Keeping a block in a certain height #2202
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MuJoCo: 3.2.2 Hi, I am trying to lift a block to a certain height and try to make it float on that height by applying external force F = W = mg, but when I try to apply that, the block's height keeps increasing, instead of remaining constant minimal XML<mujoco model="block scene">
<asset>
<texture type="2d" name="groundplane" builtin="checker" mark="edge" rgb1="0.2 0.3 0.4" rgb2="0.1 0.2 0.3"
markrgb="0.8 0.8 0.8" width="300" height="300"/>
<material name="groundplane" texture="groundplane" texuniform="true" texrepeat="5 5" reflectance="0" rgba="1 1 1 0.7"/>
</asset>
<worldbody>
<light pos="0 0 1.5" dir="0 0 -1" directional="true"/>
<camera name="fixed" pos="0 0 0" xyaxes="1 0 0 0 0 1"/>
<geom name="floor" size="0 0 0.05" type="plane" material="groundplane" solimp="0.995 0.999 0.0000001 0.5 2"/>
<body name="block_0" pos="0 0 .03">
<joint name="block_joint" type="free" damping="0"></joint>
<inertial pos="0 0 0" mass="0.1" diaginertia="0.001 0.001 0.001" />
<geom name="blue_subbox" size="0.030 0.03 0.03" pos="0 0 0" type="box" rgba="0.3 0.5 0.8 1"
solimp="0.99 0.995 0.0000001 0.5 2" solref="0.005 2" friction="5 0.3 0.001" />
</body>
</worldbody>
<sensor>
<framepos name= "block_pos" objtype = "body" objname="block_0" />
</sensor>
</mujoco>
</details>
Code:
model = mujoco.MjModel.from_xml_string(xml_string)
data = mujoco.MjData(model)
mujoco.mj_resetData(model, data)
#viewer = mujoco.viewer.launch_passive(model, data)
n_frames = 1000
height = 240
width = 320
frames = []
times = []
heights = []
fps = 60.0
with mujoco.Renderer(model, height, width) as renderer:
for i in range(n_frames):
while data.time < i/fps:
block_mass = model.body('block_0').mass[0]
gravity = -model.opt.gravity[2]
mg = block_mass * gravity
block_pos = data.sensor('block_pos').data.copy()
block_height = block_pos[2]
block_body_id = model.body('block_0').id
print(f"Block height: {block_height}")
if block_height < 0.7:
data.xfrc_applied[block_body_id] = [0, 0, mg + 0.01, 0, 0, 0]
else:
data.xfrc_applied[block_body_id] = [0, 0, mg, 0, 0, 0]
mujoco.mj_step(model, data)
times.append(data.time)
heights.append(block_height)
renderer.update_scene(data, "fixed")
frame = renderer.render()
frames.append(frame)
plt.plot(times, heights)
plt.xlabel('Time (s)')
plt.ylabel('Block Height (m)')
plt.title('Block Height vs Time')
plt.grid(True)
plt.savefig("block_height_vs_time.png")
print("Plot saved as 'block_height_vs_time.png'.")
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Answered by
yuvaltassa
Nov 4, 2024
Replies: 1 comment
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This is due to Newton's Second Law of motion. You are accelerating the body and then not accelerating any more, so it keeps moving. Also, read about |
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Answer selected by
adawne
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This is due to Newton's Second Law of motion. You are accelerating the body and then not accelerating any more, so it keeps moving.
Also, read about
<body gravcomp>