Portrait of Inna Sharf

Inna Sharf

Affiliate Member
Full Professor, McGill University, Department of Mechanical Engineering
Research Topics
Robotics

Publications

Resonant Motion of Echo I: A Case Study of SRP and $$J_2$$ Coupling
Catherine Massé
Path Following Guidance Strategy for Autonomous Dynamic Soaring
Zihao Zhuo
Meyer Nahon
Dynamic soaring is a flight mode that harvests energy from the vertical gradient of horizontal wind and can be used to increase the enduranc… (see more)e and range of unmanned aerial vehicles. Previous studies have mainly focused on trajectory optimization for dynamic soaring, while the problem of following these optimal paths with an autonomous glider has received limited attention. This study proposes a novel guidance strategy that enables precise tracking of an optimal dynamic soaring path on an autonomous glider vehicle. The proposed guidance strategy combines a geometric path-following guidance law with a command projection module specifically designed to address the unique challenges of dynamic soaring, such as the presence of crosswind components and the underactuated nature of glider vehicles. The performance of the proposed guidance strategy is demonstrated through numerical simulations of a 2 m wingspan glider executing dynamic soaring maneuvers in both ridge and surface wind shear layers.
Designing Experimental Setup Emulating Log-Loader Manipulator and Implementing Anti-Sway Trajectory Planner
Iman Jebellat
George Sideris
Forestry machines are not easily accessible for experimentation or demonstration of research results. These mobile robots are massive, very … (see more)expensive, and require a large outdoor space and permits to operate. These factors hinder conducting experiments on real forestry robots. Thus, it is essential to design experimental setups utilizing easily accessible robots in indoor labs that can effectively replicate the behavior of interest of a forestry machine. We design a setup to resemble a log-loader crane and grapple motions using a Kinova Jaco2 arm by manufacturing a specialized end-effector to attach passively to the Jaco2 arm. Passively attached grapple causes undesirable sway, which is problematic and dangerous in forestry. To address the sway problem, we employ dynamic programming to develop an anti-sway motion planner, and validate its performance for different point-to-point maneuvers in our experimental setup. We also repeat each experiment at least 6 times to ensure the repeatability and reliability of the experiments. The experimental results showcase the excellent sway-damping performance of our planner and also the very good repeatability of our experiments.
Learning the Latent Space of Robot Dynamics for Cutting Interaction Inference
Utilization of latent space to capture a lower-dimensional representation of a complex dynamics model is explored in this work. The targeted… (see more) application is of a robotic manipulator executing a complex environment interaction task, in particular, cutting a wooden object. We train two flavours of Variational Autoencoders---standard and Vector-Quantised---to learn the latent space which is then used to infer certain properties of the cutting operation, such as whether the robot is cutting or not, as well as, material and geometry of the object being cut. The two VAE models are evaluated with reconstruction, prediction and a combined reconstruction/prediction decoders. The results demonstrate the expressiveness of the latent space for robotic interaction inference and the competitive prediction performance against recurrent neural networks.
Cascaded Gaussian Processes for Data-efficient Robot Dynamics Learning
Motivated by the recursive Newton-Euler formulation, we propose a novel cascaded Gaussian process learning framework for the inverse dynamic… (see more)s of robot manipulators. This approach leads to a significant dimensionality reduction which in turn results in better learning and data efficiency. We explore two formulations for the cascading: the inward and outward, both along the manipulator chain topology. The learned modeling is tested in conjunction with the classical inverse dynamics model (semi-parametric) and on its own (non-parametric) in the context of feed-forward control of the arm. Experimental results are obtained with Jaco 2 six-DOF and SARCOS seven-DOF manipulators for randomly defined sinusoidal motions of the joints in order to evaluate the performance of cascading against the standard GP learning. In addition, experiments are conducted using Jaco 2 on a task emulating a pouring maneuver. Results indicate a consistent improvement in learning speed with the inward cascaded GP model and an overall improvement in data efficiency and generalization.