FANUC α iS servo HRV calibration practice

FANUC α iS/β iS Series Servo Systems: A Complete Guide to HRV Control Optimization and Vibration Elimination

In modern high-precision CNC machining, the response speed and stability of the servo system directly determine the surface quality and machining efficiency of the parts. For engineers using FANUC α iS, α iF, and β iS series, they often feel at a loss when faced with hundreds of parameters in the servo parameter manual, multiple versions of HRV control (HRV1-HRV4), and complex vibration suppression functions. This article will be based on practical debugging experience to dismantle the complete process from parameter initialization, HRV control selection to mechanical resonance elimination and contour error compensation, helping you quickly locate and solve common problems in machine tool operation.

Quick initialization of servo parameters: avoiding the trap of "invalid parameters"

Parameter initialization is the cornerstone when replacing servo motors or conducting initial debugging. Many engineers often encounter alarms such as "SV0456 Invalid Current Control Cycle" or "SV0457 Invalid High Speed HRV Setting", which are fundamentally caused by conflicting control cycle settings or motor ID numbers that do not match the software version.

1.1 Key check items before initialization

Before starting, please make sure to confirm the following information:

NC models: such as 30i/31i/32i, 16i/18i, etc.

Servo motor model: such as α iS8/4000, pay attention to distinguishing between 200V and 400V drive versions.

Pulse encoder type: α iA1000 (absolute) or α iI1000 (incremental).

Whether to use a separate detector, such as a fully closed-loop grating ruler.

Mechanical transmission parameters: lead screw (mm/rev), detection unit (e.g. 0.001mm), command unit.

1.2 Key Points for Setting Core Parameters

The initialization process is usually carried out through the servo setting screen, and the following parameters are key to avoiding "illegal parameter" alarms:

Motor ID number (No.2020): must be strictly selected according to the manual. For example, for servo software 90D0/90E0, α iS8/4000 corresponds to ID number 285 (HRV2). Special note: For the 30i series, the ID number controlled by HRV2 should be specified; For series such as 16i, if the axis number is continuous, the HRV control type must be consistent.

Flexible feed gear (No.2084/2085): conversion between CMR and detection unit. For example, if the lead of the screw is 10mm, the detection unit is 1 μ m, the number of pulses required for one rotation of the motor is 10000, and the α i pulse encoder feedbacks 1000000 pulses per rotation, then FFG=10000/100000=1/100.

Full closed-loop setting: When using a serial output grating ruler, it is necessary to set No.1815 # 1=1 and calculate the number of flexible feed gears and position pulses. If the result exceeds 32767, the "Position Feedback Pulse Conversion Coefficient (No.2185)" should be used.

1.3 Quickly handle "illegal parameter" alarms

When the alarm displays "PRM" as 1, the error details can be viewed through diagnostic number 352 (16i series) or servo alarm screen (15i series). For example:

Alarm detail 23: If the number of position pulses exceeds 13100, it needs to be scaled 10 times through PLC0 (No. 2000 # 0).

Alarm detail 84: Speed proportional gain (PK2V) overflow, internal format can be changed by setting No.2200 # 6=1.

Alarm detail 10092: Invalid current control cycle. This usually means that HRV1 and HRV2 are mixed under the same servo CPU, or HRV1 is mistakenly set in the 30i series.

Deep Analysis of HRV Control: The Path to Advancement from HRV1 to HRV4

HRV (High Response Vector) control is the core of FANUC servo performance. Choosing the correct HRV version is the key to improving acceleration and deceleration characteristics and machining accuracy.

2.1 HRV2: A stable and reliable all-around foundation

For most standard machine tools, HRV2 is the most robust choice.

Features: Adopting a 125 μ s current control cycle, providing TCMD filters (mid frequency resonance cancellation), resonance cancellation filters (high frequency), and disturbance cancellation filters (low frequency).

Setting: After setting the motor ID number, set 2004 to 0X000011. If manual conversion from HRV1 is required, the current integral gain (PK1) needs to be multiplied by 0.8, and the current proportional gain (PK2) needs to be multiplied by 1.6.

2.2 HRV3: Performance multiplier for high-speed cutting

When higher loop gain is required in cutting feed, enable HRV3.

Enabling steps: Based on HRV2, set 2013 # 0=1. At the same time, it is recommended to enable No.2202 # 1 (cutting/fast moving speed loop gain switching).

Gain adjustment: During cutting, the speed loop gain will be amplified by parameter No.2335 (recommended 150% -200%), and the current loop gain will be amplified by No.2334 (recommended 150%).

Limitation: When using the 90B0/90B5 series software, the torque command in HRV3 mode will be automatically limited to 70% of the amplifier's maximum current. Therefore, it is more suitable for precision machining.