Endless slew Actuators

Endless Slew Actuator (Endless Rotation Actuator)

An Endless Slew Actuator is an actuator type that allows for continuous 360-degree rotation, meaning it can rotate endlessly in either direction. This type of actuator can be configured from both linear and rotating actuator types, as the main task is to calculate the pulse count for the actuator. When the Endless Slew mode is activated, the controller will treat the actuator as an actuator capable of endless 360-degree rotation using the previously calculated pulse count.

Giant Endless slew Rig 6dof + endless slew 360°

Key Features:

1. Pulse Count: Both linear and rotating actuators can be selected for this mode because they each calculate the pulse count for the actuator. When Endless Slew mode is activated, the controller uses this pulse count to operate the actuator in a 360-degree endless mode.

2. No Hardstop: The actuator in Endless Slew mode does not have a mechanical hard stop (like in regular rotating actuators with limited range, e.g., 180°). This means that the actuator can rotate endlessly.

3. Limit Switch / Homing Sensor: Because there is no hard stop, a limit switch or homing sensor is required to define a reference position for the actuator. This sensor allows the system to recognize when the actuator has completed a full rotation or has reached a reference point. Without it, the system won't be able to track or reset the actuator's position accurately.

4. Pulse Count Accuracy: The pulse count must be set correctly for 360 degrees. If the pulse count is incorrect, the zero point of the actuator will "drift" over time, meaning that the system will lose its position accuracy, and the actuator could keep rotating past its intended 360-degree range without returning to the correct position.

MaxPulse Calculation for Endless Slew Actuators

For Endless Slew Actuators, the MaxPulse calculation follows the same principles as that of rotating actuators but with the key difference that the actuator operates without range limitations. Once the Endless Slew mode is activated, the controller will treat the actuator's calculated pulse count as if it's in continuous rotation.

For rotating actuators, the formula for calculating MaxPulse is:

MaxPulse=RIG.ppr×RIG.mechanik_GearRatio_ServoRIG.elektrik_GearRatio_Servo×(360RIG.Rangefaktor)MaxPulse = \frac{RIG.ppr \times RIG.mechanik\_GearRatio\_Servo}{RIG.elektrik\_GearRatio\_Servo} \times \left( \frac{360}{RIG.Rangefaktor} \right)

For example:

• Encoder Resolution (ppr) = 10,000

• Mechanical Gear Ratio = 1:50

• Electrical Gear Ratio = 1:2

• Range = 180°

MaxPulse would be:

MaxPulse=10,000×502×(360180)MaxPulse = \frac{10,000 \times 50}{2} \times \left( \frac{360}{180} \right) MaxPulse=125,000 pulses per half rotation (180°)MaxPulse = 125,000 \text{ pulses per half rotation (180°)}

Once Endless Slew Mode is activated, this pulse count is used for a full 360-degree rotation, with no physical range limit.

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Calibration and Homing

Since there is no physical hard stop, the actuator needs a limit switch or homing sensor to track its position. The Cal. Offset function is used to define a reference position for the actuator, typically after it completes a homing procedure.

1. Homing: The homing procedure involves using a limit switch or sensor to define a known reference point for the actuator. This step is crucial to ensure that the actuator's position is correctly tracked as it enters the Endless Slew mode.

2. Offset Calibration: After the actuator is homed, the Cal. Offset defines how many pulses to move the actuator after the homing process. This is useful for correcting any slight inaccuracies due to mechanical tolerances or sensor misalignment.

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Park Position

In the case of Endless Slew Actuators, the Park Position may not be necessary in the same way as for actuators with fixed ranges. However, you can set a Park Position to mark a reference point for the actuator, which could be useful for safely storing or resting the actuator when it's not in use.

• The Park Position can be defined in terms of pulses, even though it won't physically "stop" the actuator due to the lack of a hard stop.

• The calculation of the Park Position would be based on the pulse count that corresponds to a specific position the actuator should return to after being homed.

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Standby Position

The Standby Position can be set to a neutral or zero position, where the actuator stays stationary until required to rotate again. This position is often set based on the calculated pulse count for 360 degrees and is useful when the system needs to return the actuator to a resting state.

• The Standby Position is defined in terms of pulses and can be set as a percentage of the total pulse range (e.g., 0% or 50%).

• This value ensures that the actuator is ready to move when the system requires it, but the actuator remains stationary otherwise.

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Conclusion

To summarize, when using an Endless Slew Actuator, the system operates as follows:

• The actuator can rotate continuously in either direction without a physical limit.

• The pulse count is calculated like a standard rotating actuator, but the system is configured for continuous movement.

• A limit switch or homing sensor is required to define a reference point for the actuator, ensuring position accuracy.

• If the pulse count is set incorrectly for a full 360 degrees, the system's zero point can drift, causing position errors.

• The Park Position and Standby Position can be used for logical position reference and are defined by the pulse count corresponding to specific actuator states.

By enabling the Endless Slew mode, you can take full advantage of a 360-degree rotating actuator, ensuring smooth and continuous operation with precise control and positioning.