Using a 2nd IMU - Revision history

OlliW: /* IMU Configuration */

2015-06-20T01:02:10Z

IMU Configuration

← Older revision		Revision as of 03:02, 20 June 2015
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	The 2nd IMU support is determined by the parameter {{PARAMNAME\|Imu2 Configuration}} found in the {{GUI\|Setup}} tab. To activate the 2nd IMU, set it to		The 2nd IMU support is determined by the parameter {{PARAMNAME\|Imu2 Configuration}} found in the {{GUI\|Setup}} tab. To activate the 2nd IMU, set it to
	* {{PARAMVALUE\|~~gimbal support~~}}: activate 2nd IMU above the yaw motor		* {{PARAMVALUE\|full}}: activate 2nd IMU above the yaw motor
	* {{PARAMVALUE\|~~gimbal support~~ xy}}: activate 2nd IMU above the yaw motor, with the IMU rotated by 45°.		* {{PARAMVALUE\|full xy}}: activate 2nd IMU above the yaw motor, with the IMU rotated by 45°.

	== PID Tuning ==		== PID Tuning ==

OlliW: /* PID Tuning */

2015-01-15T10:03:58Z

PID Tuning

← Older revision		Revision as of 12:03, 15 January 2015
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	== PID Tuning ==		== PID Tuning ==

	The initial PID tuning~~, to get a well working gimbal,~~ should be done with the 2nd IMU deactivated.		The initial PID tuning should be done with the 2nd IMU deactivated.

	When the 2nd IMU is now activated, the pitch and yaw axis often work "out of the box", but on roll vibrations might occur at smaller roll angles than expected. The reasons are the imperfections in the gimbal, such as the balance, the motor quality or insufficiently stiff gimbal arms. With the 2nd IMU activated the controller is much faster and can compensate gimbal motions much better, as a view on the {{GUI\|DataDisplay}} impressively demonstrates. The downside is that imperfections get amplified. Especially the balance of the yaw axis and play in the motor bearings are typical culprits.		When the 2nd IMU is now activated, the pitch and yaw axis often work "out of the box", but on roll vibrations might occur at smaller roll angles than expected. The reasons are the imperfections in the gimbal, such as the balance, the motor quality or insufficiently stiff gimbal arms. With the 2nd IMU activated the controller is much faster and can compensate gimbal motions much better, as a view on the {{GUI\|DataDisplay}} impressively demonstrates. The downside is that imperfections get amplified. Especially the balance of the yaw axis and play in the motor bearings are typical culprits.

	If these points cannot be further improved, it can be very successful to down-tune the roll and yaw PID controllers, i.e., to reduce their values. You need to experiment. The control precision is then reduced, but since with 2nd IMU it is much higher anyhow it overall will be still better. Another point to try is to change the {{PARAMNAME\|Motor Vmax}} values by some digits.		If these points cannot be further improved, it can be very successful to down-tune the roll and yaw PID controllers, i.e., to reduce their values. You need to experiment. The control precision is then reduced, but since with 2nd IMU it is much higher anyhow it overall will be still better. Another point to try is to change the {{PARAMNAME\|Motor Vmax}} values by some digits.

	== Benefits of a 2nd IMU ==		== Benefits of a 2nd IMU ==

OlliW at 09:56, 15 January 2015

2015-01-15T09:56:15Z

← Older revision		Revision as of 11:56, 15 January 2015
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	== Installation Options ==		== Installation Options ==
	The ~~basic "~~rule" for installation is ~~simple~~:		The primary rule for installation is:

	The 2nd IMU must be mounted on the "gimbal support" above the yaw motor so it is not moved by any of the motors.		The 2nd IMU must be mounted on the gimbal support above the yaw motor so it is not moved by any of the motors.

	It must not be mounted on one of the gimbal axes or the camera platform.		It must not be mounted on one of the gimbal axes or the camera platform.
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	So you can either mount the controller board on the gimbal support using the on-board IMU as 2nd IMU, or put the controller board somewhere else (on the yaw axis for example) and mount an external IMU module above the yaw motor. These two options are shown as option (1) and (2) in the diagram below.		So you can either mount the controller board on the gimbal support using the on-board IMU as 2nd IMU, or put the controller board somewhere else (on the yaw axis for example) and mount an external IMU module above the yaw motor. These two options are shown as option (1) and (2) in the diagram below.

