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Proceedings ArticleDOI

Path planning for reconfigurable rovers in planetary exploration

TL;DR: A path planning algorithm that takes into consideration different locomotion modes in a wheeled reconfigurable rover, providing the most appropriate locomotion mode to be used at each position, was implemented in V-REP simulation software and a Martian area was used to validate it.
Abstract: This paper introduces a path planning algorithm that takes into consideration different locomotion modes in a wheeled reconfigurable rover. Power consumption and traction are estimated by means of simplified dynamics models for each locomotion mode. In particular, wheel-walking and normal-driving are modeled for a planetary rover prototype. These models are then used to define the cost function of a path planning algorithm based on fast marching. It calculates the optimal path, in terms of power consumption, between two positions, providing the most appropriate locomotion mode to be used at each position. Finally, the path planning algorithm was implemented in V-REP simulation software and a Martian area was used to validate it. Results of this contribution also demonstrate how the use of these locomotion modes would reduce the power consumption for a particular area.

Summary (2 min read)

1. INTRODUCTION

  • Exploring the surface of other planets is one of the main interests of space agencies [1].
  • The use of rovers in several missions has contributed to solve the problem of carrying scientific tools to extract data without being necessary to send humans into remote space or have an operator online.
  • The use of more than one locomotion mode expands the possibilities of the rover regarding to finding an optimal path.
  • Prior to carrying out field tests to check the performance of this kind of algorithms, simulation software with virtual scenes can be used.
  • Later on, the same framework implemented in the real ExoTeR, i.e. Rock1, is used to communicate with V-REP.

2. SIMULATION SCENE

  • To properly build a simulation environment, the virtual elements contained within it must resemble as much as possible the real ones in terms of appearance and physical behavior.
  • In particular, to validate the path planning algorithm proposed in this paper two elements are modeled: a reconfigurable rover, ExoTeR, and a real sandbox with different types of rocks and soils resembling the Martian surface.

2.1. ExoTeR Rover

  • Such model contains all the physical properties related to inertia and masses of each of its components.
  • They are placed in the front and rear legs and are in charge of setting the direction the wheels are facing, also known as 4 Steering Joints.
  • On one hand, Normal driving mode uses of all driving and steering joints while keeps the walking ones locked in a constant angle.
  • The Ackerman Turn is the one that lets the rover advance with a nonzero translational speed while rotating along a radius determined by the rotational speed.
  • There are several gaits, i.e. patterns, of wheel-walking depending on how the legs are used.

3. IMPLEMENTATION

  • The components of the simulation environment and the way they are interconnected are shown in Fig.
  • The modeling of the interaction between wheels and terrain is simplified by means of two soil parameters [8]: the dynamic friction, which is basically the resistance to the roll of the wheels, and the slip ratio, calculated from the ideal and real speed of the rover.
  • It is in charge of making the rover reproduce the Wheel-walking gait based on readings from both active and passive joints, also known as Wheelwalking Control.
  • Inside V-REP, the physics engine VORTEX is used to model the dynamics related to the contact between the rover and terrain.
  • Such plane is formed by two axis, called primary axis and secondary axis.

4. PATH PLANNING ALGORITHM

  • The path planning algorithm to be tested in this work finds the optimal path in terms of power consumption, which is a critical factor during an exploration mission.
  • The capacity to reconfigure the locomotion mode expands the possibilities for the rover to find optimal paths.
  • The path planning algorithm proposed in this work is based on the Fast Marching method, which has been used in recent researches for underwater [10] and mobile [11] robotic applications.
  • Moreover, as the power required to traverse a terrain is always a positive value the required amount of energy increases as the wave propagates.
  • Therefore, there are never local minimum points in the resulting stationary potential field.

5. EXPERIMENTS

  • Two experiments were carried out to test the capacities of the path planning algorithm presented in this paper.
  • After executing the simulation environment for both cases, the resulting trajectories are shown in Fig.8.
  • When the rover has available the wheel-walking mode the path planner is able to find a totally different trajectory passing through the loose soil than when it has only normal driving mode available.
  • The reason can be deducted by observing the resulting potential fields for each case in Fig.7.
  • As expected, when propagating the Fast Marching wave it becomes much slower in the loose soil when wheel-walking is not available, and due to this the lines with equal cost are much more close to each other.

6. CONCLUSIONS

  • As well as it has been used to validate a Fast Marching based algorithm that takes into account two locomotion modes.
  • First, the physics related to the interaction between the rover elements and the surface of the scene have been modeled, taking into account involved friction forces, masses and inertias.
  • VORTEX, an multibody dynamics engine contained in V-REP has been used for this pur- pose.
  • Second, the complete software architecture of the simulation environment has been fully detailed.
  • The rover could find the optimal path considering more than one locomotion mode taking into account both composition and shape of the terrain.

