pulse-api 1.8.2.dev20200821090917

Python API for Pulse Robotic Arm with useful utilities

Pulse Robot Python API

This folder contains Python wrapper for the Pulse Robot REST API. Tested with Python 3. Compatibility with Python 2 is not guaranteed but the underlying API (called pdhttp) supports Python 2.

• Pulse Robot Python API
  • Requirements
  • Installation
  • Software compatibility table
    • Getting started
      • Quickstart
      • API initialization
      • Motion control
      • Freedrive mode
      • Controlling accessories and signals
      • Controlling accessories and signals during trajectory execution
      • Tool API
      • Base API
      • Environment API
      • Exception handling
      • Versions API
      • Documentation and further information

Documentation and further information

Requirements

Python 3.5+

Installation

To install from the Python Package Index:

pip3 install pulse-api

or, for a specific version

pip3 install pulse-api==v1.v2.v3

Alternatively, to get the version from our repository, use the following command:

pip3 install pulse-api -i https://pip.rozum.com/simple

To install a specific version:

pip3 install pulse-api==v1.v2.v3 -i https://pip.rozum.com/simple where v1, v2, and v3 (e.g., pulse-api==1.4.3) are version numbers as listed below in the compatibility table.

Note: To install the underlying API (pdhttp), use: pip3 install pdhttp -i https://pip.rozum.com/simple

Software compatibility table

Changelog

Pulse Desk UI version	Python API version
1.4.3	1.4.3
1.4.4	1.4.4
1.5.0, 1.5.1, 1.5.2	1.5.0
1.6.0	1.6.0
1.7.0	1.7.0, 1.7.1
1.8.0	1.8.0, 1.8.1

Getting started

Examples use the latest version of the library.

Quickstart

WARNING! Before launching this example, make sure that there are no facilities within 0.6 meters around the manipulator.

import math
from pulseapi import RobotPulse, pose, position, PulseApiException, MT_LINEAR

host = "http://127.0.0.1:8081"  # replace with a valid robot address
robot = RobotPulse(host)  # create an instance of the API wrapper class

# create motion targets
home_pose = pose([0, -90, 0, -90, -90, 0])
start_pose = pose([0, -90, 90, -90, -90, 0])
pose_targets = [
    pose([10, -90, 90, -90, -90, 0]),
    pose([10, -90, 0, -90, -90, 0]),
]
position_target = position([-0.42, -0.12, 0.35], [math.pi, 0, 0])
position_targets = [
    position([-0.37, -0.12, 0.35], [math.pi, 0, 0]),
    position([-0.42, -0.12, 0.35], [math.pi, 0, 0]),
    position([-0.42, -0.17, 0.35], [math.pi, 0, 0]),
    position([-0.37, -0.17, 0.35], [math.pi, 0, 0]),
]

# set the desired speed (controls both motor velocity and acceleration)
SPEED = 30
# set the desired motor velocity
VELOCITY = 40
# set the desired motor acceleration
ACCELERATION = 50
# set the desired tcp velocity
TCP_VELOCITY_1CM = 0.01
TCP_VELOCITY_10CM = 0.1

while True:
    try:
        robot.set_pose(home_pose, speed=SPEED)
        # checks every 0.1 s whether the motion is finished
        robot.await_stop()

        robot.set_pose(start_pose, velocity=VELOCITY, acceleration=ACCELERATION)
        robot.await_stop()

        robot.set_position(
            position_target, velocity=VELOCITY, acceleration=ACCELERATION
        )
        robot.await_stop()

        # command the robot to go through multiple position waypoints
        # (execute a trajectory)
        robot.run_positions(position_targets, SPEED)
        robot.await_stop()

        # set the linear motion type
        robot.run_positions(
            position_targets,
            velocity=VELOCITY,
            acceleration=ACCELERATION,
            motion_type=MT_LINEAR,
        )
        robot.await_stop()

