Determinants of off-road vehicle transmission ‘shift quality’

Duncan, James Robert; Wegscheid, E. L.

doi:10.1016/0003-6870(85)90004-3

Cited by 8 publications

(3 citation statements)

References 1 publication

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“…In a recent study, Huang and Wang [16] examined a large number of ground vehicle transmission shifts and found that jerk and acceleration can have a significant impact on vehicle shift harshness, with increased jerk leading to increased harshness. This appears in contrast with an earlier study by Duncan and Wegscheid [17], which found that for tractor shift quality, acceleration was much more important than jerk and that reduced jerk was actually associated with reduced shift quality. It seems that in Duncan and Wegscheid's study, the experienced tractor drivers associated high jerk levels with crisp shifts and therefore higher jerks were rated as superior.…”

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confidence: 81%

Effect of Jerk and Acceleration on the Perception of Motion Strength

Grant

Haycock

2008

Journal of Aircraft

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In a flight simulator, the calculated aircraft motions are scaled down and filtered to fit within the envelope of the simulator motion system. A number of recent flight and ground simulation studies have reported that the simulator motion was too strong, when in fact, the motion was scaled down and filtered. This paper puts forth the hypothesis that this could be due in part to the motion drive algorithm and vehicle model exaggerating the jerk. To test the plausibility of this hypothesis a paired-comparison experiment was run to determine if the subjective impression of motion strength is a function of both the acceleration and jerk of the motion. The experiment found that the level of jerk and acceleration contributed to the perceived strength of motion, with larger jerks and accelerations leading to increased motion strength. In addition, the duration of the acceleration had a significant effect on the perceived motion strength, with longer durations leading to increased motion strength. Although the relationship between jerk and motion strength suggests that exaggerated jerk in the simulator could lead to the preference for scale factors less than one, the strength of the relationship strongly suggests that it does not entirely account for the preference. Nomenclature A i = nominal acceleration of motion condition i, m=s 2 A nom = acceleration used to normalize the linear model, m=s 2 a i = total score of motion condition i (number of times selected) D i = length of constant-acceleration phase of motion, s D n = score variable for model testing J i = nominal jerk level of motion condition i, m=s 3 J nom = jerk level used to normalize the linear model, m=s 3 l = actuator length command, m n = total number of comparisons between two conditions p = probability of null hypothesis S x = simulator fore-aft displacement command, m s = Laplace variable T J = duration of the constant jerk section of the motion condition, s T s = duration of half of the motion condition, s t = number of motion conditions V x = motion-based fore-aft velocity, m=s x c = commanded X acceleration x i = intermediate X ij = total number of times that condition i was preferred over condition j A = perceived motion strength change due to a change in acceleration A = normalized perceived motion strength change due to a change in acceleration D = perceived motion strength change due to a change in the duration of constant acceleration i = perceived motion strength of motion condition i, no order effect i = perceived motion strength of motion condition i, order effect J = perceived motion strength change due to a change in jerk J= normalized perceived motion strength change due to a change in jerk = model order effect = simulator pitch command, rad i = preference probability for condition i ij = probability that condition i is selected over condition j, no order effect ij = probability that condition i is selected over condition j, when i is the first condition = standard deviation 2 = 2 distribution ! = angular jerk, time derivative of angular ac...

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contrasting

confidence: 81%

Effect of Jerk and Acceleration on the Perception of Motion Strength

Grant

Haycock

2008

Journal of Aircraft

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“…where δ 1 is the speed drop, r/min; ω 1 is the output speed before the shift, r/min; and ω 2 is the lowest output speed during the shift, r/min. According to Duncan and Wegscheid [23], the peak acceleration of a tractor in the longitudinal direction can well reflect its driving comfort during shifting. Therefore, this study took the peak acceleration as one of the indicators for evaluating the shifting quality of the CVT, and its expression is as follows:…”

Section: Evaluation Indicatorsmentioning

confidence: 99%

Optimization of Shifting Quality for Hydrostatic Power-Split Transmission with Single Standard Planetary Gear Set

Xu,

Wang,

Yang

et al. 2023

Agriculture

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To improve the driving comfort of continuously variable transmission (CVT) tractors, the shifting quality of hydrostatic power-split transmission with a standard planetary gear set was optimized. Firstly, the powertrain of the CVT and two shift strategies, direct-shift and bridge-shift, were introduced; then, a dynamic model of tractor shifting was constructed, and the models of key components such as wet clutches and proportional pressure valves were experimentally verified. Finally, the control parameters of the above two shifting strategies were optimized, and the acceleration impact and sliding energy loss caused by them were compared. The results showed the following: the minimum peak acceleration of the bridge-shift method was 0.385807 m/s2; the energy consumption of the bridge-shift method was significantly lower than that of the direct-shift method; the sliding friction work of clutches decreased by 14.92% and 75.84%, respectively, while their power loss decreased by 22.82% and 74.48%, respectively.

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“…Therefore, the speed of the tractor would fluctuate during the shift process, and the speed drop could be used as the first evaluation index of the shifting quality: (30) where v drop is the speed drop of the tractor during the shift, r/min; v o and v min are the theoretical driving speed and the minimum driving speed of the tractor during the shift, respectively, r/min. The research of Duncan [30] showed that the shifting quality that the human body can feel is closely related to the peak acceleration of the tractor. Therefore, this study took the maximum value of the acceleration during the shift as the second evaluation index of the shifting quality:…”

Section: Evaluation Indexes Of Shifting Qualitymentioning

confidence: 99%

Study on the Shifting Quality of the CVT Tractor under Hydraulic System Failure

Wang

Song

Wang³

et al. 2020

Applied Sciences

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The failure of a hydraulic system will affect the shifting quality and driving safety of a CVT tractor. In order to reveal the response of the tractor under different hydraulic system failures without destroying the transmission, the following methods are proposed in this paper: firstly, building the simulation model of CVT; secondly, building a test bench to test and verify the transmission model to ensure that the simulation model can accurately predict the response of CVT under different clutch oil pressures; thirdly, obtaining the fault oil pressure data without starting the engine and taking the data of fault oil pressure as the input variable of the simulation model; finally, obtaining the response of the CVT tractor under different hydraulic system failures by simulation. It is found that the damage of the seal ring inside the rotary joint has little effect on shifting quality; oil way block can lead to greater shift impact; when seal ring damage and oil way block occur together, the clutch cannot reach the minimum working pressure; clutch piston jamming and oil leak can cause power interruption of the tractor. The results show that it is feasible to study the response of CVT in fault mode by simulation.

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Determinants of off-road vehicle transmission ‘shift quality’

Cited by 8 publications

References 1 publication

Effect of Jerk and Acceleration on the Perception of Motion Strength

Effect of Jerk and Acceleration on the Perception of Motion Strength

Optimization of Shifting Quality for Hydrostatic Power-Split Transmission with Single Standard Planetary Gear Set

Study on the Shifting Quality of the CVT Tractor under Hydraulic System Failure

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