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Citations
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Journal ArticleDOI
TL;DR: A path planning algorithm based on the Fast Marching Method is proposed to maximize the number of places visited during the mission and shows simulation and field test results based on several reconfigurable and non-reconfigurable rover prototypes and a experimental terrain.

20 citations

Journal ArticleDOI
TL;DR: The proposed architecture for autonomous navigation relies only on the optical Localization Cameras stereo bench, a sensor that is found in all current rovers, and potentially allows for computationally inexpensive long‐range autonomous navigation in terrains of medium difficulty.
Abstract: Rovers operating on Mars are in need of more and more autonomous features to fulfill their challenging mission requirements. However, the inherent constraints of space systems make the implementation of complex algorithms an expensive and difficult task. In this paper we propose a control architecture for autonomous navigation. Efficient implementations of autonomous features are built on top of the current ExoMars navigation method, enhancing the safety and traversing capabilities of the rover. These features allow the rover to detect and avoid hazards and perform long traverses by following a roughly safe path planned by operators on ground. The control architecture implementing the proposed navigation mode has been tested during a field test campaign on a planetary analogue terrain. The experiments evaluated the proposed approach, autonomously completing two long traverses while avoiding hazards. The approach only relies on the optical Localization Cameras stereobench, a sensor that is found in all rovers launched so far, and potentially allows for computationally inexpensive long-range autonomous navigation in terrains of medium difficulty.

16 citations

01 Jan 2007
TL;DR: On May 6, 2009, Spirit got stuck in loose, flourlike sand on Mars, and the future of the entire Mars program might well have been hanging in the balance.
Abstract: On May 6, 2009, Spirit got stuck. The Mars rover, about the size of a go-kart, was traveling south on the red planet when it found itself hubcap-deep in loose, flourlike sand. To make matters worse, the rover’s right front wheel had locked up three years earlier, leaving it with only five working ones. Fearful of its digging in deeper with every turn of the wheels, Spirit’s controllers at JPL called a halt until they could find a way to get it out. Since then, the engineers have been testing maneuvers here on Earth in a big sandbox with two rovers—an exact replica and a lighter one that’s closer to what Spirit weighs on Mars. The team is still at it as of this writing, and so far this Spirit is anything but free. Such setbacks aren’t new, however. Less than three weeks after Spirit landed on January 4, 2004, it fell silent. Engineers scrambled to solve the problem, hoping there wouldn’t be a repeat of the previous two American missions to Mars. On December 3, 1999, the Mars Polar Lander had been lost, apparently due to a software error that shut off its descent engine too soon. Accompanying the lander was the Mars Climate Orbiter, which was incinerated when a mix-up between metric and imperial units caused it to enter the Martian atmosphere too low. Mars is an unforgiving destination—in fact, more than a third of all spacecraft sent there have never made it. The memory of past failures was still fresh and, with Spirit, the future of the entire Mars program might well have been hanging in the balance. Meanwhile, Spirit’s twin was

4 citations

Journal ArticleDOI
TL;DR: In this article , the authors present the system architecture and design of two planetary rover laboratory testbeds developed at the European Space Agency (ESA) to provide early prototypes for the validation of designs and serve the ESA Automation and Robotics Lab infrastructure for continuous research and testing.
Abstract: This article presents the system architecture and design of two planetary rover laboratory testbeds developed at the European Space Agency (ESA). These research platforms have been developed to provide early prototypes for the validation of designs and serve the ESA’s Automation and Robotics Lab infrastructure for continuous research and testing. Both rovers have been built considering the constraints of space systems with a sufficient level of representativeness to allow rapid prototyping. They avoid strictly space-qualified components and designs that present a major cost burden and frequently lack the flexibility or modularity that the lab environment requires for its investigations. This design approach is followed for all of the mechanical, electrical, and software aspects of the system.

3 citations

Journal ArticleDOI
TL;DR: In this paper , the authors present the system architecture and design of two planetary rover laboratory testbeds developed at the European Space Agency (ESA) to provide early prototypes for the validation of designs and serve the ESA Automation and Robotics Lab infrastructure for continuous research and testing.
Abstract: This article presents the system architecture and design of two planetary rover laboratory testbeds developed at the European Space Agency (ESA). These research platforms have been developed to provide early prototypes for the validation of designs and serve the ESA’s Automation and Robotics Lab infrastructure for continuous research and testing. Both rovers have been built considering the constraints of space systems with a sufficient level of representativeness to allow rapid prototyping. They avoid strictly space-qualified components and designs that present a major cost burden and frequently lack the flexibility or modularity that the lab environment requires for its investigations. This design approach is followed for all of the mechanical, electrical, and software aspects of the system.

