An electro-hydraulic circuit comprising: (a) a first actuator and a second actuator, said first actuator and said second actuator each being freely movable if acted upon by an external force; (b) a first sensor system and a second sensor system, said first and second sensor systems being associated, respectively, with the first and second actuators; (c) a first hydraulic valve system and a second hydraulic valve system, said first and second hydraulic valve systems being associated, respectively, with the first and second actuators; and (d) a central control unit in two-way electronic communication with the first actuator and with the second actuator; wherein: (e) each sensor system is adapted to gather data relating to movements of its associated actuator, and to transmit corresponding electronic data to the central control unit; (f) each valve system is adapted to initiate movements of its associated actuator, in accordance with control signals received from the central control unit; and (g) the central control unit is adapted: (g.1) to generate and send control signals to the first valve system in response to which the first actuator will mimic, in close to real time, movements of the second actuator in response to an external force applied to the second actuator; and (g.2) simultaneously with the generation and sending of control signals to the first valve system, to generate and send control signals to the second valve system in response to which the second actuator will mimic, in close to real time, movements of the first actuator in response to an external force applied to the first actuator; such that the movements of each actuator will be synchronized with and in proportionate correspondence to the movements of the other actuator. (a) a first actuator and a second actuator, said first actuator and said second actuator each being freely movable if acted upon by an external force; (b) a first sensor system and a second sensor system, said first and second sensor systems being associated, respectively, with the first and second actuators; (c) a first hydraulic valve system and a second hydraulic valve system, said first and second hydraulic valve systems being associated, respectively, with the first and second actuators; and (d) a central control unit in two-way electronic communication with the first actuator and with the second actuator; (e) each sensor system is adapted to gather data relating to movements of its associated actuator, and to transmit corresponding electronic data to the central control unit; (f) each valve system is adapted to initiate movements of its associated actuator, in accordance with control signals received from the central control unit; and (g) the central control unit is adapted: (g.1) to generate and send control signals to the first valve system in response to which the first actuator will mimic, in close to real time, movements of the second actuator in response to an external force applied to the second actuator; and (g.2) simultaneously with the generation and sending of control signals to the first valve system, to generate and send control signals to the second valve system in response to which the second actuator will mimic, in close to real time, movements of the first actuator in response to an external force applied to the first actuator; such that the movements of each actuator will be synchronized with and in proportionate correspondence to the movements of the other actuator. (g.1) to generate and send control signals to the first valve system in response to which the first actuator will mimic, in close to real time, movements of the second actuator in response to an external force applied to the second actuator; and (g.2) simultaneously with the generation and sending of control signals to the first valve system, to generate and send control signals to the second valve system in response to which the second actuator will mimic, in close to real time, movements of the first actuator in response to an external force applied to the first actuator;