        # limit the TCP velocity not to exceed 0.01 m/s (1 cm/s)
        robot.run_positions(
            position_targets,
            tcp_max_velocity=TCP_VELOCITY_1CM,
            motion_type=MT_LINEAR,
        )
        # checks every 0.5 s whether the motion is finished
        robot.await_stop(0.5)

        # limit the TCP velocity not to exceed 0.1 m/s (10 cm/s)
        robot.run_poses(pose_targets, tcp_max_velocity=TCP_VELOCITY_1CM)

    except PulseApiException as e:
        # handle possible errors
        print("Exception {} while calling robot at {} ".format(e, robot.host))
        break

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API initialization

from pulseapi import RobotPulse
# create an instance of the API wrapper class
host = "http://127.0.0.1:8081"  # replace with a valid robot address
robot = RobotPulse(host)

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Motion control

Possible motion targets:

• Positions (set_position, run_positions and get_position methods) - to control the location of the robot's TCP (tool center point). Use the position helper function to create a motion target.
• Poses (set_pose, run_poses and get_pose methods) - to control motor angles. Use the pose helper function to create a motion target.
• Jogging (jogging method) - enter the 'jogging' mode. If the robotic arm already in the 'jogging' mode, use this method to control the direction of the movement. Use jog helper function to create motion target. The motion target has six components ('x', 'y', 'z', 'rx', 'ry', 'rz'). Components are optional with default value equal to 0. Components control accelerations along the corresponding axis relative to the base coordinate system of the robotic arm. To disable the mode, pass jog motion target, where all components are zeros.

Possible motion types:

• Joint (MT_JOINT, default)
• Linear (MT_LINEAR)

Auxiliary methods:

• await_motion - periodically requests robot status (default: every 0.1 s) and waits until the robot finishes movements. Deprecated, use await_stop
• await_stop - periodically requests robot status (default: every 0.1 s) and waits until the robot finishes movements.
• status_motion - returns the actual state of the robotic arm: running (arm in motion), idle (arm not in motion), in the zero gravity mode, or in error state. Deprecated, use status
• status - returns the actual state of the robotic arm - whether it is initializing, or twisted, or running (in motion), or active (not in motion), or in the zero gravity mode, or failed (broken, failed initializing or in emergency).
• freeze - sets the arm in the "freeze" state. The arm stops moving, retaining its last position.
  Note: In the state, it is not advisable to move the arm by hand as this can cause damage to its components.
• relax - sets the arm in the "relaxed" state. The arm stops moving without retaining its last position. In this state, the user can move the robotic arm by hand (e.g., to verify/test a motion trajectory).
• pack - asking the arm to reach a compact pose for transportation.
• status_motors - returns the actual states of the six servo motors integrated into the joints of the robotic arm.
• stop - sets the arm in the Protection mode. The arm stops moving, retaining its last position and is disabled for command execution until recover is called.

WARNING! The following example is sample code. Before running, you must replace reference motion targets in the sample with the ones applicable to your specific case. Before launching this example, make sure that manipulator would not cause any damage to your facilities.

import math
import time
from pulseapi import position, pose, RobotPulse, MT_LINEAR, SystemState, jog

host = "http://127.0.0.1:8081"  # replace with a valid robot address
robot = RobotPulse(host)

# create motion targets
pose_target = pose([0, -90, 90, -90, -90, 0])
position_target = position([-0.42, -0.12, 0.35], [math.pi, 0, 0])
position_targets = [
    position([-0.37, -0.12, 0.35], [math.pi, 0, 0]),
    position([-0.42, -0.12, 0.35], [math.pi, 0, 0]),
    position([-0.42, -0.17, 0.35], [math.pi, 0, 0]),
    position([-0.37, -0.17, 0.35], [math.pi, 0, 0]),
]
SPEED = 30  # set the desired speed
TCP_VELOCITY_1CM = 0.01


