Watching grass grow: long-term visual navigation and mission planning for autonomous biodiversity monitoring

We describe a challenging robotics deployment in a complex ecosystem to monitor a rich plant community. The study site is dominated by dynamic grassland vegetation and is thus visually ambiguous and liable to drastic appearance change over the course of a day and especially through the growing season. This dynamism and complexity in appearance seriously impact the stability of the robotics platform, as localisation is a foundational part of that control loop, and so routes must be carefully taught and retaught until autonomy is robust and repeatable. Our system is demonstrated over a 6-week period monitoring the response of grass species to experimental climate-change manipulations. We also discuss the applicability of our pipeline to monitor biodiversity in other complex natural settings

Characterization and Modeling of Rotational Responses for an Oscillating Foil Underwater Robot

Abstract- In order to better understand the behavior of the underwater robot developed at our laboratory, a simple but relatively good model of the underwater behavior of the robot had to be developed. In order to be useful for model-based control techniques onboard the robot, the model had to have low computing requirements, yet be complex enough to capture the transient response of the robot. To achieve this, a system identification approach was taken by first capturing the robot response to various inputs, and then matching them to a simple model

A Visual Servoing System for an Aquatic Swimming Robot

This paper describes a visual servoing system for an underwater legged robotic system named AQUA and initial experiments with the system performed in the open sea. A large class of significant applications can be leveraged by allowing such a robot to follow a diver or some other moving target. The robot uses a suite of sensing technologies, primarily based on computer vision, to allow it to navigate in shallow-water environments. The visual servoing system described here allows the robot to track and follow a given target underwater. The servo package is made up of two distinct parts: a tracker and a feedback controller. The system has been evaluated in the sea water and under natural lighting conditions. The servo system has been tested underwater, and with minor modifications the system can be used while the robot is walking on the ground as well

Towards a dynamic actuator model for a hexapod robot

We describe a model predicting the output torque of the battery-amplifier-actuator-gear combination used on the hexapod robot RHex, based on requested PWM (Pulse-Width-Modulation) duty cycle to the amplifier, battery voltage, and motor speed. The model is broken into independent components, each experimentally validated: power source (battery), motor amplifier, motor, and (planetary) gear. The resulting aggregate model shows <6 % Full Scale RMS error in predicting output torque in the first quadrant of operation (positive torques). Understanding the key ingredients and the attainable accuracies of torque production models in our commonly used battery-amplifier-actuator-gear combinations is critical for mobile robots, in order to minimize sensing, and thus space, size, weight, power consumption, failure rate, and cost of mobile robots

A Visually Guided Swimming Robot

We describe recent results obtained with AQUA, a mobile robot capable of swimming, walking and amphibious operation. Designed to rely primarily on visual sensors, the AQUA robot uses vision to navigate underwater using servobased guidance, and also to obtain high-resolution range scans of its local environment. This paper describes some of the pragmatic and logistic obstacles encountered, and provides an overview of some of the basic capabilities of the vehicle and its associated sensors. Moreover, this paper presents the first ever amphibious transition from walking to swimming

AQUA: An aquatic walking robot

Abstract – This paper describes an underwater walking robotic system being developed under the name AQUA, the goals of the AQUA project, the overall hardware and software design, the basic hardware and sensor packages that have been developed, and some initial experiments. The robot is based on the RHex hexapod robot and uses a suite of sensing technologies, primarily based on computer vision and INS, to allow it to navigate and map clear shallow-water environments. The sensor-based navigation and mapping algorithms are based on the use of both artificial floating visual and acoustic landmarks as well as on naturally occurring underwater landmarks and trinocular stereo. Keywords-autonomous robot, aquatic robot, robotic sensing I

The AQUA aquatic walking robot

Based on the RHHex hexapod robot, the AQUA robot is an aquatic robot that swims via the motion of its legs, rather than using thrusters and control surfaces for propulsion. Through an appropriate set of gaits, the AQUA vehicle is capable of five-degree-of-freedom motion in the open water, it can swim along the surface and it can walk along the seabed. The vehicle itself is augmented with a variety of sensors that can be used to estimate the robot's position with respect to local visual features as well as a global frame of reference. Here we describe the basic vehicle design along with some of the sensing and localization projects that are currently underway within the project