System for producing electrical energy including at least one first generator assembly (EGa) comprising: - at least one first piezoelectric generator (Ga) suitable for generating electrical energy in response to a mechanical force applied to said first generator, - a first actuator (Aa) suitable for applying a mechanical force to the first generator (Ga) when said first actuator (Aa) is actuated, - a first rotary cam (Ca) having a cam surface (Sca), - a first follower (MSa) of the cam surface (SCa), - a first lever (La) connected to the first follower (MSa), which first lever is mounted as a lever-arm and interacts with the first actuator (Aa) in order to actuate it when the first cam (Ca) is driven to rotate and the cam surface (SCa) exerts a mechanical force on the first follower (MSa), characterized in that the system includes at least one second generator assembly (EGb) comprising: - at least one second piezoelectric generator (Gb) suitable for generating electrical energy in response to a mechanical force applied to said second generator, - a second actuator (Ab) suitable for applying a mechanical force to the second generator (EGb) when said second actuator is actuated, - a second rotary cam (Cb) having a cam surface (SCb), - a second follower (MSb) of the cam surface (SCb), - a second lever (Lb) connected to the second follower (MSb), which second lever is mounted as a lever-arm and interacts with the second actuator (Ab) in order to actuate it when the second cam (Cb) is driven to rotate and the cam surface (SCb) exerts a mechanical force on the second follower (MSb), and in that a rotary wheel is driven to rotate by a power source, which rotary wheel is coupled to the first cam (Ca) and to the second cam (Cb) so that the rotation of said rotary wheel at a rotation speed (W R) drives said cams to rotate at another rotation speed (W Ca, W Cb) that is higher than that of said rotary wheel. - at least one first piezoelectric generator (Ga) suitable for generating electrical energy in response to a mechanical force applied to said first generator, - a first actuator (Aa) suitable for applying a mechanical force to the first generator (Ga) when said first actuator (Aa) is actuated, - a first rotary cam (Ca) having a cam surface (Sca), - a first follower (MSa) of the cam surface (SCa), - a first lever (La) connected to the first follower (MSa), which first lever is mounted as a lever-arm and interacts with the first actuator (Aa) in order to actuate it when the first cam (Ca) is driven to rotate and the cam surface (SCa) exerts a mechanical force on the first follower (MSa), - at least one second piezoelectric generator (Gb) suitable for generating electrical energy in response to a mechanical force applied to said second generator, - a second actuator (Ab) suitable for applying a mechanical force to the second generator (EGb) when said second actuator is actuated, - a second rotary cam (Cb) having a cam surface (SCb), - a second follower (MSb) of the cam surface (SCb), - a second lever (Lb) connected to the second follower (MSb), which second lever is mounted as a lever-arm and interacts with the second actuator (Ab) in order to actuate it when the second cam (Cb) is driven to rotate and the cam surface (SCb) exerts a mechanical force on the second follower (MSb), and in that a rotary wheel is driven to rotate by a power source, which rotary wheel is coupled to the first cam (Ca) and to the second cam (Cb) so that the rotation of said rotary wheel at a rotation speed (W R) drives said cams to rotate at another rotation speed (W Ca, W Cb) that is higher than that of said rotary wheel.