DualGrip-NXT Rover
Close-up of the IRLink Sensor and the Power Functions IR Receiver
Those linear actuator connector barrels make for a great link to allow the drive system rotate
Front view of DG
Bottom view of DG
Future Plans:
I have also added a HiTechnic IRLink sensor to the NXT as I plan on programming a full autonomous mode where the robot would navigate on its own. When running in this mode, the NXT would issue commands through the IRLink senor to the Power Functions receiver to control the drive wheels while also monitoring the Acceleration sensor. In addition to this, I also have a Techno-Stuff DIRPD sensor on there to aid in object detection up front. Stay tuned for more on this later…
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That is cool!!
I understand this is in response to a LEGO challenge. But if you add the rubber tires to the side, what is the point of still having tracks? I mean, is there any situation where tracks would work better than the 6 wheels on the sides? Otherwise, I’d just make a robot with the 6 wheels, and get rid of the tracks altogether 🙂
@santi: In answering your below question – Yes, there is at least one situation where tracks would work better than wheels alone. I challenge you to build two similar robots (same size and wheel widths as DualGrip) – one with tracks and the other with 6 wheels as I have built it. Then, take those two robots and drive them on carpet making sure you try to do quick sharp turns in the process. Tell us which one turns faster without catching or buckling in the carpet? I am sure your answer will be the tracked robot is faster. Hence the reason for my challenge. Tracked robots are great for navigating all terrains. Tires can also meet these needs if you place the tires close together and your robot is not too wide. However, if you place a number of rubber wheels far from the center turning radius, you will see what I am talking about – they grab and bind while turning – especially on carpet.
If the LEGO tracks had rubber gromments in them, then I would not have been writing this as there would be no challenge and no robot to build. However, LEGO tracks are quite slippery on most smooth/hard surfaces. Rubber wheels satisfy the grip and climbing aspect, while the tracks satisfy the general turning and quick maneuverability requirements. Make sense?
Looking closely at your design, is the NXT also controlling the power-functions motor? how do you do that!?!? is it possible to generate an infra-red signal from the NXT to control the power-functions motor?
Yes, that is correct. If you read the “How Does it Work” section, I describe it in more detail there. Essentially, I am driving the robot FW/REV while the NXT and accelleration sensor determines the slope and causes the tracks to contract/expand automatically.
I was wondering the same thing about the wheels for climbing and tracks for driving. I would think it would be the other way around. Wheels for speed on the ground and then tracks for climbing hard obsticles where the tires might get stuck.
I do see where tracks would help on a 360 spin, where tires would need to take a big circle turn if you have room. (side note: discovery had a tank build off, one team used full tracks second team used small tracks with wheels in front. the tank track style could not 180 spin where the small track with wheels took less time. I think bad track design on the first teams part. But it was intresting to see it have such a hard time turning in dirt.)
Maybe a 4 wheel steering design would make turning easier and still be able to climb and move fast.
Thx for the comments. What you are saying would be true in a real-life setup. However, if you have these LEGO tracks, you will find that they are hard smooth plastic and have little to no grip on many surfaces (especially tile / hardwood). So, in LEGO reality, the tracks are better for quick turns etc, and rubber tires for climbing as they have sticking power.