A semi-active robot for steep obstacle ascent
14 Nov 2013-pp 122-127
TL;DR: A semi-active robot for climbing steep obstacles like steps, curbs, etc. that has the advantage of height-independent climbing motion as in the case of passive mechanism along with the extra freedom of active joints for maintaining vehicle stability, only when required.
Abstract: In this paper we propose a semi-active robot for climbing steep obstacles like steps, curbs, etc. The key novelty of the proposed robot lies in the use of a passive mechanism for climbing steps of smaller heights and motor only while climbing steps of bigger heights. Analysis of the robot's stability during its ascent phase is also investigated. Model based control is used to achieve step climbing. The other novelty of the robot, in contrast to existing active suspension step climbers, is that it does not need the knowledge of step height beforehand. Therefore, the mechanism has the advantage of height-independent climbing motion as in the case of passive mechanism along with the extra freedom of active joints for maintaining vehicle stability, only when required. Efficacy of the mechanism is exhibited through simulations on steps of various heights.
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29 Sep 2014
TL;DR: A novel compliant robot is proposed for traversing on unstructured terrains and is successfully able to climb maximum heights upto three times and six times the wheel diameter using three and five modules, respectively.
Abstract: A novel compliant robot is proposed for traversing on unstructured terrains. The robot has a set of modules where each module contains a trunk or link and an active wheel-pair, and it is connected to the adjacent module using a passive joint. This type of robots are inherently lightweight and provide high durability due to the absence of actuators at the link joints. However, they have limited climbing ability due to tendency of tipping over while climbing big obstacles. In order to overcome this disadvantage, the use of compliant joints is proposed in this work. Spring stiffness of each compliant joint is estimated by formulating an optimization problem using the static equilibrium equations of the robot. This is one of the key novelties of the proposed work. A design methodology is also proposed for developing an n-module compliant robot for climbing given height on a surface with prescribed coefficient of friction. The efficacy of the proposed formulation is illustrated for climbing big obstacles and traversing uneven terrains using simulation of 3and 5-module robots. The robot is successfully able to climb maximum heights of 17 cm and 36 cm using 3 and 5 modules, respectively. Mechanical and electrical design of the robot is conceived, and a working prototype of the robot is developed. Simulation results are validated using the prototype.
8 citations
TL;DR: Aiming at modeling of vehicle vertical dynamics, basic and geometrical parameters defined and degrees-of-freedom specified on a compromise between accuracy and complexity of two models using two different modeling methods.
Abstract: Published: Vertical dynamics modeling and simulation of a six-wheel unmanned military vehicle (MULE) studied in this paper. The Common Mobility Platform (CMP) chassis provided mobility, built around an advanced propulsion and articulated suspension system gave the vehicle ability to negotiate complex terrain, obstacles, and gaps that a dismounted squad would encounter. Aiming at modeling of vehicle vertical dynamics, basic and geometrical parameters defined and degrees-of-freedom specified on a compromise between accuracy and complexity of two models. Equations of motion provided on two linear and nonlinear 5-degree-offreedom models using two different modeling methods. There is good agreement between time responses of two presented models. The main differences of two models observed in articulated suspension degrees-offreedom while the vehicle subjected to high frequency maneuvers that cause severe oscillations on wheels and arms in comparison to vehicle body due to lower mass and inertia properties. The linear model can be used to design a controller and the nonlinear to predict vehicle motion more accurately. Sensitivity analysis of the influential parameters is also presented to specify effects of different parameters. Results of this study may be used to design articulated suspension and making next frequency analyses.
1 citations
Cites background from "A semi-active robot for steep obsta..."
...[14] designed a semiactive small robot to cross the barrier with a type of articulated suspension system....
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TL;DR: In this paper, a climbing mechanical appliance is designed to ensure smooth and steady movement of the appliance, and a counterweight balancing mechanism is used to adjust the centroid according to actual situation.
Abstract: Current climbing appliances are difficult to ensure the steady change from walking to climbing. Consequently, we come up with a climbing mechanical appliance, design it and analyze the appliance on rationality and feasibility. The appliance is lifted by rack and pinion mechanism. In order to ensure smooth and steady movement of the appliance, a counterweight balancing mechanism is designed to adjust the centroid according to actual situation. Through the movement principle analysis of transmission mechanism for the appliance, we build its 3D model by SolidWorks. A simulation analysis has also been provided to examine the feasibility of transmission mechanism under the help of ADAMS.
