOF planar linkage into a two-loop virtual linkage by adding the virtual links. Subsequently, the unchanged instant centers are identified in the virtual linkage and used to acquire all the instant centers of original single-loop multi-DOF planar linkage. As a result, the instant centers of single-loop five-bar, six-bar planar linkage with several prismatic joints are systematically researched for the first time. Finally, the validity of the proposed method is demonstrated using loop equations. It is a graphical and straightforward method and the application is wide up to single-loop multi-DOF N-bar (N ≥ 5) planar linkage.

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A Screw Theory Approach to Computing the Instantaneous Rotation Centers of Indeterminate Planar Linkages

Cited by 4 publications

References 22 publications

Applying Screw Theory to Design the Turmell-Bot: A Cable-Driven, Reconfigurable Ankle Rehabilitation Parallel Robot

Applying Screw Theory to Design the Turmell-Bot: A Cable-Driven, Reconfigurable Ankle Rehabilitation Parallel Robot

Using Screw Theory for the Kinematics and Statics Design of the Turmell-Bot: a Cable-Driven, Reconfigurable and Compliant Ankle Rehabilitation Parallel Robot

Instant Center Identification of Single-Loop Multi-DOF Planar Linkage Using Virtual Link

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