US and UK teams share the prizes

Citation

(2006), "US and UK teams share the prizes", Industrial Robot, Vol. 33 No. 2. https://doi.org/10.1108/ir.2006.04933bab.004

US and UK teams share the prizes

US and UK teams share the prizes

Keywords: Robotics, Competition

The 2005 Clawar robot climbing competition was won by a team from Duke University. And the Industrial Robot Innovation Award went to a robot developed at London South Bank University. Also participating in the competition were robots from Italy and Germany.

The robot climbing competition took place alongside the 2005 Clawar Conference in London. It aims to encourage and challenge both students and professionals to design and develop small machines capable of climbing up vertical surfaces.

The 2005 competition set entrants the task of building a machine that could travel along a horizontal surface, transfer to a vertical surface and move up it, avoiding randomly placed objects. A final challenge was to negotiate a small barrier (1 cm high, 1 cm wide) on the wall, as shown in Figure 2.

Figure 2 The Clawar competition wall showing obstacles and barrier

The wall was made of black ferrous metal sheets to accommodate magnetic adhesion, but it was also flat and smooth enough to also allow for suction attachment. The obstacles were wood and painted white.

The rules dictated that robots should not exceed 30cm in size or weigh more than 8 kg. They should also be autonomous, but need not carry an on-board power supply.

The only robot in the competition to successfully complete all the tasks was Wallter, a robot developed by a group at the Pratt School of Engineering, Duke University, Durham, North Carolina.

Wallter implements three major technologies: a vortex regenerative air movement (VRAM) system for wall adhesion, a three ultrasonic sensor array for obstacle detection, and an accelerometer for surface transitioning.

The VRAM is a development of Vortex HC, a commercial enterprise based in Morrisville, North Carolina. It produces two vortices that together generate a low pressure area in its centre. This low-pressure area creates the necessary attraction to keep the robot attached to the wall.

When detecting obstacles, the orientation of the three sensors is designed to provide the largest possible field of vision. It allows for the detection of an object 8 cm to the left of the robot at a distance of 10cm in front (Plate 2).

Plate 2 Duke University's prize-winning Wallter robot

When an object is detected, the readings from the different sensors are compared to determine its exact location and the best course to take to avoid it. Wallter is programmed to turn in the direction opposite to the object then to proceed a small distance, and finally to return to a straight path up the wall.

Duke University team members attached two small permanent magnets to the underside of the front wheel drive-train motors to provide enough `attractive' force to allow Wallter to clear the 1cm barrier. Otherwise, it would have had difficulty in staying on the wall.

The algorithms for Wallter's independent control comprise two separate sequences. One occurs while Wallter is on the floor and drives Wallter forward until the onboard accelerometer detects the wall. The VRAM is then engaged to provide attraction to the wall. The second is while Wallter is driving up the wall. When all three ultrasonic sensors detect an object less than 15cm away, the robot has reached the ceiling and the forward drive motion is shut down. The VRAM keeps the robot attached to the wall until an operator removes it.

Winner of the Industrial Robot Innovation Award was WallExplor, a climbing robot developed by a team at London South Bank University. Working at the University's Centre for Automated and Robotic Non-Destructive Testing, the team under its leader Dr Tariq Sattar developed WallExplor not just for the CLAWAR competition but also as a solution for the non-destructive testing of large steel surfaces.

The robot (Plate 3) consists of two platforms that are hinged together to enable it to move from a horizontal to a vertical surface. Each platform has sufficient adhesion to support the robot load at all times. The robot measures 300 × 240 × 200 mm and weighs 6 kg.

Plate 3 The London South Bank University's WallExplor robot, winner of Industrial Robot's Innovation Award

Adhesion to the steel wall is by permanent rare earth disk magnets (Neodymium-Iron-Boron). These are arranged in three rows underneath the three wheel axles, with a 1mm gap between the magnets and the climbing surface. By using permanent magnets adhesion is ensured in the event of power loss. They also facilitate non- destructive testing by magnetic flux leakage.

Sensors on WallExplor enable it to perform the variety of tasks required. A gravity sensor indicates whether the robot is on the floor or the wall. Two mercury sensors indicate deviation of robot motion from the vertical. The detection of the wall and the obstacles is achieved using a line array of four infrared sensors plus a fifth sensor at a higher level. The arrangement of the sensors enables the shortest path around the obstacle to be computed (Plate 4). The infrared sensors can recognise obstacles at a distance of 5-80 cm and within a beam width of 150 mm.

Plate 4 WallExplor navigates around the obstacles on the competition wall

Another participant in the CLAWAR 2005 robot climbing competition was Carlo Russo who presented PneuSCID, a climbing robot developed at the University of Catania in Italy. PneuSCID uses two active depressors that hold the robot to any kind of non- porous vertical surface. By controlling the vacuum level inside the two depressors and by using gravity, it is possible to control a downwards trajectory. It is a very light and simple robot.

Also participating was Ridha Azaiz from UniqueRobots, a German company based in Aachen. He presented the Wallwalker robot which uses suction cups to adhere to a vertical service and which is designed to step over obstacles in its path. This robot was not designed for the competition but is intended for cleaning solar panels.