velocity difference, cmd, acceleration and jerk
	modified:   objects/stretch_arm.yaml
	new file:   objects/vel_act_x.yaml
	new file:   objects/vel_cmd_x.yaml
	renamed:    objects/vel_init.yaml -> objects/vel_cmd_x.yaml~
	new file:   objects/vel_init_x.yaml
	new file:   objects/vel_init_y.yaml
	modified:   scripts/stretch_arm.py
	modified:   scripts/x_acceleration.py
	new file:   scripts/x_jerk.py
	modified:   scripts/x_velocity_difference.py
	modified:   scripts/y_acceleration.py
	new file:   scripts/y_jerk.py
	modified:   scripts/y_velocity_difference.py