Many thanks to 4Tronix for sending me a Picobot and Agobo to review. Rather than making a video and reviewing straight away I have been using both robots at school with my Pi club for a couple of weeks.
If you are looking for a robot kit to get you into robotics both of these are great starting points.
The Picobot is a low-cost swarming robot costing £21.95 which comes ready assembled (just add wheels). It is rich in features and can be bought as a class set of 6 for swarming projects.
Features include (from 4Tronix website) and more details here.
- Ready assembled - just push on the wheels and screw in the front caster assembly
- Arduino compatible ATMega328P-AU (with 2 additional analog inputs)
- 2 x N20 geared motors with "biscuit" 42mm diameter wheels
- 2 forward facing light sensors
- 2 line sensors
- 2 paired RGB LEDs underneath for mood lighting and status information depending how you want to program them - they both show the same colour, not independent
- Rear facing bright white LED - useful for "follow my leader"
- Mode selection button - general purpose input button that you can program yourself
- On - Off switch
- Reset button
- Socket for ultrasonic distance sensor HC-SR04
- Socket of 2.4GHz RF module - nRF24L01 or compatible
- Socket for programming (requires a USB to serial converter such as a CP2102 module with DTR, must be pin for pin compatible with the one 4tronix sell)
- NB. Basic model does not include battery or battery holder as you can use any LiPo or LiOn battery or battery holder with 2-pin JST plug (check the polarity)
A short video of the Picobot in action.
I haven’t yet experimented with programming the Picobot but we had great fun at school designing different mazes for him to follow. This also gave a great introduction into line following algorithms.
If you are looking for a Raspberry Pi based robot I can definitely recommend the Agobo. You will need a Raspberry Pi model A+ and WIFI dongle in addition to the robot. I have been using the Agobo in a class situation and had 6 different groups of students logged into it writing simple control programs. For more details and examples of worksheets check out the link here.
The Agobo is very easy to assemble and can built in a range of different configurations.
Do also check out this blog post of my experience in class with Agobo.
Features include (from 4Tronix website) and more details here.
- Designed for Raspberry Pi Model A+
- Pre-assembled. Only requires front caster, mounting pillars and battery holder to be screwed on and then push the wheels on
- RPi A+ plugs directly onto the main PCB
- Two N20 size geared motors fully and individually controllable in software
- Built in line-follower sensors with indicator LEDs
- Separately controllable front LEDs left and right
- Power on/off switch and LED
- Connector for optional plug-in ultrasonic distance sensor
- Breakout header for a standard serial console cable (ideal way to program a Model A+)
- Breakout I²C header for our IP Display dongle
- Prototyping area to add your own sensors
- Fully replicated 40-pin GPIO header so you can attach your own addons
- Additional mounting holes to attach sensors or extra hardware
The following optional extras are also available.
- Ultrasonic sensors (HC-SR04) which simply plugs into the connector at the front
- Super short micro USB cable to tidy up the battery connection
- Acrylic cover with mounting hardware to cover and protect the Raspberry Pi Model A+
- PlusPlate™ Additional prototyping board and mounting hardware. This allows a full size area to add your own electronics from a simple LED, to more complex items including integrated circuits, RF modules and neopixels. See separate specification later
- Serial console cable which allows easy access to the Raspberry Pi command line without any setup required
- Pre-loaded SD card with the latest Raspbian software and Agobo software (Python and Scratch)
The Python library for the Agobo makes programming it very simple and I had a great response from the students at my Pi club when I introduced him. The students also had a look at how we could use the ultrasonic detector to make a simple crash prevention system. This gave me a great opportunity to introduce a simple always turn left if blocked algorithm. For £25 + the Raspberry Pi A+ makes this an affordable introduction to robotics and programming robots. The design is very sturdy and well constructed.
One of the main thoughts with my Raspberry Pi club at school is always around how I can deliver great projects with spending the minimum amount of money. My budget for the year is relatively low so I have to make every penny count. I was therefore really excited when 4Tronix send me an Agobo robot to review and test.
The build was relatively simple and I have a sample worksheet I used with the club to download from here.
This poses an age old question, how do you share one robot with a whole club of students? It took a moment of thinking outside of the box to come up with a relatively simple plan. The Agobo runs from a Raspberry Pi model A+ with WIFI connectivity.
My starting point was to the run the A+ from a fixed power supply rather than the battery, connect it to my Raspberry Pi WIFI network and establish its IP address.
I then created 8 students folders containing the essential libraries and sample code in folders called student1 up to student8.
I got each student to SSH into the Agobo Pi from their Raspberry Pis - which they loved and found very exciting. With each student having their own work area on the Agobo they were able to tinker with their code and save it without affecting anyone else.
There was an obvious disadvantage to this method:
Firstly being tethered with a charger the students were unable to fully test their code until I shut it down and powered it back on with the battery pack. Not being fully sure of how long the battery would last I didn’t want to run it from there the whole time.
Secondly, the code needs to end cleanly with agobo.cleanup() so the students were told that they could only run the program one at a time and it should come to an end cleanly and not be stopped.
Once everyone had finished their task I rebooted the Agobo after switching over to the batter pack, checked the IP address hadn’t changed again and got the students to log back into their folder and run their code. This worked really well and I was very pleased that I was able to share 1 robot amongst 8 students.