# use the status command as shown below
def my_await_stop(robot_instance, asking_interval=0.1):
    status = robot_instance.status()
    while status.state == SystemState.MOTION:
        time.sleep(asking_interval)
        status = robot_instance.status()


robot.set_pose(pose_target, SPEED)
robot.await_stop()  # checks every 0.1 s whether the motion is finished
print("Current pose:\n{}".format(robot.get_pose()))

robot.set_position(position_target, SPEED)
robot.await_stop(0.5)  # checks every 0.5 s whether the motion is finished
print("Current position:\n{}".format(robot.get_position()))

# command the robot to go through multiple position waypoints
# (execute a trajectory)
robot.run_positions(position_targets, SPEED)
my_await_stop(robot)

# set the linear motion type
robot.run_positions(position_targets, SPEED, motion_type=MT_LINEAR)
robot.await_stop()

# limit the TCP velocity not to exceed 0.01 m/s (1 cm/s)
robot.run_positions(
    position_targets, tcp_max_velocity=TCP_VELOCITY_1CM, motion_type=MT_LINEAR
)
robot.await_stop()

# stop the arm in the last position
robot.freeze()

# get status from motors
print(robot.status_motors())

# jogging example
# command the robot to execute preparatory motion targets
robot.set_pose(pose([0, -90, 0, -90, -90, 0]), SPEED)
robot.set_position(position([-0.45, -0, 0.33], [math.pi, 0, 0]), SPEED)
robot.await_stop()
# start the jogging mode and execute motion targets
robot.jogging(jog(x=-1, y=-1))
time.sleep(2)
robot.jogging(jog(x=1, y=1))
time.sleep(7)
robot.jogging(jog(rx=1, rz=-1))
time.sleep(5)
robot.jogging(jog(-0.1, -0.8, 0.1, 0, -1, 0.7))
time.sleep(5)
# disable the jogging mode
robot.jogging(jog())

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Freedrive mode

Freedrive ("Zero-gravity") mode is intended to be used when there is a need to control the robotic arm directly "by-hand". With this functionality, for example, the user can develop an application that remembers user defined path. After mode activation, you can press and hold specific button that is described in user manual and move the robotic arm "by-hand".

from pulseapi import RobotPulse

host = "http://127.0.0.1:8081"  # replace with a valid robot address
robot = RobotPulse(host)

# enter freedrive mode
robot.zg_on()

# additional logic goes here

# disable freedrive mode
robot.zg_off()

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Controlling accessories and signals

Available methods:

• close_gripper, open_gripper with a preset timeout before executing further commands (default: 500 ms). Supported grippers: Schunk and OnRobot.
• disable_gripper and enable_gripper. Use this methods to disable (enable) power supply on wrist for gripper so that you can safely unplug and change gripper without powering off the robotic arm
• set_digital_output_high set_digital_output_low, get_digital_output - to work with output ports on the controlbox.
• get_digital_input to work with input ports on the controlbox.
• bind_stop binds stop command to high or low input signal on a specific port.

Signals:

• SIG_LOW - port is inactive
• SIG_HIGH - port is active

from pulseapi import RobotPulse, SIG_LOW, SIG_HIGH

host = "http://127.0.0.1:8081"  # replace with a valid robot address
robot = RobotPulse(host)

# ask the robot to close the gripper and continue execution of
# commands after 500 ms
robot.close_gripper()

# ask the robot to open the gripper and begin to execute further
# commands after 100 ms
robot.open_gripper(100)

# set the first output port to the active state
robot.set_digital_output_high(1)

# execute required operations when input port 3 is active
if robot.get_digital_input(3) == SIG_HIGH:
    print("Input port 3 is active")
# execute required operations when input port 1 is inactive
if robot.get_digital_input(1) == SIG_LOW:
    print("Input port 1 is inactive")

# execute stop() command if input singnal is HIGH on input port 4
robot.bind_stop(4, SIG_HIGH)

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Controlling accessories and signals during trajectory execution

Use output_action(), open_gripper_action(), close_gripper_action() functions combined with pose() and position() helper functions to control gripper/output signals during trajectory execution.

