The Canadian Space Agency, in partnership with Western University and MacDonald Dettwiler and Associates, conducted a field deployment in the Utah desert in November 2015 to emulate portions of the first steps of a Mars Sample Return mission: the identification and acquisition of scientifically interesting samples. The site was selected because of its scientific relevance to certain regions on Mars, being predominantly of sedimentary nature and preserving evidence of a previous aqueous environment. Equipment being tested at the site included the CSA’s Mars Exploration Science Rover (MESR) equipped with a mini-corer and a 3D microscope mounted on a robotic arm, a suite of cameras, and a LASER range sensor. The rover was remotely controlled over a satellite link from the Canadian Space Agency headquarters in Saint-Hubert, Canada. During the 14-day mission, the rover traversed 234 meters, acquired four samples (regolith and sedimentary material), took microscopic images at every sample location, and acquired several images and 3D LIDAR scans of the site. In addition, X-Ray fluorescence, Raman spectroscopy and X-Ray diffraction measurements were taken from hand-held instruments throughout the mission. Tubed samples have been returned to the science team for analysis, along with additional hand-collected samples from the same sites to give the science team enough material to validate its sample selection strategy.

This paper presents advances in Canadian space robotics activities that were accomplished since the last overview paper presented at the i-SAIRAS 2014 conference. Different application areas are targeted to maintain Canada’s role is space robotics. These include traditional orbital robotics applications such as the provision of space manipulators and related technologies for next-generation space stations and on-orbit servicing, as well as emerging application areas for Canada such as planetary robotics. Technologies include manipulators, rovers, robotic tools and vision systems.

Modular robot manipulators have many advantages over conventional integrated robot manipulators, including flexibility, re-configurability, versatility, and low-cost with massive production. However, the lack of control precision has been a long standing drawback in MRM applications until now. In this paper, a VDC-based control and communication system using embedded FPGA (field programmable gate array) logic devices is outlined. This solution is able to push the control precision to a new level without needing joint torque measurements. A test case on a three-module robot using harmonic drives demonstrated that the ratio of the maximum position tracking error to the maximum velocity reached 0.00012 (s).

This paper provides an overview of the Canadian Space Agency’s recent developments in space robotics and their relations to the CSA Exploration Program’s most recent mission roadmaps. The roadmap is structured by destination ranging from LEO missions focusing on the usage of the International Space Station, to Lunar, Near-Earth Objects and Mars missions. For each activity thrust, the paper describes recent and on-going robotics developments of the Canadian Space Agency. These activities span the entire space from concept studies, prototype development, field-trials, all the way to space missions and commercialization.

In this paper, a networked embedded control of modular robot manipulators without using joint torque sensing is presented. The proposed solution uses an effective control and communication mechanism based on the virtual decomposition control (VDC) approach with embedded FPGA (Field Programmable Gate Array) implementation. A hierarchical master-slaves control structure is used, supported by a high speed communication data bus. The master computer handles only kinematics computation and the dynamics-based computations are all performed by individual embedded FPGA module controllers. The virtual stability of each module is ensured, resulting in the L2/L∞ stability of the entire robot. Experimental results achieved on a three-module robot manipulator using harmonic drives are presented.

In this paper we present the approach for autonomous planetary exploration developed at the Canadian Space Agency. The goal of this work is to enable autonomous navigation to remote locations, well beyond the sensing horizon of the rover, with minimal interaction with a human operator. We employ LIDAR range sensors due to their accuracy, long range and robustness in the harsh lighting conditions of space. Irregular Triangular Meshes (ITMs) are used for representing the environment, providing an accurate, yet compact, spatial representation. In this paper a novel path-planning technique through the ITM is introduced, which guides the rover through flat terrain and safely away from obstacles. Experiments performed in CSA's Mars emulation terrain, validating our approach, are also presented.

This paper describes a collection of 272 three-dimensional laser scans gathered at two unique planetary analogue rover test facilities in Canada, which offer emulated planetary terrain at manageable scales for algorithmic development. This dataset is subdivided into four individual subsets, each gathered using panning laser rangefinders on different mobile rover platforms. This data should be of interest to field robotics researchers developing rover navigation algorithms suitable for use in three-dimensional, unstructured, natural terrain. All of the data are presented in human-readable text files, and are accompanied by Matlab parsing scripts to facilitate use thereof. This paper provides an overview of the available data.

