Author Topic: CATIA motion simulation in the use of the vehicle steering system  (Read 412 times)


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Following a heavy-duty vehicles the steering motion mechanism, for example. Using CATIA motion simulation module DMU their motion simulation.
A digital-to-analog steering mechanism parts to establish
Complete the "1 - frame". "- Steering gear bracket. 3 - steering gear". "- Steering arm." "5 - steering drag link". "6 - front axle assembly. 7 - wheel assembly "and" 8 - suspension "parts of the three-dimensional digital to analog to prepare specific modeling process is not described here. assembly parts involved in the movement simulation needs to be there at the same level due to the motion simulation analysis. the assembly of these items can be of a single part (part) can also be the assembly member (assembly) for the front axle assembly of its own steering mechanism can exercise need to be split to ensure that the various moving parts is with an assembly flexible sub-assembly can be achieved the assembly movement between the different levels, but in the motion simulation. we do not use the front axle assembly, we will split into four parts. "61 - front axle beam 62 - left knuckle and trapezoidal arm assembly of 63 - steering tie rod and 64 - to make it appear right knuckle and trapezoidal arm assembly in an assembly directory.
Steering Institutions mold assembly
Should provide a vehicle assembly before assembly coordinate system we take the frame below the wing to the xy plane. Symmetrical center plane of the frame to the xz plane. The front axle theoretical centerline where the transverse vertical plane yz plane also provides x rearward axial direction and the y-axis direction right up the z-axis direction, so that on the vehicle coordinate system of the agreement.
In the assembly module. Before loading or create a only a new part of the coordinate system fixed constraints. Named the vehicle coordinate system and this part contains only one coordinate system without other entities surface feature if the frame total into the assembly itself is assembled in accordance with this rule, or the frame assembly coordinate system is the vehicle assembly coordinate system you do not need to define a new vehicle coordinate system. simply first load frame assembly and fixed Constraints can be.
Followed by re-assembling fixed pieces involved in the movement. "- Steering gear bracket." 3 - steering gear ". 8 - Suspension" and "61 - front axle beams and other components short constrained as little as possible. Insufficient follow-up can be added as shown in Figure 1.

Figure 1
Steering motion analysis
Start steering input Duanyou steering wheel. Pass through the steering drive shaft to the steering gear. Simulation of this process is very simple. Were rotating vice. Steering gear mechanical transmission mechanism is actually a power transmission deceleration mechanism of reversible play decelerating growth twist to change the direction of the torque transmission. internal structure will not elaborate here.
"3 - the output terminal of the diverter has a rocker arm and is connected to the output shaft of such diverter may be a large angle of rotation of the input shaft into the output shaft of the small angle of the steering arm swing." 4 - steering arm " The swing is a rotation pair (RevoluteJoint). motion simulation of this article will be steering arm with the rotation of the steering gear output shaft as the initial movement of the entire motion simulation.
"5 - steering drag link" at both ends of the the ball twisted structure. Connected to the front with 4 - steering arm. Backend with "62 - knuckle arm connection. Formation the the two balls twisted Vice (SphericalJoint).
62 - knuckle arm "with the knuckle. Hub. The left steering trapezoid arm fastened together. Around" 61 - front axle beam "kingpin rotation. Formation of a rotation Vice (RevoluteJoint).
63 - both ends of the tie rod ball twisted structure. Connection with the "62 - left steering trapezoid arm" and "64 - right turn trapezoid arm" respectively. To form two the ball twisted Vice (SphericalJoint).
64 - right knuckle and trapezoidal arm assembly "around" 61 - front axle beam "kingpin rotation a rotation pair (RevoluteJoint).
Back when the steering arm swing wheel right turn; steering arm swings forward. Steering wheel left. This is the whole movement of the steering mechanism. Therefore to do the kinematic simulation must acquire a certain amount of mechanical principles related infrastructure knowledge.
Each deputy campaign are actually composed by one or several constraints. These constraints can be added by adding motion vice motion simulation module assembly constraints convert command (AssemblyConstraintsConversion) can also use the right side of the toolbar will be equipped some constraints directly convert existing deputy campaign.
Steering the establishment of the movement mechanism simulation
From the the assembled assembly module into motion simulation module. Click "Start" → "Digital Assembly → DMU sports institutions to enter CATIA motion simulation module as shown in Figure 2.

