56 lines
1.5 KiB
Python
56 lines
1.5 KiB
Python
import numpy as np
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import rbdl
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# Create a new model
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model = rbdl.Model()
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# Create a joint from joint type
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joint_rot_y = rbdl.Joint.fromJointType ("JointTypeRevoluteY")
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# Create a body for given mass, center of mass, and inertia at
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# the CoM
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body = rbdl.Body.fromMassComInertia (
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1.,
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np.array([0., 0.5, 0.]),
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np.eye(3) * 0.05)
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xtrans= rbdl.SpatialTransform()
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xtrans.r = np.array([0., 1., 0.])
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# You can print all types
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print (joint_rot_y)
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print (model)
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print (body)
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print (body.mInertia)
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print (xtrans)
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# Construct the model
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body_1 = model.AppendBody (rbdl.SpatialTransform(), joint_rot_y, body)
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body_2 = model.AppendBody (xtrans, joint_rot_y, body)
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body_3 = model.AppendBody (xtrans, joint_rot_y, body)
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# Create numpy arrays for the state
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q = np.zeros (model.q_size)
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qdot = np.zeros (model.qdot_size)
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qddot = np.zeros (model.qdot_size)
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tau = np.zeros (model.qdot_size)
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# Modify the state
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q[0] = 1.3
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q[1] = -0.5
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q[2] = 3.2
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# Transform coordinates from local to global coordinates
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point_local = np.array([1., 2., 3.])
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point_base = rbdl.CalcBodyToBaseCoordinates (model, q, body_3, point_local)
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point_local_2 = rbdl.CalcBaseToBodyCoordinates (model, q, body_3, point_base)
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# Perform forward dynamics and print the result
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rbdl.ForwardDynamics (model, q, qdot, tau, qddot)
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print ("qddot = " + str(qddot.transpose()))
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# Compute and print the jacobian (note: the output parameter
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# of the Jacobian G must have proper size!)
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G = np.zeros([3,model.qdot_size])
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rbdl.CalcPointJacobian (model, q, body_3, point_local, G)
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print ("G = \n" + str(G))
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