	The external IMU module ~~has to~~ be connected to the I2C#2 connector on the bottom side of the STorM32 board. Doing so automatically selects the external IMU module as 2nd IMU. If no IMU module is connected to I2C#2, the on-board IMU is selected. So you don't have to change anything in the GUI, the external IMU is used automatically when connected.		The external IMU module would be connected to the I2C#2 connector on the bottom side of the STorM32 board. Doing so automatically selects the external IMU module as 2nd IMU. If no IMU module is connected to I2C#2, the on-board IMU is selected. So you don't have to change anything in the GUI, the external IMU module is used automatically when connected.

	{{COMMENT\|The on-board mpu6050 IMU is connected to the I2C#2 connector internally and is set to a non default i2c address. If you connect an external IMU to the I2C#2 connector it can be recognized by its default i2c address and is selected. }}		{{COMMENT\|The on-board mpu6050 IMU is connected to the I2C#2 connector internally and is set to a non default i2c address. If you connect an external IMU to the I2C#2 connector it can be recognized by its default i2c address and is selected. }}
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	It is also very important to ensure that at startup the camera is aligned properly with respect to the gimbal support; it needs to point forward to within a degree or so.		It is also very important to ensure that at startup the camera is aligned properly with respect to the gimbal support; it needs to point forward to within a degree or so.

	This is most conveniently achieved by using the {{GUI\|Configure Gimbal Tool}}. Alternatively, the yaw axis orientation at startup may be adjusted manually by setting the {{PARAMNAME\|Yaw Startup Motor Pos}} parameter in the {{GUI\|Gimbal Configuration}} tab.		This is most conveniently achieved by using the {{GUI\|Configure Gimbal Tool}}, which in one step allows you to adjust the camera orientation. Alternatively, the yaw axis orientation at startup may be adjusted manually by setting the {{PARAMNAME\|Yaw Startup Motor Pos}} parameter in the {{GUI\|Gimbal Configuration}} tab.

	{{COMMENT\|It is '''not''' required to orient the camera precisely by hand '''before''' the controller is switched on. Here it is sufficient to have the camera aligned to within typically +-25° (for a 14 pole yaw motor). However, when the controller is powered up, it first moves the motors to default startup positions~~. After~~ this step, the camera must precisely point to the forward.}}		{{COMMENT\|It is '''not''' required to orient the camera precisely by hand '''before''' the controller is switched on. Here it is sufficient to have the camera aligned to within typically +-25° (for a 14 pole yaw motor). However, when the controller is powered up, it first moves the motors to default startup positions, and after this step the camera must precisely point to the forward.}}

	== IMU Configuration ==		== IMU Configuration ==
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	The initial PID tuning, to get a well working gimbal, should be done with the 2nd IMU deactivated.		The initial PID tuning, to get a well working gimbal, should be done with the 2nd IMU deactivated.

	When the 2nd IMU is now activated, the pitch and yaw axis often work ~~just~~ "out of the box", but on roll vibrations might occur at smaller roll angles than expected. The reasons are the imperfections in the gimbal, such as the balance, the motor quality or ~~that the~~ arms ~~are not sufficiently stiff~~. With the 2nd IMU activated the controller is much faster and can compensate gimbal motions much better, as a view on the {{GUI\|DataDisplay}} ~~will~~ impressively ~~demonstrate~~. The downside is that imperfections get amplified. Especially the balance of the yaw axis and play in the motor bearings are typical culprits.		When the 2nd IMU is now activated, the pitch and yaw axis often work "out of the box", but on roll vibrations might occur at smaller roll angles than expected. The reasons are the imperfections in the gimbal, such as the balance, the motor quality or insufficiently stiff gimbal arms. With the 2nd IMU activated the controller is much faster and can compensate gimbal motions much better, as a view on the {{GUI\|DataDisplay}} impressively demonstrates. The downside is that imperfections get amplified. Especially the balance of the yaw axis and play in the motor bearings are typical culprits.

