This paper presents the CSA robotic manipulatorbased system developed to remotely conduct sample acquisition, storage, and transfer back to a lander/ascent vehicle. The prototype system was integrated with a rover and demonstrated during an emulated lunar sample return mission scenario.

In 2017 and 2019 the Canadian Space Agency (CSA) and the European Space Agency (ESA) conducted joint mission simulations in preparation for a potential sample return lunar rover mission. These simulations were conducted to study several mission elements such as: concepts of operation, robotic systems, and to measure driving performance metrics such as achievable average speed. The 2017/2019 simulations cumulated 6.8 km of distance traveled by the rover and 67 hours of on-console operation. In 2019, the operators achieved an overall average speed of 3.4 m/min (0.2 km/h) when they explicitly controlled the rover using several driving modes. This was found to be slower when compared to the rover average speed of 4.4 m/min measured in autonomous navigation .

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.

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 outlines the Teleoperation Robotic Testbed (TRT) project, which aims at testing simple concepts of operation (ConOps) for remotely driving a rover on the Moon, under a constrained Earth-Moon communication link. The ConOps under study focuses on teleoperating a rover with very little onboard autonomy, with ground operators actively and continuously involved in the control loop. The remote control station features enhanced situational awareness tools such as predictive displays, overlays on imagery, rover trajectory plot and panoramic imagery. The main source of feedback to the operators were monocular cameras and a basic localization system that were integrated on the TRT rover. During the 2013 field testing season, the TRT was deployed in many planetary analogue sites in order to exercise the ConOps. A total of sixteen teams remotely operated the TRT rover, taking turns on three-hour driving missions and traveled a total of 5.8 km over 48 hours of operation. The results of the campaign suggest that the ConOps studied might support simple lunar driving tasks. However, the rover average speed would be low (around 2 to 4 m/min), resulting from the rover being stationary most of the time, moreover, fatigue would prevent the operators from supporting long uninterrupted operations.

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.

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.

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.

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.

A real-time kinematic (RTK) global positioning system (GPS) has been identified for potentially being used as a ground-truth sensor for testing robotic rovers for planetary exploration. A series of environmental tests needs to be performed in order to validate the performance of the sensor at hand before being used as a ground-truth system. This paper focuses on the performance evaluation of the RTK GPS at Axel Heiberg Island Canadian Space Agency’s Analogue Research Network (CARN) site. This is one of the officially recognized terrestrial analogues, that is places on Earth that approximate the geological, environmental and putative biological conditions on Mars and other planetary bodies (Hipkin et al.). The challenge lies in the use of the equipment at Arctic latitudes. The results show that the system performed according to specifications even in this challenging environment.

High-stiffness environment emulation requires a haptic device to have a large damping coefficient in order to keep the stability during a virtual contact. Aimed at increasing the maximum allowable damping coefficient, two new approaches of using a velocity derived from both acceleration and position measurements are presented in this paper. An adaptive mechanism is provided to accommodate both offset and gain uncertainties of the accelerometer. The feasibility of using the velocity derived from both accelerometer and encoder is demonstrated experimentally when a one-degree of freedom (DOF) haptic device contacts with a virtual wall. The contribution of this paper suggests that any existing haptic device would be able to expand its capacity of emulating high-stiffness virtual environments when velocities estimated from both accelerometers and encoders are used.

Being widely used in industrial systems and manufacturing lines, precision position control systems need to use high feedback control gains to reject disturbances. However, phase-lag in velocity estimation resulting from encoder measurement imposes a limitation on maximum allowable feedback gains, when system stability and control smoothness are concerned. In this paper, use of velocities derived from both acceleration and position measurements is suggested. The derived velocity possesses a much higher bandwidth without having theoretical phase-lag. Experimental results reveal that the use of velocities derived from practical accelerometers and encoders allows a typical position control system to substantially increase its feedback gains without compromising stability and control smoothness. It in turn results in much smaller tracking errors, compared to scenarios when velocities are created from position sensors only.

Knowledge of velocity is crucial to certain industrial applications involving high bandwidth modeling and control. In conventional approaches, the velocities obtained from encoders or tachometers are quite noisy, and low-pass filters are usually engaged to generate usable velocity signals. The low-pass filter, however, causes significant phase lag that can severely affect both modeling and control accuracy in the mid- and high-frequency ranges. In this paper, two approaches using a combination of an encoder and an imperfect accelerometer are proposed to estimate velocities with high bandwidth. The two approaches, namely the two-channel approach and the observer-based approach, estimate velocities by applying proper frequency weightings to the encoder and accelerometer signals. The encoder mainly contributes to the low-frequency components of velocity estimation, and the accelerometer mainly contributes to the high-frequency components of velocity estimation. An adaptive mechanism for estimating the accelerometer gain is also presented. The effectiveness of the two velocity estimation approaches is verified experimentally with respect to a one-degree-of-freedom robot performing both rigid contact modeling and control. Extension to 3-D applications is discussed.

While versatility and flexibility make modular and reconfigurable robots particularly suitable for applications in unstructured environments, the use of embedded electronics and local computers imposes an inherent limitation on control performance and payload capability. The virtual decomposition control (VDC) supported with a high-speed communication system has been suggested to effectively handle the dynamics and control issues aimed at allowing modular and reconfigurable robots to have the same control performance as integrated robots. In this paper, the payload capability issue is addressed by using a preloaded torsional spring to counter-balance static torques caused by gravity. Brief concept on spring design is presented, together with a review on system structure, communication mechanism, and VDC algorithms.

Modular (re-configurable) robots have been studied and developed over two decades. Compared to common industrial robot manipulators, modular robots usually end up showing relatively poorer control performance. This is mainly because most of modular robots' designs typically concentrate on mechatronic interfaces, packaging and re-configurable features, leaving little space for dynamics and control considerations. In our current research frame, we are looking at "virtual decomposition control" (VDC) to significantly improve modular robots dynamics and control performance. A key element to successful implementation of the related algorithms has to do with the inter-modules communication link capabilities. Presented here is the first 2 DOF prototype built to demonstrate the feasibility of implementing VDC on a real system, including the Spacewire Bus based communication protocol used.

Modular or re-configurable robots have been studied and developed over two decades. Most researches focus on mechatronic interfaces and re-configurable capabilities. However, less attention has been paid to dynamics and control. Consequently, the control performance of a modular robot has never been comparable with an integrated robot, due to the lack of proper handling of the dynamic interactions among the modules. In this paper, the application of the virtual decomposition control to modular robot manipulators is discussed. A high-speed databus with a data rate of 100 Mbps is used for necessary information exchange among the modules. The dynamics based control is fully handled by the local embedded controllers, whereas the host computer handles the kinematics related computation. The stability of the entire robot is rigorously guaranteed. This research aims at giving the modular robots the comparable control performance as the integrated robots, while keeping the fundamental feasibilities such as low cost for mass production, high flexibility, and easy use and expansion.

The success of NASA's Mars Exploration Rovers has demonstrated the important benefits that mobility adds to planetary exploration. Very soon, mission requirements will impose that planetary exploration rovers drive autonomously in unknown terrain. This will require an evolution of the methods and technologies currently used. This paper presents our approach to 3D terrain reconstruction from large sparse range data sets, and the data reduction achieved through decimation. The outdoor experimental results demonstrate the effectiveness of the reconstructed terrain model for different types of terrain. We also present a first attempt to classify the terrain based on the scans properties.