If you tell the average person in the street that you work in cybernetics, the chances are he’ll assume you design or build robots. This is a common misconception, probably put about by science fiction stories and films that use the word “Cybernetic”, or the prefix “Cyber” in relation to robots. For example, the Cybermen in Doctor Who, Cyberdyne Systems – the company that built the Terminators, and of course, the classic Cyborg.
It is true that an autonomous robot (and non-autonomous or semi-autonomous for that matter) would use cybernetics, but the term “cybernetics” does not mean “robotics”.
In a nutshell, Cybernetics means the study of changes of state or behaviour of a system in response to external changes in its environment. The study can be applied to living beings as well as machines, so it definitely does not mean robotics.
For an in-depth explanation of Cybernetics, check out the Wikipedia entry for Cybernetics.
How Cybernetics Applies to Robotics
An autonomous robot must be able to react to its environment and changes in its environment, otherwise it can not serve a useful purpose.
One of the simplest examples of cybernetics is one of those “Bump and Go” toys. These are motorised toy vehicles that when switched on, will move forward in a straight line. As long as there are no obstacles, the toy will continue to move forward. When the toy runs out of space and hits a wall, furniture etc., a micro-switch on the front of the toy operates to tell it that it has hit something. The toy then reacts by reversing its motor and often, steering to one side. After a fixed distance travelling in reverse, the toy may straighten its steering and start moving forward again. Other toys will continue to travel backwards until they hit another obstacle, when they will then start travelling forwards again.
Another example of a simple cybernetic system is employed in robotic vacuum cleaners. These have obstacle avoidance as described above, but also monitor the charge of their batteries. When the charge has fallen below a set threshold, the vacuum cleaner automatically stops cleaning and attempts to return to its charging station, where it automatically connects up to its charger. When fully charged, it can resume its cleaning duties.
Sensors Used in Cybernetics
There are a plethora of different sensors that can be used in robots to implement cybernetic systems. These can include
- Micro switches and pressure pads
- Ultrasonic range-finding sonar
- Light sensors
- Strain gauges
- Rotation sensors and gyro compasses
- Accelerometers, altimeters and tilt sensors
- Water and moisture sensors
- Gas sensors
- Power sensors
Implementing Cybernetic Systems
If you are building a robot that has any kind of autonomy, you will need to include some kind of sensor which will provide feedback to the control unit of the robot. Some sensors can be connected using simple electronics. For example, the bump and go toys could use simple micro-switches and relays (or the electronic equivalent) to reverse their motors, because the action that occurs as a result of the sensory feedback is very simple; reverse a motor. Other cybernetic systems will require a more complex reaction, which may require a programmable controller or microprocessor to determine what action to take and to change the state of any controls within the system.
My on-going project of a walking biped robot is programmed to limit the travel of its servos to ensure that it will not topple over. However, this assumes that the robot will be walking on flat, level ground. This is ok for an experimental robot that I am constructing with the help of my young sons, but definitely not ok for a working robot. Once the initial robot is complete and operational, I might modify it to include micro-switches and tilt-switches so that if it is on uneven or sloping ground, it will be able to compensate for it.
Several years ago, I planned to enter the UK TV Series, Technogames, in which home-made robots compete with each other in sporting events. When the last series was made, they mentioned that the following year they would have walking biped events. So armed with a set of servos, MDF, plastic tubes and strong wire, I set about putting a walking biped robot together. The result was R2-See-Thru – a set of skeletal legs fashioned from sheets of MDF. Unfortunatley, these legs were too heavy for my servos, so it failed to even take one step.
After a trip back to the drawing board, I constructed a Mark II version using plastic drain pipes in place of the MDF. I was really surprised to find that the plastic weighed only slightly less than the MDF. I renamed the robot to Murray (after Murray Walker, the motor racing commentator) after it took its first faltering steps. Murray didn’t walk far though – the servos were still straining to move the heavy load.
My next plan was to make the legs out of L-shaped aluminium sections, which would have weighed considerably less, but would have required a lot more work to construct.
It was at about that time that BBC TV decided to cancel the Technogames show, so the super-lightweight version of Murray never made it into existence. Since then a lot of changes happened in my life and I didn’t have the spare cash, and couldn’t find the time to experiment with robotics any more.
Now, many years later, I have two young sons who I know will be interested in making a robot, so I’m going to be dusting off the old servos, cranks and rods and building an all new Murray. So that my sons can join in, I’m planning to use balsa wood for most of the construction, with aluminium for strength where required.
I hope to be using a PIC (Peripheral Interface Controller), which is like a very small computer on a chip, to control the robot. Its joints will be operated using servos, and it will incorporate various sensors to try to ensure that it doesn’t fall over when it is walking.
Keep an eye out for further articles and pictures as we construct the new Murray:walker. In the meantime, I’ll see if I can find the old pictures of R2-See-Thru and the original Murray and post them on this page.
The majority of wheeled or tracked robots use two motors; one for each side. This would usually require a two-joystick controller to drive it, with each joystick controlling a single motor. Turning the robot involves pushing one stick forward and the other backward. For some people, this is not very intuitive, and would prefer to use a single 2-way joystick.
With a V-Tail mixer, you can do just that. It basically takes your 2-way joystick input and converts it to “tank” style control. This means that you can use up and down to move forwards and backwards, and left and right to turn. This is generally a lot easier than the two-stick tank control. It means that you can control the motion of the robot with one thumb, leaving your other hand free to control other things, such as a weapon, if it is a fighting robot.
The V-Tail mixer is a very small device weighing about 4 or 5 grams, so it won’t add a lot of weight to your robot.
The best part is that they are available for under £5, so you can transform the way your robot is controlled at very little cost.
Wiring a V-Tail Mixer
This is simplicity itself, although you might need to swap some connectors around if you find that it doesn’t behave as expected.
- Identify the Aileron and Elevator channels on your receiver.
- Connect the two input leads of the V-Tail Mixer to those channels.
- Connect the two ESCs (Electronic Speed Controllers) to the outputs of the V-Tail Mixer.
- Connect the motors to the outputs of the ESCs.
If you have them connected the right way round, when you move your joystick left or right, the motors will rotate in opposite directions. When you push the stick forward, they will rotate the same way, and reverse when you pull the stick back.
If your robot doesn’t behave this way, try swapping the Aileron and Elevator conenctions and try again. You might also need to swap the wires that connect the motor to the ESCs so that they rotate in the required direction.
Once you have it all set up, you really won’t want to go back to tank-style controls with two sticks.
This site started out many years ago as a team site for an entry to UK TV’s Robot Wars. However, Robot Wars was cancelled, so we turned our attention to TechnoGames, which was like the Olympics for robots. Sadly, TechnoGames was also cancelled, so this site fell into disuse.
Now, our interest in amateur robotics has been resurrected, and this site has now been turned over to the promotion and advancement of experimentation with robotics.
This site is intended for amateur roboticists working at home, but we welcome contributions from professionals and academics in the field.
This site has no planned direction – we want it to evolve, just like our knowledge of robotics. Whether you have a serious interest in robotics or just like playing around with them for fun, we hope you will find something useful on this site.