How to set position actuator to specific angle? #1788

leeygang · 2024-07-06T23:21:02Z

leeygang
Jul 6, 2024

I am trying to set the actuator to specific angle, but the rendered object keeps shaking, do I use the api correctly? Thanks in advanced.

the recorded screen:
https://github.com/google-deepmind/mujoco/assets/446412/9910a4c9-a1a9-49b6-add3-02b1cf4abfbb

xml file:

<mujoco>
	<worldbody>
		<geom type="plane" size="1 1 0.1" rgba=".9 0 0 1"/>
		<body pos="0 0 1.5" euler = "0 0 0">
			<joint name="pin" type="hinge" axis = "0 -1 0" pos="0 0 1"/>
			<geom type="cylinder" size="0.05 1" rgba="0 .9 0 1" mass="1"/>
		</body>
	</worldbody>
	<actuator>
		<position name="position_servo" joint="pin" kp="100" />
	</actuator>
</mujoco>

python code

model = mujoco.MjModel.from_xml_path("pendulum.xml")
data = mujoco.MjData(model)
paused = False

def key_callback(keycode):
  global paused
  if chr(keycode) == ' ':
    paused = True
    print('receive keycode: {}'.format(keycode))

def create_viewer(model, data):
    viewer = mujoco.viewer.launch_passive(model, data, key_callback=key_callback)
    return viewer

viewer = create_viewer(model, data)

target_angle = np.pi / 4  # 45 degrees

def move_position_actuator_to_angle(data, actuator_name, target_angle):
    actuator_id = mujoco.mj_name2id(model, mujoco.mjtObj.mjOBJ_ACTUATOR, actuator_name)
    while not paused:
        data.ctrl[actuator_id] = target_angle
        mujoco.mj_step(model, data)
        viewer.sync()

move_position_actuator_to_angle(data, "position_servo", target_angle)

yuvaltassa · 2024-07-07T08:47:09Z

yuvaltassa
Jul 7, 2024
Maintainer

you need to add damping with kv

1 reply

leeygang Jul 7, 2024
Author

thank you @yuvaltassa, it works!

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How to set position actuator to specific angle? #1788

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yuvaltassa Jul 7, 2024 Maintainer

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leeygang Jul 7, 2024 Author

leeygang
Jul 6, 2024

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yuvaltassa
Jul 7, 2024
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leeygang Jul 7, 2024
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