David Kohanbash

Design and field experimentation of a prototype Lunar prospector

Scarab is a prototype rover for Lunar missions to survey resources in polar craters. It is designed as a prospector that would use a deep coring drill and apply soil analysis instruments to measure the abundance of elements of hydrogen and oxygen and other volatiles including water. Scarab’s chassis can adjust the wheelbase and height to stabilize its drill in contact with the ground and can also adjust posture to better ascend and descend steep slopes. This enables unique control of posture when moving and introduces new planning issues. Scarab has undergone field testing at Lunar-analog sites in Washington and Hawaii in an effort to quantify and validate its mobility and navigation capabilities. We report on results of the experiments in slope ascent and descent and in autonomous kilometer-distance navigation in darkness.

Design and Experimentation of a Rover Concept for Lunar Crater Resource Survey

Scarab is a prospecting rover for lunar missions to survey resources, particularly water ice, in polar craters. It is designed for the deployment of a deep coring drill and for transport of soil analysis instruments. Its chassis can transform to stabilize the drill in contact with the ground and can also adjust to ascend and descent steep slopes of unconsolidated soil. Additional features include a compact body for better thermal regulation, laser scanners for dark navigation, and power system designed for a persistent, low-capacity source. Scarab was prototyped at the Robotics Institute, has undergone mobility testing in soils laboratories and field sites leading up to an integrated system test including the RESOLVE drill and instrument suite at the PISCES lunar analogue site on Mauna Kea in Hawaii.

Field Experiments in Mobility and Navigation with a Lunar Rover Prototype

Scarab is a prototype rover for lunar missions to survey resources, particularly water ice, in polar craters. It is designed as a prospector that would use a deep coring drill and apply soil analysis instruments. Its chassis can transform to stabilize its drill in contact with the ground and can also adjust posture to ascend and descent steep slopes. Scarab has undergone field testing at lunar analogue sites in Washington and Hawaii in an effort to quantify and validate its mobility and navigation capabilities. We report on results of experiments in slope ascent and descent and in autonomous kilometer-distance navigation in darkness.

A Safety Architecture for Autonomous Agricultural Vehicles

Sixty years after debuting in industrial environments, robots are making their way into our everyday life. Farmers have benefited for some time from self-guided machinery including combines and harvesters. More recently, multi-purpose autonomous vehicles have started to be deployed in orchards, groves, nurseries, and other agricultural environments to automate or augment operations such as pruning, thinning, harvesting, mowing, and spraying. Successful commercialization of such vehicles will depend heavily on them being able to operate safely and avoid accidents involving humans, animals, trees, and farm infrastructure. We propose a safety architecture to guide the design and deployment of autonomous agricultural vehicles and their introduction into production environments. The architecture spans the three elements that, combined, should ensure safe operation over a wide spectrum of applications: (1) a distributed, sensor-based, intelligent decision-making system that coordinates and guides fleets of vehicles in and around orchards and other agricultural environments; (2) multimodal interfaces for workers to interact with the vehicles using natural language, gestures, and portable devices; (3) a comprehensive regulatory framework of standards for vehicle safety that covers everything from basic robotic technology to advanced behaviors. In this paper we present the fundamental aspects of this agricultural robotic safety architecture. We illustrate its application with examples of autonomous agricultural vehicles we developed in the past that lay down the path toward full introduction of safe, intelligent machines in agricultural production environments.

Wireless Sensor Networks and Actionable Modeling for Intelligent Irrigation

Wireless Sensor Networks (WSNs) are emerging as an invaluable tool in agriculture. Current WSNs are good at reporting sensor data and many provide simple tools for viewing the data. The current approach assumes that growers are familiar with how the data should look and they are trained to use the data. This work extends the usage of WSNs to provide growers with actionable results based on the data. We are currently implementing plant physiological models for specialty crops into the CMU SensorWeb system. These models predict water usage, allowing growers to precisely control irrigation schedules. The sensor nodes used in this work also have onboard control functionality for automating crop irrigation based on the model’s output. In this paper we present a framework for integrating models into WSNs and initial field results from this model driven approach.

