$a_1, a_2, a_4$	Distance between centroid of the upper arm, forearm and the palm to its corresponding proximal joint (m)
$a_3, a_5$	Position from the attached mass to the fixed joint of “absorber 1” and “absorber 2” (m)
$B_{beam}, B_0$	Base of absorber’s cantilevered beam and the attached mass (m)
$C$	Damping coefficient matrix of the system (Nms/rd)
$C_{load}, C_{reliab}, C_{size}, C_{surf},C_{temp}$	Load, reliability, size, surface and temperature correction factors
$c_a, c_1, c_2,c_3, c_4$	Bending damping coefficient of absorber’s beam and shoulder, elbow, biceps brachii and wrist muscles (Nms/rd)
$c_{a_{1x}}, c_{a_{2x}}$	Linear damping coefficients of “absorber 1” and “absorber 2” (Ns/m)
DBS	Deep brain stimulation
DOF	Degree of freedom
DVA	Dynamic vibration absorber
$E_{beam}$	Modulus of elasticity of absorber’s beam material (GPa)
$F_i, F_{c_i}$	Generalized conservative and frictional moments (Nm)
$F_1, F_2$	Input moment at shoulder and wrist joints (Nm)
$f$	Vector of bending moment functions (Nm)
$H_{beam}, H_0$	Height of absorber’s cantilevered beam and the attached mass (m)
$H(\omega )$	Complex transfer function (rd/Nm)
$I_{beam}$	Area moment of inertia of the beam (m4)
$I_1, I_2, I_4$	Mass moment of inertia of the upper arm, forearm and the palm (kgm2/rd)
$K$	Stiffness coefficient matric of the system (Nm/rd)
$k_a, k_1, k_2,k_3, k_4$	Bending damping coefficient of absorber’s beam and shoulder, elbow, biceps brachii and wrist muscles (Nm/rd)
$k_{a_{1x}}, k_{a_{2x}}$	Linear stiffness coefficients of “absorber 1” and “absorber 2” (N/m)
$k_f$	Fatigue stress concentration factor
$L_{beam}, L_0$	Length of absorber’s cantilevered beam and the attached mass (m)
$l_a, l_3$	Distance between absorber’s joint and controller device to the elbow joint (m)
$l_1, l_2, l_4$	Distance from the location of concentrated masses of the upper arm, forearm and the palm to its corresponding proximal joint (m)
$M$	Mass matrix of the system (kgm2/rd)
$m_{a_1}, m_{a_2}$	Effective proof mass of “absorber 1” and “absorber 2” (kg)
$m_0$	Mass attached to absorber’s beam (kg)
$m_1, m_2,m_3, m_4$	Masses of the upper arm, forearm, controller device and the palm (kg)
$M_a$	Total mass of the absorber (kg)
$N_f, N_y$	Fatigue and yielding safety factors
PD	Parkinson’s disease
$q_i, {\dot{q}}_i$	Generalized coordinates of angular displacement and velocity (rd) and (rd/s)
$R$	Raleigh dissipation function (J)
$S_e, S_e^{\prime }$	Corrected and uncorrected endurance limit of the absorber’s beam (MPa)
$S_{ut}, S_y$	Ultimate and yielding strength of absorber’s beam (MPa)
$s$	Proportional constant relating stiffness and damping coefficients
$T, U$	Kinetic and potential energy of the system (J)
${ℳ}_a$	Bending reaction moment on absorber’s beam (Nm)
${\alpha }_i$	Receptance transfer function (rd/Nm)
$\theta , \dot{\theta },\ddot{\theta }$	Angular displacement, velocity and acceleration functions (rd), (rd/s) and (rd/s2)
$\Theta$	Angular displacement magnitude (rd)
${\Theta }_{contreolled}, {\Theta }_{uncontreolled}$	Angular displacement magnitude of the controlled and uncontrolled systems (rd)
$\omega$	Driving frequency (rd/s)
${\omega }_a, {\omega }_{beam}$	Fundamental frequency of absorber’s system and its beam alone (rd/s)
${\omega }_{m_0}$	Natural frequency of the attached mass (rd)
${\omega }_n$	Natural frequency of the system (rd/s)
$\phi$	Phase angle of the response ($°$)
$\sigma$	Bending stress (MPa)
$\zeta$	Damping ratio
${\rho }_{beam}, {\rho }_0$	Density of the cantilevered beam of the absorber and the attached mass (kg/m3)