ENPH 253 – Introduction to Instrument Design  

Summer 2021

DRAFT Competition Rules – 2021-04-08

MARS SAMPLE RETURN

Your engineering team has been selected to develop a proof-of-concept prototype of a rover that will participate in the Mars Sample Return mission to return soil sample vials stashed by the Perseverance rover during its 2021 mission.

As a proof-of-concept, your robot will lower itself to the ground via a sky-crane, making a gentle touchdown on the surface, and then autonomously search the surrounding area for sample containers. Once found, it will pick up the containers, which have been stashed horizontally, transport them to the return vehicle, and store them upright within the vehicle for return to earth.

Your team will engage in a collaborative design process, after which, each of your team will build their own prototype. Your team’s performance will be evaluated on the average performance of all robots built by the team.

Revision History:

1. Initial draft
2. Dimensions added

2.1 Added clarifications to sharing competition surface and sky crane, and to allowed elements of the surface.

2.2 Added various clarifications following discussions with teams

2.3 Added part marks in Skycrane section

2.4 Clarify that the rocket silos are in a 3x4 pattern

Competition Surface 

COMPETITION RULES

1. Competition Surface – Any normal floor surface is acceptable, though ideally it would measure at least 8’ x 8’. If space of that size is unavailable, a smaller surface is ok. It may be indoors or outdoors. You may surround the surface with black tape to help keep your robot within the surface. One corner of the rectangle bounding the entirety of the surface (which will include any tape paths, Return Vehicle, and the start area) must be defined as a registration corner. To locate the Samples (cans) before the start of the competition, the 8’ x 8’ Sample Pattern (see below) must be aligned to this corner and overlaid on the surface without scaling regardless of the surface size. The pattern must be aligned with the corner only through rotation operations, not by flipping or mirroring operations.

        A single competition surface may be shared within a team.

Other than the Robot, Return Vehicle, and Samples, and optional IR Beacon, there cannot be any other objects or structures present on the competition surface (eg, ramps, physical walls, etc.).

2. Tape path – It is your choice how to lay this out, or whether to do it at all. It can serve to bring the robot to the center of the surface, and can help the robot line up properly at the Bin. The tape path must be laid out before the sample location pattern is disclosed.

3. Return Vehicle  - The Return Vehicle should be a cardboard box with dividers as used for cases of wine. This should be easily available from any liquor store but could also be fabricated from cardboard if necessary. There should be 12 vertical Sample Silos for the samples to be stored in, in a 3x4 pattern. The box and dividers should be cut to be 4” high.

        Silos are roughly 3” by 3”

Optical emitters, magnets, retroreflectors, barcodes or similar identification devices may be attached to the Return Vehicle and may be powered independently of the Robot.

Once located on the competition surface at the beginning of the competition, the Return Vehicle cannot be moved.

4. Sky Crane and Start Area - The robot will begin its journey by being lowered to the ground from a Sky Crane. The location in which this happens can be anywhere within the confines of the competition surface, but cannot be changed after the sample locations are disclosed.

The Sky Crane will be a structure that can suspend the robot, at countertop height from the ground (~ 36”).  Once the competition begins, and the start button on the robot is pressed, the robot must lower itself as fast as possible to the ground, while making a gentle landing (Ideally by sensing the proximity of the ground). Lowering to the ground, disengaging from the Sky Crane, and initiating sample recovery will all be autonomous and triggered by a single command (through a switch on the robot or Sky Crane) at the beginning of the competition.

A single Sky Crane Structure (but not any motors, sensors, or other electrical or mechanical items) may be shared within a single team.

5. Samples – Six 355mL (approx.)  soda cans (Sample containers) will be located on the surface in an approximate shape dictated the morning of the competition (Sample Pattern). Cans will be lying sideways. A small dent may be made in the can to prevent them from rolling. The dent should not be big enough to be visible. No alteration can occur to any tape path or other feature of the surface after the Sample Pattern has been released to the teams. The cans must be empty and unaltered except as described above. The Sample Pattern will include 6 primary locations and 2 backup locations. If any can location conflicts with the robot start location or Return Vehicle, it must be moved to one of the backup locations. If any sample location is within 3” of the robot start or Return Vehicle, it may be moved to one of the backup locations. Any and all samples may be removed from the pattern, but not relocated elsewhere except as stated above. If more than two samples are in conflict, the remaining conflicting samples will simply be removed from the surface. Sample orientation is dictated as part of the Sample Pattern.

6. IR Beacon – You may construct an IR beacon to help your robot find the Return Vehicle. This beacon may be located anywhere you like, but must stay stationary for the competition.

7. Scoring - Scoring is as follows:  

1 point will be awarded for every Sample that is picked up off the ground by the robot and rotated to an Upright position (point is scored once sample is off the ground and upright even if dropped after being turned upright). 2 points are awarded for each sample correctly inserted into a Sample Silo in the Return Vehicle.  Upright for the cans means in a substantially vertical orientation regardless of which end faces up or down - i.e. it is ok for the can to be upright but upside down.

7 points will be scored for robots that successfully initiate the competition by being lowered by the Sky Crane. For these points to be scored, it should be visually obvious without the need for measurement, that the robot descent velocity decreases dramatically before the robot makes contact with the ground. If the robot makes a contact velocity descent, or one that does not appear to require the robot to sense the ground, then only 4 of the 7 marks will be awarded.

Robots may choose to skip the Sky Crane descent and begin on the ground, but will then forfeit the 7 Sky Crane points.

Maximum points = 25.

Competition heats are limited to 1 minute. Any points scored after one minute do not count. Point ties are resolved in favor of the robot(s) that scored the total number of points first. The competition is team-based. Team scores will be the total of all the team’s robots points for that heat. (Ties are therefore highly unlikely).

General Rules

1. Autonomy: Robots must be completely autonomous – no form of remote control is allowed.

2. Robot Size: Limited to 24” in any direction at all times. Robots must stay in one piece.

3. Power: Robots may be powered by any batteries.

4. Start Mechanism: Robots will initiate motion only when a button (or similar) on the robot (or sky crane) is pressed at the start of the run.

5. Rules Finalization: Rules and dimensions will change slightly between now and the competition. Finalized rules will be issued after completion of the competition surface construction in class. Qualifying heats (“Time Trials”) will take place 2 weeks prior to the competition on a final version of the surface.

6. Sportsmanship Rules: Other strategies or designs that obviate the design elements of the course or that do not follow the intent of the competition will be disallowed whether or not they explicitly break these rules.

7. Each student must spend no more than $150 on extra robot parts (not including replacement of broken parts in the original kit, and not including batteries).

ALLOWED AND RESTRICTED MATERIALS

Approved

1. Solenoids
2. Elastic bands.
3. Wheels and hubs from existing RC or other small vehicles.
4. Air or fluid pumps

Must be Reviewed By Course Instructors

1. Springs are generally allowed, but must be reviewed individually for safety.
2. Gas or fluid pressure over 30psi is generally not allowed.

Banned:

1. Discrete H-bridge driver chips other than supplied gate driver chips.
2. Any components other than wheels and hubs from existing RC or other small vehicle chassis, including (but not limited to) suspensions, differentials, steering mechanisms.