	If these points cannot be further improved, it ~~also~~ can be very successful to down-tune the roll and yaw PID controllers, i.e., to reduce their values. You need to experiment. The control precision is then ~~of course~~ reduced, but since it is much higher ~~with the 2nd IMU~~ anyhow it overall will be still better. Another point to try is to change the {{PARAMNAME\|Motor Vmax}} values by some digits.		If these points cannot be further improved, it can be very successful to down-tune the roll and yaw PID controllers, i.e., to reduce their values. You need to experiment. The control precision is then reduced, but since with 2nd IMU it is much higher anyhow it overall will be still better. Another point to try is to change the {{PARAMNAME\|Motor Vmax}} values by some digits.

	~~{{COMMENT\|Please take the advices in this chapter seriously, they condense quite some truth.}}~~

	== Benefits of a 2nd IMU ==		== Benefits of a 2nd IMU ==

OlliW at 09:11, 15 January 2015

2015-01-15T09:11:45Z

OlliW: /* PID Tuning */

2015-01-14T19:45:42Z

PID Tuning

← Older revision		Revision as of 21:45, 14 January 2015
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	The initial PID tuning, to get a well working gimbal, should be done with the 2nd IMU deactivated.		The initial PID tuning, to get a well working gimbal, should be done with the 2nd IMU deactivated.

	When the 2nd IMU is now activated, the pitch and yaw axis often work just "out of the box", but on roll vibrations might occur at smaller roll angles than expected. The reasons are the imperfections in the gimbal, such as the balance or that the arms are not sufficiently stiff. With the 2nd IMU activated the controller is much faster and can compensate gimbal motions much better, as a view on the {{GUI\|DataDisplay}} will impressively demonstrate. The downside is that imperfections get amplified. Especially the balance of the yaw axis and play in the motor bearings are typical culprits.		When the 2nd IMU is now activated, the pitch and yaw axis often work just "out of the box", but on roll vibrations might occur at smaller roll angles than expected. The reasons are the imperfections in the gimbal, such as the balance, the motor quality or that the arms are not sufficiently stiff. With the 2nd IMU activated the controller is much faster and can compensate gimbal motions much better, as a view on the {{GUI\|DataDisplay}} will impressively demonstrate. The downside is that imperfections get amplified. Especially the balance of the yaw axis and play in the motor bearings are typical culprits.

	If these points cannot be further improved, it also can be very successful to down-tune the roll and yaw PID controllers, i.e., to reduce their values. You need to experiment. The control precision is then of course reduced, but since it is much higher with the 2nd IMU anyhow it overall will be still better. Another point to try is to change the {{PARAMNAME\|Motor Vmax}} values by some digits.		If these points cannot be further improved, it also can be very successful to down-tune the roll and yaw PID controllers, i.e., to reduce their values. You need to experiment. The control precision is then of course reduced, but since it is much higher with the 2nd IMU anyhow it overall will be still better. Another point to try is to change the {{PARAMNAME\|Motor Vmax}} values by some digits.

OlliW at 19:44, 14 January 2015

2015-01-14T19:44:15Z

← Older revision		Revision as of 21:44, 14 January 2015
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	== IMU Orientation ==		== IMU Orientation ==

	For a correct functioning it is ~~extremely~~ important to set the IMU orientation correctly, i.e., the parameter field {{PARAMNAME\|Imu2 Orientation}} in the {{GUI\|Gimbal Configuration}} tab.		For a correct functioning it is very important to set the IMU orientation correctly, i.e., the parameter field {{PARAMNAME\|Imu2 Orientation}} in the {{GUI\|Gimbal Configuration}} tab.

	This is most conveniently achieved by using the {{GUI\|Configure Gimbal Tool}}. Alternatively, it may be set manually following the recipe described in [[Manually Setting the IMU Orientation]].		This is most conveniently achieved by using the {{GUI\|Configure Gimbal Tool}}. Alternatively, it may be set manually following the recipe described in [[Manually Setting the IMU Orientation]].

			== Yaw Axis Alignment ==

			It is also very important to ensure that at startup the camera is aligned properly with respect to the gimbal support: It has to point forward at startup to within a few degrees.

