SRS Build Challenges

Revised Jan. 12. 2024
[See Bold, Italic, Underlined changes]

Rules applicable throughout document —

Overview – The SRS Build Challenges (SBC) consists of (mostly) outdoor autonomous navigation events that give robots an excuse to take their humans out for a walk and get some air.  The 5 events are staged in increasing order of difficulty.  All events are friendly to new builders but challenging even for the seasoned builder.  The format will generally be low-key and flexible, adjusting for changes in weather, number of entries and whatever else is significant on the day of “competition”.  The SBC shall be easy to plan and execute, so the club can hold several per year.

The premise of this rule set is to enable builders to ‘gain builder confidence and skills’ in stair-step sophistication of building difficulty as they complete and enter each challenge. This contest is intended (via its multi-level challenges design) to build skill-sets needed for the SRS (Seattle Robotics Society) higher-level contests: for example Pop-Can Challenge and Robo-Magellan.

Robots and their builders can enter any one of the 5 events, any group of events, or all 5 events.

Stages of the contest – In addition to each builder’s robot performing their event run(s), the builder also needs to do the following on contest day:

  • Check-in with entry details and sign the liability waiver
  • Qualify their robot entry (per event they enter): demonstrate their ‘safety stop mechanism’ and that the robot passes the judges assessment for that event

Per event on contest day, the course is set up a minimum of 1 hour before the start of that event.

Per event on contest day, the builder is free to review the course \ environment, make any robot configuration changes they wish – for up to 1 hour before that event officially starts. Also, the builder has unlimited practice run-time available for up to 1 hour before actual start of that event. For a specific event, once its official start time begins, the builder no longer has access to its practice time.

Variability of Setup and Requirements per Event – The rules contained here-in are designed to be flexible – for both the builders and event organizers (whether in person or remote).

It is an expectation that the event organizer clearly state within ample time ahead of the events, the particular constraints, setup, and general requirements for builders and also clearly provide details on how the course will be setup; including specific equipment and supplies.

A good example of choices and detail to be communicated is with allowed ‘markers’ used in a challenge – whether it be orange cones and their size or specifying a different choice of marker.

Organizers also need to identify how they will run the contest – which and how many events run per day. Again, it is anticipated that organizers will clearly state all parameters and constraints used in holding their contest.

Venue – The venue for a SBC event will be announced by the organizers.  Hopefully, several will be held each year and ideally they would be held at changing locations for variety of challenge. The event can be held at schools, parks, fair-grounds, stadiums, industrial sites and maybe even exotic vacation retreats.  It is not (yet) intended that the SBC be held in extreme weather conditions.  The organizer may call off the event ahead of time based on severe weather forecasts or on the spot if the weather turns too nasty.  Also it is not intended that robots travel through water deeper than 0.5″.  Some other features not intended are stairs, cliffs, pits, interiors of buildings, traffic-bearing roads, active bike paths, and so forth.  These are all regarded as aspects of common sense.

Note on “(mostly) outdoor” mentioned above – all Challenge Events are intended to be run outdoors EXCEPT Challenge Event #1 which can be done as an indoor or outdoor contest; depending on organizer preferences.

Safety – Robots must be fundamentally safe and sane.  The head judge has the right to scratch, at any time before or during the event, any robot  deemed risky, unsafe or hazardous.  Robots must have some practical system that allows the operator and/or judge to halt, disable or change the course of the robot if it is about to get in trouble; all robots must include a ‘safety stop mechanism’.

Suitable Safety Stop Mechanism – The robot builder is responsible for devising the safety stop mechanism. Some possibilities include:

  • Wired tether operated by the handler walking alongside the robot
  • Some wireless contrivance operated by the handler
  • Some other mechanism, with prior permission from the SRS

In any case the safety stop switch must be fail-safe: The robot handler must demonstrate that by dropping, or letting go of the stop mechanism the robot comes to an immediate stop and makes no further movement. The stop mechanism does not need to cut primary power as long as it can be demonstrated that the robot reliably comes to a complete halt.

The safety stop mechanism may be built to allow the robot to continue its run after it is reengaged. The intent of this feature is to stop the robot and allow it to continue if, for example, a small child runs in front of the robot. The safety switch should be able to stop the robot rapidly (within 3 seconds all motion must stop) and completely to prevent damage to itself or the environment. The safety switch will not be used to stop the robot in order to reposition it or remove an obstacle like a garbage can from the robot’s path (for a ‘for credit’ run). If the robot is stopped temporarily, it may continue and the time during which the robot was paused will be subtracted from the final score. In other words, there is no time penalty for stopping the robot due to safety concerns.

No other “remote” control beyond the safety stop is allowed during a ‘for credit’ contest run.