A systematic solution to precision control of modular robot manipulators without using joint torque sensing is presented in this paper for the first time. Using the virtual decomposition control (VDC) approach with embedded field programmable gate array (FPGA) logic devices, the proposed solution solves a long-standing problem of lacking control precision fundamentally associated with the modular robot manipulators. As a result, this solution allows modular robot manipulators to possess not only their traditional advantages (such as reconfigurability, flexibility, versatility, and ease of use) but precision control capability as well. A hierarchical master-slave control structure is used, which is supported by a high-speed communication system modified from SpaceWire (IEEE 1355), transferring a limited amount of data between the master and slave nodes at a rate of 1000 Hz. In each module, the FPGA logic implementation uses multiple sampling periods of 163.8 μs, 1.28 μs, and 20 ns. A gravity counterbalance spring provides a design option for the purpose of energy saving. Experimental results demonstrate unprecedented control precision, which is attributed to the use of both the VDC approach and embedded FPGA implementation. The ratio of the maximum position tracking error to the maximum velocity reaches 0.00012 s-more than an order of magnitude better than available technologies in control of robots with harmonic drives. The solution presented in this paper is also applicable to integrated robot manipulators using embedded FPGA controllers.

This paper describes a proposed operational architecture for a planetary worksite mapping mission concept. To map three-dimensional (3D) planetary terrain, we propose to use a rover equipped with a laser rangefinder, and employ a stop-scan-go approach with a human-in-the-loop. In the operational cycle, the rover collects locally consistent 3D range data while stationary. The range data are coupled with visual odometry to estimate the rover pose at each scan and create a consistent 3D map. The 3D map is then used to evaluate candidate next-best views (NBV). The operator selects a NBV with the aid of three evaluation criteria and the rover autonomously travels to the NBV using a network of reusable paths (NRP). Finally, the rover collects another 3D scan and the cycle repeats. This mission concept was validated through hardware experiments on the CSA’s Mars Emulation Terrain (MET), which measures 60m x 120m and includes inclines, rocks, cliffs and a 5.5m-diameter crater.

In this paper, we present a robust framework suitable for conducting three-dimensional simultaneous localization and mapping (3D SLAM) in a planetary work site environment. Operation in a planetary environment imposes sensing restrictions, as well as challenges due to the rugged terrain. Utilizing a laser rangefinder mounted on a rover platform, we have demonstrated an approach that is able to create globally consistent maps of natural, unstructured 3D terrain. The framework presented in this paper utilizes a sparse-feature-based approach and conducts data association using a combination of feature constellations and dense data. Because of feature scarcity, odometry measurements are also incorporated to provide additional information in feature-poor regions. To maintain global consistency, these measurements are resolved using a batch alignment algorithm, which is reinforced with heterogeneous outlier rejection to improve its robustness to outliers in either measurement type (i.e., laser or odometry). Finally, a map is created from the alignment estimates and the dense data. Extensive validation of the framework is provided using data gathered at two different planetary analogue facilities, which consist of 50 and 102 3D scans, respectively. At these sites, root-mean-squared mapping errors of 4.3 and 8.9 cm were achieved. Relative metrics are utilized for localization accuracy and map quality, which facilitate detailed analysis of the performance, including failure modes and possible future improvements. (c) 2012 Wiley Periodicals, Inc.

This paper presents the Mojave Desert field test results of planetary rover visual motion estimation (VME) developed under the “Autonomous, Intelligent, and Robust Guidance, Navigation, and Control for Planetary Rovers (AIR‐GNC)” project. Three VME schemes are compared in realistic conditions. The main innovations of this project include the use of different features from stereo‐pair images as visual landmarks and the use of vision‐based feedback to close the path‐tracking loop. The multiweek field campaign, conducted on relevant Mars analogue terrains, under dramatically changing lighting and weather conditions, shows good localization accuracy on the average. Moreover, the MDA‐developed inertial measurement unit (IMU)‐corrected odometry was reliable and had good accuracy at all test locations, including loose sand dunes. These results are based on data collected during 7.3 km of traverse, including both fully autonomous and joystick‐driven runs. © 2012 Wiley Periodicals, Inc.

Exploration of unknown planets using autonomous rovers requires an efficient onboard localization system capable of estimating precisely rover position and orienta tion. This paper presents a method to refine rover odometry using an Iterative Closest Point (ICP) algorithm applied on 3-D LIDAR panoramas collected by a rover. Our approach takes two LIDAR scans from different locations, subsamples and simplifies them. Then it performs a registration which gives a 6 degrees of freedom rigid body transformation representing the estimation of rover odometry error accumulated during the rover motion from the first scanned location to the other. The proposed LIDAR ICP Pose Refiner (LIPR) can perform registrations in the presence of large misalignments and with overlap ratios below 50%. An intensive benchmark test using field data has shown that LIPR can tolerate larger error than three standard approaches. The paper also reports experimental results of rover pose refinement tests performed at the Mars Emulation Terrain (MET) of the Canadian Space Agency (CSA). LIPR has been tested online at more than 174 different locations of MET, keeping odometry error on the order of 1% of distance traveled.

