A New Yaw Dynamic Model for Improved High Speed Control of a Farm Tractor

2002 ◽  
Vol 124 (4) ◽  
pp. 659-667 ◽  
Author(s):  
David M. Bevly ◽  
J. Christian Gerdes ◽  
Bradford W. Parkinson
Keyword(s):  
Dynamic Model ◽  
High Speed ◽  
Kinematic Model ◽  
Second Order ◽  
Lateral Control ◽  
Relaxation Length ◽  
High Speeds ◽  
Farm Tractor ◽  
Bicycle Model ◽  
Higher Order Models

This paper presents the system identification of a new model for the farm tractor’s yaw dynamics in order to improve automatic control at higher speeds and understand controller limitations from neglecting these dynamics. As speed increases, higher order models are required to maintain accurate lateral control of the vehicle. Neglecting these dynamics can cause the controller to become unstable at the bandwidths required for accurate control at higher speeds. The yaw dynamic model, which is found to be dominated by a second order response, is identified for multiple speeds to determine the effect of velocity on the model. The second order yaw dynamics cannot be represented by the traditional bicycle model. An analytical derivation shows that the model characteristics can, however, be captured by a model consisting of a significant (non-negligible) relaxation length in the front tire. Experimental results are presented showing that the new yaw dynamic model can provide lateral control of the tractor to within 4 cm (1σ) at speeds up to 8 m/s. These results are shown to be an improvement, at high speeds, over controllers based on models (such as a kinematic model) previously used for control of farm equipment.

Verification of a Wheeled Mobile Robot Dynamic Model and Control Ramifications

1999 ◽  
Vol 121 (1) ◽  
pp. 58-63 ◽  
Author(s):  
Daehie Hong ◽  
Steven A. Velinsky ◽  
Xin Feng
Keyword(s):  
Dynamic Model ◽  
High Speed ◽  
Kinematic Model ◽  
High Load ◽  
Wheeled Mobile Robots ◽  
Model Based Control ◽  
Practical Applications ◽  
High Speeds ◽  
Kinematic Models ◽  
And Control

For low speed, low acceleration, and lightly loaded applications, kinematic models of Wheeled Mobile Robots (WMRs) provide reasonably accurate results. However, as WMRs are designed to perform more demanding, practical applications with high speeds and/or high loads, kinematic models are no longer valid representations. This paper includes experimental results for a heavy, differentially steered WMR for both loaded and unloaded conditions. These results are used to verify a recently developed dynamic model which includes a complex tire representation to accurately account for the tire/ground interaction. The dynamic model is then exercised to clearly show the inadequacy of kinematic models for high load and/or high speed conditions. Furthermore, through simulation, the failure of kinematic model based control for such applications is also shown.

Study on Tractor-Semitrailer Shimmy of High Speed

2012 ◽  
Vol 433-440 ◽  
pp. 7420-7424
Author(s):  
Mei Zhi Xie ◽  
Bei Li ◽  
Chao Yi Wei ◽  
Feng Yan Yi
Keyword(s):  
Transfer Function ◽  
Dynamic Model ◽  
Fourth Order ◽  
High Speed ◽  
Damping Ratio ◽  
Second Order ◽  
Original Model ◽  
The Third

Through the establishment of dynamic model of tractor-semitrailer, calculate its transfer function. In the case of the third and fourth state of balanced coefficient is very small in the original model, the model of the tractor-semitrailer of fourth-order drop for second-order using MATLAB-modred () function and balreal () function, seek of relationship between damping ratio and the speed of tractor-semitrailer, The results show that: the tractor-semitrailer shimmy of high-speed is speed inversely proportional to the damping ratio, the higher the speed, the smaller the damping ratio, and thus more likely to shock and shimmy.

Effect of Leg Inertia on Dynamics of Sliding-Leg Hexapods

2001 ◽  
Vol 123 (2) ◽  
pp. 265-271 ◽  
Author(s):  
Fengfeng Xi ◽  
Rosario Sinatra ◽  
Wanzhi Han
Keyword(s):  
Dynamic Model ◽  
High Speed ◽  
High Speeds ◽  
Numerical Studies ◽  
New Type ◽  
Moving Platform ◽  
Low Speeds ◽  
Total Leg ◽  
Two Parameters

In this paper the effect of leg inertia on hexapod dynamics is investigated. Hexapods under investigation are a new type that is made of sliding legs with constant lengths. A complete dynamic model of sliding-leg hexapods is developed including leg inertia. Based on this dynamic model, the effect of leg inertia on hexapod dynamics is investigated in terms of two parameters. The first parameter is the ratio of the total leg mass to the mass of the moving platform, and the second parameter is the acceleration of the moving platform. Numerical studies reveal that the effect of leg inertia may be negligible at low speeds, but becomes significant at high speeds. Hence, leg inertia must be included for modeling hexapod dynamics for high-speed applications.