3 citations

References
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Journal ArticleDOI
TL;DR: The HiRISE camera as mentioned in this paper provides detailed images (0.25 to 1.3 m/pixel) covering ∼1% of the Martian surface during the 2-year Primary Science Phase (PSP) beginning November 2006.
Abstract: [1] The HiRISE camera features a 0.5 m diameter primary mirror, 12 m effective focal length, and a focal plane system that can acquire images containing up to 28 Gb (gigabits) of data in as little as 6 seconds. HiRISE will provide detailed images (0.25 to 1.3 m/pixel) covering ∼1% of the Martian surface during the 2-year Primary Science Phase (PSP) beginning November 2006. Most images will include color data covering 20% of the potential field of view. A top priority is to acquire ∼1000 stereo pairs and apply precision geometric corrections to enable topographic measurements to better than 25 cm vertical precision. We expect to return more than 12 Tb of HiRISE data during the 2-year PSP, and use pixel binning, conversion from 14 to 8 bit values, and a lossless compression system to increase coverage. HiRISE images are acquired via 14 CCD detectors, each with 2 output channels, and with multiple choices for pixel binning and number of Time Delay and Integration lines. HiRISE will support Mars exploration by locating and characterizing past, present, and future landing sites, unsuccessful landing sites, and past and potentially future rover traverses. We will investigate cratering, volcanism, tectonism, hydrology, sedimentary processes, stratigraphy, aeolian processes, mass wasting, landscape evolution, seasonal processes, climate change, spectrophotometry, glacial and periglacial processes, polar geology, and regolith properties. An Internet Web site (HiWeb) will enable anyone in the world to suggest HiRISE targets on Mars and to easily locate, view, and download HiRISE data products.

1,511 citations


"Path planning for reconfigurable ro..." refers methods in this paper

  • ...This repository provides high resolution images from the surface of Mars using a camera system [14]....

    [...]

Journal ArticleDOI
TL;DR: In this paper, a new dynamic friction force model for the longitudinal road/tire interaction for wheeled ground vehicles is derived, based on a dynamic friction model developed previously for contact-point friction problems, called the LuGre model.
Abstract: In this paper we derive a new dynamic friction force model for the longitudinal road/tire interaction for wheeled ground vehicles. The model is based on a dynamic friction model developed previously for contact-point friction problems, called the LuGre model. By assuming a contact patch between the tire and the ground we develop a partial differential equation for the distribution of the friction force along the patch. An ordinary differential equation (the lumped model) for the friction force is developed, based on the patch boundary conditions and the normal force distribution along the contact patch. This lumped model is derived to approximate closely the distributed friction model. Contrary to common static friction/slip maps, it is shown that this new dynamic friction model is able to capture accurately the transient behaviour of the friction force observed during transitions between braking and acceleration. A velocity-dependent, steady-state expression of the friction force versus the slip coefficient is also developed that allows easy tuning of the model parameters by comparison with steady-state experimental data. Experimental results validate the accuracy of the new tire friction model in predicting the friction force during transient vehicle motion. It is expected that this new model will be very helpful for tire friction modeling as well as for anti-lock braking (ABS) and traction control design.

372 citations


"Path planning for reconfigurable ro..." refers background or methods in this paper

  • ...Therefore, taking into account experimental results from [10], it can be assumed the friction coefficient is null (μ ≈ 0) if there is no slip (s ≈ 0), therefore, the last term of (14) can be removed....

    [...]

  • ...To calculate the power consumption for both locomotion modes, terrain features have been simplified by means of two parameters [10]: dynamic friction (μ) and slip ratio (s)....

    [...]

Journal ArticleDOI
TL;DR: A self‐supervised learning framework that will enable a robotic system to learn to predict mechanical properties of distant terrain, based on measurements of Mechanical properties of similar terrain that has been traversed previously, is proposed.
Abstract: In future planetary exploration missions, improvements in autonomous rover mobility have the potential to increase scientific data return by providing safe access to geologically interesting sites that lie in rugged terrain, far from landing areas To improve rover-based terrain sensing, this paper proposes a self-supervised learning framework that will enable a robotic system to learn to predict mechanical properties of distant terrain, based on measurements of mechanical properties of similar terrain that has been traversed previously In this framework, a proprioceptive terrain classifier is used to distinguish terrain classes based on features derived from rover–terrain interaction, and labels from this classifier are used to train an exteroceptive (ie, vision-based) terrain classifier Once trained, the vision-based classifier is able to recognize similar terrain classes in stereo imagery This paper presents two distinct proprioceptive classifiers—a novel approach based on optimization of a traction force model and a previously described approach based on wheel vibration—as well as a vision-based terrain classification approach suitable for environments with unexpected appearances The high accuracy of the self-supervised learning framework and its supporting algorithms is demonstrated using experimental data from a four-wheeled robot in an outdoor Mars-analogue environment © 2012 Wiley Periodicals, Inc © 2012 Wiley Periodicals, Inc

