About the action of Jaco-reach

[yingchengyang]

I'm curious about the action of Jaco-reach (https://github.com/google-deepmind/dm_control/blob/main/dm_control/manipulation/reach.py). Whether the actions are directly related to the position of the robot and thus are not related to some attributes of the robot? For example, if I change the mass or damping of the robot (by changing env._physics.model.body_mass or env._physics.model.dof_damping), it seems that the environments are the same.

Thanks a lot!

[yuvaltassa]

You are probably not changing them enough or changing them and then they get overwritten. Changing the physical properties of the robot will definitely change the behaviour.

[yingchengyang]

Thanks a lot! I hope to create two reach environments with different masses. I directly change the variable env._physics.model.body_mass, but it seems that I do not successfully change its mass as the return after stepping one action is the same as below:

>>> from dm_control import manipulation
>>> import numpy as np
>>> env_a = manipulation.load('reach_duplo_vision', seed=0)
>>> env_b = manipulation.load('reach_duplo_vision', seed=0)
>>> env_b._physics.model.body_mass = 100.0 * env_b._physics.model.body_mass
>>> obs_a = env_a.reset()
>>> obs_b = env_b.reset()
>>> action_spec = env_a.action_spec()
>>> action = np.random.uniform(action_spec.minimum, action_spec.maximum, size=action_spec.shape)
>>> obs_a = env_a.step(action)
>>> obs_b = env_b.step(action)
>>> print(obs_a)

         [ 61,  92, 122],
         [ 61,  91, 122],
         [ 61,  91, 121]],

        [[ 30,  60,  90],
         [ 30,  60,  90],
         [ 30,  61,  91],
         ...,
         [ 61,  91, 122],
         [ 61,  91, 122],
         [ 60,  90, 121]],

        [[ 30,  60,  90],
         [ 30,  60,  90],
         [ 30,  61,  91],
         ...,
         [ 61,  91, 122],
         [ 61,  91, 121],
         [ 60,  90, 121]]]], dtype=uint8)), ('jaco_arm/joints_pos', array([[[ 0.99019207, -0.13971277],
        [ 0.32524643, -0.94562929],
        [-0.99679483,  0.08000038],
        [ 0.37522412,  0.92693412],
        [-0.97989668,  0.19950564],
        [-0.86523415,  0.501368  ]]])), ('jaco_arm/joints_torque', array([[-5.17356959e-02,  2.01732767e+00, -1.49492643e+00,
        -4.86451538e-01,  2.67781563e-02,  1.53640458e-03]])), ('jaco_arm/joints_vel', array([[ 0.14820925, -0.10040166, -0.21730423,-0.10535219, -0.11907987,
         0.11611988]])), ('jaco_arm/jaco_hand/joints_pos', array([[1.00143412, 1.01505313, 1.01504966]])), ('jaco_arm/jaco_hand/joints_vel', array([[-0.30883389,  0.31029122,  0.31021528]])), ('jaco_arm/jaco_hand/pinch_site_pos', array([[0.01938608, 0.00727906, 0.28493621]])), ('jaco_arm/jaco_hand/pinch_site_rmat', array([[ 4.02349688e-03,  9.99987751e-01,  2.88256540e-03,
         9.99991895e-01, -4.02305274e-03, -1.59858894e-04,
        -1.48260224e-04,  2.88318522e-03, -9.99995833e-01]]))]))
>>> print(obs_b)

         [ 61,  92, 122],
         [ 61,  91, 122],
         [ 61,  91, 121]],

        [[ 30,  60,  90],
         [ 30,  60,  90],
         [ 30,  61,  91],
         ...,
         [ 61,  91, 122],
         [ 61,  91, 122],
         [ 60,  90, 121]],

        [[ 30,  60,  90],
         [ 30,  60,  90],
         [ 30,  61,  91],
         ...,
         [ 61,  91, 122],
         [ 61,  91, 121],
         [ 60,  90, 121]]]], dtype=uint8)), ('jaco_arm/joints_pos', array([[[ 0.99019207, -0.13971277],
        [ 0.32524643, -0.94562929],
        [-0.99679483,  0.08000038],
        [ 0.37522412,  0.92693412],
        [-0.97989668,  0.19950564],
        [-0.86523415,  0.501368  ]]])), ('jaco_arm/joints_torque', array([[-5.17356959e-02,  2.01732767e+00, -1.49492643e+00,
        -4.86451538e-01,  2.67781563e-02,  1.53640458e-03]])), ('jaco_arm/joints_vel', array([[ 0.14820925, -0.10040166, -0.21730423,-0.10535219, -0.11907987,
         0.11611988]])), ('jaco_arm/jaco_hand/joints_pos', array([[1.00143412, 1.01505313, 1.01504966]])), ('jaco_arm/jaco_hand/joints_vel', array([[-0.30883389,  0.31029122,  0.31021528]])), ('jaco_arm/jaco_hand/pinch_site_pos', array([[0.01938608, 0.00727906, 0.28493621]])), ('jaco_arm/jaco_hand/pinch_site_rmat', array([[ 4.02349688e-03,  9.99987751e-01,  2.88256540e-03,
         9.99991895e-01, -4.02305274e-03, -1.59858894e-04,
        -1.48260224e-04,  2.88318522e-03, -9.99995833e-01]]))]))

So how can I change the mass of a reach robot to change its dynamic? Thanks a lot!