Abstract
The design of a teleoperated 8-DoF redundant robot for Doppler sonography is detailed in this paper. The proposed robot is composed of a 7-DoF robotic arm mounted on a 1-DoF linear axis. This solution has been conceived to allow Doppler ultrasound examination of the entire patient’s body. This paper details the design of the platform and proposes two alternative control modes to deal with its redundancy at the torque level. The first control mode considers the robot as a full 8-DoF kinematics chain, synchronizing the action of the eight joints and improving the global robot manipulability. The second control mode decouples the 7-DoF arm and the linear axis controllers and proposes a switching strategy to activate the linear axis motion when the robot arm approaches the workspace limits. Moreover, a new adaptive Joint-Limit Avoidance (JLA) strategy is proposed with the aim of exploiting the redundancy of the 7-DoF anthropomorphic arm. Unlike classical JLA approaches, a weighting matrix is actively adapted to prioritize those joints that are approaching the mechanical limits. Simulations and experimental results are presented to verify the effectiveness of the proposed control modes.
Highlights
Nowadays, the use of medical robot assistants arises as a suitable solution to improve the working conditions of practitioners, cooperating with them to accomplish the medical tasks
This paper presents an innovative redundant robotic assistant that combines a 7-DoF
Collaborative Franka robot and a linear axis to achieve a 7 + 1 DoF platform. This robot assistant is conceived to assist sonographers in Doppler Sonography exams and, unlike existing systems, is suitable for full body scanning without requiring manual repositioning of the robot base
Summary
The use of medical robot assistants arises as a suitable solution to improve the working conditions of practitioners, cooperating with them to accomplish the medical tasks. The first control mode considers the robot as a full 8-DoF kinematics chain The advantage of this approach is that the eight joints are simultaneously activated, avoiding the presence of certain singularities typically linked to the limits of the workspace when only moving the 7-DoF arm. An improved approach is proposed here, where the weighting matrix is actively adapted to prioritize those joints approaching the mechanical limits This feature allows an enhanced distribution of the redundant space of the robot. The main contributions of the paper are summarized as follows: (a) detailed presentation of an 8-DoF teleoperated platform for Doppler sonography, (b) validation of a fully redundant control mode at the torque level for the 8-DoF robotic system and (c) introduction of a new adaptive JLA strategy for redundant robots controlled by torque by means of an optimal variation of the weighting matrix. The last section concludes the presented work and opens the perspectives of future works
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