Dynamic Modeling and Power Modeling of Robotic Skid-Steered Wheeled Vehicles

Abstract

IntroductionDynamic models and power models of autonomous ground vehicles are needed to enable realistic motion planning Howard & Kelly (2007); Yu et al. (2010) in unstructured, outdoor environments that have substantial changes in elevation, consist of a variety of terrain surfaces, and/or require frequent accelerations and decelerations. At least 4 different motion planning tasks can be accomplished using appropriate dynamic and power models:1. Time optimal motion planning. Energy efficient motion planning.3. Reduction in the frequency of replanning. 4.Planning in the presence of a fault, such as flat tire or faulty motor.For the purpose of motion planning this chapter focuses on developing dynamic and power models of a skid-steered wheeled vehicle to help the above motion planning tasks. The dynamic models are the foundation to derive the power models of skid-steered wheeled vehicles. The target research platform is a skid-steered vehicle. A skid-steered vehicle can be either tracked or wheeled . Fig. 1 shows examples of a skid-steered wheeled vehicle and a skid-steered tracked vehicle. This chapter is organized into five sections. Section 1 is the introduction. Section 2 presents the kinematic models of a skid-steered wheeled vehicle, which is the preliminary knowledge to the proposed dynamic model and power model. Section 3 develops analytical dynamic models of a skid-steered wheeled vehicle for general 2D motion. The developed models are characterized by the coefficient of rolling resistance, the coefficient of friction, and the shear deformation modulus, which have terrain-dependent values. Section 4 develops analytical power models of a skid-steered vehicle and its inner and outer motors in general 2D curvilinear motion. The developed power model builds upon a previously developed dynamic model in Section 3. Section 5 experimentally verifies the proposed dynamic models and power models of a robotic skid-steered wheeled vehicle. Ackerman steering, differential steering, and skid steering are the most widely used steering mechanisms for wheeled and tracked vehicles. Ackerman steering has the advantages of good lateral stability when turning at high speeds, good controllability Siegwart & Nourbakhsh (2005) and lower power consumption Shamah et al. (2001), but has the disadvantages of low maneuverability and need of an explicit mechanical steering subsystem Mandow et al.

Model Based On-Line Energy Prediction System for Semi-autonomous Mobile Robots

“…Wei Yu et al [10] emphasize that power models of motors are needed for the locomotion planning to complete time or energy constrained missions. Power models for skid steered wheeled [10], [11] and tracked vehicles [12] are proposed for various turning radius and surface conditions. Some works analyse the energy consumption of different components in robots.…”

“…(10) Once the power model is generated, it can be used to calculate the on-line energy consumption of each component while the robot is performing some task or can be used to predict the energy requirements before the mission based on the nature of the tasks. The list of active components at any instant is determined by the operator (manual teleoperation) or by the program (autonomous).…”

A survey of energy-efficient motion planning for wheeled mobile robots

“…In contrast to the coulomb model, another research proposes a function relationship between the shear stress and the shear displacement in the tracked robots (Wong and Chiang, 2001). After that, the result in tracked robots is extended to the skid-steered-wheeled robots for general curvilinear planar motion (Yu et al , 2011). The model takes many factors into consideration, such as acceleration and deceleration, terrain elevation, motor property and robot’s control system.…”

“…As is shown in Figure 5, it is assumed that the skid-steered-wheeled robot is always symmetric and the center of gravity is the geometric center of robot. The kinematic model of skid-steered-wheeled robots is given by the following equation: where α is the ratio of the longitudinal distance between the left and right wheels over the robot width under the assumption mentioned above (Yu et al , 2011): …”

“…That energy-savings strategy avoids frequent acceleration and deceleration because of the resulting high energy consumption, but the work was limited to only straight-line motion and did not consider more general curvilinear motion. From 2000 to present, more and more comprehensive approaches to EEMP for wheeled mobile robots are presented (Yu et al , 2011; Ordonez, et al , 2012). The constraints of a dynamic model are considered in EEMP.…”