			This is most conveniently achieved by using the {{GUI\|Configure Gimbal Tool}}. Alternatively, the yaw axis orientation at startup may be adjusted manually by setting the {{PARAMNAME\|Yaw Startup Motor Pos}} parameter in the {{GUI\|Gimbal Configuration}} tab.

	== IMU Configuration ==		== IMU Configuration ==

OlliW: /* PID Tuning */

2015-01-10T14:06:10Z

PID Tuning

← Older revision		Revision as of 16:06, 10 January 2015
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	The initial PID tuning, to get a well working gimbal, should be done with the 2nd IMU deactivated.		The initial PID tuning, to get a well working gimbal, should be done with the 2nd IMU deactivated.

	When the 2nd IMU is now activated, the pitch and yaw axis often work just "out of the box", but on roll vibrations might occur at smaller roll angles than expected. The reasons ~~for this~~ are the imperfections in the gimbal, such as the balance or that the ~~roll and yaw~~ arms are not sufficiently stiff. With the 2nd IMU activated the controller ~~gets~~ much faster and ~~is able to~~ compensate gimbal motions much better, as a view on the {{GUI\|DataDisplay}} will impressively demonstrate. The downside is that imperfections get amplified. Especially the balance of the yaw axis and play in the motor bearings are typical culprits.		When the 2nd IMU is now activated, the pitch and yaw axis often work just "out of the box", but on roll vibrations might occur at smaller roll angles than expected. The reasons are the imperfections in the gimbal, such as the balance or that the arms are not sufficiently stiff. With the 2nd IMU activated the controller is much faster and can compensate gimbal motions much better, as a view on the {{GUI\|DataDisplay}} will impressively demonstrate. The downside is that imperfections get amplified. Especially the balance of the yaw axis and play in the motor bearings are typical culprits.

	If these points cannot be further improved, it also can be very successful to down-tune the roll and yaw PID controllers, i.e., to reduce their values. The control precision is then of course reduced, but since it is much higher with the 2nd IMU anyhow it overall will be still better. Another point to try is to change the {{PARAMNAME\|Motor Vmax}} values.		If these points cannot be further improved, it also can be very successful to down-tune the roll and yaw PID controllers, i.e., to reduce their values. You need to experiment. The control precision is then of course reduced, but since it is much higher with the 2nd IMU anyhow it overall will be still better. Another point to try is to change the {{PARAMNAME\|Motor Vmax}} values by some digits.

	{{COMMENT\|Please take the advices in this chapter seriously, they condense quite some truth.}}		{{COMMENT\|Please take the advices in this chapter seriously, they condense quite some truth.}}

	== Benefits of a 2nd IMU ==		== Benefits of a 2nd IMU ==

OlliW at 14:03, 10 January 2015

2015-01-10T14:03:05Z

@@ Line 37: / Line 37: @@
 * {{PARAMVALUE|gimbal support}}: activate 2nd IMU above the yaw motor
 * {{PARAMVALUE|gimbal support xy}}: activate 2nd IMU above the yaw motor, with the IMU rotated by 45°.
 == Benefits of a 2nd IMU ==

OlliW at 12:25, 9 January 2015

2015-01-09T12:25:18Z

← Older revision		Revision as of 14:25, 9 January 2015
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	It must not be mounted on one of the gimbal axes or the camera platform.		It must not be mounted on one of the gimbal axes or the camera platform.

	So you can either mount the controller mainboard on the gimbal support using the ~~onboard~~ IMU as 2nd IMU, or put the mainboard somewhere else (on the yaw axis for example) and mount an external IMU module above the yaw motor. These two options are shown as option (1) and (2) in the diagram below.		So you can either mount the controller mainboard on the gimbal support using the on-board IMU as 2nd IMU, or put the mainboard somewhere else (on the yaw axis for example) and mount an external IMU module above the yaw motor. These two options are shown as option (1) and (2) in the diagram below.

