The present invention provides a rock movement sensor including an inertial measurement assembly, a control assembly responsive to said inertial measurement assembly and a communication assembly coupled to the control assembly. The control assembly is arranged to determine a displacement associated with a blast or drop based on signals from the inertial measurement assembly. The communication assembly is preferably a wireless communication assembly. A surface unit corresponding to the rock movement sensor is provided which includes a processor programmed to operate a communications assembly to receive displacement data from the rock movement sensor. Consequently, the movement of an ore body due to a blast may be determined by locating a number of the rock movement sensors at known locations about the ore body prior to the blast and subsequently retrieving data values indicating a displacement relative to the known locations from the rock movement sensor post blast.

The present invention provides a rock movement sensor including an inertial measurement assembly, a control assembly responsive to said inertial measurement assembly and a communication assembly coupled to the control assembly. The control assembly is arranged to determine a displacement associated with a blast or drop based on signals from the inertial measurement assembly. The communication assembly is preferably a wireless communication assembly. A surface unit corresponding to the rock movement sensor is provided which includes a processor programmed to operate a communications assembly to receive displacement data from the rock movement sensor. Consequently, the movement of an ore body due to a blast may be determined by locating a number of the rock movement sensors at known locations about the ore body prior to the blast and subsequently retrieving data values indicating a displacement relative to the known locations from the rock movement sensor post blast.

Printed circuit boards (PCBs) are configured with an athermalized mounting suitable for securing and positioning and the PCBs within an inertial measurement unit (IMU). The PCBs include integrated circuit (IC) components, such as accelerometers and/or gyroscopes, which require relative positional stability within the IMU environment in order to provide accurate results. The athermalized mounting configuration of the PCB enables the PCBs to experience thermal expansion within the IMU without causing significant displacement of the IC relative to the IMU environment.

Printed circuit boards (PCBs) are configured with an athermalized mounting suitable for securing and positioning and the PCBs within an inertial measurement unit (IMU). The PCBs include integrated circuit (IC) components, such as accelerometers and/or gyroscopes, which require relative positional stability within the IMU environment in order to provide accurate results. The athermalized mounting configuration of the PCB enables the PCBs to experience thermal expansion within the IMU without causing significant displacement of the IC relative to the IMU environment.

Systems and methods for detecting touch events with an accelerometer are disclosed. In one aspect, a method includes measuring first accelerometer data at a first rate, detecting a first touch event based on the first accelerometer data, in response to detecting the first touch event, measuring second accelerometer data at a second rate, determining whether a second touch event is detected based on the second accelerometer data, measuring third accelerometer data at the first rate in response to an absence of the second touch event being detecting in the second accelerometer data over a predetermined threshold period of time.

An acceleration measuring device is disclosed, for use as a gravimeter or gradiometer for example. The device has a support and a proof mass, connected to each other by at flexures allowing displacement of the proof mass relative to the support. The support defines a space for displacement of the proof mass. The device is configured so that the modulus of the gradient of the force-displacement curve of the proof mass decreases with increasing displacement, for at least part of the force-displacement curve. This is the so-called anti-spring effect. The resonant frequency of oscillation of the proof mass is determined at least in part by the orientation of the device relative to the direction of the force due to gravity. The proof mass is capable of oscillating with a resonant frequency of 10 Hz or less. The proof mass has a mass of less than 1 gram.

An acceleration measuring device is disclosed, for use as a gravimeter or gradiometer for example. The device has a support and a proof mass, connected to each other by at flexures allowing displacement of the proof mass relative to the support. The support defines a space for displacement of the proof mass. The device is configured so that the modulus of the gradient of the force-displacement curve of the proof mass decreases with increasing displacement, for at least part of the force-displacement curve. This is the so-called anti-spring effect. The resonant frequency of oscillation of the proof mass is determined at least in part by the orientation of the device relative to the direction of the force due to gravity. The proof mass is capable of oscillating with a resonant frequency of 10 Hz or less. The proof mass has a mass of less than 1 gram.

This disclosure relates to heading misalignment estimation with a portable device and more specifically to estimating misalignment between a portable device having a sensor assembly and a platform transporting the portable device when the platform is undergoing motion having periodic characteristics. In one aspect, a suitable method includes obtaining inertial sensor data for the portable device and determining an effective frequency characteristic of the inertial sensor data representing the motion having periodic characteristics. The inertial sensor data may be processed using the determined frequency characteristic so that a heading misalignment may be estimated between the heading of the portable device and the platform.

A thermal stabilization system stabilizes inertial measurement unit (IMU) performance by reducing or slowing operating variations over time of the internal temperature. More specifically, a thermoelectric heating/cooling device operates according to the Peltier effect, and uses thermal insulation and a mechanical assembly to thermally and mechanically couple the IMU to the thermoelectric device. The thermal stabilization system may minimize stress on the IMU and use a control system to stabilize internal IMU temperatures by judiciously and bidirectionally powering the thermoelectric heating/cooling device. The thermal stabilization system also may use compensation algorithms to reduce or counter residual IMU output errors from a variety of causes such as thermal gradients and imperfect colocation of the IMU temperature sensor with inertial sensors.

A thermal stabilization system stabilizes inertial measurement unit (IMU) performance by reducing or slowing operating variations over time of the internal temperature. More specifically, a thermoelectric heating/cooling device operates according to the Peltier effect, and uses thermal insulation and a mechanical assembly to thermally and mechanically couple the IMU to the thermoelectric device. The thermal stabilization system may minimize stress on the IMU and use a control system to stabilize internal IMU temperatures by judiciously and bidirectionally powering the thermoelectric heating/cooling device. The thermal stabilization system also may use compensation algorithms to reduce or counter residual IMU output errors from a variety of causes such as thermal gradients and imperfect colocation of the IMU temperature sensor with inertial sensors.