Teams from several UK universities competed for the UK's first annual Robot Football Open Championships, held at Warwick University recently. In this competition there is no human or radio control, such as is seen on certain television programmes. Rather each robot is programmed to perform a task autonomously. Once the game commences, all the operators can do is cheer them on!

The Warwick team, Warwick Evolution, is co-sponsored by our supplier DVT Sensors. They wanted to see how their SmartImage sensors perform and enable innovative solutions for robots working in unpredictable environments, as opposed to more common industry applications in repetitive Q/A and test line environments.

Warwick's 7.5 cm cubic robots are guided round an internationally specified tournament pitch by the sensor cameras rather than a human operator. In this way the sensors provides the robots with 'eyes' to enable each 'player' to make its own autonomous decisions and take independent action.

WORKING AS A TEAM
Each robot is programmed either to defend, attack or keep goal. "The robots all have something different to do, but collectively they act as a unit," said Warwick Robot Football Project Director Dr. Ken Young, Reader at Warwick Manufacturing Group (WMG), part of Warwick University's Engineering Department. He added "The team of robots has to perform its task collectively, they are not just working individually and the environment has to be continually re-evaluated using the cameras. The opposition is unpredictable and the ball movements can be volatile and random. Playing robot football sounds simple, but when you analyse it, this is a remarkably complex task."

Students from Warwick have been using DVT Sensors' SmartImage cameras to guide their team, Warwick Evolution, since 2002. Dr. Young explained: "With the strain and complexity of the visual decoding removed from the programming, the opportunity was given to change the programming language from visual C++ to Java."

GETTING INTO POSITION
Warwick Evolution currently uses three robots, though it has plans to upgrade soon to five. Three DVT SmartImage Sensors detect the various positions of the robots and ball. Small enough to fit in the palm of your hand, these are intelligent cameras with on board computing. These 'smart cameras' operate as nodes on the network to acquire and process data from each robot and the ball, to the computer. In industry, they are most commonly used for reporting inspection results for QA, or to deliver part tracking and inventory control data.

A Legend 542C high speed colour camera, operating at up to 1,400 mips, uses blob detection to search for the RGB value of the ball, (an orange golf ball), and to detect its motion. Identifying patterns on the top of each robot enables two additional cameras to detect the motion of the robots, using both object detection and blob recognition. A high-resolution black and white Legend 544 camera detects the motion of the striker, while a high speed Legend 540 mono camera tracks both the goal keeper and defender robots.

The three cameras then transmit the co-ordinates of the robots and ball back to a PC. Through the use of simple algorithms, the next movement of each robot is determined, according to each individual robot's strategy that has been programmed in Java. This is then transmitted to the robots over the radio interface.

DVT is soon to provide Warwick Evolution with an upgrade of these cameras. The recently launched Legend 55x series sensors will provide the team with speeds up to eight times faster, typically producing over 4,000 mips. "It's an exciting prospect," said Caroline Browne, a Manufacturing and Management student and Team Secretary responsible for Business Practices. "We are hoping that with this latest technology, we'll have an edge over our Championship competitors."

TEAM TALK
Once each robot's next movement is determined, instructions are then relayed via single way communication in the form of packets, from the computer to the robots. These packets are sent over a set frequency to the entire team, agreed as either 418MHz or 433MHz by both sides before each match. This transmit module is driven directly out of the computer's serial port, at a BAUD rate of 9,600bps. Figure 1) below illustrates the packet form.

Fig. 1/ Packet Form For Determining Robot Movement

GOING FOR GOAL
Once the next movement is determined, an Atmel AT90S8515 processor on each robot controls the speed of two Marbuchi 6V DC motors (one for each wheel) driven by a L298N H bridge motor driver. The motors then rotate at the assigned speeds. The amount of revolutions achieved is monitored by an optical encoder arrangement taken from the axle of the motor, with a resolution of 8 bits per revolution. This relays information back to the processor in the form of electrical pulses. Once sufficient pulses have been achieved, (set by the magnitude), the motor ceases movement.

The drive of the motors to the floor is provided by a spur to worm gear arrangement of ratio 16:1, while the power to the robot is provided by eight AA size Nickel Metal Hydride Batteries of 600mAh capacity, providing 9.6 Volts in total. Figure 2) below, shows the complete set up for operating the team.

TEAM TROPHIES
Begun as an individual project in 2000, from 2003 Warwick Robot Football has been operating as a 4th year multi-disciplinary group project with a systems engineering approach. During this time, key developments have occurred relating to:

· Integration of two-way wireless communication
· Identification methods
· Robot heading detection
· Alternate sources of power
· Chassis design
· Motor and drive train
· Programme strategy and robot control

Using standard Ethernet communications, SmartImage Sensors support TCP/IP, Modbus/TCP and EtherNet/IP. Profibus and DeviceNet are supported with the optional SmartLink module. These self contained inspection systems provide a visual data source with low connectivity costs, high speeds, seamless data exchange throughout the smart factory enterprise and enhanced tools to support automation locally and worldwide.

'Funny old game robotics'