	The external IMU module has to be connected to the I2C#2 connector on the bottom side of the STorM32 board. Doing so automatically selects the external IMU module as 2nd IMU. If no IMU module is connected to I2C#2, the ~~onboard~~ IMU is selected. So you don't have to change anything in the GUI, the external IMU is used automatically when connected.		The external IMU module has to be connected to the I2C#2 connector on the bottom side of the STorM32 board. Doing so automatically selects the external IMU module as 2nd IMU. If no IMU module is connected to I2C#2, the on-board IMU is selected. So you don't have to change anything in the GUI, the external IMU is used automatically when connected.

	{{COMMENT\|The ~~onboard~~ mpu6050 IMU is connected to the I2C#2 connector internally and is set to a non default i2c address. If you connect an external IMU to the I2C#2 connector it can be recognized by its default i2c address and is selected. }}		{{COMMENT\|The on-board mpu6050 IMU is connected to the I2C#2 connector internally and is set to a non default i2c address. If you connect an external IMU to the I2C#2 connector it can be recognized by its default i2c address and is selected. }}

	{{COMMENT\|The configuration (3) in the diagram is NOT supported by the STorM32 firmware, as by principle it provides only very limited benefits}}.		{{COMMENT\|The configuration (3) in the diagram is NOT supported by the STorM32 firmware, as by principle it provides only very limited benefits}}.
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	== Calibration ==		== Calibration ==

	As with the camera IMU, also the 2nd IMU, be it the ~~onboard~~ IMU or an external IMU module, needs to be calibrated for optimal performance.		As with the camera IMU, also the 2nd IMU, be it the on-board IMU or an external IMU module, needs to be calibrated for optimal performance.

	However, fortunately, for the 2nd IMU it's not critical to get the most accurate calibration, and a good 1-point calibration should be enough for most situations. Exceptions are then motors with high motor pole counts, larger than 14, are used.		However, fortunately, for the 2nd IMU it's not critical to get the most accurate calibration, and a good 1-point calibration should be enough for most situations. Exceptions are then motors with high motor pole counts, larger than 14, are used.

OlliW at 12:22, 9 January 2015

2015-01-09T12:22:55Z

← Older revision		Revision as of 14:22, 9 January 2015
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	The external IMU module has to be connected to the I2C#2 connector on the bottom side of the STorM32 board. Doing so automatically selects the external IMU module as 2nd IMU. If no IMU module is connected to I2C#2, the onboard IMU is selected. So you don't have to change anything in the GUI, the external IMU is used automatically when connected.		The external IMU module has to be connected to the I2C#2 connector on the bottom side of the STorM32 board. Doing so automatically selects the external IMU module as 2nd IMU. If no IMU module is connected to I2C#2, the onboard IMU is selected. So you don't have to change anything in the GUI, the external IMU is used automatically when connected.

	{{COMMENT\|The onboard mpu6050 IMU is connected to the I2C#2 connector internally and is set to a non default i2c ~~adress~~. If you connect an external IMU to the I2C#2 connector it can be ~~recognised~~ by its default i2c ~~adress~~ and is selected. }}		{{COMMENT\|The onboard mpu6050 IMU is connected to the I2C#2 connector internally and is set to a non default i2c address. If you connect an external IMU to the I2C#2 connector it can be recognized by its default i2c address and is selected. }}

	{{COMMENT\|The configuration (3) in the diagram is NOT supported by the STorM32 firmware, as by principle it provides only very limited benefits}}.		{{COMMENT\|The configuration (3) in the diagram is NOT supported by the STorM32 firmware, as by principle it provides only very limited benefits}}.
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	== IMU Orientation ==		== IMU Orientation ==

	For a correct functioning it is extremely important to set the IMU orientation correctly, i.e., the parameter field {{PARAMNAME\|Imu2 ~~Orientaion~~}} in the {{GUI\|Gimbal Configuration}} tab.		For a correct functioning it is extremely important to set the IMU orientation correctly, i.e., the parameter field {{PARAMNAME\|Imu2 Orientation}} in the {{GUI\|Gimbal Configuration}} tab.

	This is most conveniently achieved by using the {{GUI\|Configure Gimbal Tool}}. Alternatively, it may be set manually following the recipe described in [[Manually Setting the IMU Orientation]].		This is most conveniently achieved by using the {{GUI\|Configure Gimbal Tool}}. Alternatively, it may be set manually following the recipe described in [[Manually Setting the IMU Orientation]].