Note: actions are performed asynchronously.

from pulseapi import (
    RobotPulse, 
    SIG_LOW, 
    SIG_HIGH, 
    output_action, 
    position,
    open_gripper_action,
    close_gripper_action,
)

host = "http://127.0.0.1:8081"  # replace with a valid robot address
robot = RobotPulse(host)

# create motion targets with actions

# ask the robot to set output signal to SIG_LOW value on port 1
# when it reaches the specified pose
pose_target = pose([0, -90, 90, -90, -90, 0], [output_action(1, SIG_LOW)])

# ask the robot to set output signal to SIG_HIGH value on port 1
# when it reaches the specified position
position_target = position(
    [-0.42, -0.12, 0.35], [math.pi, 0, 0], [output_action(1, SIG_HIGH)]
)

position_targets = [
    # ask the robot to open gripper at the specified position
    position([-0.37, -0.12, 0.35], [math.pi, 0, 0], [close_gripper_action()]),
    position([-0.42, -0.12, 0.35], [math.pi, 0, 0]),
    position([-0.42, -0.17, 0.35], [math.pi, 0, 0]),
    # ask the robot to close gripper at the specified position and 
    # to set output signal to SIG_LOW value on port 1 at the specified position 
    position([-0.37, -0.17, 0.35], [math.pi, 0, 0], [
        open_gripper_action(),
        output_action(1, SIG_LOW),
    ]),
]
SPEED = 30  # set the desired speed

robot.set_pose(pose_target, SPEED)
robot.await_stop()

robot.set_position(position_target, SPEED)
robot.await_stop()

robot.run_positions(position_targets, SPEED)
robot.await_stop()

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Tool API

Use the Tool API methods when you need to calculate a robot motion trajectory with regard to the used tool and to take the tool into account when the robot calculates collisions.

Available methods:

• change_tool_info - set tool info for trajectory calculations.
• change_tool_shape - set tool shape for collision validation.
• get_tool_info, get_tool_shape - receive information about current tool settings.

Helper functions:

• tool_info - creates a tool info instance to be passed into change_tool_info method.
• tool_shape - creates a tool shape instance to be passed into change_tool_shape method.

from pulseapi import RobotPulse, position, Point
from pulseapi import create_simple_capsule_obstacle, tool_shape, tool_info

host = "http://127.0.0.1:8081"  # replace with a valid robot address
robot = RobotPulse(host)

# get info about the current tool
current_tool_info = robot.get_tool_info()
current_tool_shape = robot.get_tool_shape()
print("Current tool info\n{}".format(current_tool_info))
print("Current tool shape\n{}".format(current_tool_shape))

# create new tool properties
new_tool_info = tool_info(position([0, 0, 0.07], [0, 0, 0]), name="CupHolder")
new_tool_shape = tool_shape(
    [create_simple_capsule_obstacle(0.03, Point(0, 0, 0), Point(0, 0, 0.07))]
)

# change tool properties
robot.change_tool_info(new_tool_info)
robot.change_tool_shape(new_tool_shape)
print("New tool info\n{}".format(robot.get_tool_info()))
print("New tool shape\n{}".format(robot.get_tool_shape()))

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Base API

Use the Base API methods when you need to calculate a robot motion trajectory relative to a specific point in space.

Available methods:

• change_base
• get_base

from pulseapi import RobotPulse, position

host = "http://127.0.0.1:8081"  # replace with a valid robot address
robot = RobotPulse(host)

current_base = robot.get_base()
print("Current base\n{}".format(current_base))

# move the new base point along x and y axes
new_base = position([0.05, 0.05, 0], [0, 0, 0])
robot.change_base(new_base)

print("New base\n{}".format(robot.get_base()))

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Environment API

Use the Environment API to add virtual obstacles to be taken into account when calculating collisions.

