Generic base class for gripper control implementations. More...

#include <mBaseGripper.h>

Inheritance diagram for bioscara_hardware_drivers::BaseGripper:

Public Member Functions
	BaseGripper (float reduction, float offset, float min, float max, float backup_init_pos)
	Construct a new BaseGripper object.

	~BaseGripper (void)
	Destroy the BaseGripper object.

virtual err_type_t	init (void)
	Initializes the gripper.

virtual err_type_t	deinit (void)
	Deinitializes the gripper.

virtual err_type_t	enable (void)
	Enables the gripper.

virtual err_type_t	disable (void)
	Disables the gripper.

virtual err_type_t	setPosition (float width)
	Sets the gripper width in m.

virtual err_type_t	getPosition (float &width)
	Gets the gripper width.

virtual void	setReduction (float reduction)
	Manually set reduction.

virtual void	setOffset (float offset)
	Manually set offset.

Protected Member Functions
err_type_t	save_last_position (float pos)
	Stores the latest position to the buffer file.

err_type_t	retrieve_last_position (float &pos)
	Retrieves the stored position from the buffer file.

Protected Attributes
float	_reduction = 1
	gripper width to actuator reduction ratio

float	_offset = 0
	gripper width position offset

float	_min = 0
	gripper width lower limit

float	_max = 0
	gripper width upper limit

float	_backup_init_pos = 0.0
	Initial position assumed if none can be retrieved from the buffer file.

float	_pos = _backup_init_pos
	stored position

float	_pos_get = _pos
	reported position

Private Attributes
std::chrono::_V2::system_clock::time_point	_new_cmd_time = std::chrono::_V2::system_clock::time_point()

Detailed Description

Generic base class for gripper control implementations.

This class is a wrapper function to interact with the robot gripper either through a MockGripper or hardware Gripper object.

Constructor & Destructor Documentation

◆ BaseGripper()

bioscara_hardware_drivers::BaseGripper::BaseGripper	(	float	reduction,
		float	offset,
		float	min,
		float	max,
		float	backup_init_pos
	)

Construct a new BaseGripper object.

The gripper has the reduction and offset parameters which are used to translate from a desired gripper width to the servo angle. The relationship between gripper width and acutator angle $\alpha$ is as follows:

$\alpha = r (w-o)$

To determine these parameters execute the following steps:

Manually set the gripper to an open position by setting a actuator angle. Be carefull to not exceed the physical limits of the gripper since the actuator is strong enough to break PLA before stalling.
Measure the gripper width and note the set actuator angle $\alpha_1$ .
Move the gripper to a more closed position that still allows you to accurately measure the width
Measure the second width and note the corresponding angle $\alpha_2$
Calculate the offset :
$o = \frac{\alpha_1 w_2 - \alpha_2 w_1}{\alpha_1 - \alpha_2}$
Calculate the reduction :
$r = \frac{\alpha_1}{w_1 - o}$

Parameters

reduction	the gripper width to actuator reduction ratio
offset	gripper width to actuator zero offset
min	lower limit in m
max	upper limit in m
backup_init_pos	initial position assumed if none can be retrieved from the buffer file

◆ ~BaseGripper()

bioscara_hardware_drivers::BaseGripper::~BaseGripper ( void )

Destroy the BaseGripper object.

invokes the disable() and deinit() method to clean up.

Member Function Documentation

◆ deinit()

err_type_t bioscara_hardware_drivers::BaseGripper::deinit ( void )

virtual

Deinitializes the gripper.

Returns: err_type_t::OK

◆ disable()

err_type_t bioscara_hardware_drivers::BaseGripper::disable ( void )

virtual

Disables the gripper.

As described in enable()

Returns: err_type_t::OK

Reimplemented in bioscara_hardware_drivers::Gripper.

◆ enable()

err_type_t bioscara_hardware_drivers::BaseGripper::enable ( void )

virtual

Enables the gripper.

