MTS FlexTest SE Controller Introduction, Networking, and Trouble Shooting Information

Transcription

1 MTS FlexTest SE Controller Introduction, Networking, and Trouble Shooting Information 12 July 2011 i

2 Contents Back Panel Configuration... 1 Hardware... 2 Front Panel Configuration... 4 Powering up the FlexTest SE and Hydraulics and Running Simple Functions through the Actuator... 4 Calibrating and Tuning AC and DC Transducers... 5 Calibrating Valve Driver Conditioners... 6 Sending Command Signals to Other Controllers and Using External Command Signals for Control... 6 Troubleshooting... 7 ii

3 Introduction The MTS FlexTest SE Controller is a digital servo controller that provides complete control of one servo hydraulic channel/station in an MTS testing system. This includes AC and DC transducer conditioning, basic function generation, servovalve drive signal generation, and hydraulic pressure control. The following introduction provides a brief overview of FlexTest SE operation and trouble shooting and should not be used in place of the controller manuals. Back Panel Configuration Transducers and servo controls used to control testing equipment are plugged into the back panel of the FlexTest SE controller. Control transducers typically include actuator LVDTs and load cells, however different transducers can be used for different testing applications. The back panel of a typical FlexTest SE controller in the istar lab is shown in Figure 1. This panel consists of two transducer conditioners (both may be configured for AC or DC transducers) and one servo valve conditioner (two stage or three stage). Other important components of the back panel have been highlighted including the conditioner plugs, HSM plug, network port, and Analog In/Out plugs. The functions of these plugs have been described below. Conditioner Plugs Connect transducers to conditioner cards and servo valves to the valve conditioner card. Note when configured for a three-stage servo valve, a splitter is required for the J7 servo valve plug to accommodate the valve driver and valve LVDT cables. HSM Plug Connect the controller to the HSM Analog In/Out Plugs Receive and send control signals respectively. Network Port Used to connect the controller to a computer with a controller management tool. This port requires a crossover networking cable. Figure 1: FlexTest SE Back Panel 1

4 Hardware Transducer and valve driver conditioner cards in the FlexTest SE can be replaced to satisfy parameters in different testing equipment. Table 1 shows the different capabilities of transducer and valve driver cards in the istar lab, while the basic hardware layout of the FlexTest SE is shown in Figure 2. When changing the valve driver conditioner card controller software must also be updated to reflect the change (see networking section). Table 1: Conditioner Card Properties Card Number Conditioner Function Excitation B Force/Displacement 10VAC/19.99VDC Transducer C Force/Displacement 10VAC/10VDC Transducer Stage Servo Valve 19.99VDC Driver Stage Servo Valve Driver 19.99VDC Networking Figure 2: Standard Hardware Configuration Parameters on the FlexTest SE controller are defined by hardware (.hwi) and configuration (.cfg) files. These files are automatically updated in the controller when tuning and calibration values are changed, however when reconfiguring the controller to accommodate 3-stage or 2-stage valve driver conditioner cards it is necessary to update the system software using the controller 2

5 management tool. The following will provide a step by step guide to networking the controller with a supporting computer for the purpose of updating system files. 1) Load the Controller Management Tool onto Supporting Computer The controller management tool is used to add and remove software from the FlexTest SE controller and can be loaded using the MTS disc labeled 793 System Software. 2) Configure Supporting Computer Network Settings The required network configuration for the supporting computer is given in the document FlexTest SE Update Instructions which located in the stash (\\STASH\istar\library\iSTAR equipment\controller MTSFlexTestSE\Manuals). The controller will not connect to the computer if the network settings have not been properly configured. 3) Connect the Controller to the Supporting Computer Using a crossover Ethernet cable, connect the controller to the computer in the networking port labeled 10/100 BASE T. 4) Reboot the Controller in Stand Alone w/ Net Mode This boot mode allows the controller to communicate with the computer. The navigation to change the controller boot mode is as follows: Configuration Local Settings Networking. 5) Reboot the Controller in Service Mode After the controller has successfully connected to the computer, use the controller management tool to change the boot mode to service, and reboot from controller front panel. 6) Update System Files Update the system files to accommodate testing equipment and controller hardware. Standard 2-stage and 3-stage valve driver configuration and hardware files have been included on the stash (\\STASH\istar\library\iSTAR equipment\controller MTSFlexTestSE). 7) Reboot the Controller Change to boot mode to stand alone with net and reboot the controller using the controller management tool. Note: If the hardware is incompatible with the system files the controller will not properly load, and an error reading System is in an unstable state will appear. If this occurs as a result of hardware incompatibility manually turn the controller off using the switch on the back and change the valve driver card. If this occurs as a result of software incompatibility, reboot the controller in service mode using the controller management tool and update the software. 3

