CANopen Programmer's Manual - Maccon.de

CANopen Programmer’s Manual 7: Profile Position, Velocity, and Torque Mode Operation
7.1: Profile Position Mode Operation
Point-to-Point Motion Profiles
In profile position mode, an amplifier receives set points from the trajectory generator to define a
target position and moves the axis to that position at a specified velocity and acceleration. This is
known as a point-to-point move.
The amplifier performs profile position moves in Profile Position Mode (Mode Of Operation [index
0x6060, p. 64] =1).
Jerk
In a point-to-point move, the rate of change in acceleration is known as jerk. In some applications,
high rates of jerk can cause excessive mechanical wear or material damage.
Trapezoidal and S-curve Motion Profiles
To support varying levels of jerk tolerance, the profile position mode supports two motion profiles:
the trapezoidal profile, which has unlimited jerk, and the jerk-limited S-curve (sinusoidal) profile.
Velocity
Trapezoidal S-Curve
Time
Target Velocity (Run Speed)
Deceleration Rate
Acceleration Rate
Velocity
In a trapezoidal profile, jerk is unlimited at the corners of the profile (start of the move, when the
target velocity is reached, when deceleration begins, and at the end of the move). S-curve profiling
limits jerk or “smooths” the motion.
Note that an S-curve profile move does not support an independent deceleration rate. Instead, the
acceleration rate is applied to both the acceleration and deceleration of the move. Further,
trapezoidal and profile position special velocity mode profiles support changing of the parameters
of the current move, whereas an S-curve profile does not. This difference is discussed in Handling
a Series of Point-to-Point Moves, p. 192.
The Motion Profile Type object (index 0x6086, p. 205) controls which type of profile is used.
For guidance in choosing a trapezoidal or S-curve profile, read the following sections and then
refer to Trapezoidal vs. S-Curve Profile: Some Design Considerations, p. 198.
(Copley Controls CANopen amplifiers also support a profile position special velocity mode. This
profile type resembles the trapezoidal profile, but with no target position specified. The motion
obeys the acceleration, deceleration, and velocity limits, but continues to move as though the
target position were infinite.)
Relative vs. Absolute Moves
In a relative move, the target position is added to the instantaneous commanded position, and the
result is the destination of the move. In an absolute move, the target position is offset from the
home position.
Copley Controls 191
Time