Trajectory planner - Revision history

Tero K at 11:47, 9 February 2017

2017-02-09T11:47:46Z

Tero K: /* Operation */

2017-02-08T18:52:56Z

‎Operation

Tero K: /* When to use */

2017-02-08T18:52:17Z

‎When to use

Tero K: /* When to use */

2017-02-08T18:51:04Z

‎When to use

Tero K: /* When to use */

2017-02-08T18:50:40Z

‎When to use

Tero K: /* When to use */

2017-02-08T18:49:40Z

‎When to use

Tero K at 18:32, 8 February 2017

2017-02-08T18:32:01Z

Tero K: Created page with "Trajectory planner in GD drives is an internal function to produce smooth acceleration and velocity trajectories based on user input, that may be just a rapid setpoint val..."

2017-02-08T18:30:39Z

Created page with "Trajectory planner in GD drives is an internal function to produce smooth acceleration and velocity trajectories based on user input, that may be just a rapid setpoint val..."

New page

Trajectory planner in GD drives is an internal function to produce smooth acceleration and velocity trajectories based on user input, that may be just a rapid [[setpoint]] value change. The main purpose of trajectory planner is to allow creating simple point-to-point motion with minimal complexity from the [[controller]].

==Operation==
Trajectory planner has two main parameters which define the motion profile limits:
*{{param|CVL}}
*{{param|CAL}}

Following example illustrates a case where user setpoint changes instantly, and causes trajectory planner to generate acceleration & velocity limited motion.
{{picturebox|Trajectory planner.svg|caption=Signal change inside Trajectory planner}}

Trajectory planner has no limit of how often setpoint may be changed. It is possible to give new setpoint even when motion has not reached it's target position, and output motion still follows the given speed limits.

==Application==
===When to use===
Trajectory planner is mostly used in following cases:
*Point-to-point positon control
*Velocity control (such as spindle)
*Velocity limiting for safety reasons on all position & velocity control mode applications
===When to avoid===
As trajectory planner causes limited rate of change, it is not desirable in applications that demand high bandwidth position or velocity control such as:
*[[Dual-loop feedback position control]], or any system where setpoint of drive is output of another closed loop system
*Systems where external motion controller takes care of acceleration limit calculation and trajectory generation

To prevent trajectory planner from distorting or causing lag in such systems, it can be effectively disabled by setting {{param|CAL}} to maximum value. Velocity limit may be still used for safety reasons as it will not alter the signal unless setpoint velocity exceeds the {{param|CVL}} limit.

==See also==
*[[Signal path of motor drive]]

[[Category:Glossary]]

← Older revision		Revision as of 11:47, 9 February 2017
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	To prevent trajectory planner from distorting or causing lag in such systems, it can be effectively disabled by setting {{param\|CAL}} to maximum value. Velocity limit may be still used for safety reasons as it will not alter the signal unless setpoint velocity exceeds the {{param\|CVL}} limit.		To prevent trajectory planner from distorting or causing lag in such systems, it can be effectively disabled by setting {{param\|CAL}} to maximum value. Velocity limit may be still used for safety reasons as it will not alter the signal unless setpoint velocity exceeds the {{param\|CVL}} limit.
		+
		+	== Extending CAL and CVL parameter range ==
		+	Especially when using high resolution feedback devices, one may hit the maximum settable range of CAL and CVL parameters.
		+
		+	Due to [[Signal path of motor drive\|the structure of signal path of drive]], effective scale of these parameters depend on parameter {{Param\|DIV}}. In other words, adjusting DIV will give different sensitivity to velocity and acceleration limits.
		+
		+	To extend range, use smaller DIV value. It's worth noting that if one adjusts only DIV, then setpoint scaling changes unless also {{Param\|MUL}} is adusted proportionally.
		+
		+	{{Info\|Example: default MUL & DIV values are 50 and 50. In order to increase acceleration and velocity range by 10 times, set MUL & DIV to 5 & 5.}}

	==See also==		==See also==

@@ Line 14: / Line 14: @@
 ===When to use===
 Trajectory planner is mostly used in following cases:
-*Point-to-point positon control (controller gives just target position and let's drive to perform the motion)
+*Point-to-point positon control (controller gives just target position and let drive to perform the motion)
 *Simple velocity control tasks (such as spindle)
 *Velocity limiting for safety reasons on all position & velocity control mode applications

← Older revision		Revision as of 18:32, 8 February 2017
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	*[[Signal path of motor drive]]		*[[Signal path of motor drive]]

		+	[[Category:Downloads]]
	[[Category:Glossary]]		[[Category:Glossary]]

@@ Line 7: / Line 7: @@
 Following example illustrates a case where user setpoint changes instantly, and causes trajectory planner to generate acceleration & velocity limited motion.
-{{picturebox|Trajectory planner.svg|caption=Signal change inside Trajectory planner}}
+{{picturebox|Trajectory planner.svg|caption=Signal change inside Trajectory planner during typical point-to-point operation}}
 Trajectory planner has no limit of how often setpoint may be changed. It is possible to give new setpoint even when motion has not reached it's target position, and output motion still follows the given speed limits.