19 accepted papers
We present a low-cost, autonomous, rotating-camera system that increases the usable data yield for 3D markerless motion capture of animals in uncontrolled outdoor settings. A lightweight detector (YOLOv4-Tiny) locates the subject at 10 Hz; an Extended Kalman Filter bridges sparse detections to a 50 …
Scientists have long theorized that the cheetah’s tail contributes to its impressive maneuvrability at high speeds by stabilizing its body. This has inspired the design of several agile robots, including Dima - a wheeled platform that used cheetah-inspired inertial tail swings to better execute rapi…
This paper introduces a framework for monocular 3D reconstruction of cheetah movements, leveraging a combination of data-driven and physics-based modeling as well as trajectory optimization. Unlike traditional methods that rely solely on kinematics, our approach integrates dynamic motion principles,…
With their combination of power and compliance, pneumatic actuators have great potential for enabling dynamic and agile behaviors in legged robots, but their complex dynam-ics impose control challenges that have hindered widespread use. In this paper, we describe the development of a tractable model…
Collisions between rigid bodies are impulsive events, meaning they create near-instantaneous, finite discontinuities in the velocity state of the dynamic system. If velocity is assumed to be continuous, that requirement may come into conflict with the desire for bodies to not interpenetrate, or with
Tracking the 3D motion of agile animals in the wild will enable new insight into the design of robotic controllers. However, in-field 3D pose estimation of high-speed wildlife such as cheetahs is still a challenge [1]. In this work, we aim to solve two of these challenges: unnatural pose estimates d…
It has been shown that changing the coordinates describing a multi-body system to use absolute rather than relative angles produces a significant improvement in the tractability of trajectory optimization problems. This simplifies the equations of motion when modelling long kinematic chains. In this…
Animals are capable of extreme agility, yet understanding their complex dynamics, which have ecological, biomechanical and evolutionary implications, remains challenging. Being able to study this incredible agility will be critical for the development of next-generation autonomous legged robots. In…
For robots to leave the safety of the laboratory and explore the world, maneuverability will need to be mastered. However, transient motions, such as rapid acceleration and deceleration, have received little attention in the literature. This is mainly due to the complexity of analyzing these high di…
Many different coordinate formulations have been established to describe the position of multi-body robot models, but the impact of this choice on the tractability of trajectory optimization problems has yet to be investigated. Relative formulations, which reference the position of each link to its
Elaborate trajectory optimization models with many degrees of freedom can be a useful locomotion-planning tool, as they provide rich solutions that take advantage of the robot's specific morphology. They are, however, prone to falling into local minima. Depending on the seed that initializes the sol…
In this letter, we propose a method to improve the accuracy of trajectory optimization for dynamic robots with intermittent contact by using orthogonal collocation. Until recently, most trajectory optimization methods for systems with contacts employ mode-scheduling, which requires an a priori knowl
Transient locomotion is still poorly understood in terms of planning and implementation on robotic platforms, with most research concentrated on steady-state motion. In this letter, we investigate optimal rapid acceleration (positive and negative) maneuvers of a planar numerical quadruped and biped
The natural world hosts a few mammals that display both a high degree of agility and speed. However these animals have complex leg morphologies. Robot designers are thus faced with the dilemma of which morphology to employ when designing the next generation of agile legged robots. Thus this letter p…
Rapid acceleration manoeuvres have been avoided by researchers due to the aperiodicity and complexities of this motion. With the recent improvements in optimal control, this paper presents the first examination of a biped completing a time optimal sprint, starting and ending in rest, to provide insi…
For fast-moving legged robots, the ability to stop rapidly is essential if they are to move safely through unpredictable environments. There is a trade-off between stability and rapidity however, as the forces that slow the robot down also tend to cause a toppling moment. This paper examines how rap…
An actuated spine appears to be a critical component for maneuverability in quadruped animals. However, robotic systems have yet to capitalize on this mechanism. This research compares three different spine morphologies in the planar case, namely the rigid, revolute and prismatic spine. Using a wide…
Animals are able to accelerate rapidly from rest with incredible dexterity but these transient motions are poorly understood. Here we present the first examination of the time optimal behaviour of a quadruped sprinting from rest. We develop a planar multi-body model and employ modern trajectory opti…
This paper presents a novel approach to achieving aerial pitch righting in a mobile robot, inspired by the draglines used by jumping spiders. We developed and simulated a mathematical model of the spider during the aerial phase of its jump to gain further insight into the factors affecting the pitch…