Predicting the Behavior of Slipper Pads in Swashplate-Type Axial Piston Pumps

1996 ◽  
Vol 118 (1) ◽  
pp. 41-47 ◽  
Author(s):  
R. M. Harris ◽  
K. A. Edge ◽  
D. G. Tilley
Keyword(s):  
Dynamic Model ◽  
Dynamic Stability ◽  
High Speed ◽  
Axial Piston Pumps ◽  
High Speeds ◽  
Axial Piston ◽  
Plate Type ◽  
Simulation Package

This paper describes a dynamic model for slipper-pads that allows lift and tilt behavior to be predicted, including the effects of possible contact with the swashplate or slipper retaining plate. This model has been incorporated in the Bathfp simulation package and used to examine the dynamic stability of slipper-pads over the pumping cycle, and to compare the behavior over a range of pump speeds. The centripetal tilting moments acting on the slipper-pad increase with speed and as a consequence can lead to contact between the slipper and the swashplate at high speed. This is particularly likely to occur as the piston makes the transition between suction and delivery, where the pressure forces acting on the piston-slipper assembly change abruptly. The predicted nature of the swashplate contacts at high speeds correspond closely with witness marks on a dismantled pump. The model presented may also be used for predicting slipper behavior in other types of pump, for example, wobble-plate type pumps, or in piston motors.

A Statistical Study of Process Variables to Optimize a High Speed Curtain Coater: Part I

TAPPI Journal ◽  
2009 ◽  
Vol 8 (1) ◽  
pp. 20-26 ◽  
Author(s):  
PEEYUSH TRIPATHI ◽  
MARGARET JOYCE ◽  
PAUL D. FLEMING ◽  
MASAHIRO SUGIHARA
Keyword(s):  
Boundary Layer ◽  
Experimental Design ◽  
High Speed ◽  
Statistical Study ◽  
Process Variables ◽  
High Speeds ◽  
The Stability ◽  
Air Removal ◽  
Removal System

Using an experimental design approach, researchers altered process parameters and material prop-erties to stabilize the curtain of a pilot curtain coater at high speeds. Part I of this paper identifies the four significant variables that influence curtain stability. The boundary layer air removal system was critical to the stability of the curtain and base sheet roughness was found to be very important. A shear thinning coating rheology and higher curtain heights improved the curtain stability at high speeds. The sizing of the base sheet affected coverage and cur-tain stability because of its effect on base sheet wettability. The role of surfactant was inconclusive. Part II of this paper will report on further optimization of curtain stability with these four variables using a D-optimal partial-facto-rial design.

RED CUT COBALT

Alloy Digest ◽  
1980 ◽  
Vol 29 (8) ◽  
Keyword(s):  
Fracture Toughness ◽  
Cast Iron ◽  
High Speed ◽  
Elevated Temperatures ◽  
High Speed Steel ◽  
Heat Treating ◽  
High Speeds ◽  
Red Hardness ◽  
Nonferrous Alloys ◽  
Cutting Point

Abstract RED CUT COBALT steel is made by adding 5% cobalt to the conventional 18% tungsten -4% chromium-1% vanadium high-speed steel. Cobalt increases hot or red hardness and thus enables the tool to maintain a higher hardness at elevated temperatures. This steel is best adapted for hogging cuts or where the temperature of the cutting point of the tool in increased greatly. It is well adapted for tools to be used for reaming cast-iron engine cylinders, turning alloy steel or cast iron and cutting nonferrous alloys at high speeds. This datasheet provides information on composition, physical properties, and hardness as well as fracture toughness. It also includes information on forming, heat treating, and machining. Filing Code: TS-367. Producer or source: Teledyne Vasco.

CPM REX 25

Alloy Digest ◽  
1980 ◽  
Vol 29 (7) ◽  
Keyword(s):  
Heat Treatment ◽  
High Speed ◽  
High Speed Steel ◽  
High Hardness ◽  
Heat Treating ◽  
High Speeds ◽  
Aisi Type ◽  
Tool Performance ◽  
End Mills ◽  
Machining Operations

Abstract CPM REX 25 is a super high-speed steel made without cobalt. It is comparable to AISI Type T15 cobalt-containing high-speed steel in response to heat treatment, properties, and tool performance. CPM REX 25 is recommended for machining operations requiring heavy cuts, high speeds and feeds, and difficult-to-machine materials of high hardness and abrasion resistance. Typical applications are boring tools, drills, gear cutters, punches, form tools, end mills and broaches. This datasheet provides information on composition, physical properties, hardness, and elasticity as well as fracture toughness. It also includes information on forming, heat treating, machining, and surface treatment. Filing Code: TS-365. Producer or source: Crucible Materials Corporation.