Recent Canadian activities in space robotics include the successful robotic operations on the Space Shuttle and on the International Space Station but also technology demonstration missions in low-Earth orbit. Other activities are advancing technology for future space missions in advanced on-orbit servicing or for planetary exploration. Space exploration is seen by Canada as the next series of opportunities to pursue the expertise in space robotics that started 30 years ago.

Recent Canadian activities in space robotics include the successful robotic operations on the Space Shuttle and on the International Space Station but also technology demonstration missions in low-Earth orbit. Other activities are advancing technology for future space missions in advanced on-orbit servicing or for planetary exploration. Space exploration is seen by Canada as the next series of opportunities to pursue the expertise in space robotics that started 30 years ago.

This paper presents the design, fabrication and field testing of the third generation FW-350 Lunar earth analogue flexible wheel prototype which is 24 inches in diameter and designed for a 300-Kg four-wheeled rover class. A set of four lunar wheels were manufactured, assembled and field tested. Wheel prototypes were installed on the PUD-II prototype rover and tested at the CSA‟s Mars Emulation Terrain (MET). All the wheel prototype structure components performed as per functional specification: Tread, side wall bands, beads, rim clamps, rims, and fastener system. Some grousers deformed while driving over rocks under severe testing. Those are being reinforced. While performance and reliability goals were identified early on in the concept design phase, future work will focus on verification aspects.

In this paper, we present a robust framework suitable for conducting three-dimensional Simultaneous Localization and Mapping (3D SLAM) in a planetary worksite environment. By utilizing a laser rangefinder mounted on a rover platform, we have demonstrated an approach that is able to create globally consistent maps of natural, unstructured 3D terrain. The framework presented in this paper utilizes a sparse-feature-based approach, and conducts data association using a hybrid combination of feature constellations and dense data. To maintain global consistency, the measurements are resolved using a batch alignment algorithm, which is reinforced with batch outlier rejection to improve its robustness. Finally, a map is created from the alignment estimates and the dense data. Validation is provided using data gathered at two different planetary analogue facilities.

The Planetary U-Shaped Dolly (PUD) is a configurable rover chassis developed to test various planetary rover mechanical and electrical concepts. This chassis concept emerged from an internal study as one of the solutions to address requirements for a scalable, multifunctional, remotely reconfigurable lunar rover. This paper presents the work carried out on developing the PUD-II rover prototype by the above team as one implementation of a multi-utility rover concept using a U-shaped chassis. The features of this implementation will be presented alongside all the development activities and field testing. Also, the impact of using a U-shaped chassis on rover subsystems will be discussed.

Mobile robots using a 360° field of view LIDAR ranging sensor can generate enormous 3D point clouds. To reduce the quantity of data in memory a compression can lead to unstructured environment models such as irregular meshes. This kind of structure can contain deformed cells and the path planning can be cumbersome. This paper presents a path planning method based on fluid mechanics able to deal with unstructured terrain models. The algorithm uses the finite element method to compute a velocity potential function free from local minima. Then, several streamlines are computed as a road map and the optimal path is selected among the candidate paths. The approach is implemented on the Canadian Space Agency (CSA) Mars Robotics Testbed (MRT) rover and tested at the CSA Mars Emulation Terrain (MET). To confirm the feasibility of the method, the path planner has been tested on 284 LIDAR scans collected in a realistic outdoor challenging terrain.

A two-step approach is presented to generate a 3D navigable terrain model for robots operating in natural and uneven environment. First an unstructured surface is built from a 360 degrees field of view LIDAR scan. Second the reconstructed surface is analyzed and the navigable space is extracted to keep only the safe area as a compressed irregular triangular mesh. The resulting mesh is a compact terrain representation and allows point-robot assumption for further motion planning tasks. The proposed algorithm has been validated using a large database containing 688 LIDAR scans collected on an outdoor rough terrain. The mesh simplification error was evaluated using the approximation of Hausdorff distance. In average, for a compression level of 93.5%, the error was of the order of 0.5 cm. This terrain modeler was deployed on a rover controlled from the International Space Station (ISS) during the Avatar Explore Space Mission carried out by the Canadian Space Agency in 2009.

The Canadian Space Agency (CSA) Mobile Robotics Test-bed (MRT) underwent a major redesign during the Winter 2009. This paper reports on the mechatronics design of the rover. Two rugged laptops are integrated onto the redesigned rover along with an infrared camera and three network devices. A custom-made mechanism is developed in order to move out of the LIght Detection And Ranging (LIDAR) field of view the rover antenna during the scan. A custom-designed bumper module is also developed. Finally a proof of concept prototype is provided. The redesigned rover was controlled from the International Space Station (ISS) during the operations of the Avatar EXPLORE Mission that took place in the Summer 2009.