6 Figure 3: Controller Management Tool Front Panel Configuration Controls on the front panel are used to calibrate and tune conditioners and conduct experiments. See page in the FlexTest SE User Information and Software Reference manual for a description of all front panel controls. A brief front panel overview is provided in Figure 4. Figure 4: Front Panel Powering up the FlexTest SE and Hydraulics and Running Simple Functions through the Actuator After transducers and servo valves have been plugged into the conditioner channels, the FlexTest SE can be powered up using the power switch on the back panel. The controller automatically navigates to a home menu as shown in Figure 4. The following will provide a step by step guide to run simple functions using the FlexTest SE controller assuming the transducer conditioners have been calibrated. 1) Clear Active Interlocks Red lights on the right hand side of the front panel indicate if any software or hydraulic interlocks have been tripped. Interlocks act as safety mechanisms by cutting hydraulic pressure to testing equipment if pre-defined parameters in the FlexTest have been exceeded or conditioner cables become disconnected. Note that pressure will only be cut if the controller is used in conjunction with the HSM. If the HSM is not used, the interlocks will 4

7 disable command signals but hydraulic pressure will still be applied to the system. To clear the interlocks, simply push the reset button next to the interlock indicators. To clear hydraulic interlocks, all conditioner cards must be plugged in, and the proper excitation value must be supplied to the transducers and servo valves. 2) Apply Hydraulic Pressure After the interlocks have been cleared hydraulic pressure can be applied to the system. If the HSM is not being used, hydraulic pressure is applied directly to the system by turning on the pump unit. If the HSM is being used, hydraulic pressure is applied to the test system using the HSM pressure buttons on the front panel of the FlexTest after the pump unit has been turned on. If the HSM is being used, make sure the FlexTest has been appropriately configured and the HSM is plugged in before turning on the pump unit. The navigation to check the hydraulic configuration is as follows Configuration Edit Hardware Power Options. Power type should be set to HSM Only and HSM Type should be set to Solenoid. 3) Select Control Channel and Define Control Signal Navigate to the FG menu to select control channel and control function. Calibrating and Tuning AC and DC Transducers Detailed procedures for calibrating and tuning force and displacement transducers are provided in the 793 Tuning and Calibration Manual. The following is a brief note regarding the PIDF tuning parameters for transducer conditioners. The response of the actuator to command signals sent from the control conditioner can be adjusted using the gain values in the tuning menu. The function of each gain value is described in detail in the 793 Tuning and Calibration Manual. It is highly recommended that the manual is referenced before these values are adjusted. The following is a brief description of the function of each gain value. Proportional Gain (P Gain) P gain is generally adjusted first when tuning a control conditioner. P gain determines how closely the feedback signal follows the control signal. The greater the gain, the more the servo valve opens for a given error. If the feedback signal is sluggish, the P gain can be increased to a certain point to reduce error. The proportional gain should be slowly adjusted using the dial on the front panel of the controller. If the P gain is too large, instability will be introduced to the system in the form of hydraulic ringing which can result in damage to specimens. Each transducer and conditioner requires a different P gain value for optimum control, and this gain value can only be achieved using trial and error. Derivative Gain (D Gain) D gain is adjusted after the P gain. D gain can improve loop performance by allowing higher P gain values without overshoot or ringing. Integral Gain (I Gain) I gain reduces error between command and feedback signals by slowly integrating out residual error between command and feedback. I gain also compensates for offsets and thermal drift of a servo valve. Too large of an I gain value will result in slow oscillation when the command signal is constant. 5

