The original WeDo Resource Set introduced 1st-3rd grade kids to the world of robotics. The one thing I did not like about it, is that the robot had to stay connected, by wire, to the computer. With the introduction of WeDo 2.0 Core Set, bluetooth frees the robot from the computer. It is also more versatile with the use of tablets, as well as computers; so from one device you can learn about WeDo, build from, program, execute from, and record observations about your WeDo model.
For those of you would might be considering LEGO's WeDo 2.0 Core Set, you will find that it is a good platform for Grades 1-5 and a good introduction to robotics for the older students who are starting to explore the world of robotics. It is a natural lead in to LEGO Mindstorms robotics.
So, the Brics~2~Bots engineers have been tinkering with the WeDo 2.0 set and have made some interesting discoveries.
If you haven’t seen the Smart Hub yet, it does not have a display screen or speakers like the NXT or EV3 Controllers. However, it does have programming blocks foe both sound and display; the sound is played and the display is seen through your tablet/computer.
As you may or may not know, the Smart Hub has only 2 Input/Outs for motors and/or sensors. So it really doesn’t matter which Input/Output you use.
When 2 motors are connected to the Smart Hub, both motors are programmed by the same motor block, they cannot be controlled separately. Also, when 2 of the same sensors are connected, both sensors are programmed by the same sensor block and either one will respond.
Two or more Smart Hubs can be paired with (connected) and programmed by one program from one device (tablet/computer). Any sensor from any of the Smart Hubs can receive input and all motors respond. So tablet/computer 1 can be paired with Smart Hub A and Smart hHub B at the same time. This is a handy titbit when testing the effectiveness of a design model to another using the exact same program - a side by side comparison, which we did when we compared a Pulley driven vehicle to a Differential Gearing driven vehicle.
In order to control two or more WeDo models separately, you will need two or more devices (tablets/computers). Each model will be paired to one device and the programs on that device will only effect the model paired to that device.
When inputing the power of a motor, the maximum power is about 9-10, even though you can input a larger number.
Since the motor blocks only control forward and backward movement, it is hard to control a vehicle’s turn. An example is given of a turn using a coupling element between the drive wheels and follower wheels. However, it will only turn in one direction going forward and the opposite direction going backward.
Good news, with the new Boost Creative Toolbox set, coming out in August 2017, new program blocks have been added, including turning blocks.
We wanted to know the relationship between the number (seconds) input for motors to actual motor rotations, so we did some tests:
How does the number (seconds) input relate to actual motor rotation with motor using a Power of 1?
We built two cars, a pulley driven care and a gearing driven car.
Pulley driven car - 1:1 ratio of Wedge Belt Wheel to Wedge Belt Wheel
0 seconds = .65 rotation
1 second = 1.75 rotations
Gearing driven car - 1:1 ration of 20 Bevel to 20 Double Bevel
0 seconds = .75 rotation
1 second = 2.25 rotations
(Some useful info & you would think that at 0 seconds it would not move at all!)
Next, we did a test comparison on the performance of the same pulley driven car to the gearing car, comparing the distance travelled using two extreme Power settings of 1 and 9. The cars were tested for various durations (seconds) inputs. Our hypothesis was that the gearing driven car would perform better.
And the results are in….
As you can see from the data, the pulley driven car did not travel as far as the gearing driven car.
Our conclusion: the gearing driven car, based on the observations, performances better by going faster, further, and straighter that the pulley driven car. We believe the gearing has more clutch/grip so its performance is more accurate and consistent; whereas the pulley driven system might tend to slip, particular with wear the rubber band will stretch slightly resulting in slippage. Also, with the pulley driven system, one has to make sure the car/vehicle is balanced from side to side, otherwise it will have a tendency to drift to the weighted side of the vehicle.