Autonomous \ RC designs –  All robots must be autonomous while performing an actual\real ‘for credit’ run of a course\challenge, with exceptions noted in Challenge Events #4 and #5.

Note that RC design and control is allowed for practice and setup of the robot on the course; ONLY in the absence of a ‘for credit’ run – this is to enable the builder to not have to physically pickup\move their robot, instead allowing for remote movement of the robot.

During a contest run, the handler can only use \ hold their fail safe device. Once the contest run is over, the handler may use an RC system to drive the robot.

Robot design – This section details design constraints and allowed-elements that apply to any of the 5 challenges. Reference the specific challenge sections below for robot design elements that apply to that event.

The robot cannot use an internal or external combustion engine; which includes gas or nitro.

There are no limits on instrumentation, size, and weight of the robot other than the safe/sane rule and that it is a usable size to execute the constraints of the chosen event.

Robots must remain in contact with the ground. Flying or hovering robots are not permitted. Also, no projectiles are allowed.

GPS – This section details GPS data that will be used for events #4 and #5. All waypoint or orange cones data will be specified as degrees and minutes with minutes carried out to four positions right of the decimal point (N 47.22.1245 W 122.32.0493). The datum is WGS84. All GPS data provided to the robot builders will comply with these specifications. All orange cones will be designated with latitude/longitude coordinates and marked by standard bright orange 18″ traffic cones.

Attempts – Per event, a robot entry will have up to 3 ‘for credit’ run attempts. ‘For credit’ runs apply to official start\end times for each contest event.

Scoring and Awards – Scoring will be determined for each event and per robot.  After the contest and announcements of winners, scores will be posted on the website.  

Robots must halt at the time limit, either automatically or by their handlers. Or, they must complete the event goal objective, whichever comes first.

The robot’s score for each event is simply the distance from the robot’s stopping place to the goal point (times a fractional bonus if applicable).  The overall score is the lowest one of 3 runs for the robot in that event. The same scoring system is used per robot and per challenge event.

Tie-breaker runs may apply when one or more robots have measured distances that are too close to call. Meaning, that a replacement run is done to replace the contentious result.

Liability – Each contestant is fully responsible for any damage to person or property caused directly or indirectly by his or her robot.  The SRS, the event organizers, judges and other entrants are not responsible for damage caused by any competing robots.  Each contestant must sign the waiver of liability form prior to the competition.  A minor must have a guardian present to sign their waiver.  

Please reference a copy of the waiver here that each contestant will need to sign in-person before competing.

Judges – One or more judges will officiate the contest. Their prime responsibilities will be to determine that a robot has successfully completed the requirements of a specific challenge, to provide measurements of the robot’s stopping position for scoring, and to track all run data per robot\run attempt. It shall be the discretion of the judges to decide whether a robot meets the per event qualifications, and the judges may require the robot’s owner to supply the necessary information\demonstration of compliance. The decisions of the judges are final.

Code of Conduct – All builders, handlers and spectators are expected to comply with our organization’s code of conduct, please reference these SRS rules here.

These SRS rules also apply to all event staff. Please keep the event fun and light-hearted for all, including the organizers and humans.

Rules and Venue evolution – This first version of the rules is intended for in-person contest events only – due to the need by event staff to get the flow of running the event working well.

At a later date, remote \ virtual entries and contests will be allowed. As the rules and venues evolve, a separate set of rules may be needed for in-person contests versus remote.

It is the contest designer’s goal to keep these rules\contest separate from a similar (especially with Challenge Events #4 and #5) rules for the SRS Robo-Magellan – in that they each have separate goals and levels of skills required to compete.

If the event becomes too easy, we will make it harder. If builders start showing up with $100,000 robots and teams of 20 developers, that is great and we will split the contest into levels so that “amateurs” still have a challenge they can win. But we still won’t offer $1 million prizes.

                                                                         Rules for specific Challenges —

Challenge Event #1 – Square

Move from an origin around a square (15 feet on each side) clockwise or counter-clockwise as instructed by the judge, and stop at the origin.  Distance is then measured from the stopping place to the origin.  Shortest distance wins.

The builder can identify (and mark) any origin point on the course they wish; to start\stop their traversal of the square. This is in contrast to only allowing an origin point being one of 4 corners.

The traversal around the square must be executed within 10 minutes.

It is legal to cut the corners, pivot 90 degrees, execute a 3-pt turns or whatever it takes to transition from one leg to the next.   But robots are expected to make an honest attempt at traveling the correct distance on each leg.

There are 2 ways to set up a course and have a robot navigate it:

  1. Use only 4 corner markers to delineate the boundaries; example markers are mini orange traffic cones. Other marker types are allowed instead. Then the robot navigates around the outside edge of the course boundary defined.
  2. Use 4 corner markers that are flat, where the robot can easily move over the top of them. Also, tape markings can be used to ‘scribe’ the straight line between each corner; example tape is any painting or masking tape available with a good adhesive. For this course, the combination of corner markers and tape clearly identifies the square course boundaries. Then the robot navigates directly on the course itself; physically crossing over each corner marker.