Available methods:

• add_to_environment - adds an obstacle to an environment. Use the helper functions below to describe obstacles.
• get_all_from_environment - returns all obstacles from an environment.
• get_from_environment_by_name - returns an obstacle with a specific name from an environment.
• remove_all_from_environment - removes all obstacles from an environment.
• remove_from_environment_by_name - removes an obstacle with a specific name from an environment.

Helper functions:

• create_box_obstacle
• create_capsule_obstacle
• create_plane_obstacle

from pulseapi import RobotPulse, Point, position
from pulseapi import (
    create_plane_obstacle,
    create_box_obstacle,
    create_capsule_obstacle,
)

host = "http://127.0.0.1:8081"  # replace with a valid robot address
robot = RobotPulse(host)

print("Current environment\n{}".format(robot.get_all_from_environment()))
# add obstacles to the environment for calculating collisions
box = create_box_obstacle(
    Point(0.1, 0.1, 0.1), position((1, 1, 1), (0, 0, 0)), "example_box"
)
capsule = create_capsule_obstacle(
    0.1, Point(0.5, 0.5, 0.2), Point(0.5, 0.5, 0.5), "example_capsule"
)
plane = create_plane_obstacle(
    [Point(-0.5, 0.4, 0), Point(-0.5, 0, 0), Point(-0.5, 0, 0.1)],
    "example_plane",
)
robot.add_to_environment(box)
robot.add_to_environment(capsule)
robot.add_to_environment(plane)
print("New environment\n{}".format(robot.get_all_from_environment()))
print(
    "Get example box\n{}".format(robot.get_from_environment_by_name(box.name))
)
# remove specific obstacles
robot.remove_from_environment_by_name(box.name)
print("Environment without box\n{}".format(robot.get_all_from_environment()))
# remove all obstacles from an environment
robot.remove_all_from_environment()
print("Empty environment\n{}".format(robot.get_all_from_environment()))

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Exception handling

For information about errors, see the API reference. The client wraps errors from the robot into PulseApiException.

Available methods:

• recover - the function recovers the arm after an emergency, setting its motion status to IDLE. Recovery is possible only after an emergency that is not fatal (corresponds to the ERROR status).
• status_failure - the method returns complete list of recent failures. Each list entry could contain failure message, type, level and datetime. This information could be used for error handling or incident investigation.

For example, we can trigger an API exception by sending pose into set_position method.

from pulseapi import RobotPulse, PulseApiException, pose, SystemState

host = "http://127.0.0.1:8081"  # replace with a valid robot address
robot = RobotPulse(host)

try:
    robot.set_position(pose([0, -90, 90, -90, -90, 0]), 10)
    robot.await_stop()
except PulseApiException as e:
    print("Exception {}while calling robot at {} ".format(e, robot.host))
    status = robot.status()
    failure = robot.status_failure()
    if status == SystemState.EMERGENCY:
        print("Robot in emergency. Error message: {}".format(failure))

If the robotic arm went into "EMERGENCY" state, you can attemt to "recover" the arm in order to continue operations execution:

from pulseapi import RobotPulse, PulseApiException, pose, SystemState

host = "http://127.0.0.1:8081"  # replace with a valid robot address
robot = RobotPulse(host)

recover_result = robot.recover()
print("Recover result: {}".format(recover_result))

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Versions API

Use the Version API methods to get information about the software and hardware versions. You may need to use the methods for contacting support specialists when you notice strange robot behaviour.

Available methods:

• hardware - returns the hardware versions for all motors, the USB-CAN dongle, safety board and wrist.
• software - returns the software version for all motors, the USB-CAN dongle, safety board and wrist.
• robot_software - returns the version of the robot control software.

from pulseapi import Versions

host = "http://127.0.0.1:8081"  # replace with a valid robot address
versions = Versions(host)

print(versions.hardware())
print(versions.software())
print(versions.robot_software())

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Documentation and further information

For further details, see the API reference guide.