A sensor system includes an actuator, an accelerometer coupled with the actuator, a rigid member, a transducer, and one or more processors. The actuator generates motion. The accelerometer outputs an acceleration signal responsive to at least the motion of the actuator. The rigid member extends from a first end coupled with the accelerometer to a second end. The transducer is coupled with the second end of the rigid member. The transducer can be configured to couple with a load, and can output a force signal responsive to at least a portion of the motion of the actuator transmitted to the transducer via the rigid member. The one or more processors determine a mechanical impedance of the load based at least on the acceleration signal and the force signal.