From cineradiography to biorobots: an approach for designing robots to emulate and study animal locomotion

Abstract

Robots are increasingly used as scientific tools to investigate animal locomotion. However, designing a robot that properly emulates the kinematic and dynamic properties of an animal is difficult because of the complexity of musculoskeletal systems and the limitations of current robotics technology. Here, we propose a design process that combines high-speed cineradiography, optimization, dynamic scaling, three-dimensional printing, high-end servomotors and a tailored dry-suit to construct Pleurobot: a salamander-like robot that closely mimics its biological counterpart, Pleurodeles waltl. Our previous robots helped us test and confirm hypotheses on the interaction between the locomotor neuronal networks of the limbs and the spine to generate basic swimming and walking gaits. With Pleurobot, we demonstrate a design process that will enable studies of richer motor skills in salamanders. In particular, we are interested in how these richer motor skills can be obtained by extending our spinal cord models with the addition of more descending pathways and more detailed limb central pattern generator networks. Pleurobot is a dynamically scaled amphibious salamander robot with a large number of actuated degrees of freedom (DOFs: 27 in total). Because of our design process, the robot can capture most of the animal's DOFs and range of motion, especially at the limbs. We demonstrate the robot's abilities by imposing raw kinematic data, extracted from X-ray videos, to the robot's joints for basic locomotor behaviours in water and on land. The robot closely matches the behaviour of the animal in terms of relative forward speeds and lateral displacements. Ground reaction forces during walking also resemble those of the animal. Based on our results, we anticipate that future studies on richer motor skills in salamanders will highly benefit from Pleurobot's design.

Small-Sized Reconfigurable Quadruped Robot With Multiple Sensory Feedback for Studying Adaptive and Versatile Behaviors

“…However, it is not convenient to investigate the locomotor principles by means of animal experiments alone, because, in general, it is difficult to perform repeated measurements of the variables or quantities of unrestrained animal behaviors (Ijspeert, 2014). Fortunately, quadruped robots can serve as useful research tools for studying and validating the mechanisms or hypotheses of the various features of legged locomotion (Ijspeert, 2014;Karakasiliotis et al, 2016).…”

Development and Training of a Neural Controller for Hind Leg Walking in a Dog Robot

“…Though these torques were within 20% of peak torques recorded in the greyhound (another dog of similar limb proportions and body mass to Puppy) (Colborne et al, 2006), the method required the implementation of a PD controller, which can be very sensitive to parameter values. Recent advances in the fields of biology and biomechanics have led to more sophisticated methods for calculating joint torques using both kinematic and dynamic (force) data from the animal itself, leading to interesting implementations of biorobotic systems (Andrada et al, 2013; Karakasiliotis et al, 2016). As this data becomes available for dogs, we can use it to refine the required joint torque output of the robot similar to what we did in the simulation of rat locomotion (Hunt et al, 2015b).…”

Benchmarking Agility For Multilegged Terrestrial Robots

“…As a contrast to these cat-or dog-like robots, we also tested our sprawling posture robot Pleurobot. It features a highly actuated spine in combination with an extremely low COM (center of mass) as found in its biological counterpart, the salamander [52]. All robots are characterized in Figure 1 and Table IV.…”