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Stable Tracking-in-the-Loop Control of Cable-Driven Surgical Manipulators under Erroneous Kinematic Chains

Joglekar, Neelay, Liu, Fei, Richter, Florian, Yip, Michael C.

arXiv.org Artificial Intelligence

Remote Center of Motion (RCM) robotic manipulators have revolutionized Minimally Invasive Surgery, enabling precise, dexterous surgical manipulation within the patient's body cavity without disturbing the insertion point on the patient. Accurate RCM tool control is vital for incorporating autonomous subtasks like suturing, blood suction, and tumor resection into robotic surgical procedures, reducing surgeon fatigue and improving patient outcomes. However, these cable-driven systems are subject to significant joint reading errors, corrupting the kinematics computation necessary to perform control. Although visual tracking with endoscopic cameras can correct errors on in-view joints, errors in the kinematic chain prior to the insertion point are irreparable because they remain out of view. No prior work has characterized the stability of control under these conditions. We fill this gap by designing a provably stable tracking-in-the-loop controller for the out-of-view portion of the RCM manipulator kinematic chain. We additionally incorporate this controller into a bilevel control scheme for the full kinematic chain. We rigorously benchmark our method in simulated and real world settings to verify our theoretical findings. Our work provides key insights into the next steps required for the transition from teleoperated to autonomous surgery.


Differentiable Rendering-based Pose Estimation for Surgical Robotic Instruments

Liang, Zekai, Chiu, Zih-Yun, Richter, Florian, Yip, Michael C.

arXiv.org Artificial Intelligence

Robot pose estimation is a challenging and crucial task for vision-based surgical robotic automation. Typical robotic calibration approaches, however, are not applicable to surgical robots, such as the da Vinci Research Kit (dVRK), due to joint angle measurement errors from cable-drives and the partially visible kinematic chain. Hence, previous works in surgical robotic automation used tracking algorithms to estimate the pose of the surgical tool in real-time and compensate for the joint angle errors. However, a big limitation of these previous tracking works is the initialization step which relied on only keypoints and SolvePnP. In this work, we fully explore the potential of geometric primitives beyond just keypoints with differentiable rendering, cylinders, and construct a versatile pose matching pipeline in a novel pose hypothesis space. We demonstrate the state-of-the-art performance of our single-shot calibration method with both calibration consistency and real surgical tasks. As a result, this marker-less calibration approach proves to be a robust and generalizable initialization step for surgical tool tracking.


Robust Surgical Tool Tracking with Pixel-based Probabilities for Projected Geometric Primitives

D'Ambrosia, Christopher, Richter, Florian, Chiu, Zih-Yun, Shinde, Nikhil, Liu, Fei, Christensen, Henrik I., Yip, Michael C.

arXiv.org Artificial Intelligence

Controlling robotic manipulators via visual feedback requires a known coordinate frame transformation between the robot and the camera. Uncertainties in mechanical systems as well as camera calibration create errors in this coordinate frame transformation. These errors result in poor localization of robotic manipulators and create a significant challenge for applications that rely on precise interactions between manipulators and the environment. In this work, we estimate the camera-to-base transform and joint angle measurement errors for surgical robotic tools using an image based insertion-shaft detection algorithm and probabilistic models. We apply our proposed approach in both a structured environment as well as an unstructured environment and measure to demonstrate the efficacy of our methods.


Improved sampling via learned diffusions

Richter, Lorenz, Berner, Julius, Liu, Guan-Horng

arXiv.org Artificial Intelligence

Recently, a series of papers proposed deep learning-based approaches to sample from unnormalized target densities using controlled diffusion processes. In this work, we identify these approaches as special cases of the Schr\"odinger bridge problem, seeking the most likely stochastic evolution between a given prior distribution and the specified target. We further generalize this framework by introducing a variational formulation based on divergences between path space measures of time-reversed diffusion processes. This abstract perspective leads to practical losses that can be optimized by gradient-based algorithms and includes previous objectives as special cases. At the same time, it allows us to consider divergences other than the reverse Kullback-Leibler divergence that is known to suffer from mode collapse. In particular, we propose the so-called log-variance loss, which exhibits favorable numerical properties and leads to significantly improved performance across all considered approaches.