Dynamic model for high-speed rotors based on their experimental characterization

2017 ◽  
Vol 2 (4) ◽  
pp. 25
Author(s):  
L. A. Montoya ◽  
E. E. Rodríguez ◽  
H. J. Zúñiga ◽  
I. Mejía
Keyword(s):  
Dynamic Model ◽  
High Speed ◽  
Natural Frequencies ◽  
Mode Shapes ◽  
Experimental Characterization ◽  
Rotating Systems ◽  
Computing Performance ◽  
The Impact ◽  
Stiffness Distribution ◽  
Good Agreement

Rotating systems components such as rotors, have dynamic characteristics that are of great importance to understand because they may cause failure of turbomachinery. Therefore, it is required to study a dynamic model to predict some vibration characteristics, in this case, the natural frequencies and mode shapes (both of free vibration) of a centrifugal compressor shaft. The peculiarity of the dynamic model proposed is that using frequency and displacements values obtained experimentally, it is possible to calculate the mass and stiffness distribution of the shaft, and then use these values to estimate the theoretical modal parameters. The natural frequencies and mode shapes of the shaft were obtained with experimental modal analysis by using the impact test. The results predicted by the model are in good agreement with the experimental test. The model is also flexible with other geometries and has a great time and computing performance, which can be evaluated with respect to other commercial software in the future.

scholarly journals Observation and analysis of diving beetle movements while swimming

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Debo Qi ◽  
Chengchun Zhang ◽  
Jingwei He ◽  
Yongli Yue ◽  
Jing Wang ◽  
...  
Keyword(s):  
Swimming Speed ◽  
High Speed ◽  
Kinematic Model ◽  
Movement Pattern ◽  
Unmanned Vehicles ◽  
Power Stroke ◽  
Cross Sectional ◽  
Motion Data ◽  
The Cross ◽  
Diving Beetle

AbstractThe fast swimming speed, flexible cornering, and high propulsion efficiency of diving beetles are primarily achieved by their two powerful hind legs. Unlike other aquatic organisms, such as turtle, jellyfish, fish and frog et al., the diving beetle could complete retreating motion without turning around, and the turning radius is small for this kind of propulsion mode. However, most bionic vehicles have not contained these advantages, the study about this propulsion method is useful for the design of bionic robots. In this paper, the swimming videos of the diving beetle, including forwarding, turning and retreating, were captured by two synchronized high-speed cameras, and were analyzed via SIMI Motion. The analysis results revealed that the swimming speed initially increased quickly to a maximum at 60% of the power stroke, and then decreased. During the power stroke, the diving beetle stretched its tibias and tarsi, the bristles on both sides of which were shaped like paddles, to maximize the cross-sectional areas against the water to achieve the maximum thrust. During the recovery stroke, the diving beetle rotated its tarsi and folded the bristles to minimize the cross-sectional areas to reduce the drag force. For one turning motion (turn right about 90 degrees), it takes only one motion cycle for the diving beetle to complete it. During the retreating motion, the average acceleration was close to 9.8 m/s2 in the first 25 ms. Finally, based on the diving beetle's hind-leg movement pattern, a kinematic model was constructed, and according to this model and the motion data of the joint angles, the motion trajectories of the hind legs were obtained by using MATLAB. Since the advantages of this propulsion method, it may become a new bionic propulsion method, and the motion data and kinematic model of the hind legs will be helpful in the design of bionic underwater unmanned vehicles.

scholarly journals Investigating the Trackability of Silicon Microprobes in High-Speed Surface Measurements

Sensors ◽  
2021 ◽  
Vol 21 (5) ◽  
pp. 1557
Author(s):  
Min Xu ◽  
Zhi Li ◽  
Michael Fahrbach ◽  
Erwin Peiner ◽  
Uwe Brand
Keyword(s):  
Dynamic Model ◽  
High Speed ◽  
High Signal ◽  
Resonant Response ◽  
High Demand ◽  
Surface Measurements ◽  
Tactile Roughness ◽  
Low Mass ◽  
Roughness Measurements

High-speed tactile roughness measurements set high demand on the trackability of the stylus probe. Because of the features of low mass, low probing force, and high signal linearity, the piezoresistive silicon microprobe is a hopeful candidate for high-speed roughness measurements. This paper investigates the trackability of these microprobes through building a theoretical dynamic model, measuring their resonant response, and performing tip-flight experiments on surfaces with sharp variations. Two microprobes are investigated and compared: one with an integrated silicon tip and one with a diamond tip glued to the end of the cantilever. The result indicates that the microprobe with the silicon tip has high trackability for measurements up to traverse speeds of 10 mm/s, while the resonant response of the microprobe with diamond tip needs to be improved for the application in high-speed topography measurements.

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