DSRP: Distributed SensorWeb Routing Protocol

We propose a new multi-hop routing protocol for wireless sensor networks, suited for monitoring and control applications. The aim of this research is to adapt flat and hierarchical architectures to create a new hybrid that draws on current protocol theories. The protocol uses a hybrid network structure to achieve scalability and is source initiated along with time driven reporting to reduce the number of packet transmissions. The protocol incorporates a link quality estimation algorithm, which enables only the nodes with high quality symmetric links to be chosen for routing. Route selection is calculated using both hop count and link quality as routing metrics. The protocol is also designed such that it is computationally simple, reliable, energy aware, does not impose any special hardware prerequisites and most importantly credible. Its credibility was verified by performing a series of field tests in a real world operating environment.

Plowing for Rover Control on Extreme Slopes

Planetary rovers are increasingly challenged to negotiate extreme terrain. Early destinations have been benign to preclude risk, but canyons, funnels, and newly discovered holes present steep slopes that defy tractive descent. Steep craters and holes with unconsolidated material pose a particularly treacherous danger to modern rovers. This research explores robotic braking by plowing, a novel method for decreasing slip and improving mobility while driving on steep unconsolidated slopes. This technique exploits subsurface strength that is under, not on, weak soil. Starting with experimental work on Icebreaker, a tracked rover, and concluding with detailed plow testing in a wheel test-bed the plow is developed for use. This work explores using plows of different diameters and at different depths as well as the associated braking force. By plowing the Icebreaker rover can successfully move on a slope with a high degree of accuracy thereby enabling science targets on slopes and crater walls to now be considered accessible.

Irrigation Control Methods for Wireless Sensor Network

Wireless Sensor Networks (WSNs) are an invaluable tool in agriculture. Currently these systems are good at reporting and logging data. Some recent work has focused on making the data useful and actionable. The next step in WSNs is the ability to automatically use that data for irrigation control. This can help minimize labor and reduce water usage.

Autonomous Robot for Small-Scale NFT Systems

Hydroponics is currently a very successful technique for growing crops like lettuce and results in cleaner, healthier and cheaper yield. Requirement of periodic labor and a systematic arrangement of plants make it a good candidate for automation. Large-scale systems that automate the growing of lettuce already exist, but these require large capital investments and large footprints that limit the use to only large-scale growers. Our goal is to develop inexpensive robotic systems that a small-medium scale grower can afford to implement and that are compatible with the existing infrastructure. The robot is designed to pick and place plants and seedlings from one spot to other on an Nutrient Film Technique (NFT) system autonomously. We describe the design and construction of the gantry-based robot with an arm that moves on rails. By using this approach a single robot can serve a large number of plants in a greenhouse. We also describe algorithms for perception, robot path planning, and manipulation of densely planted leafy crops using a camera and Microsoft Kinect 3D imaging system. Results are demonstrated experimentally using a small AmHydro NFT system we have constructed in our lab.

Slope Descent using Plowing to Minimize Slip for Planetary Rovers

Steep slopes of unconsolidated material at planetary destinations of recent interest, such as craters and skylights, defy descent by rovers due to uncontrolled slip. This work proposes a novel method based on braking by plowing to arrest slip during descent maneuvers on planetary terrains. The method covers two fundamental maneuvers: direct descent and point-turning. For direct descent, an automatic control system estimates slip through visual odometry and actuates a plow accordingly. For point-turning, the plow is engaged as a point of rotation. Experimental results showed that the slip control system for direct descent kept slip within ±5% for slopes as steep as 31i¾? and for different commanded driving speeds. In the point-turning tests, downhill displacement was less than 0.08i¾?m on inclinations up to 30i¾?. Thus, a plowing policy was developed that allows precise descent on extreme slopes by minimizing slip. As a result, this work expands current rover mobility and control capabilities.