Will detail the specific operation of the steering motion mechanism simulation the various deputy campaign tool button in the toolbar on the right. Shown in Figure 3. And we click rotating command icon button (RevoluteJoint). Pop-up rotary combine dialog box shown in Figure 4 shows.

Figure 4
Click on the upper right of the dialog box "new mechanism" button. Then pop up a dialog box. Asked to enter a name. Name of the custom here we enter the steering movement system simulation Click OK to return to Figure 5 rotation command interface.

Click on the line the right side of the space provided. Choose "4 - steering arm rotation axis. Spaces at the click straight right side select" 3 - steering gear steering axis of rotation of the rocker shaft; click on the plane 1 at the right spaces. choose "- steering arm on the vertical plane of the axis of rotation. clicking on the plane right side at the spaces. choose" 3 - diverter "steering arm axis perpendicular to the axis of rotation the plane two plane coincident or parallel. coincide single zero offset. parallel single select offset offset size does not matter. default values ​​prevail in order to ensure the accuracy of the simulation data. assembly after the position must be the same location as the actual assembly. not the same need to adjust the the assembly offset value. lower left side there is a driving angle here can first select and then fill in the lower limit "-40" the. cap "40" can also drive angle do not fill. finished in the command can be added. shown in Figure 6 Click OK to complete the first rotary motion of Vice.

Vice adding a steering we can by tool button (AssemblyConstraintsConversion). Already exists a coaxial overlap distance constraints between the constraint and a surface and the surface directly into a rotary motion of Vice.
Then continue to add a second deputy campaign - the ball hinge Vice (SphericalJoint). Pitman arm and steering drag link connection. Ball joints Vice is actually two parts of the point coincident constraint. The ball joints Vice (SphericalJoint) command interface shown in Figure 7 below.

A point in the center of the 5 - steering drag link ball pin on another point in the "4 - steering arm and turn to the swing arm and did a little so we need to" 4 - steering arm do a secondary point the location of this point is the actual assembly 5 - steering drag link "the central point of the ball pin in order to ensure the accuracy of motion simulation this point the position must be consistent and the actual position. complete auxiliary point were selected - steering rocker point and 5 - steering drag link ball pin center to complete the second goal hinge movement Vice. shown in Figure 8.

To note here is that you want to view the model tree on the left of the following types of constraints. Assembly was with the steering arm and steering drag link constraint types. Retain only a point coincident constraint. Excess you want to delete.
And then they need to complete the third ball joints deputy campaign. "5 - steering drag link with 62 - the ball hinge vice on the left knuckle arm assembly, similar to the situation and the the above second goal hinges pair also need left knuckle arm assembly suitable place to do auxiliary point. specific reference to the second ball hinge Vice process.
Fourth the the rotational movement Vice. "62 - left knuckle arm assembly" around "61 - front axle beam rotation left kingpin same coaxial coincidence constraints between a surface and the surface distance constraints. reference to a rotating vice the fifth ball joints Vice and the sixth ball joints Vice. "62 - left knuckle arm assembly trapezoid arm and 63 - steering tie rod ball joint connection and 64 The - right knuckle arm assembly "the ladder arm and 63 - steering tie rod ball joint link can refer to the second third ball joints Vice.
Very simple rotating the seventh rotary motion of Vice. "64 - right knuckle arm assembly 61 - front axle beam right kingpin see the fourth rotation pair.
This point. Moving parts bound basically completed. Fixed components of the connection is now complete. To use a rigid restraining order (RigidJoint) assembly systems do not participate in sports "- frame 2 - diverter bracket." - steering gear. "61 - front axle beam assembly." 8 - Suspension 11 consolidation up to form four rigid connection interface shown in Figure 9. need to select the Part 1 and Part 2 are needs the consolidation together the two parts.
7 - Tire consolidation together as a whole to participate in sports simulation. Initial movement driven with 62 - knuckle assembly where we as a driving value to the rotational motion of the steering arm. movement Vice increase the drive angle -40 ° ~ 40 °. shown in Figure 6.

