Curtis Collins

An integrated coring and caching concept

An integrated concept for core sample acquisition and caching with potential application to a Mars caching mission has been developed. The concept utilizes a five degree-of-freedom manipulator arm to deploy a rotary percussive coring tool as well as to provide alignment, feed, and preload for the tool. The tool provides coring, core break-off, core retention and bit capture and release for bit change-out. In this concept, a sample is acquired directly into its sample tube in the coring bit and bit change-out is used to transfer the sample to the caching subsystem where it is sealed and stored. 1 2

Experimental results of rover-based coring and caching

Experimental results are presented for experiments performed using a prototype rover-based sample coring and caching system. The system consists of a rotary percussive coring tool on a five degree-of-freedom manipulator arm mounted on a FIDO-class rover and a sample caching subsystem mounted on the rover. Coring and caching experiments were performed in a laboratory setting and in a field test at Mono Lake, California. Rock abrasion experiments using an abrading bit on the coring tool were also performed. The experiments indicate that the sample acquisition and caching architecture is viable for use in a 2018 timeframe Mars caching mission and that rock abrasion using an abrading bit may be feasible in place of a dedicated rock abrasion tool.1 2

ATHLETE mobility performance with active terrain compliance

The All-Terrain Hex-Limbed Extra-Terrestrial Explorer (ATHLETE) is a modular, heavy-lift vehicle being developed to support NASA operations on the lunar surface. This agile system consists of a symmetrical arrangement of six limbs, each with six articulated degrees of freedom and a powered wheel. The design enables transport of bulky payloads over a wide range of terrains and is envisioned as a tool to mobilize habitats, power generation equipment, and other supplies in for long-range lunar exploration and lunar outpost construction. The first-generation prototype transports payloads of up to 300 kg in terrestrial testing, with flight models projected to carry at least 15 metric tons in a lunar gravity environment. 1 2

Stiffness Modeling and Force Distribution for the All-Terrain Hex-Limbed Extra-Terrestrial Explorer (ATHLETE)

The All-Terrain Hex-Limbed Extra-Terrestrial Explorer (ATHLETE) is a six limbed vehicle designed for both mobility and manipulation. Each limb has six active degrees-of-freedom, plus a powered wheel. Along the axis if each wheel is a mechanical interface that allows the integration of tools that can make use of the wheel actuator. Thus each limb can act as a leg for walking, an active suspension for a driven wheel, or a manipulator with an actuated tool. Fundamental to the operation of the system is the ability to control limb pose, overall body pose, as well as regulate limb forces. Joint torques are estimated from the difference between the incremental and absolute encoder readings on each joint. Forces are then computed from joint torques and force regulation is performed by modifying the limb positions. Force regulation allows the vehicle to lift larger payloads and traverse terrain while actively complying to terrain features.

Vision-guided self-alignment and manipulation in a walking robot

One of the robots under development at the NASAs Jet Propulsion Laboratory (JPL) is the limbed excursion mechanical utility robot, or LEMUR. Several of the tasks slated for this robot require computer vision, as a system, to interface with the other systems in the robot, such as walking, body pose adjustment, and manipulation. This paper describes the vision algorithms used in several tasks, as well as the vision-guided manipulation algorithms developed to mitigate mismatches between the vision system and the limbs used for manipulation. Two system-level tasks are described, one involving a two meter walk culminating in a bolt-fastening task and one involving a vision-guided alignment ending with the robot mating with a docking station

Test and validation of the Mars Science Laboratory Robotic Arm

The Mars Science Laboratory Robotic Arm (RA) is a key component for achieving the primary scientific goals of the mission. The RA supports sample acquisition by precisely positioning a scoop above loose regolith or accurately preloading a percussive drill on Martian rocks or rover-mounted organic check materials. It assists sample processing by orienting a sample processing unit called CHIMRA through a series of gravity-relative orientations and sample delivery by positioning the sample portion door above an instrument inlet or the observation tray. In addition the RA facilitates contact science by accurately positioning the dust removal tool, Alpha Particle X-Ray Spectrometer (APXS) and the Mars Hand Lens Imager (MAHLI) relative to surface targets. In order to fulfill these seemingly disparate science objectives the RA must satisfy a variety of accuracy and performance requirements. This paper describes the necessary arm requirement specification and the test campaign to demonstrate these requirements were satisfied.

In-situ operations and planning for the Mars Science Laboratory Robotic Arm: The first 200 sols

The Robotic Arm (RA) has operated for more than 200 Martian solar days (or sols) since the Mars Science Laboratory rover touched down in Gale Crater on August 5, 2012. During the first seven months on Mars the robotic arm has performed multiple contact science sols including the positioning of the Alpha Particle X-Ray Spectrometer (APXS) and/or Mars Hand Lens Imager (MAHLI) with respect to rocks or loose regolith targets. The RA has supported sample acquisition using both the scoop and drill, sample processing with CHIMRA (Collection and Handling for In- Situ Martian Rock Analysis), and delivery of sample portions to the observation tray, and the SAM (Sample Analysis at Mars) and CHEMIN (Chemistry and Mineralogy) science instruments. This paper describes the planning and execution of robotic arm activities during surface operations, and reviews robotic arm performance results from Mars to date.

Planetary Sample Caching System Design Options

Potential Mars Sample Return missions would aspire to collect small core and regolith samples using a rover with a sample acquisition tool and sample caching system. Samples would need to be stored in individual sealed tubes in a canister that could be transfered to a Mars ascent vehicle and returned to Earth. A sample handling, encapsulation and containerization system (SHEC) has been developed as part of an integrated system for acquiring and storing core samples for application to future potential MSR and other potential sample return missions. Requirements and design options for the SHEC system were studied and a recommended design concept developed. Two families of solutions were explored: 1)transfer of a raw sample from the tool to the SHEC subsystem and 2)transfer of a tube containing the sample to the SHEC subsystem. The recommended design utilizes sample tool bit change out as the mechanism for transferring tubes to and samples in tubes from the tool. The SHEC subsystem design, called the Bit Changeout Caching(BiCC) design, is intended for operations on a MER class rover.

Accuracy Analysis and Validation of the Mars Science Laboratory (MSL) Robotic Arm

The Mars Science Laboratory (MSL) Curiosity Rover is currently exploring the surface of Mars with a suite of tools and instruments mounted to the end of a five degree-of-freedom robotic arm. To verify and meet a set of end-to-end system level accuracy requirements, a detailed positioning uncertainty model of the arm was developed and exercised over the arm operational workspace. Error sources at each link in the arm kinematic chain were estimated and their effects propagated to the tool frames. A rigorous test and measurement program was developed and implemented to collect data to characterize and calibrate the kinematic and stiffness parameters of the arm. Numerous absolute and relative accuracy and repeatability requirements were validated with a combination of analysis and test data extrapolated to the Mars gravity and thermal environment. Initial results of arm accuracy and repeatability on Mars demonstrate the effectiveness of the modeling and test program as the rover continues to explore the foothills of Mount Sharp.Copyright

A Sample Caching Concept for Planetary Missions

A sample caching subsystem (SCS) concept that provides transfer and storage of core and soil samples for planetary missions has been developed. The SCS could be carried on a rover and a rover arm-mounted coring tool could acquire samples and deposit the samples in the SCS. The SCS would transfer the samples into a sample container, with each sample in a separate sleeve. Important to the SCS design is the ability to seal each sleeve, and the sample with it, to isolate it from other samples and from the external environment. Sealing of the samples will allow for maintaining the integrity of organic materials over many years thereby allowing the samples to be analyzed in later missions or after a return trip to Earth.