> For the complete documentation index, see [llms.txt](https://yams.yassrobotics.com/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://yams.yassrobotics.com/api-reference/c++-reference/config/arm-config.md).

# ArmConfig

**Namespace:** `yams::mechanisms::config` **Java equivalent:** [Java ArmConfig](/api-reference/java-reference/config/arm-config.md)

`ArmConfig` holds physical and simulation parameters for an `Arm` mechanism.

***

## Constructor

```cpp
ArmConfig() = default;
```

***

## Builder Methods

All methods return `ArmConfig&` for chaining.

> **Required for simulation:** `WithArmLength()` must be set for `SingleJointedArmSim` to work correctly. All other methods are optional.

| Method                                       | Required                    | Description                                                                                       |
| -------------------------------------------- | --------------------------- | ------------------------------------------------------------------------------------------------- |
| `WithArmLength(units::meter_t length)`       | **Required for simulation** | Arm length from pivot to end effector. Without this, the physics simulation cannot model the arm. |
| `WithMinAngle(units::degree_t angle)`        | Optional                    | Minimum allowable mechanism angle                                                                 |
| `WithMaxAngle(units::degree_t angle)`        | Optional                    | Maximum allowable mechanism angle                                                                 |
| `WithTelemetryName(const std::string& name)` | Optional                    | Name used for SmartDashboard and log entries                                                      |
| `WithSimColor(const frc::Color8Bit& color)`  | Optional                    | Color of the simulated arm ligament                                                               |

***

## Getters

```cpp
std::string GetTelemetryName() const;
std::optional<units::degree_t> GetMinAngle() const;
std::optional<units::degree_t> GetMaxAngle() const;
std::optional<units::meter_t> GetArmLength() const;
frc::Color8Bit GetSimColor() const;
```

Getters for optional fields return `std::nullopt` if the corresponding setter was not called.

***

## Exceptions

| Exception                               | Thrown When                                                                       |
| --------------------------------------- | --------------------------------------------------------------------------------- |
| `exceptions::ArmConfigurationException` | Required fields are missing or values are invalid when used to construct an `Arm` |

***

## Example

```cpp
config::ArmConfig armConfig;
armConfig.WithMinAngle(-90_deg)
         .WithMaxAngle(90_deg)
         .WithArmLength(0.6_m)
         .WithTelemetryName("Arm");
```