{"project":{"acronym":"","projectId":88486,"title":"Exploration of Extreme Terrain Using a Polyhedral Rover","primaryTaxonomyNodes":[{"taxonomyNodeId":10618,"taxonomyRootId":8816,"parentNodeId":10616,"level":3,"code":"TX04.2.2","title":"Above-Surface Mobility","definition":"Above-surface mobility provides longer range and greater coverage of planetary surfaces at a more rapid pace, independent of the terrain topography and in substantial gravity and extreme heat or cold.","exampleTechnologies":"Ballistic systems, static-lift systems, dynamic-lift systems, power-lift systems","hasChildren":false,"hasInteriorContent":true}],"startTrl":2,"currentTrl":3,"endTrl":3,"benefits":"Development of a reliable, power-efficient and terrain-adaptable autonomous polyhedral rover will enable exploration of previously unexplored areas of celestial bodies in our solar system such as the surface of Europa or Enceladus and the currently inaccessible valleys, crags, and rock beds on Mars. Exploring these areas could help discover water content, microbes, mineral content, among others. The rover would also be ideal for supporting manned missions, like the planned mission to Mars in the 2030s and the mission to an asteroid in 2025. It could travel to the celestial body ahead of time and explore potential landing zones to ensure they are safe. After the arrival of the mission, the rover could carry supplies for the astronauts and help with exploration. ","description":"Exploring celestial bodies with extreme terrains in our solar system, like Mars, Europa, Enceladus, and asteroids, are of great importance to NASA because these bodies are often rich with scientific data (TA 4.2.1, TA 4.2.4). In the past, many bodies have been inaccessible to exploration missions because current rover technology is not effective on these terrains. To address this problem, my research will focus on developing an autonomous polyhedral rover that has many advantages over current rover technology. It has three main features that make it especially effective for navigating extreme terrains. First, the rover will use an internal momentum control system to roll from side to side for locomotion. The momentum control system will never come in contact with the environment, eliminating the risk of actuator failure from terrain interaction, thus increasing the reliability of the rover. Second, the momentum control system will generate enough torque to quickly navigate obstacles like rocks and steep inclines. Third, the rover will have spikes or gripping pads on the corners of the chassis, allowing it to get traction on almost any surface. There are 4 stages to the completion of the rover: Stage 1: Optimize momentum control system arrays with respect to torque output, power usage, and mass. Create generalized control algorithms for the optimized arrays, taking into account the power usage and dynamics of the momentum control system and the dynamics of the chassis (TRL 1-2). Stage 2: Create a path planning algorithm that is optimized for power generation and usage, and travel time. This algorithm will use the control algorithm created in Stage 1 to model the power usage and dynamics of the momentum control system. This algorithm will model the traction between the chassis spikes and the terrain. It will also model the rover's power generation according to the sun's position and the shading of the solar cells. This algorithm will be generalized to various polyhedral chassis shapes and momentum control system array configurations (TRL 1-2). Stage 3: Simulate the performance of various combinations of chassis shapes and momentum control system arrays using the path planning algorithm created in Stage 2 (TRL 3). Stage 4: Choose the best performing rover for a selected mission using the simulation in Stage 3. Build the selected rover and compare its actual performance to the simulated performance. I will use Cornell University's Space System Design Studio for testing and fabrication (TRL 3-7). The final rover can explore many celestial bodies in our solar system. The power- and torque-efficient internal momentum control system and the novel chassis design make this rover reliable, power-efficient and terrain-adaptable, allowing for a long mission lifetime. The rover could explore previously unexplored areas, like the surface of Europa and Enceladus. It could also explore currently inaccessible valleys, crags, and rock beds on Mars. Exploring these areas could help discover water content, microbes, mineral content, among others. The rover would also be ideal for supporting manned missions, like the planned mission to Mars in the 2030s and the mission to an asteroid in 2025. It could travel to the celestial body ahead of time and explore potential landing zones to ensure they are safe. After the arrival of the mission, the rover could carry supplies for the astronauts and help with exploration. Additionally, my work could help the development of polyhedral rovers for future missions. I will generalize all of the algorithms and simulations to other chassis shape, momentum control array configurations, and terrains, allowing future projects to quickly iterate through rover designs to select the optimal robot for a specific mission.","startYear":2016,"startMonth":8,"endYear":2019,"endMonth":12,"statusDescription":"Completed","principalInvestigators":[{"contactId":319695,"canUserEdit":false,"firstName":"Mason","lastName":"Peck","fullName":"Mason A Peck","fullNameInverted":"Peck, Mason A","middleInitial":"A","primaryEmail":"mason.a.peck@nasa.gov","publicEmail":true,"nacontact":false}],"programDirectors":[{"contactId":84634,"canUserEdit":false,"firstName":"Claudia","lastName":"Meyer","fullName":"Claudia