129 citations


"Path planning for reconfigurable ro..." refers methods in this paper

  • ...An example of the estimation of these parameters in a real world is explained in [11], where it used a vision-based classifier....

    [...]

  • ...they could be obtained through sensors and estimated using different algorithms [11]....

    [...]

Proceedings ArticleDOI
20 Jun 2005
TL;DR: An anisotropic version of fast marching is proposed by adding directional constraints in a cost function to minimize and a path planning method able to deal with vectorial fields of force for the first time is proposed.
Abstract: In this paper, new tools for obstacle avoidance and path planning for underwater vehicles are presented. The authors' technique, based on a level set formulation of the path planning problem, extracts optimal paths from complex and continuous environments in a complete and consistent manner. Fast marching algorithm is known to be efficient for finding cost optimal path in mobile robotics because of its reliability, precision, and simple implementation. Fast marching algorithm originally propagates a wave front to isotropically explore the space. We propose an anisotropic version of fast marching by adding directional constraints in a cost function to minimize. We then propose a path planning method able to deal with vectorial fields of force for the first time. Furthermore we explore the relation between the curvature of the optimal path and the cost function generated from scalar and vectorial constraints. This a priori knowledge of the influence of the environment on the final path's curvature allows us to propose a solution to make sure a path is reachable by the vehicle according to its kinematics. A multi-resolution scheme based on an adaptive mesh generation is eventually introduced to speed up the overall algorithm. Results are shown computed from real and simulated underwater environments.

84 citations


"Path planning for reconfigurable ro..." refers background in this paper

  • ...Previous contributions [9] and [13] considered this cost as the minimal arrival time....

    [...]

Journal ArticleDOI
Masataku Sutoh1, Junya Yusa1, Tsuyoshi Ito1, Keiji Nagatani1, Kazuya Yoshida1 
TL;DR: The influence of a rover's weight on its performance was evaluated by conducting experiments using a monotrack rover and an inline four-wheeled rover with different rover weights, and the influence of the wheel diameter and width was quantitatively determined.
Abstract: In designing a planetary rover, it is important to consider and evaluate the influence of parameters such as the weight and dimensions of the rover on its traveling performance. In this study, the influence of a rover's weight on its performance was evaluated by conduct experiments using a monotrack rover and an inline four-wheeled rover with different rover weights. Then the influence of the wheel diameter and width was quantitatively determined by performing experiments using a two-wheeled rover, equipped with wheels, with different diameters and widths. The results of the experiments were compared with those of a numerical simulation based on terramechanics. Finally, the influence of the wheel surface pattern on the traveling performance of planetary rovers was evaluated by conducting experiments using a two-wheeled rover equipped with wheels with different numbers of lugs (i.e., grousers) on their surfaces. Based on the results of these experiments, we confirmed the following influences of the parameters: in the case of the track mechanism, the traveling performance does not change with the increase in rover weight. On the other hand, in the case of the wheel mechanism, an increase in rover weight decreases the traveling performance. Moreover, the experimental results show that the wheel diameter contributes more to the high traveling performance than the wheel width. In addition, a comparison between the experimental and simulation results shows that it is currently difficult to accurately predict the traveling performance of lightweight vehicles on the basis of terramechanics models. Finally, the experimental results show that having lugs always improves the traveling performance, even at the expense of wheel diameter. © 2012 Wiley Periodicals, Inc. © 2012 Wiley Periodicals, Inc.

83 citations


"Path planning for reconfigurable ro..." refers background in this paper

  • ...However, while there is so much research on modeling wheel-soil interaction in normal driving locomotion [7], to the authors knowledge, there are no works related to wheel-walking....

    [...]

Frequently Asked Questions (2)
Q1. What have the authors contributed in "Path planning for reconfigurable rovers in planetary exploration" ?

This paper introduces a path planning algorithm that takes into consideration different locomotion modes in a wheeled reconfigurable rover. 

As future work it is intended to consider more parameters like slope when extracting power consumption for each locomotion mode.