Safety

The construction and operation of all rovers must comply with the CIRC Rover Safety Requirements unless an exemption has been granted.

Exemptions may be granted on a case-by-case basis by submitting a request to [email protected], including the problematic requirement and proposed alternative. Your proposed alternative should still meet the spirit of the requirement, if not the letter.

Rovers will be subject to safety compliance inspections by organizers whenever the rover is operational. Teams must resolve any issues to the satisfaction of the inspecting organizer before continuing operation.

All rovers will be required to pass an initial safety compliance inspection at some point between registration and the start of their first competition task.

Sufficient evidence (such as schematics, datasheets, calculations) of safety compliance must be provided to competition organizers by the Safety Report Deadline:

• June 19, 2025

Teams are encouraged to submit partial or full documentation at any time before the deadline for feedback from the organizers. Submissions will be through a google forms link provided to your team when they register.

Inspections will be available at CIRC Central from 7AM to 10PM daily.

Safety Guidelines

The purpose of this document is to define and enforce a minimum standard of rover design for all CIRC participants. This standard is intended to reduce the likelihood of rovers creating safety hazards or environmental damage. Rovers which do not comply with this document will be excluded from CIRC until all issues are resolved. Any questions or requests for exemptions should be directed to [email protected].

A basic example of a report for the competition.

Definitions

1. The word “should” indicates a suggestion which may become a requirement in future competitions.
2. A Circuit is one or more electricity-consuming devices (and the connections between them) which draw current from a single power source through a common circuit protection element.
3. Regulators consume and provide power, with their input and outputs counting as at least one circuit each.
4. The Rated Current Consumption of a component is the manufacturer-published value indicating the maximum safe amperage consumed by the device in normal continuous conditions, or for motors, their stall current.
5. The Rated Current Capacity of a component is the amount of current that can be safely carried by wires, connectors, traces, switches, in a circuit on an ongoing basis. Transient, burst, or peak current limits are not acceptable for use when determining Rated Current Capacity.
6. The Rated Supply Current of a component is the maximum acceptable amperage provided by a component like a battery, power supply, or regulator on a continual basis. Transient, burst, or peak current limits are not acceptable for use when determining Rated Supply Current.
7. The Interrupt Current Rating of circuit protection is the amperage above which it is designed to interrupt current flow.
8. Circuit Protection is a fuse or electromechanical circuit breaker which reliably interrupts excessive current flows through a connected circuit. Software-based solutions are insufficient. Motor controllers, power regulators, or other devices with current limiting capabilities are not sufficient for use as Circuit Protection. Self-resetting fuses are also insufficient.
9. A Kill Switch is a physical switch mounted on a rover which, when pressed down, causes the interruption of power to all rover systems until the switch is manually reset.

