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HA0276T Rev Bk Jan 2017
Chapter 7
Backlash
Distance
- The system compensates for lead screw backlash during reverse direction
moves, by moving passed the demanded position by a specified amount, and then
reversing. This ensures that positions are always approached in a forward direction.
The Backlash Distance is specified in real world units (millimeters or degrees). To
remove backlash correction, this value should be set to zero.
Velocity Profile Settings
To prevent the motor from stalling, it must be ramped up gradually to its maximum
velocity. Certain limits to velocity and acceleration result from the torque and speed
limits of the motor, and the inertia and friction of the parts it drives.
The system incorporates a trajectory generator, which performs calculations to
determine the instantaneous position, velocity and acceleration of each axis at any
given moment. During a motion profile, these values will change continuously. Once
the move is complete, these parameters will then remain unchanged until the next
move begins.
The specific move profile created by the system depends on several factors, such as
the profile mode and profile parameters presently selected, and other conditions such
as whether a motion stop has been requested.
Profile
– This field is used to set the profile mode to either Trapezoidal or S-curve. In
either case, the velocity and acceleration of the profile are specified using the
Velocity
Profile
parameters on the
Moves/Jogs tab.
The
Trapezoidal
profile is a standard, symmetrical acceleration/deceleration motion
curve, in which the start velocity is always zero.
In a typical trapezoidal velocity profile, (see Fig. 7.4.), the stage is ramped at
acceleration ‘
a’
to a maximum velocity ‘
v’
. As the destination is approached, the stage
is decelerated at ‘
a’
so that the final position is approached slowly in a controlled
manner
.
Fig. 7.4 Graph of a trapezoidal velocity profile
The
S-curve
profile is a trapezoidal curve with an additional '
Bow Value
' parameter,
which limits the rate of change of acceleration and smooths out the contours of the
velocity
maximum
velocity (v)
time
acceleration (slope) a
Summary of Contents for Kinesis MLJ050
Page 1: ...MLJ050 Motorized Lab Jack Kinesis User Guide Original Instructions ...
Page 42: ...42 D 3 CE Certificate ...
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