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Introduction
Introduction
The Harness subsystem focuses on how to physically connect hardware using wires and connectors. All off-from-board components connections and inter-modular connections will be taken into consideration. Harness subsystem ensures the safety and reliability of power/data interactions between subsystems. The selections of harnessing components (wires, connectors, and etc.) will conform to NASA standard EEE-INST-002.
Design Philosophy
Design Philosophy
The function of harnessing is to physically integrate all subsystems. The overall harness will be divided into two: power distribution and data transmission. Power cables and data cables will be separated so that the noises in the data bus due to currents in the power cable will be eliminated.
The following functional block diagram outlines the logic of the harness design.
Power harnessing diagram
Power harnessing diagram
The following figure demonstrates power harnessing, each line stands for twisted pairs of power wires. The number along each line gives the amount of wires.
Data harnessing diagram
Data harnessing diagram
The data harnessing diagram is shown below, for inter-modular data communication, there are 2 types of protocols: SPI and CAN. The connections between internal components (cameras, sensors, and etc.) and control boards conform to electrical interface specifications of each subsystem.
Key Risks
Key Risks
The key risks of harnessing are collected in the table below:
Risk registry.docxSingle Point Failure Analysis
Single Point Failure Analysis
The single point failure mode on harness's perspective is the failure of connection components (connectors and wires). In this case, every single failure of the inter-modular connectors would fail the whole satellite. If the satellite is properly assembled and the whole satellite assembly is able to pass through the ground test then the likelihood of connector failure is sufficiently low for us to accept this risk.
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