Challenge Event #2 – Out and Back

Move from the origin to a point 25, 50 or 100 feet away [determined by event organizers so contest can be run in multiple types of venues] and back to the origin and stop. Distance is then measured from the stopping place to the origin.  Shortest distance wins.

Typically each point is marked with an orange traffic cone – mini or full 18 inch size orange traffic cones.

The traversal out and back must be executed within 20 minutes.

Challenge Event #3 – Out and Back With Obstacles

Identical to Event #2 but this time with obstacles in the way.  

The traversal out and back must be executed within 35 minutes.

Typical obstacles are garbage cans, people and pets, other robots, shrubs and branches. Other non-traditional man-made obstacles may include wooden\card-board boxes and soda cans. The terrain may include pavement, dirt, small rocks, grass, hills, gullies, trees and weeds.

Obstacles and terrain listed here are not an exhaustive list.

Challenge Event #4 – Cross Country

This event challenges the robot to travel several hundred yards toward an unseen goal point with buildings and trees and other objects in the way.  There is a time limit of 1 hour and the course will be laid out such that the expected straight line path will be approx. 25, 50 or 100 feet [determined by event organizers so contest can be run in multiple types of venues]. Robots can travel at whatever speed they prefer, as long as they are safe.

Scoring is based on distance from the goal point to when the robot stops.  Shortest distance wins. Unofficially, scoring also includes favoring of the shortest run-time to complete the course; say in contrast to the robot that took the entire 1 hour to complete the course.

The course is defined by the start and goal points, which will be made available to the builders 1 hour before the start of the event.  Google Earth lat/long coordinates (or via a hand-held GPS reading device) will serve as the reference for the start \ goal markings. The GPS course points will be marked by 18 inch orange traffic cones. Builder entry of these GPS points is the only information allowed to be programmed into the robot.  The builder is not permitted to enter intermediate waypoints.  Also prohibited are pre-programmed maps or object location inputs.

Robots that lack vision can and should still compete and do well.  Robots that lack good navigation, obstacle detection or all-terrain skills will likely get lost or stuck.

It is likely that there will be people and pets on the course and they may constitute serious unplanned obstacles.  Normally this should be taken in stride but in a severe case, the judges may allow a re-run or make a distance adjustment, at their discretion.

Robots are expected to be fully autonomous, however there may be special hazards on this course for which a bit of herding or downright steering by the operator is allowed.  This includes avoiding bodies of water, flower beds, cliffs and maybe some others, all at the judges’ discretion.  There will likely be a distance penalty assigned by the judges for substantial operator steering or herding.  

Note that off-board computing is allowed during a contest run. For example, wireless communication between an off-board computer and the controller board on the robot. This type of design can enable off robot data log collection and path planning.

Challenge Event #5 – Cross Country with Gates

Identical to Event #4 but this time gates are added to the course. There is a time limit of 1.5 hours to complete the course.

There will be 2 gates placed along the course out of sight of each other.  A gate is made of two 18 inch orange traffic cones placed 4 feet apart.  They will be placed  along the most likely path, but a bit off to the side, easy to see with a camera but unlikely to pass through without a camera.  It does not matter which direction the robot passes through a gate.  A bonus is collected if the robot passes completely through a gate without moving either of the cones out of place.

Gate GPS coordinates will be provided to the builder in addition to the start and goal points. Only these GPS data points may be entered before a contest run.

One GPS lat\long pair will be measured and provided PER GATE. The GPS coordinate will be the measured linear ½ length point between the 2 gate cones. Therefore, for the 2 gates included in the course, the builder will receive 2 lat\long pairs for the gate marking points.

Bonuses for each gate successfully negotiated will reduce the effective distance to the finish by 10% for each gate.


Revision history – These rules have been adopted from the PARTS Group; based on their “PARTS Outdoor Challenge” rules circa 2008.

— Revision 1.0,   released 7-16-2022

Revision 2.0:

  • The following update was made to these rules on 9-9-23 – change straight-line distance for course parameter applicable to events #2 and #4.

Revision 2.5:

  • The following update was made to these rules on 8-3-23 – to add clarity on GPS data used in events #4 and #5.

Revision 3.0:

  • The following update was made to these rules on 1-12-24 – to allow for variable (depending on venue and course parameters) “orgin to a destination point” distances.The previous rules had fixed (depending on Event #) distances that were not attainable at recent (2023) Robothon events – there was not ample course area available. It is intended that this “flexible” distance be clearly communicated ahead of the event once the venue has been chosen.