Servo Erector Set – Part 1
Welcome to the FlowStone Workshop number 11, Part 1, where we give a beginners’ guide to computer programming using the FlowStone graphical programming language inside FlowBotics Studio.
Together with the launch of the new robotics programming platform FlowBotics Studio, RobotShop also launched the Servo Erector Set V1.1 from LynxMotion. This is a kit of over 500 parts, enabling you to build five different robots and control them via pre-made robot applications inside FlowBotics Studio, which is also included.
The hardware kit comes with detailed instructions on how to build each robot; many of the parts are shared so you need to decide which robot to build at a time. This is a neat idea, as you can start simple and work your way up to the more complex kits as your experience builds. I would suggest starting with the Rover, then the Robot Arm, Hexapod, Biped, and finally the Quadruped. You also get a wireless LynxMotion PS2 controller included to control your robot. The Servo Erector Set comes complete with everything you need, even a powerful rechargeable battery and charger, in fact over 500 components!
In this article we are going to focus on the software side, using FlowStone inside FlowBotics Studio to control these awesome little robots, although there is also an Arduino control board included in the kit if you prefer a low level approach.
Each robot is controlled by a LynxMotion SSC-32 servo controller board; this allows up to 32 servos to be controlled from a single board. In addition, there is a Bluetooth daughterboard that gives you wireless control over your creations. All of the processing is done via the PC and FlowBotics Studio, so you have masses of processing power at your disposal to do clever things like Inverse Kinematics, etc. This wireless telemetry approach is really smart and more importantly, it gives you a lot of future possibilities for enhancing your robot.
So the system looks like this: Wireless PS2 Controller – PC – Bluetooth – SSC-32 – Robot
So you have your robot built and wired up, now it’s time to take control using the FlowBotics Studio software. On opening FlowBotics Studio, you can navigate to the LynxMotion folder where you will see five pre-made robot control applications. Double-click to open one of these and you will be presented with the application window for that app, running like a stand-alone applica- tion. This app is an on-screen simulation of your robot, where you can use the mouse to drag the limbs of your robot around on screen.
To connect to the physical robot, click on the “Port” button and wait for you robot to be connected via Bluetooth (these devices will need to be paired initially).This will scan the various serial ports on your PC until it finds the LynxMotion SSC-32 controller board. Once connected, any movements you make on-screen will be relayed directly to the robot hardware. Now that you have control, it’s time to discover the new Robot Sequencer. If at any point you need help, in addition to the comprehensive user’s manual, there is a simple on-screen information system if you hit the “I” button.
Included in each of the robot applications is a very powerful robot pattern sequencer. This is here to allow you to create patterns of movement. Since many of the robots can walk or move in so many different ways, this is really useful to build up a library of movements such as walk forwards, walk sideways, rotate, etc.
Also included are demo patterns and sequences for each robot. To load these go to the import pattern button and select the correct file for your current robot. This will load various example patterns that you can use or modify to take control over your robot. There is also some pre-programmed control for each robot using the wireless PS controller; once the demo patterns are loaded you can literally make you robot walk straight out of the box.
Once you have explored the example patterns and sequences, you can start the fun part…creating your own robot! To do this, you first need to understand how the patterns are constructed. Each pattern contains a series of “Frames,” each frame representing a particular position of your robot. By building up frames of movement, almost like a movie, you can animate your robot. Frames can be infinitely modified and refined to perfect the movement and the frame length can also be modified to give you control over the speed of move- ment. You can save and load your work to a disk at any time.
Once you are happy with your patterns, they can be added to the time- line in any order you like, including multiples to create a sequence of movement. These sequences can then be played, paused, looped, etc., using the transport controls – and sped up or slowed down, using the playback speed options. If you spot any errors in your work, fear not, as you can always modify any sequence, pattern or frame at any time.
