Implementation of a simple reducer transmission. More...

#include <simple_transmission.h>

Inheritance diagram for transmission_interface::SimpleTransmission:

Public Member Functions
void	actuatorToJointEffort (const ActuatorData &act_data, JointData &jnt_data)
	Transform effort variables from actuator to joint space. More...

void	actuatorToJointPosition (const ActuatorData &act_data, JointData &jnt_data)
	Transform position variables from actuator to joint space. More...

void	actuatorToJointVelocity (const ActuatorData &act_data, JointData &jnt_data)
	Transform velocity variables from actuator to joint space. More...

double	getActuatorReduction () const

double	getJointOffset () const

void	jointToActuatorEffort (const JointData &jnt_data, ActuatorData &act_data)
	Transform effort variables from joint to actuator space. More...

void	jointToActuatorPosition (const JointData &jnt_data, ActuatorData &act_data)
	Transform position variables from joint to actuator space. More...

void	jointToActuatorVelocity (const JointData &jnt_data, ActuatorData &act_data)
	Transform velocity variables from joint to actuator space. More...

std::size_t	numActuators () const

std::size_t	numJoints () const

	SimpleTransmission (const double reduction, const double joint_offset=0.0)

Public Member Functions inherited from transmission_interface::Transmission
virtual	~Transmission ()

Private Attributes
double	jnt_offset_

double	reduction_

Detailed Description

Implementation of a simple reducer transmission.

This transmission relates one actuator and one joint through a reductor (or amplifier). Timing belts and gears are examples of this transmission type, and are illustrated below.

	Effort	Velocity	Position
Actuator to joint	$\tau_j = n \tau_a$	$\dot{x}_j = \dot{x}_a / n$	$x_j = x_a / n + x_{off}$
Joint to actuator	$\tau_a = \tau_j / n$	$\dot{x}_a = n \dot{x}_j$	$x_a = n (x_j - x_{off})$

where:

, $\dot{x}$ and $\tau$ are position, velocity and effort variables, respectively.
Subindices and are used to represent actuator-space and joint-space variables, respectively.
$x_{off}$ represents the offset between motor and joint zeros, expressed in joint position coordinates.
is the transmission ratio, and can be computed as the ratio between the output and input pulley radii for the timing belt; or the ratio between output and input teeth for the gear system. The transmission ratio can take any real value except zero. In particular:
- If its absolute value is greater than one, it's a velocity reducer / effort amplifier, while if its absolute value lies in it's a velocity amplifier / effort reducer.
- Negative values represent a direction flip, ie. actuator and joint move in opposite directions. For example, in timing belts actuator and joint move in the same direction, while in single-stage gear systems actuator and joint move in opposite directions.

Definition at line 95 of file simple_transmission.h.

Constructor & Destructor Documentation

transmission_interface::SimpleTransmission::SimpleTransmission	(	const double	reduction,
		const double	joint_offset = `0.0`
	)

inline

Parameters

reduction	Reduction ratio.
joint_offset	Joint position offset used in the position mappings.

Precondition: Nonzero reduction value.

Definition at line 177 of file simple_transmission.h.

Member Function Documentation

void transmission_interface::SimpleTransmission::actuatorToJointEffort	(	const ActuatorData &	act_data,
		JointData &	jnt_data
	)

inlinevirtual

Transform effort variables from actuator to joint space.

Parameters

[in]	act_data	Actuator-space variables.
[out]	jnt_data	Joint-space variables.

Precondition: Actuator and joint effort vectors must have size 1 and point to valid data. To call this method it is not required that all other data vectors contain valid data, and can even remain empty.

Implements transmission_interface::Transmission.

Definition at line 189 of file simple_transmission.h.

void transmission_interface::SimpleTransmission::actuatorToJointPosition	(	const ActuatorData &	act_data,
		JointData &	jnt_data
	)

inlinevirtual

Transform position variables from actuator to joint space.

Parameters

[in]	act_data	Actuator-space variables.
[out]	jnt_data	Joint-space variables.

Precondition: Actuator and joint position vectors must have size 1 and point to valid data. To call this method it is not required that all other data vectors contain valid data, and can even remain empty.

Implements transmission_interface::Transmission.

Definition at line 207 of file simple_transmission.h.

void transmission_interface::SimpleTransmission::actuatorToJointVelocity	(	const ActuatorData &	act_data,
		JointData &	jnt_data
	)

inlinevirtual

Transform velocity variables from actuator to joint space.

Parameters

[in]	act_data	Actuator-space variables.
[out]	jnt_data	Joint-space variables.

Precondition: Actuator and joint velocity vectors must have size 1 and point to valid data. To call this method it is not required that all other data vectors contain valid data, and can even remain empty.

Implements transmission_interface::Transmission.

Definition at line 198 of file simple_transmission.h.

double transmission_interface::SimpleTransmission::getActuatorReduction ( ) const

inline

Definition at line 169 of file simple_transmission.h.

double transmission_interface::SimpleTransmission::getJointOffset ( ) const

inline

Definition at line 170 of file simple_transmission.h.

void transmission_interface::SimpleTransmission::jointToActuatorEffort	(	const JointData &	jnt_data,
		ActuatorData &	act_data
	)

inlinevirtual

Transform effort variables from joint to actuator space.

Parameters

[in]	jnt_data	Joint-space variables.
[out]	act_data	Actuator-space variables.

Precondition: Actuator and joint effort vectors must have size 1 and point to valid data. To call this method it is not required that all other data vectors contain valid data, and can even remain empty.

Implements transmission_interface::Transmission.

Definition at line 216 of file simple_transmission.h.

void transmission_interface::SimpleTransmission::jointToActuatorPosition	(	const JointData &	jnt_data,
		ActuatorData &	act_data
	)

inlinevirtual

Transform position variables from joint to actuator space.

Parameters

[in]	jnt_data	Joint-space variables.
[out]	act_data	Actuator-space variables.

Precondition: Actuator and joint position vectors must have size 1 and point to valid data. To call this method it is not required that all other data vectors contain valid data, and can even remain empty.

Implements transmission_interface::Transmission.

Definition at line 234 of file simple_transmission.h.

void transmission_interface::SimpleTransmission::jointToActuatorVelocity	(	const JointData &	jnt_data,
		ActuatorData &	act_data
	)

inlinevirtual

Transform velocity variables from joint to actuator space.

Parameters

[in]	jnt_data	Joint-space variables.
[out]	act_data	Actuator-space variables.

Precondition: Actuator and joint velocity vectors must have size 1 and point to valid data. To call this method it is not required that all other data vectors contain valid data, and can even remain empty.

Implements transmission_interface::Transmission.

Definition at line 225 of file simple_transmission.h.

std::size_t transmission_interface::SimpleTransmission::numActuators ( ) const

inlinevirtual

Returns: Number of actuators managed by transmission, ie. the dimension of the actuator space.

Implements transmission_interface::Transmission.

Definition at line 166 of file simple_transmission.h.

std::size_t transmission_interface::SimpleTransmission::numJoints ( ) const

inlinevirtual

Returns: Number of joints managed by transmission, ie. the dimension of the joint space.

Implements transmission_interface::Transmission.

Definition at line 167 of file simple_transmission.h.

Member Data Documentation

double transmission_interface::SimpleTransmission::jnt_offset_

private

Definition at line 174 of file simple_transmission.h.

double transmission_interface::SimpleTransmission::reduction_

private

Definition at line 173 of file simple_transmission.h.

The documentation for this class was generated from the following file:

simple_transmission.h

Public Member Functions

Private Attributes

Detailed Description

Constructor & Destructor Documentation

Member Function Documentation

Member Data Documentation