Robot Contest - Tower of Hanoi

Contest setup

A possible set up for the robot contest Tower of Hanoi is visualized in Figure 2. We assume a confined contest area, which is typically around 2.5 x 2.5 sqm large. In cases, where the size of a participating robot takes up to much space of the contest area it will be adjusted to ensure that all robots stand an equal chance. The contest area will contain three distinguished locations related to the task: one will serve as a target location to erect the final tower the two others will serve as initial and auxiliary location. A fourth location will be the home position of the robot from where it will start and to which it has to return after the task is accomplished. The exact positions of these locations will be announced at the beginning of a run. The locations will be marked by clearly visible, distinguishable markers.

Figure 2: Tower of Hanoi as robot contest

We further use a color code to distinguish the objects and also to establish an order in which they must be stacked or be placed with respect to each other. We use three different colors: red, yellow, green. The relation between the objects, which must be obeyed, are explained below.
Variations of the set up (to be decided one month before the qualifications)

• use of cuboids rather than cubes,
• placement of additional obstacles in the contest area,
• use more or fewer objects than shown in Figure 2,
• use different color code

Robots

In general we allow any robot which qualifies as mobile manipulators. This means that the robot:

• has to move on the ground and has to be capable of navigating in unknown environments,
• has to be capable of perceiving and localizing objects, and
• has to be capable of manipulating objects.

Robots may be self-designed and self-built or commercial off-the-shelf products.
Robots should neither require any specific floor covering nor damage the floor covering in the contest area. The latter would lead to a disqualification.

Task

The task is to move the objects from their current locations to the target location and to stack them there in a certain order to form a tower in the fastest way possible. While doing so, the robot has to obey certain rules:

• The "color code" from the bottom to the top of a stack must be green < yellow < red. This means, for ex-ample, that a green object must never be placed on top of a yellow or red one or a yellow one must never be placed on top of a red one.
• Objects on one level of a stack must always be of the same color. This means that objects of different colors must never be placed besides each other. For example, a red object must never be placed next to a yellow one.
• Objects must be placed only within the marked locations. All locations apart from the home location can be used as temporary storage place for the objects. An accidental drop of an object is not considered as a violation of this rule, provided the lost object is immediately grasped again.
• The robot must never transport more than 2 objects at a time.
• The task is accomplished once all objects are stacked in the target location such that rules 1 and 2 are satisfied.

At the beginning of a run, the objects are typically stacked at the initial location obeying rules #1 and #2.

Variations (to be decided one month before qualifications):

• The robot is allowed to carry more than two objects.
• A run starts with an arbitrary configuration of objects obeying rule #1 and #2.

Additional rules

Besides the rules directly related to the task, there are a few additional rules the violation of which will lead to immediate disqualification:

• The task must be solved fully autonomously. Communication or physical or virtual interaction with human operators or team members are strictly prohibited. Remote computing through wireless is allowed, provided there is no human intervention.
• No auxiliary facilities supporting the robots’ onboard recognition, navigation, or manipulation are allowed other than those provided by the contest organizers.
• During the contest runs team members are not allowed to enter the contest area.
• Team members are not allowed to modify the contest set up provided by the organizers.
• The robots must not place objects outside the areas specified in Section 2.3 item 3.

Scoring 

The primary criterion for the performance evaluation of a team is time. A team that solves that task in a shorter time naturally receives higher scores than a team which needs longer.
There will be a time limit for every trial. The time limit will be announced before the contest. Should a team not finish within the given time limit, the criteria to evaluate the performance will be the number of correct / optimal moves which the team has made already towards solving the task.

For example, if the time is used up and a team has only two blocks left to move for the final configuration then the performance will be scored as n – 2, where n is the number of optimal moves. So, the further away the team is from the final configuration the lower its scores.

In a nutshell the ranking of the teams will be as follows:

• A team that finishes the task in time is higher ranked than a team that does not finish the task in time.
• For teams who managed to solve the task in time, the ranking will be according to the time, which the teams needed to solve the task, the shorter the time the higher the rank.
• For those teams who do not manage to solve the task within the time limit, the ranking will be reciprocal to the number of moves left to solve the problem; the more moves a team would have to make the lower the ranking. 

Course of contest

The contest event itself will consist of a preliminary, a semifinal and a final. The contest will take place in two adjacent contest areas, so that two teams can perform at a time. The two teams, however, will not directly compete against each other in a knock out manner, but only race against time. In every round each team has two trials, of which only the better one counts. The trials are organized in two subsequent series. Should a team fail to finish its trail for whatever reason – hardware failure, software failure, power loss – the trial counts as a regular run. There will be no extra chance. The two preliminaries and the final will follow the model just described.

All teams, which pass the qualification rounds described below, will be allowed to participate in the preliminary. The eight best teams in the preliminary will reach the semifinal. In the semifinal, the best four teams out of these eight will be selected for the finals.

Depending on the number of teams the contest will take place on two subsequent days. The preliminary will take place on the first day, the semifinal and the final will take place on the second day.

Qualifications

The qualifications will take place four weeks before the actual contest and will be organized as a cyber-contest. Technical and organizational details of this cyber-contest will be announce in due time.

Teams, which participate with their own robots, will be invited to demonstrate the performance of their system at their own sites. To allow a jury to evaluate their performance they will have to broadcast their trial via some video-conferencing or life-stream facility to the organizer’s site. Time will be taken at the organizers site.

Teams, which do not have their own hardware and instead use the hardware provided by the sponsors, will have to develop and test their system in simulation first. Several simulators and simulations of the available hardware will be provided free of cost to the participants (see Section Hardware and Software Support). These teams will get access to the hardware either physically at the site of the organizer or remotely in due time to test their software on the real robot and prepare for the qualification. For the qualification, their software will be run and demonstrated on the sponsored hardware by staff at the organizers site.