The PC application will connect to the NXT and EV3 bricks by Bluetooth (for the EV3, we are investigating if we can write a block for sending messages over a WiFi connection, but that isn’t easy).
In the previous post, I mentioned already that the Candy Crane does ‘in principal’ what it has to do, but the movements were not smooth enough and the accuracy was also a problem. In the last weeks, I have improved the movement and positioning. Below you find the final version:
And the LDD version:
This final version of the Candy Crane is controlled by two EV3 bricks:
1. Brick 1 (in the right tower) controls the movement of the complete crane:
- Two touch sensors are used for the positioning.
- Due to the weight (~1.5 kg), I have to use two M-motors (which are mechanically connected) to move the crane. One motor didn’t had enough torque. Another problem was the force on the axles when I used one motor. The motor movement had to go ‘all the way’ to the other tower. I was afraid that the axles would break due to the weight they had to move.
2. Brick 2 (in the hoist) controls the movement of the hoist and the grabber:
- Y-movement of the hoist. The hoist is moved by an M-motor, the positioning is done by a color sensor.
- Z-movement of the grabber. The grabber is also moved by an M-motor, the positioning is also done by a color sensor.
- The grabber is controlled by a third M-motor.
The two bricks are connected by a flexible USB cable (Belkin) in Daisy Chain modus. This means that the two bricks are seen as one large brick. Both EV3′s are running on a rechargeable battery (all the motor movements consume lots of energy).
In the previous post, you have seen that the candy will be delivered by a mechanism that flips the whole wagon. But how are the wagons refilled? This is done by the Candy Crane:
The crane picks up the candy from the grey area in the middle and moves it to the empty colored wagon. The candy will be in the same colors as the four wagons (yellow = lemon flavor, green = apple flavor, red = strawberry flavor, blue = blueberry flavor). I wrote a demo EV3 program to check if the crane operates conform expectations. In principal: it does. But the sensors are not always working and the up/down movement is not controlled by a sensor. The brick has to move it up all the way to know the position. So, it is not ready yet. It has to be made more reliable for Lego World.
You can watch the video at Youtube:
The train has to deliver the candy (or whatever) to the visitor. We are aiming at a delivery mechanism with a huge “WOW” factor. This is the proof of concept to tilt the complete wagon (made in Lego Digital Designer).
You can find an animated gif at Youtube:
Jan Willem van Silfhout reviewed the first version of the PUI Receiver and came up with the great idea to add a cover to the sensor when it is hit. Below you find the result:
A more detailed view:
And a small demo video of the real version:
I have finished the design of the PUIstols receiver:
The sensor of the color that is hit, ‘falls’ backwards to indicate that it has been hit. The colored flag turns left or right to indicate which PUIstol did the job (left = PUIstol 1, right = PUIstol 2).
The dimensions of this PUI (Physical User Interface) is appr. 110 cm x 20 cm. Need to work on the transportability ;-). Three sensors (yellow, green and red) are already functional in the real version. To connect the red and blue sensors/motors, I used the 90 cm cables of HiTechnic. Unfortunately, I don’t have enough of these long cables to connect the blue one.
You can view a demo of the receiver at our Youtube channel:
In the sketch below, you’ll find the current track layout that we are building for Lego World 2014:
In total we have 4 NXT bricks and 4 EV3 bricks. Two of the EV3 bricks are not used yet. They will be needed for the component which will load the wagons with candy.
The visitor shoots with one of the PUIstols ‘”one” or “two” a color (red, yellow, green or blue). The chosen color is read by EV3 #2. The computer directs the train (number one or two, controlled by NXT #1 or NXT #2) to the marshalling yard to pick up the corresponding wagon. The switch controls NXT #3 and NXT #4 have to set the switches to the right track. Next, the train delivers the candy (or something sweet) to the visitor. Finally, the train goes back to the marshalling yard to bring back the wagon. When the train hits the buffer (which is detected by EV3 #1), the train decouples the wagon.