FARMS: Framework for Animal and Robot Modeling and Simulation

Abstract

The study of animal locomotion and neuromechanical control offers valuable insights for advancing research in neuroscience, biomechanics, and robotics. We have developed FARMS (Framework for Animal and Robot Modeling and Simulation), an open-source, interdisciplinary framework, designed to facilitate access to neuromechanical simulations for modeling, simulation, and analysis of animal locomotion and bio-inspired robotic systems. By providing an accessible and user-friendly platform, FARMS aims to lower the barriers for researchers to explore the complex interactions between the nervous system, musculoskeletal structures, and their environment. Integrating the MuJoCo physics engine in a modular manner, FARMS enables realistic simulations and fosters collaboration among neuroscientists, biologists, and roboticists. FARMS has already been extensively used to study locomotion in animals such as mice, drosophila, fish, salamanders, and centipedes, serving as a platform to investigate the role of central pattern generators and sensory feedback. This article provides an overview of the FARMS framework, discusses its interdisciplinary approach, showcases its versatility through specific case studies, and highlights its effectiveness in advancing our understanding of locomotion. In particular, we show how we used FARMS to study amphibious locomotion by presenting experimental demonstrations across morphologies and environments based on neural controllers with central pattern generators and sensory feedback circuits models. Overall, the goal of FARMS is to contribute to a deeper understanding of animal locomotion, the development of innovative bio-inspired robotic systems, and promote accessibility in neuromechanical research.

Role and modulation of various spinal pathways for human upper limb control in different gravity conditions

“…The MN output rates were finally provided as muscle excitation signals to the musculoskeletal model. We used FARMS Python library, developed at the BioRobotics laboratory [40] to model this modular SC.…”

Balancing central control and sensory feedback produces adaptable and robust locomotor patterns in a spiking, neuromechanical model of the salamander spinal cord

“…The mechanical model consists of a salamander body, inclusive of axial and limb joints, that was previously introduced in [ [92]. For simplicity, the density of the model was considered constant across the length of the body and equal to 981.0kg/m 3 .…”

“…The topology of the synaptic connectivity was constrained using indirect evidence from neuronal and kinematic recordings of Pleurodeles waltl, and by taking inspiration from that of the lamprey and zebrafish [12,22,82]. The 3D mechanical salamander model (see Fig 2) consists of multiple connected rigid links that faithfully resemble the body of the real salamander and it is actuated by virtual muscles [92]. This actuation allows the model to move in simulated water or a flat terrain to reproduce swimming and walking, respectively.…”

“…This actuation allows the model to move in simulated water or a flat terrain to reproduce swimming and walking, respectively. This model is simulated in the MuJoCo physics engine [93] through the FARMS framework [92]. Physical and muscles parameters were optimised to match the swimming kinematics of Pleurodeles waltl salamanders using a novel system design based on the transfer function of the linearized muscle model response (more details in S3 File).…”

“…These encompass flexion/extension, abduction/adduction, and internal/external rotation of the shoulder (or hip) along with flexion/extension of the elbow (or knee, see Fig 2C). The geometrical and dynamical properties of the model were derived from Pleurodeles waltl biological data.More details about its design are given in[92]. For simplicity, the density of the model was considered constant across the length of the body and equal to 981.0kg/m 3 .…”