We may have found a way around the looming potential redesign. It is too early to tell for sure, but we are hopeful. We may be able to use some rather odd pieces which may or may not have been originally intended as gears to transfer torque instead of the older bevel gears. There will be spacing problems, and we may decide to move the ninety-degree torque shift that these gears provide further back, closer to the central transmission. This will allow more room for the gears to operate, and will also eliminate the problem of the drive axle twisting. The play in the wheels that was present because of this will, however, be replaced by play in the form of the gears shifting slightly with respect to each other; the teeth don’t lock perfectly. However, this is not going to be as much of a problem. Having a larger train of gears between the bevels and the differentials should allow for more torque, and completely eliminate skipping. If the motor stalls during testing, we have done a good job. Then we will try to provide it with more power (this is where our battery research comes in). If the motor has too much power behind it and a drive train that is not sturdy enough, it will skip.
The gallery of today’s work has pictures of the new “gears” that we’re planning to use, in the context of a mock-up drive assembly we created to see how they work. They are rather large, and only have four “teeth”, which are really more like arms. For this reason, we think they will be a lot more robust, even though they’re rather unorthodox.
Well, we’re having some problems. To say the least. After installing the new steering systems at either end, we had a lot of problems with the gears not locking correctly in the drive train. When under a lot of force, the motor would stall and the gears would skip repeatedly. We reinforced and consolidated the central drive axle bracing system, which helped solve the problem, but the interface between this axle and differentials at either end of the car also skips. We don’t think we can fix this problem. We have been dealing with the physical limits of the Lego system since we started this project, but we’re feeling it now more than ever. We have pushed the pieces up to, if not past, the very upper edge of their capabilities.
More and more, we are realizing that we are nearing the end of the road. Whether or not the car functions as desired is somewhat immaterial. At a certain point, we have to deal with the fact that we can’t make it do any more stuff.
We’re considering some potential drastic overhauls to the car’s basic functionality. The concept of a central two-speed transmission with a driveshaft extending to two differentials at either end may need to be rethought. I suggested an articulated steering module, doing away with the need for a driveshaft, with a motor and transmission at each end, and full-axle suspension. This would do away with the need for differentials, universal joints, and almost all axles. It would also require completely rebuilding the entire car from scratch and scrapping all existing systems. Bar none.
We may yet be able to salvage the existing systems’ functionality. And regardless of what happens, we will press on. The LC(A) will never die.
We have successfully incorporated a worm gear into the steering rack. We used one of the weird double-beveled gears to achieve the right clearance. We are about to duplicate this system to the other side of the car, and then we will start working on the touch bumpers again.
We incorporated rack-and-worm drive systems into both the shifting assembly and the steering. We are still working on mounting the drive motor for the steering. We had a lot of trouble at first, but then we realized that we could use an intermediary gear between the worm and the rack. This makes it a lot easier to drive the worm axle; we had been having trouble before because whatever gear we put on it would interfere with the rack. The system we’re working with now promises a lot of power in a compact space, and allows next to no flexing by the wheels.
We will be working again not this coming weekend, but the weekend after, and will hopefully finish up the steering then.
As you can see, we are now on the new site. Please bear with us as we work on it. For the moment, you can see the Plog and the galleries here. Soon this section of the website will be integrated into the theme we are designing for the rest (you can see how it’s going at carofawesomeness.com. Thanks.
I am taking tomorrow off work, and Will and I will be working the entire day and part of Thursday morning. We are going to get a lot done.
We also finally have the server information for the new location of the website, so by the end of our work, this Plog and the image galleries should be on the new site, carofawesomeness.com. This is going to be awesomer, and much easier to use.
Will’s gearbox system worked, but we decided to try a worm gear again. We’ve come up with a system that may work, but we have not finished it. We raised the worm gear up, and decreased the length of the rack, allowing us to place a gear on the worm shaft closer to the center without it interfering with the rack. We have begun mounting a motor to drive the gear. We both have this week off, so we’ll be meeting again on Wednesday-Thursday and next weekend.
Our main problem right now is the steering system. We are trying to find a way to make it slower and more powerful. We attempted to come up with a system that would drive the rack with a worm gear, but we had problems physically fitting a drive gear onto the worm gear’s axle without interfering with the rack. We tried a system of two worm gears, one driving the other which drove the rack, but couldn’t overcome the limits of friction; the axles just shifted parallel to each other instead of spinning. Worm gears are tricky like that; they are next to impossible to drive with a gear. This is a characteristic we want in the steering system, so that the wheels are held in place and can’t turn the motor themselves, but it worked against us in this particular instance.
Will is currently working on a gearbox he though of. If it works we will probably adopt it; it could potentially provide a very good gearing ratio and be very compact.
We have finished work for the day, and are currently cleaning up. We designed a new touch bumper based off of the one from the Mindstorms manual, extending the arms and remounting the touch sensors within the system, as well as redesigning the actual mount for the whole system. It functions almost perfectly. It will require a little bit of revision as we extend the arms to cover more of the car vertically, but it is a great start, and is extremely solid.
We are having a very hard time making the bumper system work. I spent about an hour and a half working on a system which we then completely discarded. This is a rather common occurrence; one of us has a brilliant idea which turns out to completely suck. This time it was my turn. I built a compound dual-track and carriage system, designed to split the bumper into three interlocking levered sections. Will, meanwhile, built a rather robust sensor mounting block which we are currently incorporating into the existing sprung bumper. However, we are inherently unsatisfied with this bumper; there are too many problems with torque where there shouldn’t be torque and no torque where there should be torque. As I write, Will is assembling the touch bumper from the Mindstorms 2.0 catalog. It’s unlikely that this exact design will work on our car, as it’s far too small, but we are hoping to learn something and get some ideas from it.