The 2WD Rover has two con- tinuous rotation servos connected to the SSC-32 servo controller and a Bluetooth wireless connection back to FlowBotics Studio running on the PC. With the software, you can control each wheel’s speed of rotation to steer your robot around the floor. If you use the included PS2 controller, you can control the Rover like a remote-controlled car, but since FlowBotics Studio is as much about robotics programming, there is also an autonomous mode using the Sharp distance sensor. The Rover will then autonomously navigate around the room. All of the source code is available at the touch of a button if you enter the FlowStone programming part of FlowBotics Studio (shift ESC). Most of this is contained in the User Programming area (more on this next issue).
THE AL5 ROBOT ARM
The Robot Arm is a 3-axis arm with base rotate and a gripper. This can be wireless using Bluetooth or connected directly to the PC using the serial to USB adapter. Inside the software, the arm app allows you to drag the graphical arm around on the screen and the real arm will fol- low. Seeing is believing and this is a really neat feature. In addition, you can take control of the arm (both graphically and for real) using the PS2 controller and position the arm as you need using the remote control. Now the robot sequencer part of the FlowBotics software comes into its own: using the sequencer you can move the arm to a specific position, for example, to pick up an object, and create the moves necessary to complete the task. Once you are happy with your pattern, this can be saved to disk and re-used as part of a sequence to achieve bigger, more complex tasks. In the classroom, students can even work on individual patterns and bring them together to form a better sequence at the end. In addition to the sequencer, there is the ability to add buttons and sensors and interconnect different robots electronically and allow them to communicate. This can be achieved by using the “User Programming” area in FlowStone.
THE MH2 HEXAPOD
The Hexapod is a two-DOF (degrees of freedom) hexapod with two joints per leg. Using the SSC-32 and the Bluetooth adapter gives you wireless control. With the FlowBotics software, you can move each joint and explore the various gaits to make this robot walk, turn and more. Again you can use the PS2 controller to control the hexapod using the default demo files. THE BRAT BIPED The BIPED is a great robot with three DOF in each leg, allowing it to walk and turn smoothly. Each leg uses Inverse Kinematics (IK) to create a more human-like walking movement and also makes the programming of this robot much easier. You can move the feet in the soft- ware and the whole leg will follow because of the IK. The BRAT uses the SSC-32 servo controller with the Bluetooth board to gain wireless control, and also the PS2 control- ler for remote control.
THE BRAT BIPED
The BIPED is a great robot with three DOF in each leg, allowing it to walk and turn smoothly. Each leg uses Inverse Kinematics (IK) to create a more human-like walking movement and also makes the programming of this robot much easier. You can move the feet in the software and the whole leg will follow because of the IK. The BRAT uses the SSC-32 servo controller with the Bluetooth board to gain wireless control, and also the PS2 controller for remote control.
Finally the Quadruped; this is the most sophisticated and complex of all of the robots in the SES kit with 3 DOF for each leg. This is achieved using IK to simplify the programming. Using the PS2 controller, you can even rock and roll the IK (make it move in all directions while keeping all of the feet on the ground) to bring this creature to life. The SSC-32 and Bluetooth adapter are again used for wireless control.
Each of the robotics projects included in the Servo Erector Set has a User Programming area inside FlowStone where you can easily modify, add to and enhance your robot application. You can even connect to the MyRobots.com robotics Cloud (‘Facebook’ for Robots) and log your robots’ movements or communicate with other robots around the world. In the next issue we will focus on the User Programming side of FlowBotics Studio and the Servo Erector Set to show you what the possibilities really are using the FlowStone programming language.
The Servo Erector Set offers fantastic value for the money and excellent build quality, building on LynxMotion’s robotics reputation. The great thing about this kit is that for the price of a single robot, you get five different robots to build. You also get the FlowBotics Studio software, giving you not only a very slick user interface to program your robots’ movements but the full FlowStone programming language inside along with the source code for each project. This gives you massive possibilities to pimp your robot in the future and enhance it by programming it inside the FlowStone environment. There is nothing else like this on the market right now offering a versatile multi robot kit, with industry-leading software and programmability. The Servo Erector Set is available from $999.99 including FlowBotics Studio. Or, if this is out of your budget, each of the robots is available individually. FlowBotics Studio is also available standalone for only $39.00 directly from RobotShop.