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Perceiving and Avoiding Rollover in Agricultural Tractors
Published in Peter Hancock, John Flach, Jeff Caird, Kim Vicente, Local Applications of the Ecological Approach to Human-Machine Systems, 2018
Steven B. Flynn, Thomas A. Stoffregen
Of course, tractors do not roll over when they are stationary; they roll over while they are being used, while they are moving. For the moving tractor it is useful to define rollover with respect to a given perturbation rather than an absolute angle. This allows us to emphasize the fact that different factors interact in determining the likelihood of rollover. The factors that influence the stability of a moving tractor are (a) linear velocity, (b) the slope of the ground relative to the GIF vector operating on the tractor, (c) the turning radius (steering angle) of the tractor relative to the ground slope, and (d) the roughness of the ground, either in general or in the case of individual bumps.5 For turnovers in the roll axis the bumps that matter are those that are encountered solely by the uphill rear wheel. Symmetrical bumps will not influence roll stability, whereas bumps to the downhill wheel will move the tractor toward rather than away from stability. The reverse is true for holes or depressions in the ground (for clarity these will not be considered in our analysis).
Design of the omnidirectional mobile robot control system based on dSPACE
Published in Jimmy C.M. Kao, Wen-Pei Sung, Civil, Architecture and Environmental Engineering, 2017
Huan-huan Liu, Chang-sheng Ai, Hong-hua Zhao, Xuan Sun
Four-wheel drive (Xin, 2015), also called all wheel drive, refers to the front wheel and the rear wheel have driving force, and the engine output torque is distributed in all the wheels according to the different road conditions. Its main function is to effectively control the vehicle’s lateral movement characteristics and improve the ability of the vehicle. Four-wheel drive relies on the four-wheel independent steering. All wheels can be turned around the same instantaneous center of rotation to achieve different steering radius and even zero turning radius so that it has a high degree of flexibility in the steering wheel. The narrow working space brings great challenge to the mobile robot. Therefore, the control system of the omnidirectional mobile robot adopted the four-wheel drive. The four-wheel drive system is mainly composed of a motor and its driver, driving power supply, and deceleration device. Among them, the servo motor is controlled by pulse and direction.
Advantages of parameter estimation in electric vehicles
Published in Maksym Spiryagin, Timothy Gordon, Colin Cole, Tim McSweeney, The Dynamics of Vehicles on Roads and Tracks, 2018
where R = turning radius at the centre of gravity (CoG); lr = distance from rear axle to the CoG longitudinally; l = vehicle wheelbase; and δ = averaged steering angle of front wheels. Then the vehicle slip angle (β) is calculated below in Equation 2. () β=tan−1lrR2−lr2
Optimal synthesis of steering mechanism using double loop four bar mechanism
Published in Australian Journal of Mechanical Engineering, 2022
It is desired for the vehicle to have a small turning radius. So it can take turns in a small space. DLFM steering mechanism checked for minimum turning radius. Left front wheel turn beyond 60° in the interval of 10° till intersection point of front wheel axis coincide with midpoint of rear wheel pivots as shown in Figure 8(a). The mechanism remains true beyond the 60° turning of the inner front wheel axis. The respond from the mechanism is shown in Figure 8(b). From Figure 8(a), it is clear that vehicle can take left turn by considering midpoint of rear wheel pivots as a centre of turning, which is the smallest turning radius in any vehicle. Lower than this turning radius is not possible in any vehicle which is having an only front wheel steering mechanism.