Abstract: A chassis dynamometer includes at least one roll for engaging the driven wheel of a motor vehicle and a power supplying and/or absorbing unit ("PAU") coupled to the roll. Speed and force sensors are also coupled to the roll for providing signals representative of the roll speed and force supplied to or received from the roll, respectively. Vehicle inertia, road load and parasitic loss signals, representative of the vehicle inertia, the vehicle road load and dynamometer parasitic losses, respectively, are also provided. A processing unit, such as a computer, calculates a velocity error signal based on the above signals, representative of the difference between the desired and actual speed of the vehicle. The processing unit further generates a feed-forward signal in response to the speed and inertia signals, representative of at least a portion, and preferably one hundred percent, of the inertial force signal to be simulated by the PAU.

Abstract: A dynamometer for testing engine powered vehicles including an induction motor coupled directly to the vehicle engine or the driven wheels thereof. A computer in response to the engine or wheel speed and the torque applied to or received from the engine or wheels by the motor provides a desired torque signal to a motor power controller to similate the road load and/or vehicle inertial forces encountered by the vehicle during actual operation and to compensate for the parasitic losses of the dynamometer. The motor power controller in turn applies a d.c. voltage to the motor when the desired torque signal is negative to cause the motor to absorb power from the engine or driven wheels and applies an a.c. voltage to the motor when the desired torque signal is positive to cause the motor to supply power to the engine or driven wheels in accordance with the parasitic losses and the road load and/or inertial forces to be simulated by the induction motor.

Abstract: A chassis dynamometer apparatus and method for testing motor vehicles includes at least one roll for engaging the driven wheels of the vehicle. A power supplying and/or absorbing unit such as an electric motor supplies and/or absorbs power from the roll. In addition, a force transducer and speed sensor are coupled to the roll for providing force and speed signals. Signals representative of the desired vehicle inertia, the road load to be simulated, the forces attributable to the parasitic losses and the out-of-loop inertia of the dynamometer and vehicle are also provided. A system controller in response to the above signals controls the power supplying and/or absorbing unit in accordance with: ##EQU1## where: Vd=the desired roll velocity;Fm=the measured force signal associated with the roll;PL=the dynamometer parasitic loss signal;RL=the road load signal;Io=The out-of-loop inertia of the dynamometer and vehicle;Ac=the roll acceleration signal;Iv=the vehicle inertia signal; anddt=the interval of integration.

Abstract: A dynamometer apparatus and a method for testing two and four wheel drive vehicles under simulated road conditions is described. The apparatus includes a front roll and a rear roll for engaging the front and rear wheels of the vehicle. A power supplying and/or absorbing unit such as an electric motor is coupled to each roll. In addition, a force transducer and speed sensor is coupled to each roll for providing signals representative of (a) the forces imported to or received by the rolls from the vehicle wheels minus the forces attributed to the parasitic losses of the rolls and (b) the speed of the rolls. Elements are also included for providing signals representative of the desired vehicle inertia and the forces attributable to the parasitic losses of the rolls. A system controller in response to the above signals controls the power supplying and/or absorbing units in accordance with: ##EQU1## where: V.sub.d =the desired velocity of the driven and driving rolls;F.sub.

Abstract: Individual switch actuators are formed by etching offset grooves in opposite sides of a thin metal plate. The groove on one side of the plate falls just within the groove on the other side of the plate. A web is formed between the adjacent groove walls which provides significant localized flexibility. A discrete contact pad is defined on the inside that is in the plane of the metal plate.

Abstract: A temperature achievement controller for controlling the temperature of a device which is heated by a heating unit in accordance with a predetermined temperature versus time schedule. The controller includes apparatus for producing an analog signal which corresponds to the achieved temperature of the device under test and apparatus for producing an analog signal which corresponds to the desired temperature versus time schedule. An error signal equal to the difference between the achieved and desired temperature is generated and coupled to a three mode control unit which produces a control signal proportional to the sum of the derivative of the error signal, the integral of the error signal and the error signal itself. The control signal is received by a duty cycle modulator which controls the ratio of power on time to power off time of the power applied to the heating unit in accordance with the magnitude of the control signal.