A differential wheeled robot is a mobile robot

Robot

A robot is a mechanical or virtual intelligent agent that can perform tasks automatically or with guidance, typically by remote control. In practice a robot is usually an electro-mechanical machine that is guided by computer and electronic programming. Robots can be autonomous, semi-autonomous or...

 whose movement is based on two separately driven wheels

Wheel

A wheel is a device that allows heavy objects to be moved easily through rotating on an axle through its center, facilitating movement or transportation while supporting a load, or performing labor in machines. Common examples found in transport applications. A wheel, together with an axle,...

 placed on either side of the robot body. It can thus change its direction by varying the relative rate of rotation of its wheels and hence does not require an additional steering motion.

More number of wheels (not driven) may be added to the robot for additional balance.

Details

If both the wheels are driven in the same direction and speed, the robot will go in a straight line. Otherwise, depending on the speed of rotation and its direction, the centre of rotation may fall anywhere in the line joining the two wheels. Since the direction of the robot is dependent on the rate and direction of rotation of the two driven wheels, these quantities should be sensed and controlled precisely. This usually creates some problem. If both wheels are turned with equal speed in opposite directions, as it is clear from the diagram shown, the robot will rotate about the central point of the axis.

A differentially steered robot is similar to the differential gears used in automobiles in that both the wheels can have different rates of rotations, but unlike the differential gearing system,a differentially steered system will have both the wheels powered. Differential wheeled robots are used extensively in robotics

Robotics

Robotics is the branch of technology that deals with the design, construction, operation, structural disposition, manufacture and application of robots...

, since their motion is easy to program and can be well controlled. Virtually all consumer robots on the market today use differential steering primarily for its low cost and simplicity.

Examples of differential wheeled robots

• Pioneer, PeopleBot, PowerBot & PatrolBot
  PatrolBot
  PatrolBot is a programmable autonomous general purpose service robot rover built by MobileRobots Inc. PatrolBots are manufactured in various configurations and serve as bases for companies developing delivery robots, security robots, environmental monitoring rovers, robot guides and other indoor...
  
  - the ActivMedia Robotics
  ActivMedia Robotics
  ActivMedia Robotics, former name of MobileRobots Inc, is a company in Amherst, New Hampshire that designs and manufactures autonomous robots, commercial service robots, robot software and navigation systems for robot developers and manufacturers....
  
   mobile robots.
• Khepera
  Khepera mobile robot
  The Khepera is a small differential wheeled mobile robot that was developed at the LAMI laboratory of Prof. Jean-Daniel Nicoud at EPFL in the mid '90s. It was developed by Edo...
  
   and e-puck
  E-puck mobile robot
  The e-puck is a small differential wheeled mobile robot. It was originally designed for micro-engineering education by Michael Bonani and Francesco Mondada at the ASL laboratory of Prof...
  
  
• Sbot
• Alice
  Alice mobile robot
  The Alice is a very small "sugarcube" mobile robot developed at the ASL at the EPFL in Lausanne, Switzerland between 1998 and 2004.It was designed with the following goals:* Design an intelligent mobile robot as cheap and small as possible...
  
  
• Roomba
  Roomba
  The Roomba is a series of autonomous robotic vacuum cleaners sold by iRobot. Under normal operating conditions, it is able to navigate a living space and common obstacles while vacuuming the floor...
  
  
• RoboMow

External links

• A Tutorial and Elementary Trajectory Model for the Differential Steering System of Robot Wheel Actuators by G.W. Lucas at the open source Rossum Project