References
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TL;DR: The tragedy of September 11th 2001 at the World Trade Center is likely to propel search-and-rescue robotics into its next stage, just as the Kobe earthquake and the Oklahoma City bombing were the catalysts for this research domain.
Abstract: The tragedy of September 11th 2001 at the World Trade Center is likely to propel search-and-rescue robotics into its next stage, just as the Kobe earthquake and the Oklahoma City bombing were the catalysts for this research domain. Tragedy hasn't been the only motivator for urban search-and-rescue advancements in the USA and Japan; international competition has motivated both countries, first with RoboCup Soccer and more recently with RoboCup Rescue. We may see inexpensive urban search-and-rescue robots mass-produced within five years if advances in hardware and software keep up.
196 citations
"A semi-active robot for steep obsta..." refers background in this paper
...The last decade has seen a surge of interest in the potential applications of robots in urban search and rescue missions [1]....
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17 Feb 2000
TL;DR: Shrimp as discussed by the authors is a high mobility wheeled rover for uneven terrain off-road that uses passive locomotion concept robot on uneven terrain, and is based on the SHRIMP concept.
Abstract: Keywords: passive locomotion concept robot uneven terrain off-road ; SHRIMP : High Mobility Wheeled Rover Reference LSA-CONF-2000-003View record in Web of Science Project Web Site: http://asl.epfl.ch/research/systems/shrimp/shrimp.php Record created on 2006-12-07, modified on 2016-08-08
156 citations
"A semi-active robot for steep obsta..." refers background in this paper
...The elegance of passive suspension vehicles [2], [7], [6] lies in their ability to surmount steep obstacles by the virtue of only wheel-ground contact forces with the help of appropriately designed linkages....
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TL;DR: A method to control actively articulated suspensions to enhance rover tipover stability using a quasi-static model, and optimized on-line, relies on estimation of wheel-terrain contact angles.
Abstract: Future robotic vehicles will perform challenging tasks in rough terrain, such as planetary exploration and military missions Rovers with actively articulated suspensions can improve rough-terrain mobility by repositioning their center of mass This paper presents a method to control actively articulated suspensions to enhance rover tipover stability A stability metric is defined using a quasi-static model, and optimized on-line The method relies on estimation of wheel-terrain contact angles An algorithm for estimating wheel-terrain contact angles from simple on-board sensors is developed Simulation and experimental results are presented for the Jet Propulsion Laboratory Sample Return Rover that show the control method yields substantially improved stability in rough-terrain
136 citations
"A semi-active robot for steep obsta..." refers background in this paper
...On the other hand, active suspension mechanisms [3], [5], [9], [4] have simplified kinematic architecture but may require complicated control algorithms to maintain stability while climbing....
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07 Jun 2004
TL;DR: A decoupled posture and trajectory control algorithm based on the velocity model of the robot is proposed and the performance and feasibility of the control algorithm are evaluated through simulations and experiments with the Hylos robot.
Abstract: This paper addresses the control of a hybrid wheel-legged system evolving on rough terrain. First, the posture and trajectory parameters are introduced. Then, a decoupled posture and trajectory control algorithm based on the velocity model of the robot is proposed. Last, the performance and feasibility of the control algorithm are evaluated through simulations and experiments with the Hylos robot.
84 citations
"A semi-active robot for steep obsta..." refers background in this paper
...On the other hand, active suspension mechanisms [3], [5], [9], [4] have simplified kinematic architecture but may require complicated control algorithms to maintain stability while climbing....
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18 Apr 2005
TL;DR: The proposed method for wheel-ground contact angle measurement and a traction control strategy minimizing slip in rough terrain has the advantage to avoid relying on complex wheel-soil interaction models, whose parameters are generally unknown in challenging terrains.
Abstract: This paper presents a method for wheel-ground contact angle measurement and a traction control strategy minimizing slip in rough terrain. The slip minimization algorithm has been tested and compared with a standard speed control in simulation, which allows to verify the validity of the assumptions taken during the modeling phase. The simulations show clearly the advantage of torque control versus speed control. Furthermore, the proposed method has the advantage to avoid relying on complex wheel-soil interaction models, whose parameters are generally unknown in challenging terrains.
79 citations
"A semi-active robot for steep obsta..." refers background in this paper
...The elegance of passive suspension vehicles [2], [7], [6] lies in their ability to surmount steep obstacles by the virtue of only wheel-ground contact forces with the help of appropriately designed linkages....
[...]