Specifications

2
Several different configurations of the system can be utilized in experiments. Either sensor, the motor or load
encoder, can be used for the feedback of the control loop. The selection is made in the software interface. The
motor encoder is known as a “collocated” sensor since it is co-located with the input to the mechanical system, the
motor torque. The load sensor is separated from the input to the system by a spring and is therefore known as a
“non-collocated” sensor. In addition to varying which sensor is used, the mechanical system can be changed with
the lock down screw and the spring coupling. Also, a choice can be made between velocity control or position
control by selecting the appropriate control program. Any of the following mechanical models may be realized
using the motorlab hardware and software.
1
ω
2
ω
T
2
b
1
θ
s
k
1
b
2
θ
1
J
2
J
Fourth order system
with a free integrator
T
2
b
s
k
1
b
1
J
2
J
Third order system
1
ω
T
1
θ
s
k
1
b
1
J
Second order system
T
s
k
1
b
1
J
Second order system
with a free differentiator
1
ω
T
1
θ
1
b
1
J
Second order system
with a free integrator
T
1
b
1
J
First order system
Software
The software can be found in the “c:\motorlab” directory on the laboratory machines. All the needed functions
and shortcuts to the executables can be found here. The “c:\motorlab\student data” directory can be used to store
data files and gain files temporarily. It should be cleaned out at the end of the lab session. Students have
read/write/delete access to this directory.
Control Software
There are three different programs used to control the motorlab hardware. Each program consists of a GUI
interface that runs on the host PC and a low-level control program that runs on the DSP microprocessor on the
MC4000 motion control card. The PC’s processor and the DSP communicate over the PCI bus in the host computer.
For the two programs that implement closed loop control, a PID controller is used. In addition the user has the
option of including feedforward velocity and acceleration gains. Each of the three programs may be run by
executing the host program, which loads the appropriate DSP program onto the motion control card and begins its
execution. WARNING: The software will not function properly if more than one host program is running. The
three programs are described below.
This is the open loop program. The feedback sensors (encoders) are not actually used for
closed loop control. The DAC output from the motion control card to the motor amplifier is
determined directly by the wave command buttons and the jog buttons.
This is the position control program. The feedback sensors (encoders) are used to close
the position control loop. The DAC output from the motion control card to the motor
amplifier is determined by the controller algorithm, while the position command is
determined by the wave command buttons and the jog buttons.
Motor LabOL.exe
MotorLabPosition.exe