LEGO Engineering

How can I attach motors to the NXT with the fewest number of pieces?
1. Two Motor Car: Materials i. 9-holed beams (3) ii. 7-holed beams (2) iii. NXT motors (2) iv. Assortment of friction pins Attach the back of the two motors together (above the wire input) using a 9-hole beam ...

How can I build a 2-motor NXT car?
You can download these building instructions (1.3 MB) for a very simple, but not incredibly sturdy, 2-motor NXT car. KAB

How can I generate three-dimensional images of LEGO creations like the ones I see on LEGOengineering.com?
MLCAD and LDraw are the software applications used to generate the 3D images seen on LEGOengineering.com. You can obtain these applications for free at this website:http://www.ldraw.org/download/start/win/ KAB

I tried to use the touch sensor, but it didn't work.
Often times programming problems are the result of how you have built your robotic creation. In the above program there is no modifier wired into the Wait For Touch icon, therefore it defaults to waiting for a touch sensor to be pressed on Port 1. However, if in your creation you have th...

I used the gears with spikes (crown gears), and everything shakes.
Problem: Crown gear does not run smoothly.Cause: This may be because the horizontal crown gear is resting directly on top of the vertical gear. In other words, the weight of the horizontal crown gear and anything on top of it are being held up by the vertical gear. This is a bad design and it ...

Is it possible to plug a motor into the input ports?
Yes, on the RCX. The motors can be treated as sensors.The NXT motors can be used as sensors while plugged into an output port. By clicking on the NXT comands icon, in the new Robolab software, a selection of "Value of" icons will be avaible for output ports A, B, and CBy connecting a motor ...

Is it possible to use other sensors with the RCX?
There are a lot of other sensors that can be used in conjunction with the RCX, all of which can be found in the sensor adaptors list. For example, here is a program that logs the pH over a time span of 10 seconds. All of these sensors are treated exactly the same as the standard RCX sensors and ar...

My car drives, but not straight.
Potential causes:The motors are on different power levels.The wheels are not lined up properly (height).The wheels may be bent.Each pair of wheels has the same two wheels.The gears are not lined up properly.Mismatched motors, all Lego motors do not have exactly the same power level.Bad: The bot...

My car falls or tips backwards when I drive.
If the car tips forward or backwards when driven, the car might not be not balanced well. If the front of the car pops up when it is driven forward it is too heavy in the back or too light in the front. This is shown in the pictures below. &n...

My car is driving backwards.
If the car is driving in the wrong direction, know that the wheels are turning in the direction that the program tells them to.Change the direction of both motor inputs or the direction of the motors in the program. Also, see the section on "car spins in place". ses

My car won't move when I push Run on the RCX.
If the wheels do not spin and car does not move.1) Pick the car up and now see if the wheels move. If the wheels now move, it could mean that there was not enough power coming from the motors. One way to fix this is to use smaller wheels that do not require as much power to get going. If progra...

My motors/wheels fall off when I drive my car.
Cause: The car in the picture below has only the motors attached to the bottom of the RCX. It is possible that the car will be able to remain at rest on its own, but as soon as it starts moving the motors will probably break off from the rest of the vehicle. This happens because when the wheels turn...

My RCX car spins in place - Why won't it move?
If the wheels are turning in opposite directions, the direction of a motor can be changed by rotating the wire 180 degrees and plugging it back in. Bad: Car spins clockwise Good: Car goes forw...

My wheels spin, but the car does not move.
If the wheels are not touching the ground, use bigger wheels or move the motors and axles down.The wheels could be going too fast for their own good. They spin too fast to be able to catch the surface. One way to fix this is to use larger wheels or to gear down the wheels (i.e. use gears so that y...

When I use the LEGO camera, I have shadows across my images. What can I do to get rid of these?
If you have a lot of dark spots in your image then it is a good idea to build some sort of enclosed structure for your light. This is so that it will be isolated from extraneous light.Here is a picture of several Lego bricks with very bad shadows:These are two pictures of the light box I built...

Why am I having problems loading my program to my RCX?
If you are getting this message it is because you are having trouble communicating between your tower and your RCX.Problems connecting to the tower include:If the green light on the tower is not on, then the tower is not transmitting to the RCX. Check which port the tower is configured to (using the...

Why is the light in my light sensor off?
In order for the light in the light sensor to be on, the sensor port must be configured as a powered sensor. Check your program to be sure that you configured the correct port as a light sensor and that the light sensor is plugged into the correct port. ses