Dataset Information

Design, Implementation, and Observer-based Output Control of a Super-coiled Polymer-Driven Two Degree-of-Freedom Robotic Eye.

ABSTRACT: The prevalence of ineffective corrective surgeries for ocular motor disorders calls for a robotic eye platform in aiding ophthalmologists to better understand the biomechanisms of human eye movement. This letter presents the first hardware design and implementation of a 2-DOF robotic eye driven by super-coiled polymer (SCP) artificial muscles. While our previous work designed and simulated a deep deterministic policy gradient (DDPG) learning-based controller that requires full-state feedback of the SCP-driven robotic eye, measuring the temperature states of the slender SCPs is generally impractical for the ubiquitously aimed robot. To address this predicament, this letter proposes a reduced-order state observer to estimate the temperature of SCPs given the kinematic measurements. Combining the designed observer and the learning-based controller, the closed-loop output feedback control is implemented on the robotic eye prototype to examine its performance on three classical types of eye movements: visual fixation, saccadic pursuit, and smooth pursuit. The experimental results are presented which successfully validate the observer-based output control of the SCP-driven robotic eye.

SUBMITTER: Rajendran SK

PROVIDER: S-EPMC10593108 | biostudies-literature | 2023 Sep

REPOSITORIES: biostudies-literature

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Design, Implementation, and Observer-based Output Control of a Super-coiled Polymer-Driven Two Degree-of-Freedom Robotic Eye.

Rajendran Sunil Kumar SK Wei Qi Q Yao Ningshi N Zhang Feitian F

IEEE robotics and automation letters 20230802 9

The prevalence of ineffective corrective surgeries for ocular motor disorders calls for a robotic eye platform in aiding ophthalmologists to better understand the biomechanisms of human eye movement. This letter presents the first hardware design and implementation of a 2-DOF robotic eye driven by super-coiled polymer (SCP) artificial muscles. While our previous work designed and simulated a deep deterministic policy gradient (DDPG) learning-based controller that requires full-state feedback of ...[more]

PMID: 37877111

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Project description:BackgroundTo introduce a novel method of patient positioning for high precision intracranial radiotherapy.MethodsAn infrared(IR)-array, reproducibly attached to the patient via a vacuum-mouthpiece(vMP) and connected to the table via a 6 degree-of-freedom(DoF) mechanical arm serves as positioning and fixation system. After IR-based manual prepositioning to rough treatment position and fixation of the mechanical arm, a cone-beam CT(CBCT) is performed. A robotic 6 DoF treatment couch (HexaPOD) then automatically corrects all remaining translations and rotations. This absolute position of infrared markers at the first fraction acts as reference for the following fractions where patients are manually prepositioned to within +/- 2 mm and +/- 2 degrees of this IR reference position prior to final HexaPOD-based correction; consequently CBCT imaging is only required once at the first treatment fraction.The preclinical feasibility and attainable repositioning accuracy of this method was evaluated on a phantom and human volunteers as was the clinical efficacy on 7 pilot study patients.ResultsPhantom and volunteer manual IR-based prepositioning to within +/- 2 mm and +/- 2 degrees in 6 DoF was possible within a mean(+/- SD) of 90 +/- 31 and 56 +/- 22 seconds respectively. Mean phantom translational and rotational precision after 6 DoF corrections by the HexaPOD was 0.2 +/- 0.2 mm and 0.7 +/- 0.8 degrees respectively. For the actual patient collective, the mean 3D vector for inter-treatment repositioning accuracy (n = 102) was 1.6 +/- 0.8 mm while intra-fraction movement (n = 110) was 0.6 +/- 0.4 mm.ConclusionsThis novel semi-automatic 6DoF IR-based system has been shown to compare favourably with existing non-invasive intracranial repeat fixation systems with respect to handling, reproducibility and, more importantly, intra-fraction rigidity. Some advantages are full cranial positioning flexibility for single and fractionated IGRT treatments and possibly increased patient comfort.

Project description:PurposeAmong various test methods for different human joints, the use of robot systems has attracted major interest and inherits the potential to become a gold standard in biomechanical testing in the future. A key issue associated with those robot-based platforms is the accurate definition of parameters, e.g., tool center point (TCP), length of tool or anatomical trajectories of movements. These must be precisely correlated to the physiological parameters of the examined joint and its corresponding bones. Exemplified for the human hip joint, we are creating an accurate calibration procedure for a universal testing platform by using a six degree-of-freedom (6 DOF) robot and optical tracking system for recognition of anatomical movements of the bone samples.MethodsA six degree-of-freedom robot (TX 200, Stäubli) has been installed and configured. The physiological range of motion of the hip joint composed of a femur and a hemipelvis was recorded with an optical 3D movement and deformation analysis system (ARAMIS, GOM GmbH). The recorded measurements were processed by automatic transformation procedure (created in Delphi software) and evaluated in 3D CAD system.ResultsThe physiological ranges of motion were reproduced for all degrees of freedom with the six degree-of-freedom robot in adequate accuracy. With the establishment of a special calibration procedure by using a combination of different coordinate systems, we were able to achieve a standard deviation of the TCP depending of the axis between 0.3 and 0.9 mm and for the length of tool between + 0.67 and - 0.40 mm (3D CAD processing) resp. + 0.72 mm to - 0.13 mm (Delphi transformation). The accuracy between the manual and robotic movement of the hip shows an average deviation between - 0.36 and + 3.44 mm for the points on the movement trajectories.ConclusionA six degree-of-freedom robot is appropriate to reproduce the physiological range of motion of the hip joint. The described calibration procedure is universal and can be used for hip joint biomechanical tests allowing to apply clinically relevant forces and investigate testing stability of reconstructive osteosynthesis implant/endoprosthetic fixations, regardless of the length of the femur, size of the femoral head and acetabulum or whether the entire pelvis or only the hemipelvis will be used.

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Dataset Information

Design, Implementation, and Observer-based Output Control of a Super-coiled Polymer-Driven Two Degree-of-Freedom Robotic Eye.

Publications

Design, Implementation, and Observer-based Output Control of a Super-coiled Polymer-Driven Two Degree-of-Freedom Robotic Eye.

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