arXiv subjects

Christoph Scherer

Publications and source records attributed to Christoph Scherer.

4 recordsLinked to original sources

arXiv2026

Rusty Flying Robots: Learning a Full Robotics Stack with Real-Time Operation on an STM32 Microcontroller in a 9 ECTS MS Course

We describe a novel masters-level projects class that teaches robotics along the traditional robotics pipeline (dynamics, state estimation, controls, planning). One key motivational part is that students have to directly apply the algorithms they learn on a highly constrained compute platform, effectively making a robot fly. We teach nonlinear algorithms as deployed in state-of-the-art flight stacks such as PX4. Didactically, we rely on two core concepts: 1) avoidance of provided black-box software infrastructure, and 2) usage of the safe and efficient programming language Rust that is used on the PC (for simulation) and an STM32 microcontroller (for robot deployment). We discuss our methodology and the student feedback over two years with ten students each. Teaching material: https://imrclab.github.io/teaching/flying-robots

physics.ed-ph↗

arXiv2026

How to Model Your Crazyflie Brushless

The Crazyflie quadcopter is widely recognized as a leading platform for nano-quadcopter research. In early 2025, the Crazyflie Brushless was introduced, featuring brushless motors that provide around 50% more thrust compared to the brushed motors of its predecessor, the Crazyflie 2.1. This advancement has opened new opportunities for research in agile nano-quadcopter control. To support researchers utilizing this new platform, this work presents a dynamics model of the Crazyflie Brushless and identifies its key parameters. Through simulations and hardware analyses, we assess the accuracy of our model. We furthermore demonstrate its suitability for reinforcement learning applications by training an end-to-end neural network position controller and learning a backflip controller capable of executing two complete rotations with a vertical movement of just 1.8 meters. This showcases the model's ability to facilitate the learning of controllers and acrobatic maneuvers that successfully transfer from simulation to hardware. Utilizing this application, we investigate the impact of domain randomization on control performance, offering valuable insights into bridging the sim-to-real gap with the presented model. We have open-sourced the entire project, enabling users of the Crazyflie Brushless to swiftly implement and test their own controllers on an accurate simulation platform.

cs.RO↗

arXiv2017

Understanding three-body contributions to coarse-grained force-fields

Coarse-graining (CG) is a systematic reduction of the number of degrees of freedom (DOF) used to describe a system of interest. CG can be thought of as a projection on coarse-grained DOF and is therefore dependent on the functions used to represent the CG force field. In this work, we show that naive extensions of the coarse-grained force-field can result in unphysical parametrizations of the CG potential energy surface (PES). This issue can be elevated by coarse-graining the two- and three-body forces separately, which also helps to evaluate the importance of many-body interactions for a given system. The approach is illustrated on liquid water, where three-body interactions are essential to reproduce the structural properties, and liquid methanol, where two-body interactions are sufficient to reproduce the main features of the atomistic system.

cond-mat.soft↗

arXiv2008

Inflation and Quintessence: Theoretical Approach of Cosmological Reconstruction

In the first part of this paper, we outline the construction of an inflationary cosmology in the framework where inflation is described by a universally evolving scalar field, with the Lagrangian ${\cal L}_ϕ=-{1/2}(\partialϕ)^2 -V(ϕ)$. By considering a generic situation that inflaton attains a nearly constant velocity, during inflation, $m_P^{-1} (dϕ/dN)\equiv α$ (where $N\equiv \ln a$ is the e-folding time), we find the conditions that have to satisfied by the (reconstructed) scalar potential to be consistent with the WMAP inflationary data. In the second part of this paper, we introduce a novel approach of constructing dark energy within the context of the standard scalar-tensor gravity. The assumption that a scalar field might roll with a nearly constant velocity, during inflation, can also be applied to {\it quintessence} or dark energy models. For the minimally coupled quintessence, $α_Q\equiv dA(Q)/d(κQ)=0$ (where $A(Q)$ is the standard matter-quintessence coupling), the dark energy equation of state in the range $-1\le w_{DE} < -0.82$ can be obtained for $0\le α< 0.63$. For $α<0.1$, the model allows for only modest evolution of dark energy density with redshift. The effect of the matter-quintessence coupling can be significant only if $|α_Q| \gtrsim 0.1$, while a small coupling $|α_Q|< 0.1$ will have almost no effect on cosmological parameters. The best fit value of $α_Q$ in our model is found to be $α_Q \simeq 0.06$, but it may contain significant numerical errors, viz $α_Q=0.06\pm 0.35$, which thereby implies the consistency of our model with general relativity (for which $α_Q=0$) at $1σ$ level.

astro-ph↗