← Older revision		Revision as of 11:11, 15 January 2015
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	The STorM32 controller allows the use of a 2nd IMU, in addition to the camera IMU mounted to the camera platform, for superior performance. It's usage and advantages are described here.		The STorM32 controller allows the use of a second IMU (2nd IMU), in addition to the camera IMU mounted to the camera platform, for superior performance. It's usage and advantages are described here.

	== Installation Options ==		== Installation Options ==
	The basic "rule" for installation is simple:		The basic "rule" for installation is simple:

	The ~~second~~ IMU must be mounted on the "gimbal support" above the yaw motor so it is not moved by any of the motors.		The 2nd IMU must be mounted on the "gimbal support" above the yaw motor so it is not moved by any of the motors.

	It must not be mounted on one of the gimbal axes or the camera platform.		It must not be mounted on one of the gimbal axes or the camera platform.

	So you can either mount the controller ~~mainboard~~ on the gimbal support using the on-board IMU as 2nd IMU, or put the ~~mainboard~~ somewhere else (on the yaw axis for example) and mount an external IMU module above the yaw motor. These two options are shown as option (1) and (2) in the diagram below.		So you can either mount the controller board on the gimbal support using the on-board IMU as 2nd IMU, or put the controller board somewhere else (on the yaw axis for example) and mount an external IMU module above the yaw motor. These two options are shown as option (1) and (2) in the diagram below.

	The external IMU module has to be connected to the I2C#2 connector on the bottom side of the STorM32 board. Doing so automatically selects the external IMU module as 2nd IMU. If no IMU module is connected to I2C#2, the on-board IMU is selected. So you don't have to change anything in the GUI, the external IMU is used automatically when connected.		The external IMU module has to be connected to the I2C#2 connector on the bottom side of the STorM32 board. Doing so automatically selects the external IMU module as 2nd IMU. If no IMU module is connected to I2C#2, the on-board IMU is selected. So you don't have to change anything in the GUI, the external IMU is used automatically when connected.
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	== Yaw Axis Alignment ==		== Yaw Axis Alignment ==

	It is also very important to ensure that at startup the camera is aligned properly with respect to the gimbal support~~: It has~~ to point forward ~~at startup~~ to within a ~~few degrees~~.		It is also very important to ensure that at startup the camera is aligned properly with respect to the gimbal support; it needs to point forward to within a degree or so.

	This is most conveniently achieved by using the {{GUI\|Configure Gimbal Tool}}. Alternatively, the yaw axis orientation at startup may be adjusted manually by setting the {{PARAMNAME\|Yaw Startup Motor Pos}} parameter in the {{GUI\|Gimbal Configuration}} tab.		This is most conveniently achieved by using the {{GUI\|Configure Gimbal Tool}}. Alternatively, the yaw axis orientation at startup may be adjusted manually by setting the {{PARAMNAME\|Yaw Startup Motor Pos}} parameter in the {{GUI\|Gimbal Configuration}} tab.

			{{COMMENT\|It is '''not''' required to orient the camera precisely by hand '''before''' the controller is switched on. Here it is sufficient to have the camera aligned to within typically +-25° (for a 14 pole yaw motor). However, when the controller is powered up, it first moves the motors to default startup positions. After this step, the camera must precisely point to the forward.}}

	== IMU Configuration ==		== IMU Configuration ==

	The 2nd IMU support is ~~activated via~~ the parameter {{PARAMNAME\|Imu2 Configuration}} found in the {{GUI\|Setup}} tab. To activate the 2nd IMU, set it to		The 2nd IMU support is determined by the parameter {{PARAMNAME\|Imu2 Configuration}} found in the {{GUI\|Setup}} tab. To activate the 2nd IMU, set it to
	* {{PARAMVALUE\|gimbal support}}: activate 2nd IMU above the yaw motor		* {{PARAMVALUE\|gimbal support}}: activate 2nd IMU above the yaw motor
	* {{PARAMVALUE\|gimbal support xy}}: activate 2nd IMU above the yaw motor, with the IMU rotated by 45°.		* {{PARAMVALUE\|gimbal support xy}}: activate 2nd IMU above the yaw motor, with the IMU rotated by 45°.