M Meyer","fullNameInverted":"Meyer, Claudia M","middleInitial":"M","primaryEmail":"claudia.m.meyer@nasa.gov","publicEmail":true,"nacontact":false}],"programExecutives":[{"contactId":84634,"canUserEdit":false,"firstName":"Claudia","lastName":"Meyer","fullName":"Claudia M Meyer","fullNameInverted":"Meyer, Claudia M","middleInitial":"M","primaryEmail":"claudia.m.meyer@nasa.gov","publicEmail":true,"nacontact":false}],"programManagers":[{"contactId":183514,"canUserEdit":false,"firstName":"Hung","lastName":"Nguyen","fullName":"Hung D Nguyen","fullNameInverted":"Nguyen, Hung D","middleInitial":"D","primaryEmail":"hung.d.nguyen@nasa.gov","publicEmail":true,"nacontact":false}],"projectManagers":[{"contactId":187151,"canUserEdit":false,"firstName":"Issa","lastName":"Nesnas","fullName":"Issa A Nesnas","fullNameInverted":"Nesnas, Issa A","middleInitial":"A","primaryEmail":"issa.a.nesnas@jpl.nasa.gov","publicEmail":true,"nacontact":false}],"coInvestigators":[{"contactId":111362,"canUserEdit":false,"firstName":"David","lastName":"Sawyer Elliott","fullName":"David Sawyer Elliott","fullNameInverted":"Sawyer Elliott, David","publicEmail":false,"nacontact":false}],"website":"https://www.nasa.gov/strg#.VQb6T0jJzyE","libraryItems":[],"transitions":[{"transitionId":75947,"projectId":88486,"transitionDate":"2019-12-01","path":"Closed Out","details":"The terrains of different celestial bodies are often extreme and vary wildly; their surfaces can be icy, rocky, or sandy. In these extreme environments, traditional rovers with wheels are not the most effective means of exploring the surfaces, as seen with the NASA rover, Spirit. The 400 million-dollar rover got stuck in deep sand on the surface of Mars. After unsuccessful attempts to free it, the rover’s useful lifetime ended, because it was unable to charge its batteries. Had the rover had different means of mobility, its mission to gather scientific data may not have ended prematurely. To avoid such problems, I am developing a polyhedral rover that does not use wheels, but instead steps by rolling around from side to side. The rover is called Polyhedral Extreme Terrain Exploration Rover (PETER). To locomote, PETER uses a control moment gyroscope (CMG) array, which provides two key benefits. First, due to a phenomenon called torque amplification, small CMGs can produce large torques, enabling PETER to navigate bodies with a wide range of terrains and gravitational field strengths. Second, the CMG array is internal to the chassis, so there is no interaction between the actuators and the environment, eliminating the risk of actuator failure from terrain interaction, which occurred to Spirit’s right front wheel. PETER can be used for missions to moons and planets with extreme terrains in our solar system, like Mars, Europa, or Enceladus. Figure 1. PETER navigating Mars. To date, there has been little research on polyhedral rovers. NASA’s JPL developed one such rover called Hedgehog, which has many of the polyhedral rover traits described above. It has gripping pads at the corners and rolls from side to side. However, unlike PETER, Hedgehog uses a reaction wheel system to create movement. The MINERVA rovers are also polyhedral and roll for locomotion. However, like Hedgehog, these rovers use reaction wheels for locomotion. To expand upon the previous research, my research investigated using CMGs as the rover’s actuator. Specifically, I developed a general method for controlling PETER that enables the rover to locomote over extreme terrain with a wide array of system architectures. Additionally, I developed design principles for the rover, informing the development of a rover capable of exploring extreme terrain efficiently and predictably. In conjunction, the design principles and general control architecture enable researchers to quickly adapt PETER’s design to enable exploration of various environments and complete a wide array of missions. PETER will be able to explore extreme terrain on many celestial bodies, including Mars, Enceladus, and Europa. Furthermore, PETER could explore currently unexplored craters, valleys, and crags on Mars, which are believed to contain valuable water content information. PETER enables the exploration and gathering of scientific data from icy terrains like Europa and Enceladus. Additionally, the rover could be scaled easily to support future manned missions. It could help explore future landing areas before manned missions arrive, and carry supplies across the extreme terrains on these celestial bodies. Because bodies like these are rich with scientific potential, NASA regards terrain-adaptable rovers as an important piece of technology development (TA 4.2.1 – TA 4.2.4). This research also expands NASA’s use of CMGs beyond large spacecraft momentum control. NASA has used CMGs in two of its previous largest missions, Skylabs and the International Space Station. The general control methodologies that I have developed are applicable to a wide array of applications, including spacecraft and robotics systems, enabling higher performance control of these systems than is possible with contemporary methods. 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\tThe Space Technology Research Grants Program will accelerate the development of "push" technologies to support the future space science and exploration needs of NASA, other government agencies and the commercial space sector. Innovative efforts with high risk and high payoff will be encouraged. The program is composed of two competitively awarded components.
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