Marco Santello, School of Biological and Health Systems Engineering, Arizona State University
"Control and adaptation of dexterous manipulation: Integration of predictive and reactive sensorimotor mechanisms."
Motor control and adaptation rely on complex interactions between reflexes and anticipatory control mechanisms. Through repeated exposure to mechanical interactions with the environment, the sensorimotor system learns to expect sensory consequences arising from motor actions, whereas reflexes would intervene when a discrepancy occurs between expected and actual sensory feedback. We have tested this theoretical framework in the context of grasping and dexterous manipulation using tasks that allow subjects to explore and choose relations between digit forces and positions. We have proposed that successful execution of manipulation of object grasped at self-chosen contacts likely requires prediction and sensing of digit placement for modulating digit force distribution. In contrast, grasping at the same constrained contacts can rely on sensorimotor memories of digit forces built through previous manipulations. We have tested this proposition by using behavioral experimental approaches to identify mechanisms underlying learning and execution of dexterous manipulation, and non-invasive brain stimulation to determine the role of specific brain areas within the cortical grasp network. I will review experimental evidence supporting the following notions: (1) interactions with objects grasped at unconstrained versus constrained contacts are mediated by different sensorimotor mechanisms, and (2) high-level representations acquired through sensorimotor adaptation allow the CNS to compensate for motor variability. I will conclude my talk with an overview of potential applications of this work to robotic grasping and prosthetics.
George Lauder, Museum of Comparative Zoology, Harvard University,
Robotic models of aquatic locomotion have many advantages over studying live animals, including the ability to manipulate and control individual morphological or kinematic factors that affect performance, substantially easier measurement of locomotor forces and torques, and the ability to abstract complex organismal designs into simpler components. Such simplifications, while not without their drawbacks, facilitate interpretation of how individual traits alter swimming performance and the discovery of underlying physical principles. In this presentation I will discuss the use of a variety of robotic models for fish locomotion, ranging from simple flexing panels to complex biomimetic designs incorporating flexible, actively moved, fin rays on multiple fins. Mechanical devices have provided great insight into the dynamics of aquatic propulsion and, integrated with studies of locomotion in freely-swimming fishes, promise new insights into how fishes move through the water.
Daniel Goldman, School of Physics, Georgia Institute of Technology
"Swimming lizards, sidewinding snakes, and digging ants: animal and robophysical experiments reveal principles of effective environmental interaction"
Using three examples, I will discuss how animal experiments coupled to ``robophysical” modeling enables advances in biology and soft matter physics, and creates more life-like robots. First, 1) to illustrate how this approach can lead to new biological control templates and soft matter physics (when models of the environment are not available), I will discuss our studies of subsurface sand-swimming. We discovered that the sand-swimming sandfish lizard [Maladen et al, Science, 2009] uses a travelling wave of body undulation to swim through dry granular media. Robot experiments and computational models have enabled us to understand how the animal controls its gait to maximize speed and minimize energy use during locomotion. These models have also given us confidence to develop a new class of continuum models (based on resistive force theory) which show promise for theoretical explanation of locomotion in complex environments. Next 2) to demonstrate how the discovery of basic locomotor principles can advance real-word robots, I will next discuss our studies of the locomotion of sidewinding snakes on dry granular media [Marvi et al, Science 2014; Astley et al, PNAS, 2015]. I will show how, based on animal experiments performed at Zoo Atlanta (in collaboration with Dr. Joseph Mendelon III), we have used a multi-module robot (in collaboration with Prof. Howie Choset’s group at Carnegie Mellon) to reveal how the snakes modulate orthogonal body waves (control templates) to manipulate the substrate (e.g. remain below the yield stress) to climb sandy slopes and perform turning maneuvers. Finally, 3) to illustrate the benefits of this approach in multi-agent systems, I will discuss collective soil excavation by social organisms (fire ants) in crowded and confined conditions [Gravish et al, Interface 2012; Gravish et al, PNAS 2013; Monaenkova, J. Exp. Biol. 2015]. Theoretical models inspired by measurements of colony members’ activity during excavation of soil “pellets” in narrow tunnels indicate that the digging fire ant workload distribution enables high performance in crowded, confined conditions. We test the theory using fully autonomous digging robot models. An aggressive digging strategy yields benefits as worker number increases (in terms of the rate of tunnel growth and energy use) but these benefits diminish when the number of workers exceeds a certain value; the biological workload distribution buffers excavation efficacy against crowding. In summary, I emphasize the need for detailed systematic laboratory robot experiments (what we call robophysics) to provide models for biology as well as to improve real-world robot performance.
Akio Ishiguro, Research Institute of Electrical Communication, Tohoku University
"Toward Understanding the Inter-limb Coordination Mechanism in Legged Locomotion"
Animals are able to exhibit surprisingly adaptive and resilient behavior in real time under real world constraints. Such movements are achieved via spatiotemporal coordination of a large number of bodily degrees of freedom in response to the environment. Clarifying the control principle underlying this remarkable ability of animals allow us to understand biological systems more deeply as well as to construct truly adaptive robot that could not be realized solely by the conventional robotics methodology. We have so far been investigating the control principles underlying various types of animal locomotion, ranging from amoeboid locomotion to human bipedal locomotion, from the viewpoint of decentralized control. In this talk, I will mainly introduce the latest results of our robotic case study on the interlimb coordination mechanism for quadruped locomotion. I will then show how this model could be applied to understanding the interlimb coordination mechanism in legged locomotion with different number of legs.
"Motion Science of Animals and Machines – An Exemplar of Convergence"
The motion science of animals and machines is an exemplar of convergence integrating knowledge, tools, and ways of thinking and interacting from biology, physics, applied mathematics, and engineering to form a comprehensive synthetic framework for addressing scientific and societal challenges that exist at the interfaces of many traditional disciplines. Advancements embrace the challenges inherent in the approaches to biological inspiration, physical modeling, optimality versus satisficing assumptions, theory versus empirical measurements, spatial and temporal variation, simple versus representative models, selection of model animals or extreme performers, use of enabling technologies, and effective infrastructures for collaboration among disciplines, universities and businesses. In part, our admiration of animals relates to their robustness - the ability to withstand perturbations in structure without change in function - and includes concepts such as modularity, redundancy, hierarchical and heterarchical organizational structures, damage resistant, fail-safe and fault tolerant designs, self-repair, learning, adaptation, anticipation and creativity. Although biology offers enormous potential for novel designs, we must realize that natural selection is not engineering and nature is severely constrained by evolution, development, multi-functionality and sexual selection. Increasingly, key enablers, novel organizational structures, and synergies with businesses will determine the rate and direction of motion science in the future. The novel science, mathematics, and robots emerging from motion science will continue to lead to new relationships of natural and human technologies.