Real-Time Constrained 6D Object-Pose Tracking of An In-Hand Suture Needle for Minimally Invasive Robotic Surgery

Chiu, Zih-Yun, Richter, Florian, Yip, Michael C.

arXiv.org Artificial Intelligence

Autonomous suturing has been a long-sought-after goal for surgical robotics. Outside of staged environments, accurate localization of suture needles is a critical foundation for automating various suture needle manipulation tasks in the real world. When localizing a needle held by a gripper, previous work usually tracks them separately without considering their relationship. Because of the significant errors that can arise in the stereo-triangulation of objects and instruments, their reconstructions may often not be consistent. This can lead to unrealistic tool-needle grasp reconstructions that are infeasible. Instead, an obvious strategy to improve localization would be to leverage constraints that arise from contact, thereby constraining reconstructions of objects and instruments into a jointly feasible space. In this work, we consider feasible grasping constraints when tracking the 6D pose of an in-hand suture needle. We propose a reparameterization trick to define a new state space for describing a needle pose, where grasp constraints can be easily defined and satisfied. Our proposed state space and feasible grasping constraints are then incorporated into Bayesian filters for real-time needle localization. In the experiments, we show that our constrained methods outperform previous unconstrained/constrained tracking approaches and demonstrate the importance of incorporating feasible grasping constraints into automating suture needle manipulation tasks.


Robust SDE-Based Variational Formulations for Solving Linear PDEs via Deep Learning

Richter, Lorenz, Berner, Julius

arXiv.org Artificial Intelligence

The combination of Monte Carlo methods and deep learning has recently led to efficient algorithms for solving partial differential equations (PDEs) in high dimensions. Related learning problems are often stated as variational formulations based on associated stochastic differential equations (SDEs), which allow the minimization of corresponding losses using gradient-based optimization methods. In respective numerical implementations it is therefore crucial to rely on adequate gradient estimators that exhibit low variance in order to reach convergence accurately and swiftly. In this article, we rigorously investigate corresponding numerical aspects that appear in the context of linear Kolmogorov PDEs. In particular, we systematically compare existing deep learning approaches and provide theoretical explanations for their performances. Subsequently, we suggest novel methods that can be shown to be more robust both theoretically and numerically, leading to substantial performance improvements.


Synthetic Voices Want to Take Over Audiobooks

WIRED

When voice actor Heath Miller sits down in his boatshed-turned-home studio in Maine to record a new audiobook narration, he has already read the text through carefully at least once. To deliver his best performance, he takes notes on each character and any hints of how they should sound. Over the past two years, audiobook roles, like narrating popular fantasy series He Who Fights With Monsters, have become Miller's main source of work. But in December he briefly turned online detective after he saw a tweet from UK sci-fi author Jon Richter disclosing that his latest audiobook had no need for the kind of artistry Miller offers: It was narrated by a synthetic voice. Richter's book listing on Amazon's Audible credited that voice as "Nicholas Smith" without disclosing that it wasn't human. To Miller's surprise, he found that "Smith" voiced a total of around half a dozen on the site from multiple publishers--breaching Audible rules that say audiobooks "must be narrated by a human."


Can Elon Musk and Tesla really build a humanoid robot in 2022?

New Scientist

In August 2021, Elon Musk announced that Tesla would build a humanoid robot designed to "eliminate dangerous, repetitive, boring tasks" and respond to voice commands, promising to show off a prototype in 2022. Can the company deliver on Musk's goal? Tesla has achieved a great deal since Musk founded the electric car firm in 2003: building a valuation of $1 trillion, selling in excess of half a million cars and installing a global network of more than 2000 charging stations for them. But there have also been failures and delays. Musk promised to have a million self-driving taxis on the road by 2020.


Pharma startup Quris aims to use a 'patient on a chip' to target drug delivery

#artificialintelligence

Nobel Laureate, Aaron Ciechanover, is one of several notable names behind pharma startup Quris. The company aims to bring together artificial intelligence, the industry's vast knowledge of the human genome, and the concept of the "patient on a chip" to improve the effectiveness of drug delivery. Last month, the startup announced the launch of its AI platform and a $9 million seed round, led by Moshe Yanai (the mind behind EMC Symmetrix) and Dr. Judith Richter, and Dr. Jacob Richter (founders of Medinol, which has sold more than 2 million cardiovascular stents). Ciechanover, as well as Moderna cofounder, Robert Langer, are among Quris' noteworthy advisers. For decades, medical research has successfully cured cancer and treated rare diseases in innumerable quantities of mice – but has not done so as frequently in humans.


Bumpy road as aging Japan bets on self-driving cars

The Japan Times

With an aging population in need of transport, Japan is betting on autonomous cars, but an accident involving a self-driving showcase at the Paralympics illustrates the challenges ahead. Japan is far from the only place with autonomous vehicles on the roads, but its government has set acceleration of the technology as a key priority. Last year, it became the first country in the world to allow a vehicle capable of taking full control in certain situations to operate on public roads. The Honda car has "Level 3" autonomy, meaning it can take certain decisions alone, though a driver has to be ready to take the wheel in emergencies. The government has changed the law to pave the way for increasingly advanced autonomous vehicles, and the ministry of economy, trade and industry (METI) has plans for 40 autonomous taxi test sites nationwide by 2025.