Since the gripper has no position feedback its position is initially unknown. For this reason we try to retrieve the latest commanded position from a buffer file using retrieve_last_position(). If this fails the _backup_init_pos is used.

Returns: err_type_t::OK

Reimplemented in bioscara_hardware_drivers::Gripper.

◆ getPosition()

err_type_t bioscara_hardware_drivers::BaseGripper::getPosition ( float & width )

virtual

Gets the gripper width.

Note: Since the PWM servo has no position feedback, the latest position command is returned.

Parameters

width width in m.

Returns: err_type_t::OK

◆ init()

err_type_t bioscara_hardware_drivers::BaseGripper::init ( void )

virtual

Initializes the gripper.

Returns: err_type_t::OK

◆ retrieve_last_position()

err_type_t bioscara_hardware_drivers::BaseGripper::retrieve_last_position ( float & pos )

protected

Retrieves the stored position from the buffer file.

Parameters

pos	position value that is retrieved

Returns: err_type_t::OK on success, err_type_t::ERROR if parsing buffer file fails.

◆ save_last_position()

err_type_t bioscara_hardware_drivers::BaseGripper::save_last_position ( float pos )

protected

Stores the latest position to the buffer file.

Parameters

pos	position value to store

Returns: err_type_t::OK on success, err_type_t::ERROR if writing buffer file fails.

◆ setOffset()

void bioscara_hardware_drivers::BaseGripper::setOffset ( float offset )

virtual

Manually set offset.

◆ setPosition()

err_type_t bioscara_hardware_drivers::BaseGripper::setPosition ( float width )

virtual

Sets the gripper width in m.

Arguments outside the allowed range are bounded to _min and _max.

Parameters

width width in m.

Returns: err_type_t::OK

Reimplemented in bioscara_hardware_drivers::Gripper.

◆ setReduction()

void bioscara_hardware_drivers::BaseGripper::setReduction ( float reduction )

virtual

Manually set reduction.

Parameters

reduction

Member Data Documentation

◆ _backup_init_pos

float bioscara_hardware_drivers::BaseGripper::_backup_init_pos = 0.0

protected

Initial position assumed if none can be retrieved from the buffer file.

◆ _max

float bioscara_hardware_drivers::BaseGripper::_max = 0

protected

gripper width upper limit

◆ _min

float bioscara_hardware_drivers::BaseGripper::_min = 0

protected

gripper width lower limit

◆ _new_cmd_time

std::chrono::_V2::system_clock::time_point bioscara_hardware_drivers::BaseGripper::_new_cmd_time = std::chrono::_V2::system_clock::time_point()

private

◆ _offset

float bioscara_hardware_drivers::BaseGripper::_offset = 0

protected

gripper width position offset

◆ _pos

float bioscara_hardware_drivers::BaseGripper::_pos = _backup_init_pos

protected

stored position

◆ _pos_get

float bioscara_hardware_drivers::BaseGripper::_pos_get = _pos

protected

reported position

◆ _reduction

float bioscara_hardware_drivers::BaseGripper::_reduction = 1

protected

gripper width to actuator reduction ratio

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

lib/ros2_ws/src/dalsa_bioscara_grippers/bioscara_gripper_hardware_driver/include/bioscara_gripper_hardware_driver/mBaseGripper.h
lib/ros2_ws/src/dalsa_bioscara_grippers/bioscara_gripper_hardware_driver/src/mBaseGripper.cpp

Public Member Functions

Protected Member Functions

Protected Attributes

Private Attributes

Detailed Description

Constructor & Destructor Documentation

◆ BaseGripper()

◆ ~BaseGripper()

Member Function Documentation

◆ deinit()

◆ disable()

◆ enable()

◆ getPosition()

◆ init()

◆ retrieve_last_position()

◆ save_last_position()

◆ setOffset()

◆ setPosition()

◆ setReduction()

Member Data Documentation

◆ _backup_init_pos

◆ _max

◆ _min

◆ _new_cmd_time

◆ _offset

◆ _pos

◆ _pos_get

◆ _reduction