Roger D. Quinn

Biologically based distributed control and local reflexes improve rough terrain locomotion in a hexapod robot

Distributed control and local leg reflexes enable insects to cope easily with terrain that would defeat many legged robots. An insect-like hexapod robot incorporating biologically based control effectively responded to mechanical perturbations using active and passive compliance and a local stepping reflex. An elevator reflex and a searching reflex addressed unexpected obstacles and loss of support, respectively. The robot exhibited a range of gaits using stick-insect-based distributed control mechanisms and negotiated irregular, slatted and compliant surfaces with this biologically based control strategy.

Application of evolved locomotion controllers to a hexapod robot

In previous work, we demonstrated that genetic algorithms could be used to evolve dynamical neural networks for controlling the locomotion of a simulated hexapod agent. We also demonstrated that these evolved controllers were robust to loss of sensory feedback and other peripheral variations. In this paper, we show that these locomotion controllers, evolved in simulation, are capable of directing the walking of a real six-legged robot, and that many of the desirable properties observed in simulation carry over directly to the real world. In addition, we demonstrate that these controllers are amenable to hardware implementation and can thus be easily embodied within the robot.

A small wall-walking robot with compliant, adhesive feet

The ability to walk on surfaces regardless of the presence or direction of gravity can significantly increase the mobility of a robot for both terrestrial and space applications. Insects and geckos can provide inspiration for both novel adhesive technology and for the locomotory mechanisms employed during climbing. For this work, Mini-Whegs/spl trade/, a small quadruped robot that uses wheel-legs for locomotion, was altered to explore the feasibility of scaling vertical surfaces using compliant, adhesive feet. Modifications were made to reduce its weight, and its legs were redesigned to enable its feet to better attach and detach from the substrate, mimicking homologous actions observed in animals. The resulting vehicle is self-contained, power-autonomous, and weighs only 87 grams. Using pressure-sensitive tape, it is capable of walking up a vertical surface, walking upside-down along an inverted surface, and transitioning between orthogonal surfaces.

Abstracted biological principles applied with reduced actuation improve mobility of legged vehicles

Applying abstracted biological locomotion principles with reduced actuation can result in an energetic vehicle with greater mobility because a vehicle with the fewest number of motors can have the highest power to mass ratio. One such hexapod is Whegs II, which benefits from abstracted cockroach locomotion principles and has just one motor for propulsion. Similar to Whegs I, it nominally runs in a tripod gait and passive mechanisms enable it to adapt its gait to the terrain. One of the drawbacks of Whegs I is that it cannot change its body posture. Cockroaches pitch their bodies up in anticipation of climbing a step to enable their front legs to reach higher. They also flex their bodies down while climbing to permit their front legs to maintain contact with the substrate. A bidirectional servo-driven body flexion joint has been implemented in Whegs II to accomplish both of these behaviors. It is shown to be highly mobile and energetic.

A distributed neural network architecture for hexapod robot locomotion

We present fully distributed neural network architecture for controlling the locomotion of a hexapod robot. The design of this network is directly based on work on the neuroethology of insect locomotion. Previously, we demonstrated in simulation that this controller could generate a continuous range of statically stable insect-like gaits as the activity of a single command neuron was varied and that it was robust to a variety of lesions. We now report that the controller can be utilized to direct the locomotion of an actual six-legged robot, and that it exhibits a range of gaits and degree of robustness in the real world that is quite similar to that observed in simulation.

Development of a peristaltic endoscope

A device that could locomote through curving and tortuous spaces would find many applications in medicine and in industry. Invertebrates such as earthworms and leeches can solve this problem using peristaltic locomotion. We describe a device consisting of three braided pneumatic actuators in series that can successfully locomote peristaltically. The device can locomote forwards and backwards in elevated and curving tubes, and with a plastic sheath around it.

A Small, Insect-Inspired Robot that Runs and Jumps

This paper describes the latest additions to the Mini-Whegs™ series of small robots. These new robots are fully enclosed, measure 9 to 10 cm long, and range in weight from 90 g to 190 g. Mini-Whegs™ 7 weighs less than 90 g, but can run at over three body-lengths per second and surmount 3.8 cm high obstacles. The most recent iteration, Mini-Whegs™ 9J, incorporates fully independent running and jumping modes of locomotion. The controllable jumping mechanism allows it to leap as high as 18 cm.

Equations of motion for maneuvering flexible spacecraft

This paper is concerned with the derivation of the equations of motion for maneuvering flexible spacecraft both in orbit and in an earth-based laboratory. The structure is assumed to undergo large rigid-body maneuvers and small elastic deformations. A perturbation approach is presented in which the quantities defining the rigid-body maneuver are regarded as the unperturbed motion and the elastic motions and deviations from the rigid-body motions are regarded as the perturbed motion. The perturbation equations are linear, non-self-adjoint, and with time-dependent coefficients. A maneuver force distribution exciting the least amount of elastic deformation of the spacecraft is developed. Numerical results highlight the vibration caused by rotational maneuvers.

Parallel Complementary Strategies for Implementing Biological Principles into Mobile Robots

Our goal is to use intelligent biological inspiration to develop robots that capture the capacity of animals to traverse complex terrain. We follow two distinct but complementary strategies to meet this goal. In one, we have produced a series of robots that have mechanical and control designs increasingly more similar to those of a cockroach. The leg designs of these robots ensure that they can generate movements used by the cockroach to walk and climb over a range of objects. However, in order to take advantage of these complex designs, we must first solve difficult problems in actuation, proprioception and control. The second parallel strategy seeks to capture the principles of biological movement, but in an abstract form that does not require complex platforms. Following the second strategy, we designed and built two new robots that each use only one propulsion motor to generate a nominal tripod gait. Gait changes similar to those used by the animal are accomplished through passive mechanisms. Rearing movements in anticipation of climbing are accomplished by way of a body flexion joint, which also allows the robot to avoid high-centering. The parallel development of these robotic lines provides the best of both worlds. The multi-segmented leg designs will ultimately be more versatile and agile than the abstracted line, but will take more effort to perfect. The simplified line provides short-term solutions that can be deployed immediately and confirm, in principle, the value of biological properties for complex locomotion.

Robustness of a distributed neural network controller for locomotion in a hexapod robot

The robustness of a distributed neural-network controller for locomotion based on insect neurobiology has been used to control a hexapod robot. The robustness of the controller is investigated experimentally. Disabling any single sensor, effector, or central component did not prevent the robot from walking. Furthermore, statically stable gaits could be established using either sensor input or central connections. Thus, a complex interplay between central neural elements and sensor inputs is responsible for the robustness of the controller and its ability to generate a continuous range of gaits. These results suggest that biologically inspired neural-network controllers may be a robust method for robotic control. >