Basically completed. Component constraints but we found in the left analog Tree freedom. Instead of 0. Therefore, the movement can not be simulated. Involved in moving parts also need to be constrained. Now we need to find out the reasons. Problem its too many degrees of freedom. itself can rotate and can not be simulated theoretically steering rod can be rotated around the center of the ball hinge connection. therefore must limit its rotation. solve two on the connection of the two ball joints. the ball twist Vice simulation is the focus of this paper. difficulty is also a sports simulation.
Fact, there are many sites the ball twisted use in the car, such as the shift lever system, we need to introduce a third member to limit its constraints in order to constrain the rotation of the ball twist. Gimbal This piece is in two balls twist between any the ball twist at the insertion on a universal joint to limit the rotation of the trolley. the motion simulation become possible. "- steering drag link" back-end and 63 - the left end of the tie rod. were inserted into the two universal joints. named gimbal
1 "and" universal joint. "Gimbal very simple digital-to-analog three-dimensional entity only contains a master coordinate system can be a universal joint and two adjacent pieces of connections with two adjacent pieces in two mutually perpendicular directions of rotation, deputy vice added rotation is very simple. 4 rotation pair can basically complete the motion simulation in the process of completion of the constraints in order to ensure the accuracy of the simulation. adjustment. correct steering drag link and tie rod length also need to add some digital-analog auxiliary coordinate system or point line. surface elements. specific add here not 11.
All commands add complete system will automatically pop up a dialog box can see the left analog Tree degrees of freedom is shown in Figure 10 to view the directory tree on the left steering motion mechanism simulation subdirectory. "combined" command "and" fixed parts "Expand" Combining View all sports connection relationship situation. Expand command can see the movement of the input value of the command expand fixed parts can view the fixed parts beam can also use the analysis mechanism Command (MechanismAnalysis) view of the constraints connected as shown in Figure 11. saved. constraints can also be exported to the Excel file.

Figure 11
V. steering motion mechanism simulation use
A steering motion mechanism simulation
Use the movement analog command (SimulationwithCommands). Appear the dialog box shown in Figure 12. Can also double-click the directory tree on the left steering motion simulation. Use the mouse to drag the slider to the right of the command bar Click below the triangular play button on You can achieve the simulation of the movement of the steering mechanism.

Figure 12
2. Generated the simulation animation files steering motion mechanism
Use the analog command (Simulation. Figure 13) can generate motion simulation animation files. Easy from the CATIA software to view.

Figure 13
3 to generate the sweep envelope
Edit analog command (EditSimulation. Figure 14) can be generated replay using the generated replay swept envelope the body command the (SweptVolume. Figure 15) can generate a sweep of the moving parts of the envelope body. Facilitate movement interference analysis space analysis and moving parts.

Figure 16 Figure 17 sweep of the moving parts of the motion simulation envelope body. CGR files can be loaded into the vehicle assembly view and spatial interference analysis.

Rotation angle relationships checking 4.
Use the motion simulation command (SimulationwithCommands). Check to activate the sensor. Pop-up dialog box in Figure 18. Dragging commands to move the slider to the right in the the sensor dialog select set "rotation combined 5" and
Rotary linkage 6 two rotating combination represents the rotation of the left and right wheels, respectively. Click to play the triangle button. Can see the instantaneous value of the left and right wheel rotation sensor dialog. If historic values. Click file output in the lower end of the column button. the angle corresponding values ​​of the left and right wheel movement output to an Excel file. clicking on the graphical buttons can output the angular movement of the left and right wheels relations graphically.

Figure 18
Use of internal and external angle of steering trapezoidal mechanism steering relationship should satisfy the following formula: where. Θo.θi two corner. Κ the two kingpin steering section distance from the intersection of L for the automotive wheelbase.
Calculated using the above formula using the Excel spreadsheet data. Contrast with the steering the emulation system output data and results data coincide with the results. Meet the actual requirements.