Requirements

1. Rovers must not include any flammable, environmentally damaging, or otherwise hazardous liquids or gasses, except:
   1. Within a permanently sealed component such as a battery;
   2. Commercially-available lubricants as required by mechanical assemblies, where care is taken to avoid overuse and contamination.
2. Each rover must be equipped with at least one kill switch.
   1. The pressable area of the kill switch must be at least 10 cm2 and red in color. Levers or toggle switches are not acceptable.
   2. No other button on the rover may be red.
   3. Kill switches must be mounted on the top of the rover, with the button oriented toward the sky in the rover’s normal driving orientation.
   4. A keep out region must be maintained around the kill switch with a radius of 15cm: No components taller than the base of the kill switch may intrude on the keep out region.
   5. Kill switches must not be obstructed by a cover or sleeve which extends above the pressable surface, and must be mounted such that it will not be obstructed by other components during rover operation.
   6. The circuit including the kill switch must include appropriate circuit protection, and the maximum “break” or “disconnect” current rating of the kill switch must exceed the Interrupt Current Rating of the circuit protection.
   7. The function of the kill switch must not depend on the integrity of any power source or computerized system. Indirect switching by relays or similar devices is permitted as long as these are driven by the kill switch, and reliably turn off when their control line is disconnected.
   8. The function of the kill switch must not depend on the integrity of any particular wiring connection; for example, physically tearing the kill switch off the rover should produce the same effect as pressing it.
   9. If multiple kill switches are installed on the rover, pressing any one must cut all power to the rover.
   10. The function of the kill switch must not be disabled or bypassed by any means.
   11. Rovers should have a remote motion stop for disabling a run-away rover, such as a dead man’s switch on a lead, or a radio-frequency system that operates independently of the rover communications system.
3. Each battery must include or be installed with a single circuit protection element which protects all circuits supplied by the battery, and the battery itself.
   1. The Interrupt Current Rating of this protection must not exceed the lesser of:
      1. The Rated Current Capacity of the battery;
      2. 150% of the sum of the Rated Current Consumption of all connected circuits.
   2. This circuit protection must be installed as close as possible to the battery.
   3. Each Lithium battery must be protected by a battery management system that provides under-voltage lockout protection.
      1. The battery management system should provide cell voltage monitoring, over-current protection, and over-voltage protection.
      2. Batteries should be connected to their battery management systems when in use, and battery chargers should provide the same protection.
   4. All wiring and connecting hardware between the battery and circuit protection must be fully secured and insulated such that no reasonable impact, vibration, loose object, or liquid could possibly create an unprotected short circuit.
   5. If multiple batteries are used in parallel, each must have its own circuit protection element according to these requirements. You may not connect multiple batteries in parallel without a circuit protection element per battery.
   6. Multiple batteries may only be connected in series only if they feed a single circuit and each battery has a battery management system with under-voltage-lockout.
   7. Teams are responsible for the proper disposal of any compromised electrical components and/or batteries.
   8. Teams should store batteries in fireproof bags (ie Lipo storage bag).
4. Each circuit must include separate circuit protection.
   1. The Interrupt Current Rating of this protection must not exceed the lesser of:
      1. 130% of the Rated Current Consumption of the devices powered by the circuit, or 2 Amps for lower-current circuits;
      2. The Rated Current Capacity of the smallest connectors or conductors in the circuit.
         1. Use this document as a guide for continuous current.
         2. The ambient temperature outside your rover will be 40 degrees Celsius.
         3. The ambient temperature inside your rover is likely 20C higher than outdoors, depending on cooling strategy, rover material, paint colour, and other factors.
   2. The connections between your battery and any distribution board/panel are a circuit, and must be protected as such. Off the shelf battery management systems (BMSs) are allowable here, and are the only exception to the ban on protection systems that rely on software.
5. Ventilation and heat dissipation concerns should be considered when installing power sources, high-current devices, and high-current wiring.
   1. Each electronic enclosure should be specified with a maximum internal air temperature.
   2. The capacity rating of all components in an enclosure should be determined using the maximum internal temperature of the enclosure as the ambient temperature for those components.
   3. The temperature of each enclosure and high-power component should be monitored, and exceeding the maximum temperature should shut off power to that enclosure or component.
6. Precautions against short circuits and electric shocks must be observed:
   1. Each battery must be securely mounted to a suitable structural element of the rover, and should be protected against collisions or roll overs during rover operation.
   2. All electrical wiring and connections must be insulated, taped over, or securely mounted within enclosed rover bodywork.
   3. All conductive objects within enclosed rover bodywork must be securely mounted to avoid contact with electrical connections.
   4. All electrical connections, wires, and traces should be insulated to prevent accidental short circuits.
   5. All electrical connections must be routed away from mechanical pinch points. The full range of motion available to the rover will be considered when evaluating pinch points.
   6. Hard stops should be used to limit mechanical movement and reduce pinch points
   7. Structural and mechanical elements of the rover must not be used as part of any electrical circuit.
   8. All power sources should be disconnected before servicing rover electrical systems.
   9. All electronics should be within a waterproof container, or themselves be waterproof.
   10. Insulation and drainage should be considered.
7. Sufficient documentation must be provided to prove the safety of your rover before you will be allowed to compete.
   1. You may submit partial or full documentation at any time for review and approval by the organizers. We strongly recommend submitting potential designs early in the process if you have any concerns about whether they are compliant.
   2. You must submit a full copy of your documentation by June 19, 2025 for review and approval. If your design is not compliant for this deadline, you will be allowed to revise and resubmit before a second deadline, to be determined on a case-by-case basis.
   3. Your documentation must be updated to reflect ongoing changes during CIRC.
   4. The current hard or digital copy of your documentation the diagram must accompany the rover to CIRC tasks.
   5. Related low-current devices on the same circuit may be grouped into black-box subsystems to reduce the complexity of the diagram.
   6. Each power source, circuit protection element, circuit, and device/device group in your documentation on the diagram must be identified annotated with a short name and rated Supply Current, Current Capacity, Interrupt Current or Current Consumption.
   7. Evidence of claimed ratings must be provided in the documentation package.
   8. Acceptable evidence includes datasheets, industry standards, or test reports. Product pages or website screenshots are not acceptable. We will grant exemptions to this requirement on a case-by-case basis for some components when purchased from reputable vendors.
      1. Components that may be granted an exemption include batteries, battery management systems, and generic connectors (like ring terminals or ferrules).
      2. Fuses, switches, relays, or contactors will never be granted an exemption to this requirement.
      3. Components purchased from amazon/temu will never be granted an exemption to this requirement.
   9. The documentation package must be accessible to judges at all times.
   10. A block-level schematic must be included in the documentation, and the layout of the schematic circuit diagram should reflect the physical layout of the rover wiring harness where possible.
   11. Related low-current devices (less than 2A total) on the same circuit may be grouped into black-box subsystems to reduce the complexity of the diagram.
   12. A photograph or diagram of the emergency stop button mounted on the rover must be included.
8. After any safety-impacting changes or safety-related incident, your rover must pass a re-inspection before being allowed to continue competing. The re-inspection will include a discussion of the cause, and measures taken to prevent recurrence.
   1. Safety incidents include but are not limited to unprotected shorts, exposed or damaged wiring, battery damage, or any emission of smoke, fire, or sparks.
   2. A blown fuse or tripped circuit breaker is not a safety incident.
   3. Non-compliance to this requirement will be subject to penalties under our Code of Conduct, up to and including disqualification.

Commentary and Changes

1. We haven’t introduced any new “MUST” requirements this year.
2. We’ve increased the hours where safety inspections are available during the competition, and may increase them further if we have the capacity.
3. We’ve updated the terminology we use for “Current Rating”, separating sources, circuit protection, carrying capacity, and current-consuming devices to reduce ambiguity. The requirements are the same, but should be easier to follow.
4. We’re going to be more strict about requirement 7.8 for most components, but we have added an exemption for some components when purchased from reputable vendors. If you aren’t sure if your component will qualify, email us to check before you purchase it.
5. We have added some additional “SHOULD” requirements around thermal management to guide towards improved safety in the field if you choose to implement them.

Change Log