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Understanding the Power System of the SARA Robot

The power system plays a crucial role in the functionality and performance of the SARA robot. As an advanced robotics platform, SARA relies on a well-designed and efficient power system to ensure smooth operation and optimal performance. The power system is responsible for supplying electrical energy to various components of the robot, including its motors, sensors, and control systems. Without a reliable power system, the robot would not be able to function effectively.

One of the key aspects of the power system is electrical connection. The way in which electrical components are connected within the robot has a direct impact on its overall performance. A well-designed electrical connection ensures that electricity flows smoothly between different components, minimizing voltage drops and ensuring efficient power distribution. This is particularly important in a complex robotic system like SARA, where multiple motors and sensors need to work together seamlessly.

To achieve an effective electrical connection, it is essential to have a clear understanding of the electric schematic of the robot. The electric schematic provides a visual representation of how different electrical components are interconnected within the system. It helps to identify potential issues in the circuitry and allows for efficient troubleshooting when problems arise.

In addition to proper electrical connection and schematic design, SolidWorks plays a significant role in optimizing the power system of SARA. SolidWorks is a powerful computer-aided design (CAD) software that enables to create detailed 3D models of their designs. By using SolidWorks, engineers can visualize how different electrical components fit together within the robot's structure, ensuring efficient placement and arrangement.

Professional Electrical Connection and Safety in the SARA Robot

The power system of the SARA robot is intricately designed to ensure peak performance and reliability. Central to this design is the professional-grade electrical connection, which emphasizes both functionality and safety.

A hallmark of this professional approach is the use of specialized connectors and distribution boxes. These components are strategically integrated to facilitate easy plug-and-play functionality. Should any component malfunction or require side testing, it can be swiftly unplugged and addressed without disrupting the entire system. This modular approach not only streamlines troubleshooting but also enhances the robot's overall adaptability.

Cable management has been executed with precision. All cables are encased in long heat shrinks, ensuring they remain organized and protected. This method reduces the visible cable count, leading to a cleaner and more efficient layout. The organized routing minimizes potential interference and ensures that the robot's internals remain aesthetically pleasing while being functional.

Safety is paramount in the design of SARA's electrical system. Fuses and fuse boxes have been incorporated throughout the robot's circuitry. These components act as the first line of defense against electrical anomalies, safeguarding both the robot and its components from potential overloads or shorts. By integrating these safety measures, the robot achieves a balance between high performance and reliability.

In essence, the SARA robot's electrical connection is a testament to professional engineering—where every component, from connectors to cables, is optimized for performance, safety, and ease of maintenance.

Electric Schematic Design

The electric schematic design plays a crucial role in the overall functionality and performance of the SARA robot. It serves as a blueprint that outlines the electrical connections and components required for the robot to operate efficiently. Analyzing the electric schematic of the SARA robot provides valuable insights into how power is distributed and utilized within the system.

The SARA robot's primary power source is a 36v 4000mAh Li-ion battery, originally from a hoverboard. The power distribution from this battery is divided into three main branches, each serving a distinct purpose:

1. Safety and Control Branch:

  • Emergency Switch: The first component in this branch is the Normally Closed (NC) Emergency switch. This switch acts as a safety mechanism, allowing for immediate power cut-off in emergencies.

  • Power Switch: Following the emergency switch is the Normally Open (NO) power switch. This is the primary switch to turn the robot on or off.

  • Power Relay: The power then flows to the coil of a power relay, which, when activated, allows the current to flow further into the system.

2. Power Distribution Branch:

  • Relay's Normally Open Contact: This branch starts from the Normally Open contact of the relay, which is connected on one side to the 36V battery, and on the other side to the watt meter.

  • Watt Meter: The power then connects to a Watt meter, which displays the power consumed, voltage level, and current consumed, providing crucial data for monitoring the robot's load.

  • ODrive: The output from the Watt meter connects to the ODrive, which controls the BLDC Hub Motors, also sourced from the hoverboard.

  • DC-DC Buck Converters: The power also flows to 2 DC-DC buck converters, which convert the 36V power to 12V and 5V. These voltages are essential for powering most of the robot's components.

3. Charging Branch:

  • Charger Socket: This branch is dedicated to charging the battery. The battery is directly connected to a charger socket, allowing for convenient charging. A significant advantage of this direct connection is that the robot doesn't need to be turned on for charging, ensuring energy efficiency and prolonging battery life.

By structuring the power flow in this tri-branch manner, the robot ensures efficient power distribution while maintaining safety protocols and providing a dedicated charging pathway.

The rationale behind this specific connection method is strategic. By designing it this way, the robot's power doesn't directly pass through the emergency switch and the power switch. Instead, these switches control the coil of the power relay. It's the relay's contact that takes on the responsibility of passing the full voltage to the robot's components. This setup ensures a more efficient and safer power distribution, allowing for quick disconnection in emergencies without compromising the power flow to essential components when operational.

Use of SolidWorks Design

The SolidWorks CAD model serves as an invaluable tool in this regard for the SARA robot. It offers a detailed and precise visualization, allowing us to strategically position each component for optimal performance and accessibility. Beyond just a visual representation, the CAD model ensures that every part fits harmoniously within the robot's structure, minimizing potential conflicts and maximizing efficiency. With such a tool at their disposal, the team can anticipate and address challenges, ensuring that the robot's power system is both robust and user-friendly.

The CAD model provides a detailed visualization of the power system's components and their real-world placement within the SARA robot.

1. Component Placement:

  • Battery & Watt Meter: These are strategically located on the robot's backside. This placement ensures easy access, whether it's to replace the battery or monitor power consumption.

  • Relay & ODrive & Buck Converters: These are located on the front side of the robot since it is not needed to access them, and also the buck converters are connected to the distribution boxes available in the second level in the front.

2. Terminal Blocks & Power Distribution:

  • Left Terminal Block: Directly connected to the battery, this block oversees the safety and control branch and the charging branch, as previously outlined.

  • Right Terminal Block: The output from the Watt meter feeds into this block. From here, the voltage is channeled to the ODrive and the two Buck converters.

3. Safety Measures:

  • In-Wire Fuse Box: The 36V supply from the terminal block to the components is safeguarded by an in-wire fuse box. Each fuse has a 10Amp limit, adding a layer of protection against potential circuit shorts.

  • DC-DC Converter Outputs: The outputs from each converter are also connected through an in-wire fuse box to their respective terminal blocks. This ensures that in the event of an overcurrent at any voltage level, the fuses will act as the first line of defense, preventing damage to the robot's components.

By structuring the power system in this manner, the robot prioritizes both efficiency and safety, ensuring optimal performance while minimizing risks.


The power system of the SARA robot plays a crucial role in its overall performance and functionality. Throughout this blog post, we have explored various aspects of the power system, including electrical connections, electric schematics, SolidWorks design, and efficient arrangement of electrical components. By understanding these key elements, we can appreciate the complexity and importance of the power system in ensuring optimal performance.

[3/June ~ 17/June 2023]

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