New Feature: Position Controlled by External Force Sensor
Force Control
Continuous technological developments in Surface Mount Devices (SMD) and high precision Pick & Place applications, introduce new challenges for the motion control industry. Such applications require a precise control of the applied force or torque. Unlike traditional “current limit” methods, which depend to motor parameters and are subjected to temperature and manufacturing tolerances, the combination of a motor feedback and an external force sensor, provide superior position – force control for high-end OEM applications. SERVOTRONIX’S CDHD2 servo drive supports Real-Time force control together with advanced position control algorithms.
Key benefits
- High Force Control performance.
- PI Force controller – Increased smoothness and High control against overshot.
- Compatible with SERVOTRONIX’s proprietary HD controller and Linear controller.
Figure 1. Cascade Control System with Force Controller
Application examples
Best suited for force sensing applications such as:
- Screws tightening applications, where a precise torque on screw is required.
- Wires production.
- Test machines for 3C industry (Computers, Communication and Consumer)
Force Control Commands
The feature supports two input methods:
- Analog Command: +-10 VDC connected to CDHD2 analog input.
- Digital Command: Serial (USB or RS232) or EtherCAT.
The Force Control Algorithm
- Receive force setpoint in units of grams.
- Limit the force set point by means of slope.
- Read force sensor actual value via analog input and convert analog input from volts to Grams.
- Force error = force setpoint – force sensor feedback
- PI control loop
Typical Z axis Operational Sequence
- Operation starts in Position mode.
- Move axis to start position (above the pressed object).
- Switch to Force Control mode.
- Perform “Press” operation until force setpoint is reached.
- Switches back to Position mode.
- Moves back to start position.