8 Feedforward Gain (F Gain)I F gain enhances system response times even if the maximum amount of P gain has already been applied. Calibrating Valve Driver Conditioners The valve driver conditioners should be calibrated when the controller is used with different actuators. Detailed procedures for calibrating 3-stage and 2-stage valve drivers can be found in the 793 Tuning and Calibration Manual. Sending Command Signals to Other Controllers and Using External Command Signals for Control Sending control signals is an important feature of the FlexTest SE controller which can be used when multiple actuators are required to run the same command signal in phase. The following navigation is used to send a control signal: Setup Anlg Out. The readout signal should be set to Ch Command. The control signal can be read by connecting to the analog out plug on the back panel. Unlike the 407 controller, the FlexTest SE has not been configured to receive external command signals. Thus a less-than-ideal method to controlling actuators with an external control signal is shown below. The external control signal is received by the FlexTest via the analog in plug on the back panel. 1) Create a Dual Compensation Channel The navigation to create a dual compensation channel is as follows: Configuration Edit Configuration VD S2-J7 (Ch) Add Mode. The channel type should be dual compensation, the base mode should be the required control mode for the test (i.e. force or disp), and the active feedback should be anlg in. To create the channel, the configuration access level must be selected. The controller must be rebooted for the changes to take effect. 2) Assign Ext. Command to Valve The navigation to assign an ext. valve command is as follows: Configuration Edit Configuration VD S2-J7 (Ch). Change Ext. Command to Anlg In. The configuration access level must be selected, and the controller must be rebooted for the changes to take effect. 3) Set Command Type The command type must selected in the FG menu. The type should be set to Ext. Command and the control mode should be set to Anlg In/Force or Anlg In/Disp depending if the test is force or displacement controlled respectively. The target set point can be adjusted within the limits of the controlling transducer. 6

9 4) Set Amplitude When the Ext. Command control mode is selected, the target transducer amplitude cannot be adjusted in the FG menu. The conversion gain is instead used to control the target transducer of the amplitude. The navigation to adjust the conversion gain amplitude is as follows: Setup Ch Anlg/Force or Ch Anlg/Disp Dual Compensation. To set the required amplitude of the control transducer using the conversion gain, the transducer feedback must be monitored externally via LabVIEW. Additionally, when testing using the conversion gain amplitude adjustment, the initial value of the conversion gain should be set to a very low level (i.e. 0.01) because it is difficult to determine the extent to which the gain value affects the transducer amplitude. Troubleshooting Controlling hydraulic testing systems is a combination of complex electrical tuning parameters and hardware configurations. Thus, many problems can arise in which the testing equipment does not respond appropriately to control signals. When such problems develop, it recommended that the following troubleshooting steps are followed. These steps have been developed based on the most common control issues, and will not resolve all controller issues. Check Cables The most common control issues are caused by broken or improperly wired cables and connections. Check the pin assignments in the connections and continuity of the cables. Check Tuning on Controller Parameters Check the PIDF gain values in the controller menu. If the actuator is sluggish to command signals, increase the P and D gains. If the system is unstable, decrease the P gain value. If the actuator appears to oscillate when the command signal is constant, decrease the I gain. Check Calibration of Transducers If the control transducer is improperly tuned, the actuator will not recognize the extents of the stroke which can result in abrupt uncontrollable motions. Re Calibrate Valve Driver If control issues persist after the above items have been checked, recalibrate the valve driver conditioner. If the valve is not properly calibrated, the system can become unstable which can result in abrupt uncontrollable motion. Examine the Valve Driver and Transducer Conditioner Cards Damage can occur to the conditioner hardware as a result of voltage spikes. Talk to the lab tech before removing the conditioner hardware from the controller. 7