Knowledge Base

Article Number: 6 | Post Date: July 2, 2016 | Last Updated: July 2, 2016

I'm using the fast control icons to steer my vehicle, but it doesn't stay on the same path when I change the initial speed. Why not?

When you use the fast control icons to maneuver your vehicle, entries are placed in the sequences menu in the left side control panel. By default, when you manipulate the fast control icons, the sequences entries are indexed by time. If you're accustomed to using other simulation programs, then you're probably already familiar with "steering tables" and "braking tables." Virtual CRASH 3 does something very similar to these tables, but can go one step further, and offer indexing by distance rather than time.

First, let's look at a simple lane change maneuver. 

Notice in the figure above that four entries are placed in the sequences menu. The second entry initiates a left steer, the third entry a right steer, and the fourth entry straightens out the wheels. Each new entry in the sequences menu specifies a new maneuver to be completed, beginning at some time with respect to the start of the prior entry. This is indicated by the time parameter. So in the figure above, we see the third entry has a time = 0.632 seconds. This means, the right counter-steer begins 0.632 seconds after second sequence entry (the initial left steer). Since the relative timing remains constant by default, there will naturally be a dependency on the initial velocity. As we increase the initial velocity in the case shown above, we see the positions at which the maneuvers are made change in space:


Rather than keeping the relative time fixed for each maneuver, we have the option to keep the relative travel distance fixed between maneuvers. This is a great feature of Virtual CRASH 3. Selecting the three sequences entries, simply change "use:time" to "use:distance."

Now as the initial speed is increased, you'll notice roughly the same travel path. There may be some differences since there is still a dependence on steering time (the total time needed to complete the new steering input).  

A great alternative to maneuvering the vehicle by using the fast control icons is to take advantage of the auto-driver feature. Simply specify the desired path the vehicle is to follow (to within the abilities of tire forces to hold it). Then select that path using the fast control icon. This process is described in the blog post:

Here we see our vehicle nicely following the specified path (purple curve):

As we increase the vehicle speed, we see the auto-driver system doing a great job continuing to follow the same specified path:

The auto-driver is a great tool for experimenting with lane-change maneuvers, critical speeds, and more!

Tags: Steering, steer car, steer vehicle, using auto-driver, auto-drive, keep car on path, path follower, auto driver, auto drive, how to steer. 

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