Rover Safety Requirements

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 may be excluded from CIRC until all issues are resolved. Any questions or requests for exemptions should be directed to [email protected].

Definitions

  • The word “should” indicates a suggestion which which may become a requirement in future competitions.
  • 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.
  • The Current Rating of a component is the manufacturer-published value indicating the maximum acceptable amperage consumed by the device in normal conditions. The current rating of circuit protection is the amperage above which it is designed to interrupt current flow.
  • Circuit Protection is a fuse or electromechanical circuit breaker which reliably interrupts excessive current flows through a connected circuit. Software-based solutions are insufficient.
  • 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 gases, 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.

    2. 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.

    3. The kill switch should be mounted as near to the top of the rover as practical so it is easily accessible to nearby persons.

    4. The circuit including the kill switch must include appropriate circuit protection, and the “break” or “disconnect” current rating of the kill switch must exceed the current rating of the circuit protection.

    5. 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.

    6. The function of the kill switch must not depend on the integrity of any particular wiring connection; for example, physically tearing the kill switch of off the rover should produce the same effect as pressing it.

    7. The function of the kill switch must not be disabled or bypassed by any means.

  3. Each battery must include or be installed with a single circuit protection element which protects all circuits supplied by the battery.

    1. The current rating of this protection must not exceed the lesser of:
      • The current rating of the battery;
      • 150% of the sum of the current ratings of all connected circuits.

    2. This circuit protection must be installed as close as possible to the battery.

    3. All wiring and connecting hardware between the battery and circuit protection must be fully secured and insulated such that no reasonable impact, vibration, or loose object could possibly create an unprotected short circuit.

  4. Each circuit must include separate circuit protection.

    1. The current rating of this protection must not exceed the lesser of:
      • The current rating of the circuit, or 2 Amps for lower-current circuits;
      • The safe current-carrying capacity of connectors and conductors in the circuit. Use this document as an approximate guide for continuous current.

  5. Ventilation and heat dissipation concerns should be considered when installing power sources, high-current devices, and high-current wiring.

  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 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. Structural and mechanical elements of the rover should not be used as part of any electrical circuit.

    5. All power sources should be disconnected before servicing rover electrical systems.

  7. A complete circuit diagram (block-level schematic) of the rover, including all power sources, circuit protection, and power-consuming devices, must be presented at CIRC sign-in.

    1. The diagram should be updated to reflect ongoing changes during CIRC.

    2. A current hard copy of the diagram should accompany the rover to CIRC tasks.

    3. Related low-current devices on the same circuit may be grouped into black-box subsystems to reduce the complexity of the diagram.

    4. Each power source, circuit protection element, circuit, and device/device group on the diagram must be annotated with a short name and current rating.

    5. Evidence of claimed current ratings should be accessible to judges.

    6. The layout of the circuit diagram should reflect the physical layout of the rover wiring harness where possible.