Specifications
5
Hardware Specifications
Important Scaling Considerations
• Motor Amplifier Scaling = 1 Amp/Volt (i.e. one volt from the DAC on the MC4000 is a one Amp command to
the current loop in the motor amplifier). The plotting routines provided take this scaling into consideration.
• Position is measured in degrees and velocity is measured in RPM. The output of the controller algorithm on the
MC4000 is the DAC voltage, and is measured in Volts. Therefore, for example, the units of the proportional
and derivate gains in the position controller would be Volts/deg and Volts*sec/deg, respectively. When
multiplied by the amplifier scaling (1 Amp/Volt) these gains become Amps/deg and Amps*sec/deg. The units
of the proportional gain in the velocity controller would be Volts/RPM (or Amps/RPM if amplifier scaling is
included).
Inertias
Object Motor Rotor and
Motor Encoder
Stainless Steel
Coupling Collar
Stainless Steel
Load Shaft
Aluminum
Spacer for Load
Aluminum
Load Inertia
Load
Encoder
Approx. Inertia (g-cm
2
)
110 13.04 1.423 0.079 81.91 0.83
A Few Other Details
• Max motor velocity with the amplifier used is about 4000 rpm
• Max Data Acquisition Sample Rate = 10 kHz (the servo update rate of the DSP software)
• Motor Encoder Resolution = 360/1600 = 0.225 deg/count
• Load Encoder Resolution =360/2000=0.180 deg/count
Velocity measurement
The velocity is measured on the DSP motion control card using a timer to measure the time between encoder pulses
(
t∆∆≅ /
θ
ω
). This results in a time delay in the velocity measurement that can become very significant at low
velocity. This time delay can have a significant affect on a velocity controller and on the derivative term in a PID
position controller. If for example the motor encoder is spinning at 20 rpm then the time delay would be
sec002.0
min
sec60
deg 360
rev
rev/min 20
deg 225.0
/ =⋅⋅=∆=∆
ωθ
t
Theoretically, it is not possible to measure zero velocity.
Specs from Motor Manufacturer’s Data Sheet
LA052-040E Motor Dynamic Specs From Shinano Kenshi
UNITS Value
RATED POWE
R
W 40
RATED VOLTAGE VDC 24
RATED SPEED rpm 3,000
RATED TORQUE N-cm 12.7
kgf-cm 1.3
RATED CURRENT A 2.5
TORQUE CONSTANT N-cm/A 5.0
kgf-cm/A 0.51
BACK EMF CONSTANT V/krpm 5.2
PHASE RESISTANCE Ohm 1.18
PHASE INDUCTANCE mH 4.4
INSTANTANEOUS PEAK TORQUE N-cm 38.2
MAX SPEED rpm 5,000
ROTOR INERTIA g-cm
2
110
POWER RATE kW/s 1.48
MECHANICAL TIME CONSTANT ms 5.2
ELECTRICAL TIME CONSTANT ms 3.7
MASS kg 0.6